Y2B4 - Central Nervous System 📙 > Anatomy🫀 > Flashcards

Anatomy🫀 Flashcards

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1
Q

Length of spinal cord

A
  • 45 cm in the adult male
  • 42 cm in the adult female.
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2
Q

Location of spinal cord

A

in the upper two-thirds of the vertebral canal.

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3
Q

beginning of spinal cord

A

as the continuation of the medulla oblongata just below the foramen magnum.

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4
Q

Ending of spinal cord

A
  • The lower end of the cord is called the conus medullaris. It ends at:

1. Intrauterine life: Fills the whole vertebral canal.

2. In the new born: At the level of L3.

3. In the adult: At the level of the lower border of the L1.

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5
Q

Enlargments of spinal cord

A

Cervical enlargement: (C5-T1) in the cervical region & gives origin to brachial plexus.

Lumbar enlargement: (L1-S2) in the lumbar region & gives origin to lumbosacral plexus.

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6
Q

what is cauda equina?

A

individual spinal nerves within spinal cord

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7
Q

What are the layers of spinal meninges?

A
  • The dura matter
  • The arachnoid matter
  • The pia matter
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8
Q

Description of The dura mater

A

the outer layer and ends at the level of the 2nd sacral vertebra (S2).

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9
Q

Discription of the arachnoid matter

A

the middle layer and ends at the level of the 2nd sacral vertebra.

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10
Q

Description of the pia matter

A
  • inner layer and forms two types of ligaments:
  1. Filum terminale
  2. 2 denticulate ligaments
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11
Q

Filum terminale

A

It extends from the conus medullaris to the back of the coccyx.

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12
Q

2 denticulate ligaments

A

They extend from the pia mater, pierce arachnoid mater to be attached to the dura mater.

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13
Q

what is Lumbar Cistern?

A

It is a part of the subarachnoid space.

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14
Q

Extension of Lumbar Cistern

A

It extends from L2 to S2.

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15
Q

Significance of Lumbar Cistern

A

It is used for lumbar puncture (injection of drugs, anasthesia and CSF sampling).

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16
Q

Contents of Lumbar Cistern

A
  1. The CSF
  2. Cauda equina: roots of lumbar and sacral nerves
  3. Filum terminal interna.
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17
Q

which artries supply the spinal cord?

A
  • Anterior Spinal Artery
  • Two Posterior Spinal Arteries
  • Radicular Arteries
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18
Q

where does Anterior Spinal Artery arise from? and what does it supply?

A
  • Is a single artery arises from the vertebral artery.
  • It supplies the anterior 2/3rds of the spinal cord.
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19
Q

where do the Two Posterior Spinal Arterie from? and what do they supply?

A
  • Each is a branch of the vertebral artery or usually from the posterior inferior cerebellar artery (PICA).
  • They supply the posterior 1/3 of the spinal cord.
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20
Q

what is the major source of blood to the lower two-thirds of the spinal cord?

A
  • They are the major source of blood to the lower two-thirds of the spinal cord. They are branches from:

a. In the neck: from the vertebral & ascending cervical arteries.

b. In the thorax: from the intercostal arteries.

c. In the abdomen: from the lumbar arteries.

d. In the pelvis: from the lateral sacral arteries.

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21
Q

Venous drainage of the spinal cord

A

The veins correspond to the arteries and drain into the internal vertebral venous plexus in the epidural space.

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22
Q

How many spinal cord segments are there?

A
  • The spinal cord has 31 segments corresponding to the number of the spinal nerves:

8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal segment.

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23
Q

Roots of each segment

A

Each segment has a pair of dorsal and ventral nerve roots.

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24
Q

what characterizes the first and last spinal nerves?

A

Each of them only has a dorsal (Sensory) root and no ventral root

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25
what happens to The dorsal and ventral roots at the **intervertebral foramen**?
The dorsal and ventral roots join at the intervertebral foramen forming the spinal nerve.
26
what divides the spinal cord into two halves anteriorly and posteriorly?
- The spinal cord is divided into two halves by the anterior median fissure and posterior median septum, Each half is composed of an inner gray matter and outer white matter.
27
what is each half of the spinal cord composed of?
**Grey matter:** The grey matter is H-shaped contains the nerve cell bodies, It is formed of 3 horns on each side; ventral (motor), lateral (autonomic) and dorsal (sensory). **White matter:** Contains nerve fibres (tracts).
28
Definition of CSF
it is the fluid that fills the ventricles of the brain and the subarachnoid space.
29
Volume of CSF
about 130 ml mainly in the subarachnoid space: 1. 30 ml in the ventricles 2. 100 ml in the subarachnoid space.
30
Formation of CSF
- Choroid plexus: is the main source of the CSF (70%). It is produced mostly by the choroid plexus of the lateral ventricle. - Ependymal lining of the ventricles: add CSF to the ventricles. - Cells of the pia mater: add CSF to the subarachnoid space.
31
Circulation of CSF
1. It flows from the **lateral ventricles** to the **third ventricle** through the ***interventricular foramina of Monro***, then to the **fourth ventricle** through the ***aqueduct of Sylvius***. 2. It leaves the fourth ventricle to the **subarachnoid space** through the ***median foramen of Magendie*** and the **lateral foramina of Luschka**. 3. A small amount flows to the **central canal of the spinal cord.**
32
Absorbtion of CSF
Main site for drainage: arachnoid villi & granulations. They drain the CSF into the venous blood of the dural sinuses especially the superior sagittal sinus.
33
what are the functions of CSF?
➢ Reduces the brain weight 60 folds (from 1400 gm to 25 gm). ➢ Protects the brain and the spinal cord. ➢ Substitutes the lymphatic system in the CNS ➢ Maintains the chemical environment for the CNS ➢ Regulation of the intracranial pressure.
34
what are clinical conditions related to CSF?
Hydrocephalus
35
what is **Hydrocephalus**?
It is an abnormal increase in the volume of the CSF with dilatation of the ventricles and increase in size of the head.
36
what are the causes of **Hydrocephalus**?
**Obstruction to its circulation:** It is the commonest cause. **Overproduction of the CSF:** by choroid plexus tumor (rare). **Inadequate drainage of the CSF:** by thrombosis of the superior sagittal sinus.
37
Definition of ALS
neuromuscular condition involving destruction of anterior horn motor neurons
38
Symptoms of ALS
- loss of the ability to speak, swallow, and breathe
39
what are the parts of the brain stem?
- Medulla oblongata - Pons - Midbrain
40
what does the ventral surface of medulla oblongata show?
- 3 Elevations - 3 Fissures (sulci) - Exit of the lower 4 cranial nerves
41
Elevations on the ventral surface of medulla oblongata
**on each side of the midline.** - Pyramid: contains the pyramidal tract. - Olive: formed by the inferior olivary nucleus. - Inferior cerebellar peduncle (ICP): connects the medulla to the cerebellum.
42
Fissures on the ventral surface of medulla oblongata
- Anterior median fissure - Anterolateral (Pre-olivary) fissure - Posterolateral (Post-olivary) fissure
43
what does Infeior cerebellar peduncle connect?
connects the medulla to the cerebellum.
44
Site of Anterior median fissure
- In the midline. - Between the 2 pyramids.
45
what obliterates the lower part of Anterior median fissure?
Pyramidal decussation.
46
Site of **Anterolateral (Pre-olivary) fissure**
Between the pyramid and olive.
47
what nerves exit at **Anterolateral (Pre-olivary) fissure**?
Shows the exit of the XII (12) nerve.
48
Site of **Posterolateral (Post-Olivary) fissure**
Between the olive and ICP.
49
what nerves exit at **Posterolateral (Post-Olivary) fissure**?
Shows the exit of IX (9), X(10) and XI(11) cranial nerves.
50
Exit of the lower 4 cranial nerves
- **Glossopharyngeal, vagus & cranial accessory nerves:** exit at the post-olivary fissure. - **Hypoglossal nerve:** exit at the pre-olivary fissure.
51
what is the **Pons**?
- The middle part of brain stem
52
Extension of **Pons**
- Extends from Midbrain (Superiorly) to the medulla (Inferiorly)
53
what is the **Pons** divided into?
Ventral part (Basis pontis) and dorsal part (Tegmentum)
54
what does the ventral surface of the **pons** show?
- Basilar groove - Transverse pontine fibers - Exit of the middle 4 cranial nerves
55
what is the groove of **basilar artery**?
Basilar groove
56
what do **Transverse pontine fibers** form?
- they form the middle cerebellar peduncle (MCP) which connects the pons with the cerebellum.
57
Exit of the middle 4 cranial nerves
**Trigeminal:** exit at the lateral border between the upper and lower borders of pons by 2 roots; small medial motor & large lateral sensory. **Abducent nerve:** exit between the pyramid and pons. **Facial nerve:** exit at the cerebellopontine angle by 2 roots; large medial motor & small lateral sensory (nervous intermedius). **Vestibulocochlear nerve:** exit at the cerebellopontine angle lateral to the facial nerve.
58
what is the **Cerebellopontine angle**?
it is the angle between pons, medulla and cerebellum
59
what does the **Cerebellopontine angle** contain?
- 3 cranial nerves: VII (7), VIII (8) & IX (9). - Lateral recess of 4th ventricle & choroid plexus of 4th ventricle. - Flocculus of cerebellum. - AICA (anterior inferior cerebellar artery).
60
what is the **Midbrain**?
It is the upper part of brain stem.
61
Extension of **Midbrain**
Extends from the pons (inferiorly) to the diencephalon (superiorly).
62
what cavity does the **Midbrain** contain?
It contains a cavity called cerebral aqueduct of Sylvius which divides it into; ventral part (cerebral peduncle) and dorsal part (tectum).
63
what does the ventral surface of **Midbrain** show?
- 2 Cerebral peduncles - Interpeduncular fossa - Exit of oculomotor nerve
64
Divisions of **Cerebral peduncles**
**each is divided into:** - Crus cerebri - Substantia nigra - Tegmentum
65
what is **Crus cerebri**?
it is the anterior part.
66
what is **Substantia nigra**?
It is the middle pigmented part.
66
what charachterizes **Substantia nigra**?
- Contains melanin pigment, Secretes dopamine.
67
what is the **Tegmentum**?
it is the posterior part
68
what is the **Interpeduncular fossa**?
A Fossa in between the 2 cerebral peduncles.
69
Exit of cranial nerves at **midbrain**
**Exit of oculomotor nerve:** exit from the interpeduncular fossa medial to the crus cerebri.
70
parts of the dorsal part of the medulla oblongata
- Lower part (Closed medulla) - Upper part (Open medulla)
71
what does the lower part (Closed medulla) of medulla oblongata show?
**shows 3 elevations on each side of the midline:** - Gracile tubercle - Cuneate tubercle - Tuberculum cinereum
72
Where is **Gracile tubercle** located & what is it formed by?
- Located medially. - Formed by gracile nucleus.
73
Where is **Cuneate tubercle** located & what is it formed by?
- Intermediate. - Formed by cuneate nucleus.
74
Where is **Tuberculum cinereum** located & what is it formed by?
- Located laterally. - Formed by spinal nucleus of trigeminal nerve.
75
what does the upper part (Open medulla) of the medulla oblongata form?
forms the lower part of the floor of 4th ventricle.
76
what does the upper part (Open medulla) of the medulla oblongata show?
- Sulcus limitans (Inferior fovea), divides the area into: (Hypoglossal trigone - Vagal trigone - Vestibular trigone) - Area postrema (Obex) - Stria medullaris of 4th ventricle
77
Where is **Hypoglossal trigone** located & what is it formed by?
- Located medially. - Formed by hypoglossal nucleus.
78
Where is **Vagal trigone** located & what is it formed by?
- Intermediate. - Formed by dorsal motor nucleus of vagus nerve.
79
Where is **Vestibular trigone** located & what is it formed by?
- Located laterally. - Formed by the inferior and medial vestibular nuclei.
80
what is **Area postrema (Obex)**? and where is it located?
is a vomiting center located at the inferior angle of the 4th ventricle.
81
what is **Stria medullaris**?and where is it located?
at the upper end of medulla. They are arcuate-cerebellar fibers.
82
what does the dorsal surface of **Pons** form?
it forms the upper part of the floor of 4th ventricle
83
what does the dorsal surface of **Pons** show?
- Sulcus limitans (Superior fovea), divides the area into: (Medial eminence - Vestibular area) - Locus ceruleus
84
what does sulcus limitans (superior fovea) divide the dorsal surface of the pons into?
(Medial eminence - Vestibular area)
85
where is the **Medial eminence**?
Located medially.
86
what is the lower part of **Medial eminence** called? and what is it formed by?
lower part is called facial colliculus which is formed by abducent nucleus encircled by facial nerve fibers.
87
where is the **Vestibular area** located? and what is it formed by?
- Located laterally. - Formed by the superior and lateral vestibular nuclei.
88
What is **Locus cerules**?
is a pigmented area at the upper end of superior fovea. It is a noradrenaline secreting center.
89
what doe the dorsal surface of **Midbrain** show?
- 4 colliculi (2 superior & inferior) - Exit of trochlear nerve
90
what are **Colliculi**?
they are rounder elevations.
91
what are the **2 superior colliculi**? and what are they connected to?
- They are visual reflex centers. - Connected to the lateral geniculate body by superior brachium.
92
what are the **2 inferior colliculi**? and what are they connected to?
- They are auditory reflex centers and lower auditory centers. - Connected to the medial geniculate body by inferior brachium.
93
Exit of trochlear nerve
exit below the inferior colliculus
94
what does the lateral surface of **Midbrain** show?
- Superior brachium: connects the superior colliculus with the lateral geniculate body. - inferior brachium: connects the inferior colliculus with the medial geniculate body.
95
what does the lateral surface of **Midbrain** Related to?
**2 Nerves:** optic tract & trochlear nerve. **2 Arteries:** SCA (superior cerebellar artery) & PCA (posterior cerebral artery). **Vein:** basal vein.
96
what are lamina of rexed (Nuclei of the gray matter of the spinal cord)?
**Laminal I:** Posteromarginal nucleus (Pain and temperature). **Lamina II:** Substantia Gelatinosa of Rolandi (SGR) (Pain and temperature). **Laminae III and IV:** Nucleus proprious (Pain, temperature and touch). **Lamina VII:** Medially (Clark,s nucleus) & Laterally (spinal border cell): Unconscious proprioception.
97
what are the order neurons of the ascending pathways of spinal cord?
**1st order neurons:** Dorsal root ganglion or cranial nerve ganglion **2nd order neurons:** Spinal cord or brain stem **3rd order neurons:** Thalamus (Ventral posterior thalamic nucleus)
98
what are the ascending tracts in the spinal cord?
**Dorsal column tracts:** Gracile and cuneate tracts. **Lateral column tracts:** Spinocerebellar (Dorsal and ventral) and lateral spinothalamic tracts. **Ventral column tracts:** Ventral spinothalamic tract.
99
Dorsal column tracts
Gracile and cuneate tracts. **Sensitive to:** Vibration, Conscious proprioception & fine touch
100
Lateral column tracts
- Spinocerebellar (Dorsal and ventral) **Sensitive to:** UnConscious proprioception - Lateral spinothalamic tracts. **Sensitive to:** Pain & Temperature
101
Ventral column tracts
Ventral spinothalamic tract. **Sensitive to:** Simple touch and pressure
102
what are Dorsal column tracts (In details)?
- Gracile tract: carries fibers from below T6. - Cuneate tract: carries fibers from above T6.
103
First order neuron in dorsal column tracts
**Dorsal Root Ganglia** - **Peripheral** processes of **pseudo-unipolar** neurons of dorsal root ganglia end in **receptors.** - **Central** processes **enter spinal cord & form gracile or cuneate tract**, which **ascend in ipsilateral dorsal funiculus** to reach **medulla**. They end in **Gracile or cuneate nuclei,** respectively.
104
which is medial, gracile or cuneate tracts?
Gracile tract is medial to cuneate tract.
105
2nd order neuron in dorsal column tracts
**Gracile & Cuneate Nuclei** - **Axons of gracile & cuneate** nuclei cross to **opposite side** and form **medial lemniscus**. - Medial lemniscus **ascends in brainstem** to end in ventral posterior lateral nucleus of thalamus **(VPLNT).**
106
3rd order neuron in dorsal column tracts
**VPLNT** - **Axons of ventral posterior lateral nucleus of thalamus** pass through **internal capsule to end in upper 2/3 of general sensory area of cerebral cortex (area 3,1,2) in postcentral gyrus**.
107
what are the functions of dorsal column tracts?
1. Conscious proprioception: sense of movement and sense of position. 2. Fine touch. 3. Sense of vibration.
108
what does a lesion in **Gracile & Cuneate tract** cause?
Loss of Conscious proprioception, discriminative touch & sense of vibration in same side of body below level of lesion.
109
what does a lesion in **Medial lemniscus** cause?
Loss of Conscious proprioception, discriminative touch & sense of vibration on opposite side of body below level of lesion.
110
what are the receptors of Lateral spinothalamic tract?
Free nerve endings
111
First order neuron in lateral spinothalamic tract
**Dorsal root ganglia** - **Peripheral** processes of DRG neurons end in **receptors.** - **Central** processes **enter spinal cord & ascend for 1 or 2 segments forming Lissauer's tract**, which **synapses** in **posteromarginal nucleus (lamina I), substantia gelatinosa (lamina II) & nucleus proprius (laminae III & IV).**
112
second order neuron in lateral spinothalamic tract
**Lamina I to IV** - **Axons of neurons in posteromarginal nucleus & nucleus proprius cross** to opposite side in anterior gray & white commissure forming **lateral spinothalamic tract**, which ascends in spinal cord & brainstem to end in ventral posterior lateral nucleus of thalamus **(VPLNT).**
113
Third order neuron in lateral spinothalamic tract
**VPLNT** - **Axons of VPLNT** pass **posterior 1/2 of posterior limb of internal capsule** to reach **upper 2/3 of general sensory area in postcentral gyrus**
114
Functions of lateral spinothalamic tract
It carries pain and temperature sensations
115
what does a lesion in **Lateral spinothalamic tract** cause?
- loss of pain and temperature sensations on opposite side of body, two segments below the level of lesion
116
what is the role of **Substantia gelatinosa**?
- Doesn't take part in formation of lateral spinothalamic tract - Has short axons, which synapse with neurons of nucleus proprius and Posteromarginal nucleus to inhibit pain transmission
117
First order neuron in ventral spinothalamic tract
**DRG** - **Peripheral** processes of the DRG in the **receptors** - **Central** processes, enter **spinal cord**, and **divide into ascending and descending branches**, which **synapse in nucleus propius of about 10 spinal cord segments**
118
Central processes of DRG (First order neuron in ventral spinothalamic tract)
**Central** processes, enter **spinal cord**, and **divide into ascending and descending branches**, which **synapse in nucleus propius of about 10 spinal cord segments**
119
second order neuron in ventral spinothalamic tract
**Nucleus proprius** - **Axons of nucleus proprius (of ten segments)** Cross to **opposite side** of spinal cord to form **ventral spinothalamic tract** that **ascends in spinal cord & brainstem to end in VPLNT**
120
Third order neuron in ventral spinothalamic tract
**VPLNT** - **Axons of VPLNT** ascend in **posterior limb of internal capsule** to reach **general sensory area of cerebral cortex in postcentral gyrus**
121
Functions of Ventral spinothalamic tract
- it carries simple (crude) touch and pressure from the body
122
what does a lesion in **ventral spinothalamic tract** cause?
**signs are not detected clinically because:** 1. Crossing occurs at many segments. 2. Touch is also created by gracile & Cuneate tracts
123
First order neuron of Spinocerebellar tract (Unconscious propioception)
Dorsal Root Ganglia.
124
Second order neuron of Spinocerebellar tract (Unconscious propioception)
**Clarke's nucleus (laming VII):** For information from **trunk & lower limb** - **Axons of Clarke's nucleus** in **same side** form (dorsal / Post.) spinocerebellar tract. - It reaches **cerebellum through inferior cerebellar peduncle. (no crossing).** **Spinal border cells (in lateral part of laming VII:** for information from **lower limb** only. - **Axons of spinal border cells** of **opposite side** form ventral spinocerebellar tract. - It reaches **cerebellum through superior cerebellar peduncle.** - **Fibers cross back within cerebellum (double-crossing)**
125
Functions of Spinocerebellar tract
- cerebellum is responsible for coordination of movement, posture & maintenance of muscle tone
126
what does a lesion in Spinocerebellar tract cause?
Ataxia (loss of muscle coordination)
127
what carries unconscious proprioception from upper limb?
cuneocerebellar tract
128
First order neuron of sensations of the face
**Trigeminal ganglion** - **Peripheral** processes are distributed via **ophthalmic, maxillary & mandibular divisions to receptors in face** - **Central** branches: form **sensory root** of trigeminal nerve which terminate in...
129
where does sensory root of trigeminal nerve end?
130
Second order neuron of sensations of the face
**It is in the sensory nuclei of trigeminal (mesencephalic, main sensory and spinal nucleus) in the brain stem.** - The axons of second order neurons mostly cross to the opposite side and ascend to relay in the ventral postero-medial (VPM) nucleus of thalamus
131
Third order neuron of sensations of the face
**VРМNТ** - Axons of VPMNT ascend in internal capsule to end in postcentral gyrus (lower third).
132
A patient was admitted to an emergency hospital with sudden loss in pain and temperature sensations from his left foot, **what is the affected sensory tract producing this impairment?**
Right Lateral Spinothalamic tract at lumbar region
133
Parts of Auricle
- **Elevations:** helix & antihelix & tragus - **Depressions:** conchae - Lobule
134
Parts of External auditory canal
**Outer 1/3:** Cartilaginous part& directed upward **Inner 2/3:** Bony part & directed downward forward
135
Parts of Tympanic membrane
- Pars flaccida the upper 1/5 - Pars tensa the lower 4/5
136
Surfaces of Tympanic membrane
**Lateral surface:** concave **Medial surface:** convex with its maximum convexity “umbo” produced by handle of malleus. On examination, the handle forms antroinferior cone of light
137
Arterial supply of external ear
**Anterior auricular:** from superficial temporal artery **Posterior auricular:**from external carotid artery **Deep auricular:** from 1st part of maxillary artery
138
Nerve supply of Auricle
- Lesser occipital from C2 supply back of auricle - Great auricular from C2,C3 supply lobule of auricle - Auriculo-temporal of mandibular & auricular branch of vagus supply front of auricle
139
Nerve supply of External auditory canal
- Auriculo-temporal of mandibular nerve - Auricular branch of vagus nerve
140
Nerve supply of Tympanic membrane
- Outer surface: Auriculo-temporal of mandibular & auricular branch of vagus - Inner surface: from tympanic plexus of middle ear
141
Lymph drainage of auricle
- Mastoid lymph nodes - Parotid lymph nodes
142
Arterial supply of Middle ear
143
Nerve supply of Middle ear
Tympanic plexus
144
what forms Tympanic plexus?
- Tympanic branches of glossopharyngeal - Sympathetic fibres around internal carotid - Communicating branch with facial N.
145
Branches of Tympanic plexus
- Sensory branches: to middle ear & Eustachian tube. - Lesser superficial petrosal nerve: carries parasympathetic fibers to parotid gland
146
Roof of Middle ear
Tygmen tympani separating it from brain “site for infection spread”
147
Floor of Middle ear
Jugular fossa separating it from internal jugular vein “site for infection spread"
148
Anterior wall of Middle ear
1. Opening for tensor tympani 2. Opening for auditory tube 3. Bony plate separating middle ear from Internal carotid artery 4. Opening for chorda tympani “ to get out from middle ear”
149
Posterior wall of Middle ear
A. Aditus: connect it to mastoid air cells “site for infection spread” B. Vertical part of facial canal C. Pyramid: small projection containing stapedius D. Opening for chorda tympani “to enter the middle ear”
150
Medial wall of Middle ear
a. Horizontal part of facial canal b. Promontary: Round bulge produced by cochlea c. Oval window: postero-superior to promontory, closed by foot of stapes d. Round window: postero-inferior to promontory, closed by 2nd tympanic membrane.
151
Lateral wall of Middle ear
Inner layer of tympanic membrane.
152
Contents of Middle ear
**Bones:** - Malleus & Incus & Stapes **Muscles:** - Tensor tympani: it tenses the tympanic membrane, it is supplied by mandibular nerve - Stapedius: it prevents hyperaeusis, it is supplied by facial nerve **Nerves:** - Chorda tympani of facial nerve & Tympanic plexus
153
Origin of Facial nerve
**Motor:** - In lower part of pons **Sensory:** - Spinal trigeminal nucleus: receive general somatic sensation - Upper 1/3 of nucleus soliterus: receive taste sensation from anterior 2/3 of tongue **Parasympathetic:** - Superior Salivary nucleus
154
Course of Facial nerve
155
Branches of Facial nerve
- Cranial - Extra-Cranial
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Cranial branches of Facial nerve
**Greater superficial petrosal:** - parasympathetic fibers relay on pterygo-.palatine ganglion to supply lacrimal gland, nose, palate & pharynx **Nerve to Stapedius** **Chorda tympani:** it joins lingual nerve to supply: - Parasympathetic to submandibular, sublingual glands - Taste sensation from Anterior 2/3 of tongue
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Extra–Cranial branches of facial nerve
**Posterior auricular:** Supply Occipitalis **Descending motor branch:** Supply Posterior belly of digastric& Stylohyoid **Terminal:** 1. Temporal: supply orbecularis occuli & frontalis 2. Zygomatic: supply orbecularis occuli 3. Buccal: supply orbecularis oris & buccinator 4. Mandibular: supply orbecularis oris 5. Cervical: supply platysma
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what does a lesion in Upper motor neuron lesion affect? and what are its features?
**Affect:** Cortico – bulbar fibers **Features:** Contralateral Paralysis of lower 1⁄4 of face “Buccinator &Orbecularis oris”
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what does a lesion in Lower motor neuron lesion affect? and what are its features?
**Affect:** facial nucleus or facial nerve **Features:** according to site of lesion:
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Lower motor neuron lesion If the lesion is at facial colliculus
- Ipsilateral paralysis in muscles of facial expression & medial squint “due to affection of abducent nucleus”
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Lower motor neuron lesion If the lesion is at cerebello-pontine angle
- Ipsilateral paralysis in muscles of facial expression with affection of vestibulo-cocchlear , glossopharyngeal nerves
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Lower motor neuron lesion If the lesion is at internal auditory meatus
- Ipsilateral paralysis in muscles of facial expression with affection of vestibulo-cocchlear nerve
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Lower motor neuron lesion If the lesion is at middle ear
- Ipsilateral paralysis in muscles of facial expression - Vestibulo-cocchlear nerve is not affected - Greater superficial petrosal nerve is not affected - Affection of nerve to Stapedius: hyperacusis - Affection of chorda tympani: loss of taste from anterior 2/3 of tongue
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Lower motor neuron lesion If the lesion is at Stylomastoid foramen “Bell pulsy”
Ipsilateral paralysis in all muscles of facial expression
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Generally; Paralysis of muscles of facial expression causes....
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Inner ear
- Bony labyrinth - Membranous labyrinth
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Parts of Bony labyrinth
- Cochlea - Vestibule - Semicircular canals
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Content of Bony labyrinth
perilymph
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Parts of Membranous labyrinth
**Cochlear duct:** (contain organ of corti: hearing receptor) **Utricle, saccule:** (contain macula: receptor of balance) **Semicircular ducts:** (contain crista ampullaris: receptor of balance)
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Content of Membranous labyrinth
Endolymph
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what are the types of descending motor systems?
- Pyramidal system - Extrapyramidal system - Pathway to the cerebellum
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what does pyramidal system form?
Forms a direct link between the cerebral cortex and the spinal cord and brainstem. It forms: **Corticospinal tract:** descends to anterior horn cells (AHCs) of the spinal cord. **Corticobulbar tract:** descends to the cranial nerve motor nuclei in the brainstem.
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what does extrapyramidal system form?
Forms an indirect link between the cerebral cortex & spinal cord through the brainstem. The tracts reach the spinal cord outside the pyramid of the medulla.
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what are pyramidal corticospinal tracts?
1. Lateral corticospinal tract (crossed). 2. Ventral corticospinal tract (uncrossed).
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Origin of corticospinal tract
it is formed of the axons of pyramidal cells: 1. 40% of the fibers: from the upper 2/3 of the primary motor area (area 4). 2. 40% of the fibers: from the premotor area (area 6). 3. 20% of the fibers: from the general sensory area (area 3, 1 & 2).
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Course of corticospinal tract
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what happens to the fibers at the lower part of the medulla?
- **85%** of the fibers **cross** to the opposite side forming the **lateral corticospinal tract & the pyramidal (motor) decussation**. - **15%** of the fibers **remain uncrossed** and form the **ventral corticospinal tract**. They cross in the cervical & upper thoracic regions of the spinal cord.
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Termination of corticospinal tract
1. About 95% terminate on the opposite side. 2. About 5% terminate on the same side.
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Functions of corticospinal tract
1. Facilitation of the flexor muscle tone. 2. Initiation of the movements. 3. Fibers originating in the sensory area modulate sensory input to the spinal cord.
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What does UMNL in corticospinal tract cause?
**Above the decussation:** contralateral hemiplegia (paralysis of the opposite 1⁄2 of the body). **Below the decussation:** ipsilateral hemiplegia.
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Origin of corticobulbar tract
1. Lower 1/3 of the primary motor area. 2. Adjacent premotor area & sensory area.
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Course of corticobulbar tract
The tract descends through the: 1. Corona radiata of the medullary center. 2. Genu of the internal capsule. 3. Crus cerebri of the midbrain with the corticospinal fibers. 4. Basis pontis of the pons. 5. Pyramid of the medulla.
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Termination of corticobulbar tract
- It terminates on the **cranial nerve motor nuclei** of the **two sides** **mainly on the opposite side**. - **All the cranial nerve motor nuclei receive bilateral corticobulbar fibers except the lower part of the facial nucleus**, which receives fibers from the opposite side only.
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what does UMN paralysis of the lower part of the contralateral facial nucleus cause?
- paralysis of the muscles of the lower part of the opposite side & weakness of the muscles supplied by the cranial nerves.
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what causes motor system lesions?
**Trauma:** by fracture of the vertebral column, stab or by bullet. **Compression:** by tumor or herniated disc. **Vascular:** by occlusion of an artery.
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what are motor system lesions?
are either of upper motor or of lower motor neuron lesion
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what causes UMNL?
- Due to a lesion in the pyramidal & the extrapyramidal tracts.
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Signs of UMNL
after the stage of shock: - **Hypertonia:** exagerated muscle tone. - **Hyper-reflexia:** hyperactive deep tendon reflexes. - **Spastic paralysis:** resistance to passive movements due to increased muscle tone. - **Babinski sign:** extension of the big toe upon stroking the sole of the foot. - **Clonus:** alternating flexion & extension of the foot upon strong dorsiflexion of the foot.
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what causes LMNL?
due to a lesion in the anterior horn cells or their axons (peripheral nerves).
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Signs of LMNL
- **Hypotonia:** Decrease or loss of the muscle tone. - **Areflexia:** Absence of the deep tendon reflexes. - **Flaccid paralysis:** The flaccidity of muscles is due to loss of muscle tone. - **Fibrillation or fasciculation** due to spontaneous contraction of muscle fibers. - **Muscle atrophy**
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what are extrapyramidal tracts?
originate from the brainstem: - **2 From the midbrain:** rubrospinal tract & tectospinal tract (are crossed). - **2 From the vestibular nuclei:** lateral & medial vestibulospinal tracts. - **2 From the reticular formation:** lateral & medial reticulospinal tracts. - **2 others:** raphe-spinal tract & descending autonomic fibers (hypothalamospinal tract).
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what are the fuctions of **extrapyramidal tracts**?
**All** the **pyramidal & extrapyramidal** tracts **facilitate the flexor muscle tone** except the **2 tracts which arise from the pons** which facilitate the **extensor muscle tone**: 1. Pontine vestibulospinal tract. 2. Pontine reticulospinal tract.
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Origin of Rubruspinal tract
from the red nucleus of the opposite side
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Function of Rubruspinal tract
**carries information from the cerebellum & cerebral cortex to the spinal cord** & facilitation of the flexor muscle tone.
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Origin of Tectospinal tract
from the superior colliculus of the opposite side.
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Function of Tectospinal tract
Reflexes associated with vision & hearing.
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Origin of Potine vestibular tract (Vestibulospinal tract)
lateral vestibular nucleus in the pons.
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Fuction of Potine vestibular tract (Vestibulospinal tract)
facilitation of the extensor muscle tone.
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Origin of Medullary vestibulospinal tract (Sulcomarginal tract)
medial vestibular nucleus in the medulla.
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Function of Medullary vestibulospinal tract (Sulcomarginal tract)
facilitation of the flexor muscle tone.
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Origin of pontine reticulospinal tract
pontine reticular formation.
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Function of pontine reticulospinal tract
facilitation of the extensor muscle tone.
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Origin of Medullary reticulospinal tract
medullary reticular formation.
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Function of Medullary reticulospinal tract
facilitation of the flexor muscle tone.
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Origin of Descending autonomic fibers
hypothalamus & autonomic centers in the reticular formation.
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Termination of Descending autonomic fibers
sympathetic nucleus (lateral horn) & sacral parasympathetic nucleus.
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what does a lesion of Descending autonomic fibers cause?
Autonomic disturbances, Lesion above T1 will cause Horner s syndrome
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Symptoms of Horner's syndrome
**Ptosis:** drooping of the upper eyelid due to paralysis of Muller s muscle. **Miosis:** constriction of the pupil due to paralysis of the dilator pupillae. **Anhidrosis:** dry face due to paralysis of the sweat glands. **Enophthalmos:** retraction of the eyeball. **Flushing:** the face is red and warm due to vasodilation of skin blood vessels.
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Structure of cortico-ponto-cerebellar pathway
The cortico-ponto-cerebellar pathway is divided into 2 neurons: 1. Corticopontine fibers 2. Pontocerebellar fibers
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Types of Corticopontine fibers
- Frontopontine - Non-Frontopontine
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where do frontopontine fibers arise from?
frontal lobe.
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what do frontopontine fibers transmit?
motor information to the cerebellum.
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where do non-frontopontine fibers arise from?
parietal, temporal & occipital lobes
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what do non-frontopontine fibers transmit?
sensory information to the cerebellum.
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Pontocerebellar fibers
Axons of the pontine nuclei cross to the opposite side and enter the cerebellum through the middle cerebellar peduncle.
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Function of Pontocerebellar fibers
1. **Transmit motor & sensory information** from the **cerebral cortex to the neocerebellum**. 2. The pathway **brings the cerebellum under the control of the cerebral cortex** for **precise correction of movements**.
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Site of Infratemporal fossa
- Located deep to the ramus of the mandible.
218
Boundaries of Infratemporal fossa
219
Communications of Infratemporal fossa
1. Temporal fossa: deep to zygomatic arch 2. Pterygopalatine fossa: pterygomaxillary fissure
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Site of Pterygopalatine fossa
- Between bones on the lateral side of the skull Immediately posterior to the maxilla
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Boundaries of Pterygopalatine fossa
1-The anterior wall: maxilla 2- The medial wall: palatine bone 3- The posterior wall and roof: sphenoid bone.
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Communications of Pterygopalatine fossa
223
Content of Pterygopalatine fossa
224
what is the largest cranial nerve?
Trigeminal nerve
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what is the nature of trigeminal nerve?
- Mixed nerve
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Roots of trigeminal nerve
- Small motor root and large sensory root
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where does trigeminal nerve emerge from?
- It emerges from the side of the pons, near its upper border
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Origin of trigeminal nerve
**Three sensory nuclei:** 1-mesencephalic 2-principal sensory 3-spinal nuclei of trigeminal nerve) **One motor nucleus:** (motor nucleus of the trigeminal nerve)
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Type of Ophthalmic nerve
Pure sensory
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Origin of Ophthalmic nerve
- It is one of the 3 terminal divisions of the trigeminal nerve. - It arises from the convex border of the trigeminal ganglion.
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Course of Ophthalmic nerve
- It runs in the lateral wall of the cavernous sinus.
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Terminal branches of Ophthalmic nerve
- The lacrimal nerve - The frontal nerve - The nascociliary nerve
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what do the terminal branches of Ophthalmic nerve enter the orbit through?
- Its branches enter the orbit through the superior orbital fissure.
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Course of the lacrimal nerve
It runs forwards along the lateral wall of the orbital cavity
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what is the lacrimal nerve joined by?
- joined by parasympathetic Secretomotor fibers from the zygomatic branch of the maxillary nerve
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Branches of lacrimal nerve
1- Glandular branches: to the lacrimal gland. 2- Terminal palpebral branches: to the skin of the lateral part of the upper
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Course of frontal nerve
- It runs forwards below the roof the orbital - About the middle of the cavity, it divides in to 2 terminal branches.
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Branches of frontal nerve
- Supratrochlear nerve - Supraorbital nerve
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Course of supratrochlear nerve
It leaves the orbital cavity above the trochlea.
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what does supratrochlear nerve supply?
- It supplies the skin of the medial part of the upper eyelid and the median part of the forehead.
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Course of supraorbital nerve
- It leaves the orbital cavity through the supraorbital notch.
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what does the supraorbital nerve supply?
- It supplies the skin of the central part of the upper eyelid and the anterior part of the scalp.
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Course of nasociliary nerve
- It crosses over the optic nerve from lateral to medial. - Then it runs forwards along the medial wall of the orbit - It ends at the anterior ethmoidal foramen by dividing into 2 terminal branches: anterior ethmoidal and infratrochlear.
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Branches of Nasociliary nerve
- Infratrochlear branch - Anterior ethmoidal branch - Posterior ethmoidal branch - Long ciliary branches (two in number). - Sensory root to the ciliary ganglion.
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Course of Infra-trochlear nerve
It leaves the orbital cavity below the trochlea.
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what does the Infra-trochlear nerve supply?
Supplies the lacrimal sac, the skin at medial angle of the eye and the upper part of the dorsum of the nose.
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Course of anterior ethmoidal nerve
- It passes through the anterior ethmoidal foramen to enter the nasal cavity → supplies the mucous membrane of the nose. - Then, it emerges between the nasal bone and the nasal cartilage as external nasal nerve
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what does the anterior ethmoidal nerve supply?
- supplies the skin of the lower part of the dorsum of the nose.
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Course of posterior ethmoidal nerve
- It passes through the posterior ethmoidal canal.
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what does posterior ethmoidal nerve supply?
- It supplies the ethmoidal and sphenoidal air sinuses.
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Nature of long ciliary nerves
- They carry sensory fibers to the cornea & ciliary body. - They cary postganglionic sympathetic fibers to the dilator pupillae muscle.
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Site of Ciliary ganglion
post. Part of orbit lat. to optic nerve.
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Types of Ciliary ganglion
parasympathetic ganglion
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Roots of Ciliary ganglion
**Sensory:** from nasociliary N. **Sympathetic root:** internal carotid sympathetic plexus **Parasympathetic root:** EWN ---> oculomotor N. ---> N. to inf. Oblique m.s
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Branches of Ciliary ganglion
- 8-10 short ciliary nerves - Pierce the sclera around the optic N. **They carry:** 1. Sensory fibers: to the cornea, choroid body and iris 2. Postganglionic Parasympathetic fibers: to sphincter pupillae and ciliary muscles 3. Sympathetic fibers: to bl. Vessels around eye
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what is the type of maxillary nerve?
Pure sensory
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Origin of maxillary nerve
- It arises from the trigeminal ganglion in the middle cranial fossa.
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Course of maxillary nerve
* In the middle cranial fossa, the maxillary nerve runs forwards in the lateral wall of the cavernous sinus. * It passes through the foramen rotundum to enter the pterygopalatine fossa. * Then, it passes through the pterygomaxillary fissure to enter the infratemporal fossa. * Then, it passes through the inferior orbital fissure to enter the orbit as the infraorbital nerve.
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Termination of maxillary nerve
The infraorbital nerve runs forwards on the floor of the orbit in infraorbital groove→infraorbital canal→infraorbital foramen→the face.
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Branches of maxillary nerve
- In the cranial cavity - In the pterygopalatine fossa - In the infratemporal fossa - In the orbit - In the face
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Branches of maxillary nerve in the cranial cavity
**Meningeal branch:** Supplies the dura mater of the middle cranial fossa.
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Branches of maxillary nerve in the pterygopalatine fossa
**Ganglionic branches:** 2 roots to the pterygopalatine ganglion.
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Branches of maxillary nerve in the infratemporal fossa
**Zygomatic nerve** - Enters the orbit through the inferior orbital fissure → then, it runs forwards along the lateral wall of the orbital cavity. - it ends by dividing in to 2 terminal branches: 1. Zygomaticofacial→runs through the zygomaticofacial foramen to enter the face. 2. Zygomaticotermporal→runs through the zygomaticotemporal foramen to enter the temporal fossa. **Posterior superior alveolar nerve** - Enters the posterior surface of the maxilla. - Supplies the upper 3 molar teeth.
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Branches of maxillary nerve in the orbit
- Middle superior alveolar nerve - Anterior superior alveolar nerve
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Branches of maxillary nerve in the face
1- Palpebral branch→the lower eye lid. 2- Nasal branch→the side of the nose. 3- Labial branch→the upper lip.
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Nature of pterygopalatine ganglion
- It is the largest parasympathetic ganglion in the head and the neck.
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Site of pterygopalatine ganglion
It lies in the pterygopalatine fossa.
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Type of pterygopalatine ganglion
parasympathetic
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Roots of pterygopalatine ganglion
1- Sensory→from the maxillary nerve (arises from the trigeminal ganglion). 2- Parasympathetic→from the greater superficial petrosal nerve. (arises from the facial nerve). 3- Sympathetic→from the deep petrosal nerve. (arises from the superior cervical sympathetic ganglion).
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How do sympathetic and parasympathetic roots reach the pterygopalatine ganglion?
through the nerve of the pterygoid canal which is formed by the union of greater superficial petrosal nerve (parasympathetic) and deep petrosal nerve (sympathetic) **(Vidian nerve)**
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what are the branches of pterygopalatine ganglion considered?
considered branches of the maxillary nerve and each branch carries sensory, parasympathetic and sympathetic fibers.
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what is the Function of postganglionic parasympathetic fibers of pterygopalatine ganglion?
- secretomotor to the lacrimal, nasal and palatine gland.
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what is another name for pterygopalatine ganglion?
ganglion of hay fever, characterized by tears and running nose
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Branches of pterygopalatine ganglion
- Greater palatine - Lesser palatine - Long sphenopalatine (nasopalatine) - Short sphenopalatine (posterior superior lateral nasal) - orbital - Pharyngeal
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Course of greater palatine nerve
Descends through the greater palatine canal to pass through the greater palatine foramen.
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what does greater palatine nerve supply?
- Supplies the mucous membrane of the gums, the hard palate, the lateral nasal wall and the maxillary sinus.
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Course of lesser palatine nerve
- Descend through the greater palatine canal to pass through the lesser palatine foramina.
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what does lesser palatine nerve supply?
Supply the soft palate – uvula – tonsils.
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What is another name for Long sphenopalatine nerve?
nasopalatine
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Course of Long sphenopalatine nerve
- Runs through the sphenopalatine foramen to reach the nose. Then runs through the incisive foramen to reach the hard palate.
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What does Long sphenopalatine nerve supply?
* Supplies the nasal septum and the gum of the incisors.
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what is another name of short sphenopalatine nerve?
- posterior superior lateral nasal
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Course of short sphenopalatine nerve
- Runs through the sphenopalatine foramen to reach the nose.
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what does short sphenopalatine nerve supply?
- Supplies the posterior superior part of the lateral wall of the nose.
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Course of orbital nerve
Runs through the inferior orbital fissure.
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what does orbital nerve supply?
Supplies the orbital periosteum.
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Course of pharyngeal nerve
Runs through the palatovaginal canal.
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what does pharyngeal nerve supply?
* Supplies the nasopharynx.
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Type of Mandibular nerve
mixed (motor & sensory)
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Origin of Mandibular nerve
- It is the 3rd division of the trigeminal nerve. - It is formed by 2 roots: large sensory and small motor.
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Course of Mandibular nerve
- The 2 roots leave the cranial cavity through the foramen ovale - Just below the foramen ovale, The 2 roots unite to from the main trunk of the mandibular nerve.
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Termination of Mandibular nerve
- It divides in to 2 terminal divisions under cover of the lateral pterygoid muscle.
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Branches of Mandibular nerve
**From the trunk:** - Nervus spinosus - Nerve to medial pterygoid **From the anterior division:** - Nerve to the lateral pterygoid - Deep temporal nerves - Nerve to masseter - Buccal nerve **From the posterior division:** - Auriculo termporal nerve - Inferior alveolar nerve - Lingual nerve.
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branches of Mandibular nerve from the main trunk
**From the trunk:** - Nervus spinosus - Nerve to medial pterygoid
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branches of Mandibular nerve from the anterior devision
**From the anterior division:** - Nerve to the lateral pterygoid - Deep temporal nerves - Nerve to masseter - Buccal nerve
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branches of Mandibular nerve from the posterior devision
**From the posterior division:** - Auriculo termporal nerve - Inferior alveolar nerve - Lingual nerve.
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Course of nervus spinosus
- Enters the cranial cavity through the foramen spinosum with the middle meningeal artery.
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what does nervus spinosus supply?
- Supplies the dura mater of the middle cranial fossa (sensory nerve).
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what does nerve to medial pterygoid supply?
- Supplies the medial pterygoid muscle (motor nerve).
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branches of nerve to medial pterygoid
Gives 2 small branches which pass through the otic ganglion without relay to supply the tensor palati and the tensor tympani muscle.
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Course of buccal nerve
- Emerges between the 2 heads of the lateral pterygoid muscle.
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what is the only sensory nerve of the anterior division of the mandibular nerve?
Buccal nerve
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Branches from the posterior devision of the mandibular nerve
**From the posterior division:** - Auriculo termporal nerve - Inferior alveolar nerve - Lingual nerve.
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origin of Auriculo-temporal nerve
- It arises by 2 roots which encircle the middle meningeal artery
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Course of Auriculo-temporal nerve
- It runs backwards medial to the neck of the mandible to enter the substance of parotid gland. - Then, it turns upwards to leaves the upper pole of parotid gland. - Then, it crosses over the zygomatic arch to reaches the lateral side of the scalp
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Distribution of Auriculo-temporal nerve
**Sensory fibers:** * The skin of the temporal region. * The lateral surface of the auricle. * The external auditory canal. * The outer surface of the tympanic membrane. * The parenchyma of the parotid gland. * The temporomandibular joint. **Autonomic fibers:** * Parasympathetic→secretomotor to the parotid gland. * Sympathetic→vasomotor to the blood vessels of the parotid gland.
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Origin of Inferior alveolar nerve
Branch from the posterior division of mandibular nerve
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Course of Inferior alveolar nerve
- It emerges at the lower border of the lateral pterygoid muscle behind the lingual nerve - It enters the mandibular foramen to runs in the mandibular canal. - It ends at the level of the mental foramen, by dividing in to incisive and mental branches.
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Distribution of Inferior alveolar nerve
- Mylohyoid nerve - Dental nerves - Incisive nerve - Mental nerve
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Course of mylohyoid nerve
- It arises 1cm before the inferior alveolar nerve enters the mandibular foramen → then it runs in the mylohyoid groove.
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what does the mylohyoid nerve supply?
- It supplies the mylohyoid muscle and the anterior belly of digastric muscle
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what do dental nerves supplu?
- They supply the teeth of the lower jaw posterior to the canine.
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branches of inferior alveolar nerve
- Mylohyoid nerve - Dental nerves - Incisive nerve - Mental nerves
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what does incisive nerve supply?
It supplies the canine and the incisive teeth.
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Course of mental nerve
It emerges from the mental foramen.
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what does mental nerve supply?
It supplies the skin and the mucous membrane of the lower lip.
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origin of Lingual nerve
- A branch from the posterior division of mandibular nerve - It joins the chorda tympani branch of the facial nerve.
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Course of Lingual nerve
- In the infratemporal fossa: infront of the inferior alveolar nerve. - It enters the floor the mouth by passing behind and below the last molar teeth (dangerous position).
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Termination of Lingual nerve
- It ends on the under surface of the tongue by dividing into 2 terminal branches to the anterior 2/3 of the tongue and the floor of the mouth.
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Distribution of Lingual nerve
**Sensory fibers:** - General sensation from: * The anterior 2/3 of the tongue. * The floor of the mouth. * The gum of the lower teeth. * The parenchyma of the submandibular & sublingual glands. - Taste sensation from: * The anterior 2/3 of the tongue (through chorda tympani nerve) **Autonomic fibers:** - Parasympathetic (through chorda tympani nerve) → secretomotor to the submandibular and the sublingual salivary glands. - Sympathetic → vasomotor to the blood vessels of the submandibular and the sublingual glands.
321
Site of otic ganglion
lies in the infratemporal fossa immediately below foramen ovale.
322
type of otic ganglion
Parasympathetic
323
Relations of otic ganglion
* Laterally → the trunk of the mandibular nerve. * Medially → the tensor palati. * Posteriorly → the middle meningeal artery.
324
Roots of otic ganglion
325
Branches of otic ganglion
326
Nuclear groups of medulla oblongata
Medulla oblongata contains the following nuclear groups: 1. Gracile and cuneate nuclei. 2. Cerebellar relay nuclei. 3. Cranial nerve nuclei.
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Input of gracile nucleus
- Receive gracile tract - It is the 2nd order neurone for; kinesthesia, discriminative touch and vibration sense from the same side of the body (lower part)
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input of cuneate nucleus
- Receive cuneate tract - It is the 2nd order neurone for; kinesthesia, discriminative touch and vibration sense from the same side of the body (upper part)
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output of gracile & cuneate nuclei
- Their axons cross to the opposite side forming sensory decussation then ascend as medial lemniscus.
330
what are Cerebellar relay nuclei?
- Accessory cuneate nucleus - Arcuate nucleus - Inferior olivary nuclear complex - Vestibular nuclei - Reticular formation
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Input of Accessory cuneate nucleus
- It receives unconscious proprioception from the upper limb through the cuneate tract.
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Output of Accessory cuneate nucleus
- The axons form the cuneocerebellar tract (dorsal external arcuate fibers) which reaches the cerebellum through the ICP
333
Input of Arcuate nucleus
- It receives fibers from the cerebral cortex via pyramidal tract.
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Output of Arcuate nucleus
The axons form the arcuatocerebellar fibers which reaches the cerebellum through the ICP by 2 routes: **Ventral external arcuate fibers:** from arcuate nucleus of the same side. **Stria medullaris of 4th ventricle:** from arcuate nucleus of the opposite side.
335
Input of Inferior olivary nuclear complex
they receive: - Motor: from the cerebral cortex, basal ganglia & red nucleus - Sensory: from the spinal cord through spinoolivary tract.
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Output of Inferior olivary nuclear complex
- olivocerebellar tract which crosses to the opposite side & enters the cerebellum through the ICP.
337
Function of Inferior olivary nuclear complex
- cerebellar control of movement.
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Input of Vestibular nuclei
vestibular nerve.
339
Output of Vestibular nuclei
vestibulocerebellar fibers which enters the cerebellum through the ICP.
340
Input of Reticular formation
it receives: - Motor: from the motor areas of cerebral cortex. - Sensory: from the spinal cord & special sense organs.
341
Output of Reticular formation
- reticulocerebellar tract which enters the cerebellum through the ICP.
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Function of Reticular formation
1. Reticular activating system: important for arousal from sleep 2. Affects the muscle tone. 3. Contain cardiovascular and respiratory centers.
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what are Cranial nerve nuclei?
- Spinal trigeminal nucleus - Nucleus solitarius - Hypoglossal nucleus - Nucleus ambiguous - Inferior salivatory nucleus - Dorsal motor nucleus of vagus - Inferior & medial vestibular nuclei
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Type of Spinal trigeminal nucleus
sensory nucleus.
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Site of Spinal trigeminal nucleus
- extends from the medulla upwards to the lower pons & downwards to the level of C3 segment of spinal cord.
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Function of Spinal trigeminal nucleus
- mediates pain and temperature from the same side of the face.
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Output of Spinal trigeminal nucleus
The axons cross to the opposite side forming trigeminal lemniscus which terminates in the VPMNT.
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Type of Nucleus solitarius
- sensory nucleus.
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Upper 1/3 of Nucleus solitarius
receive taste fibers from; - Facial nerve: from the anterior 2/3 of the tongue. - Glossopharyngeal nerve: from posterior 1/3 of the tongue. - Vagus nerve: from the epiglottis and most posterior part of the tongue.
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lower 2/3 of Nucleus solitarius
receive general sensation from the viscera through the glossopharyngeal and vagus nerves.
351
Type of Hypoglossal nucleus
motor nucleus.
352
Site of Hypoglossal nucleus
hypoglossal trigone in the floor of 4th ventricle.
353
Function of Hypoglossal nucleus
motor to all muscles of the tongue except palatoglossus.
354
Type of Nucleus ambiguous
motor nucleus
355
Upper 1/3 of Nucleus ambiguous
give fibers to glossopharyngeal nerve to supply stylopharyngeus muscle.
356
Middle 1/3 of Nucleus ambiguous
give fibers to the vagus nerve to supply: - All muscles of the pharynx except stylopharyngeus. - All muscles of the palate except tensor palati. - Cricothyroid muscle.
357
lower 1/3 of Nucleus ambiguous
give fibers to cranial accessory nerve to supply all muscles of the larynx except cricothyroid.
358
Type of Inferior salivatory nucleus
parasympathetic nucleus.
359
Function of Inferior salivatory nucleus
- Supplies the parotid gland through the glossopharyngeal nerve.
360
Type of Dorsal motor nucleus of vagus
parasympathetic nucleus.
361
Site of Dorsal motor nucleus of vagus
vagal trigone in the floor of 4th ventricle.
362
Function of Dorsal motor nucleus of vagus
- Supplies the thoracic and abdominal viscera till the left colic flexure through the vagus nerve.
363
Site of Inferior & medial vestibular nuclei
Located in the vestibular trigone in the floor of 4th ventricle.
364
what are Vascular Lesions of Medulla Oblongata?
- Medial medullary syndrome - Lateral medullary syndrome
365
Cause of Medial medullary syndrome
- anterior spinal artery occlusion.
366
Effects of Medial medullary syndrome
damage of the followings; - Corticospinal tract: contralateral hemiplegia. - Medial lemniscus: contralateral loss of kinesethia, discriminative touch & vibration sense from the body. - Hypoglossal nucleus: ipsilateral paralysis of the tongue.
367
Cause of Lateral medullary syndrome
PICA occlusion.
368
Structures affected by Lateral medullary syndrome
- Spinal trigeminal nucleus & tract - Lateral spinothalamic tract - Nucleus ambiguous - ICP - Vestibular nuclei - Sympathetic fibers to the head
369
Effects of Lateral medullary syndrome
- **Spinal trigeminal nucleus & tract:** Ipsilateral loss of pain & temp from the face. - **Lateral spinothalamic tract:** Contralateral loss of pain & temp from the body. - **Nucleus ambiguous:** next question - **ICP:** Ipsilateral ataxia. - **Vestibular nuclei:** Nausea, vomiting, vertigo & nystagmus. - **Sympathetic fibers to the head:** Ipsilateral Horner’s syndrome.
370
what does damage to nucleus ambigous cause?
Ipsilateral paralysis of: 1. Pharyngeal muscles causing dysphagia & loss of gag reflex. 2. Laryngeal muscles causing hoarseness of voice. 3. Palatine muscles causing deviation of the uvula to the healthy side.
371
Internal features of pons
- Basis pontis - Tegmentum
372
what does **Basis pontis** contain?
1. Pontine nuclei: the 2nd order neuron of cortico-ponto-cerebellar pathway. 2. Transverse pontine fibers: axons of pontine nuclei forming MCP. 3. Bundles of pyramidal tract: corticospinal & corticobulbar. 4. Fibers of middle 4 cranial nerves.
373
what does **Tegmentum** contain?
Tracts: medial, trigeminal, spinal and lateral lemnisci. Nuclei: of middle 4 cranial nerves & pontine reticular formation.
374
Internal features of midbrain
- Crus cerebri - Subsatntia nigra - Tegmentum
375
what does **Crus cerebri** contain?
it contains: - In the medial 1/5: frontopontine fibers. - In the middle 3/5: pyramidal tract. - In the lateral 1/5: nonfrontopontine fibers.
376
Parts of **Subsatntia nigra**
**Pars compacta:** contains melanin & secretes dopamine. **Pars reticularis:** secretes GABA (gama aminobutric acid).
377
what is **Subsatntia nigra**?
extrapyramidal motor nucleus.
378
Connection of **Subsatntia nigra**
- projects 2 inhibitory fibers; **Nigrostriate fibers:** inhibits the caudate nucleus (by dopamine). **Nigrothalamic:** inhibits the ventral anterior & ventral lateral thalamic nuclei (by GABA).
379
What does a lesion in **Subsatntia nigra** cause?
Parkinson's disease.
380
what does **Tegmentum** of midbrain contain?
**Tracts:** - medial, trigeminal, spinal and lateral lemnisci. **Nuclei:** - 3 cranial nerve nuclei: 1. Oculomotor: at the level of superior colliculus. 2. Trochlear: at the level of inferior colliculus. 3. Mesencephalic nucleus of trigeminal nerve. **3 others:** 1. Red nucleus: at the level of superior colliculus. 2. Reticular formation. 3. Locus ceruleus.
381
What does tectum contain?
- Superior colliculus - Inferior colliculus
382
Connection and function of Superior colliculus
**Connected with:** - The opposite one by posterior commissure. - The lateral geniculate body by superior brachium. **Function:** - visual reflex center & auditory reflex center.
383
Connection and function of Inferior colliculus
**Connected with:** - The opposite one by commissure of inferior colliculus. - The medial geniculate body by inferior brachium. **Function:** - auditory reflex center & relay nucleus in auditory pathway (lower auditory center).
384
what causes Midbrain vascular lesions?
usually due to occlusion of branches of PCA.
385
Types of Midbrain vascular lesions
- Weber’s syndrome - Benedikt’s syndrome
386
Signs of Weber’s syndrome
- Ipsilateral oculomotor nerve. - Corticospinal tract (in crus cerebri) causing contralateral hemiplegia.
387
Signs of Benedikt’s syndrome
- Ipsilateral oculomotor nerve. - Red nucleus causing contralateral tremors and ataxia.
388
Definition of Cranial nerves
- The 12 pairs of cranial nerves are part of the peripheral nervous system (PNS) and pass through foramina or fissures in the cranial cavity.
389
Which of cranial nerves doesn't originate from the brain?
390
what are the names of Cranial nerves?
- I: olfactory - II: Optic - III: oculomotor - IV: trochlear - V: trigeminal - VI: abducent - VII: facial - VIII: vestibulo-cochlear - IX: glossopharyngeal - X: Vagus - XI: accessory - XII: hypoglossal
391
what are the types of cranial nerve nuclei?
- Motor (efferent) - Sensory (afferent)
392
Motor (efferent) cranial nerve nuclei
- General somatic efferent (GSE) N. - special visceral efferent (SVE) or Branchial efferent (BE) N. - General visceral efferent (GVE) N.
393
Sensory (Afferent) cranial nerve nuclei
- General somatic afferent (GSA) N. - General visceral afferent (GVA) N. - Special Afferent (SA) N.
394
Function of General somatic efferent (GSE) N.
- innervate skeletal muscles derived from somites
395
Examples of General somatic efferent (GSE) N.
1) Somator motor nucleus of oculomotor nerve 2) Somator motor nucleus of trochlear nerve 3) Somator motor nucleus of abducent nerve 4) Hypoglossal nucleus
396
Function of special visceral efferent (SVE) or Branchial efferent (BE) N.
- innervate muscles derived from the pharyngeal (branchial) arches
397
Examples of special visceral efferent (SVE) or Branchial efferent (BE) N.
1) Trigeminal motor nucleus 2) facial motor nucleus 3) Nucleus ambiguous
398
Function of General visceral efferent (GVE) N.
- innervate smooth & cardiac muscles and glands (parasympathetic).
399
Examples of General visceral efferent (GVE) N.
1) Edinger Westphal nucleus 2) Sup. Salivatory nucleus 3) Inf. Salivatory nucleus 4) Dorsal motor nucleus of vagus
400
Function of General somatic afferent (GSA) N.
- receive somatic sensations.
401
Examples of General somatic afferent (GSA) N.
1) Mesencephalic nucleus 2) Main sensory nucleus 3) Spinal trigeminal nucleus
402
Function of General visceral afferent (GVA) N.
- receive visceral sensations
403
Examples of General visceral afferent (GVA) N.
1) Lower 2/3 of nucleus solitarius
404
Function of Special Afferent (SA) N.
- receive special sensations (taste, vision, hearing and balance)
405
Examples of Special Afferent (SA) N.
1) Upper 1/3 of nucleus solitarius 2) Vestibular n.
406
Definition of Pharyngeal (branchial) arches
- Six pharyngeal arches developed around the primitive pharynx, but the fifth arch never develops. - Each of the pharyngeal arches is associated with a developing cranial nerve or one of its branches.
407
Nerve associated with each Pharyngeal (branchial) arch
- First arch: trigeminal nerve [V] - Second arch: facial nerve [VII] - Third arch: glossopharyngeal nerve [IX] - Fourth arch: superior laryngeal branch of vagus nerve [X] - Sixth arch: recurrent laryngeal branch of vagus nerve [X].
408
Contents of the bony orbit
1) the eyeball 2) the optic nerve 3) the extraocular muscles 4) the lacrimal apparatus 5) adipose tissue and fascia 6) nerves and vessels
409
Fissures and foramina of the bony orbit
1) Optic canal 2) Superior orbital fissure 3) Inferior orbital fissure 4) Infra-orbital foramen 5) anterior and posterior ethmoidal foramina 6) lacrimal fossa continuous with nasolacrimal canal
410
what are the muscles of the orbit?
- extrinsic muscles of eyeball (extra-ocular muscles) - intrinsic muscles of the eyeball (intra-ocular muscles)
411
Function of extrinsic muscles of eyeball (extra-ocular muscles)
- involved in movements of the eyeball or raising upper eyelids
412
Examples of extrinsic muscles of eyeball (extra-ocular muscles)
- Levator palpebrae superioris - **Four recti:** 1) Superior rectus 2) Inferior rectus 3) Medial rectus 4) Lateral rectus - **Two obliques:** 1) Superior oblique 2) Inferior oblique
413
Function of intrinsic muscles of the eyeball (intra-ocular muscles)
- control the shape of the lens and size of the pupil
414
Examples of intrinsic muscles of the eyeball (intra-ocular muscles)
- Constrictor pupillae - Dilator pupillae - Ciliary muscle
415
Characteristcs of constrictor pupillae
➢ Produce meiosis ➢ parasympathetic
416
Characteristcs of dialator pupillae
➢ produce mydriasis ➢ sympathetic
417
Characteristcs of ciliary muscle
➢ accomodation ➢ Sympathetic & parasympathetic
418
Function of Levator palpebrae superioris
- Raises the upper eyelids
419
what causes elevation of eyeball?
- by the superior rectus and inferior oblique.
420
what causes depression of eyeball?
- by the inferior rectus and superior oblique.
421
what causes adduction of eyeball?
- by the superior rectus, inferior rectus and medial rectus.
422
what causes abduction of eyeball?
- by the lateral rectus, superior oblique and inferior oblique.
423
Type of olfactory nerve (I)
Pure sensory
424
Fiber content of olfactory nerve (I)
- Special Afferent (SA) fibers for the sense of smell.
425
Course of olfactory nerve (I)
The sensory neurons have: - Peripheral processes - Central processes
426
Peripheral processes of olfactory nerve (I)
- That act as receptors in the nasal mucosa - The receptors are in the roof and upper parts of the nasal cavity.
427
Central processes of olfactory nerve (I)
- return information to the brain and enter the cranial cavity by passing through cribriform plate of the ethmoid bone. - They terminate by synapsing with secondary neurons in the olfactory bulbs.
428
Type of Optic nerve (II)
Pure sensory
429
Fiber content of Optic nerve (II)
- Special Afferent (SA) fibers for the sense of vision.
430
Course of Optic nerve (II)
- The nerve is formed by axons of retinal ganglion cells. - It reaches the cranial cavity by passing through optic canal. - The optic nerves are surrounded by cranial meninges and subarachnoid space, which is filled with cerebrospinal fluid (CSF). - The central artery and vein of the retina run in the anterior part of the optic nerve.
431
Termination of Optic nerve (II)
- forms the optic chiasma and the optic tract.
432
Type of Vestibulocochlear nerve [VIII]
Pure sensory
433
Fiber content of Vestibulocochlear nerve [VIII]
- Special Afferent (SA) fibers for the sense of hearing and balance.
434
Course of Vestibulocochlear nerve [VIII]
- The vestibulocochlear nerve [VIII] leaves the inner ear through the internal acoustic meatus. - Then, it attaches to the lateral surface of the brainstem, between the pons and medulla at the cerebello-pontine angle.
435
what does a lesion in Olfactory nerve cause?
Anosmia
436
what does a lesion in Optic nerve cause?
Blindness
437
what does a lesion in Vestibulocochlear nerve cause?
Deafness
438
Type of Occulomotor Nerve (III)
Motor
439
Deep origin & Fiber content of Occulomotor Nerve (III)
**Somatic motor nucleus (GSE):** - Supplies all extraocular muscles except lateral rectus and superior oblique. **Parasympathetic nucleus (Edinger-Westphal nucleus) (GVE):** - Supply the sphincter pupillae muscle and the ciliary muscle. **Interstitial nucleus of Cajal:** - for the vertical movements of the two eyes. **Pretectal nucleus:** - for pupillary light reflex
440
Occulomotor Nerve (III) Attachment to brain stem
- From the anterior aspect of midbrain medial to cerebral peduncle (in the inter- peduncular fossa).
441
Course of Occulomotor Nerve (III)
- It runs forwards in the lateral wall of the cavernous sinus above the trochlear nerve.
442
Occulomotor Nerve (III) Exit from the skull
- Enters the orbit by passing through the superior orbital fissure.
443
Branches & Distribution of Occulomotor Nerve (III)
It divides into superior & inferior: - Superior division supplies: A. Superior rectus. B. Levator palpebrae superioris. - Inferior division supplies: A. Inferior oblique. B. Inferior rectus. C. Medial rectus. - Parasympathetic fibers: a. Constrictor pupillae muscle. b. Ciliary muscle.
444
what does a lesion in Occulomotor Nerve (III) cause?
- Ptosis - . Deviation of the eye down and out - mydriasis (dilatation of the pupil)
445
Explain ptosis due to lesion in Occulomotor Nerve (III)
- due to Paralysis of levator palpebrae superioris
446
Explain **Deviation of the eye down and out** due to lesion in Occulomotor Nerve (III)
- by unopposed action of lateral rectus and superior oblique.
447
Explain **mydriasis (dilatation of the pupil)** due to lesion in Occulomotor Nerve (III)
- due to Paralysis of the sphincter pupillae muscle.
448
Type of Trochlear Nerve (IV)
Motor
449
Deep origin & Fiber content of Trochlear Nerve (IV)
**Somatic motor nucleus (GSE):** - The axons cross inside the midbrain to the opposite side to supply the opposite superior oblique muscle.
450
what does a lesion in right trochlear nerve cause?
- Paralysis in the **Same** side
451
what does a lesion in right trochlear Nucleus cause?
- Paralysis in the **Contralateral** side
452
Trochlear Nerve (IV) attachment to the brain stem
From the back of the midbrain just below the inferior colliculus.
453
Course of Trochlear Nerve (IV)
- It runs forwards in the lateral wall of the cavernous sinus below the oculomotor nerve and above the ophthalmic nerve.
454
How does the Trochlear Nerve (IV) exit the skull?
- Enters the orbit by passing through the superior orbital fissure.
455
Branches & Distribution of Trochlear Nerve (IV)
Supplies the superior oblique muscle.
456
What does a lesion in Trochlear Nerve (IV) cause?
- Paralysis of the superior oblique muscle
457
Explain **Paralysis of the superior oblique muscle** due to lesion in Trochlear Nerve (IV)
inability to depress the adducted eye (inability to look downwards & inwards) causing difficulty in walking downstairs.
458
Type of Abducent Nerve (VI)
Motor
459
Deep origin & Fiber content of Abducent Nerve (VI)
- **Abducent motor nucleus (GSE):** Forms the facial colliculus with the encircling facial nerve fibers, Supplies lateral rectus. - **Paraabducent nucleus (horizontal gaze center)**
460
Abducent Nerve (VI) attachment to brain stem
- From the anterior surface of the brain stem in the groove between pons and pyramid of medulla.
461
Course of Abducent Nerve (VI)
- It runs forwards in the floor of the cavernous sinus inferolateral, to the internal carotid artery.
462
How does the Abducent Nerve (VI) leave the skull?
- Enters the orbit by passing through the superior orbital fissure.
463
Branches & Distribution of Abducent Nerve (VI)
- Supplies the lateral rectus muscle.
464
what does a lesion in Abducent Nerve (VI) cause?
- Paralysis of the lateral rectus muscle
465
Explain **Paralysis of the lateral rectus muscle** due to lesion in abducent nerve (VI)
- internal strabismus (by the medial rectus).
466
Type of Facial nerve
Mixed nerve
467
Deep origin & Fiber content of Facial nerve
468
action of each nucleus and its fibers of facial nerve
469
Type of Glossopharyngeal nerve
Mixed nerve
470
Deep origin & Fiber content of Glossopharyngeal nerve
471
action of each nucleus and its fibers of Glossopharyngeal nerve
472
Attachment of Glossopharyngeal nerve to brain stem
- Between olive and inferior cerebellar peduncle (post- olivary fissure).
473
Exit of Glossopharyngeal nerve from skull
- The nerve passes through the middle part of the jugular foramen.
474
Course of Glossopharyngeal nerve
- The nerve runs in the upper part of the carotid sheath between the internal carotid artery and the internal jugular vein. - Then, it leaves the sheath and runs between external and internal carotid arteries. - Then, it enters the pharynx between superior & middle constrictors of the pharynx. - Then, it passes deep to hyoglossus muscle to reach the tongue.
475
Branches of Glossopharyngeal nerve
- Tympanic nerve - Carotid nerve - Motor branch - Pharyngeal branches - Tonsillar branches - Lingual branches
476
what does the Tympanic nerve enter?
- Enters the tympanic cavity (middle ear)
477
what does the Tympanic nerve join?
In the middle ear it joins with a branch of the facial nerve to form the tympanic plexus,
478
Branches of Tympanic plexus
**Sensory branches:** to the middle ear & auditory tube. **Lesser superficial petrosal nerve:** derived from the inferior salivatory nucleus which supplies the otic ganglion and parotid gland.
479
Carotid nerve of glossopharyngeal
to the carotid sinus and the carotid body.
480
Motor branch of glossopharyngeal nerve
to the stylopharyngeus muscle.
481
Pharyngeal branches of glossopharyngeal nerve
- Sensory branches to the pharynx. Share in formation of pharyngeal plexus.
482
Tonsillar branches of glossopharyngeal nerve
the pharynx & the auditory tube.
483
Lingual branches of glossopharyngeal nerve
Supply mucous membrane of the posterior 1/3 of tongue.
484
what does a lesion in Glossopharyngeal nerve cause?
- Loss of taste sensation from the posterior third of the tongue. - Loss of the pharyngeal gag reflex. - Loss of the carotid sinus reflex.
485
Type of Vagus Nerve
- Mixed nerve
486
Deep origin & fiber content of Vagus Nerve
487
Action of each nucleus and its fibers of Vagus Nerve
488
Attachment of Vagus Nerve to brain stem
- Between olive and inferior cerebellar peduncle (post- olivary fissure).
489
Exit of Vagus Nerve from the skull
- The nerve passes through the middle part of the jugular foramen.
490
Course of Vagus Nerve
- It enters the carotid sheath between internal jugular vein and internal carotid artery and descends through the neck within the sheath, then passes the first part of subclavian artery to enter the thoracic cavity. - **In the thorax:** it passes in the superior and posterior mediastinum, then passes through the esophageal opening of the diaphragm to enter the abdominal cavity - **In the abdomen:** it terminates by forming the anterior and posterior gastric nerves of both surfaces of the stomach.
491
Braches of Vagus Nerve in the neck
- meningeal branch - auricular nerve - pharyngeal branch - Superior laryngeal nerve - recurrent laryngeal nerves - carotid branches - cardiac branches
492
what does meningeal branch of Vagus Nerve supply?
supply dura of posterior cranial fossa.
493
what does auricular nerve of Vagus Nerve supply?
- Supplies the mucous membrane of the concha of external auditory meatus and the outer surface of the tympanic membrane (with auriculotemporal nerve).
494
where does pharyngeal branch of Vagus Nerve pass?
- It passes between internal carotid & external carotid arteries.
495
Action by pharyngeal branch of Vagus Nerve
- It shares in the pharyngeal plexus. - motor to the muscles of pharynx except stylopharyngeus and muscles of soft palate except tensor palati.
496
what does Superior laryngeal nerve of vagus divide into?
a) Internal laryngeal branch (Sensory) b) external laryngeal branch (motor)
497
Course and function of Internal laryngeal branch
- Pierces the thyrohyoid membrane supplies: 1. The laryngopharynx. 2. The upper part of the larynx above the vocal cord. 3. Most posterior part of the tongue & epiglottis.
498
Course and function of External laryngeal branch
- accompanies the superior thyroid artery at its origin and supplies the cricothyroid muscle.
499
Course of recurrent laryngeal nerves of vagus
* On the right side: It hooks around the subclavian artery. * On the left side: It hooks around arch of aorta.
500
what do recurrent laryngeal nerves supply?
Both nerves supply: - All the intrinsic muscles of the larynx except the cricothyroid muscle. - sensory fibers to the larynx below the vocal cords.
501
Carotid branches of vagus nerve
A small branch to the carotid sinus and carotid body.
502
Cardiac branches of vagus
- They are usually 2 in number. - Arise from the vagus in the neck. - Run into the thoracic activity and join the cardiac plexus.
503
what does a lesion in vagus nerve cause?
- paralysis of muscles of the Pharynx, Causing dysphasia and loss of pharyngeal gag reflex - Paralysis of muscles of the larynx, causing hoarseness of voice - Paralysis of muscles of the palate, causing regurgitation of food from the nose and the deviation of the uvula to the normal side - Anesthesia of larynx causes loss of cough reflex
504
Parts of Accessory Nerve
- cranial part - spinal part
505
Type of Accessory Nerve
Pure motor
506
Nuclei & Fibers content of Accessory Nerve
**Cranial part:** lower part of nucleus ambiguus - special visceral efferent (SVE) or Branchial efferent (BE) **Spinal part:** Anterior Horn cells of (C1-C6) - General somatic efferent (GSE)
507
Course of Accessory Nerve
- The **cranial part** Passes Between olive and inferior cerebellar peduncle **(post- olivary fissure)**. - The **spinal part** arises from the **spinal cord** and **ascends** to enter the cranial cavity through the **foramen magnum**. - Within the **cranial cavity, both unite** to form a common nerve. - The **nerve** passes through the **middle part of the jugular foramen**. - **Outside the skull** the nerve runs in the **upper part of the carotid sheath between internal jugular v. and internal carotid a**. - **Here the trunk divides** * The **cranial part** of the nerve **joins the vagus.** * The **spinal part descends through the substance of the sternomastoid muscle, crosses the posterior triangle of the neck to reach the trapezius**.
508
Branches of Accessory Nerve
**Cranial part:** - Is distributed through the pharyngeal and laryngeal branches of the vagus nerve to the pharyngeal, soft palate and laryngeal muscles **Spinal part:** - Sternomastoid muscle. - Trapezius muscle.
509
what does a lesion in Accessory Nerve cause?
**Spinal part:** a) Paralysis of sternomastoid: causes inability to rotate the head to the opposite side. b) Paralysis of trapezius: causes inability to shrug (up and down) the shoulder.
510
Type of Hypoglossal Nerve
Motor nerve
511
Nuclei & Fibers content of Hypoglossal Nerve
- Hypoglossal nucleus of the medulla: General somatic efferent (GSE) fibers to all intrinsic and extrinsic muscles of the tongue, except the palatoglossus.
512
Hypoglossal Nerve attachment to brain stem
- Between the olive and the pyramid (pre-olivary fissure).
513
Hypoglossal Nerve exit from the skull
The nerve passes through anterior condylar (hypoglossal) canal.
514
Course of Hypoglossal Nerve
- At the base of the skull: it enters the upper part of the carotid sheath. - Within the carotid sheath: It descends between IJV and ICA. - At the lower border of the digastric muscle: The nerve turns forwards to pass from the carotid triangle to the digastric triangle. - It enters the floor of the mouth superficial to the hyoglossus muscle.
515
Branches of Hypoglossal Nerve
**From the nerve itself:** - It gives branches to all intrinsic and extrinsic muscles of the tongue, except the palatoglossus (supplied by vago-accessory complex). **From the C1 fibers:** - These fibers join the hypoglossal nerve, they give: * descendens hypoglossi. * Muscular branches to the thyrohyoid and geniohyoid muscles. * A meningeal branch supplying the dura matter of the posterior cranial fossa via the anterior condylar canal.
516
what does a lesion in Hypoglossal Nerve cause?
a) paralysis of the same side of the tongue (hemiparalysis). b) Deviation of the protruded tongue toward the affected side.
517
Arterial supply of the brain
518
Origin of Vertebral artery
519
Termination of Vertebral artery
520
Branches of Vertebral artery
521
Origin of Basilar artery
522
Termination of Basilar artery
523
Branches of Basilar artery
524
Origin of posterior cerebral artery
525
Course of posterior cerebral artery
526
Branches of posterior cerebral artery
527
Origin of Internal carotid artery
528
Course of Internal carotid artery
529
Termination of Internal carotid artery
530
Branches of Internal carotid artery
531
Compare between ACA & MCA in terms of: - Origin - Course - Branches
532
Location of Circulus arteriosus (circle of willis)
533
Formation of Circulus arteriosus (circle of willis)
534
Anatomical & Clinical importance of Circulus arteriosus (circle of willis)
535
Venous drainage of the brain
536
What do Superficial cerebral veins drain?
537
what do Superficial cerebral veins end into?
538
what are Superficial cerebral veins?
539
what do Deep cerebral veins drain?
540
what are Deep cerebral veins?
541
Arterial supply of spinal cord
542
Origin of Radicular arteries
543
Course of Radicular arteries
544
what do Radicular arteries supply?
545
Venous drainage of the spinal cord
Y2B4 - Central Nervous System 📙
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