1
Q
What do the pharyngeal arches initially appear as?
A
Tissue bulges separated by clefts (as the cranial neuropore closes)
2
Q
What do the pharyngeal arches consist of?
A
Mesoderm core, ectoderm external cleft, internal endodermal pouch
3
Q
What do each pharyngeal arch (1,2,3,4 5 disappears, 6) give rise to?
A
Distinct sets of structures in head & neck
4
Q
Describe the development of early face/jaw from frontonasal prominence 1st pharyngeal arch?
A
- 24days stomodeum is closed by oropharyngeal membrane, which later ruptures
- 1st arch has smaller upper maxillary prominence & larger lower mandibular prominence
5
Q
What are the 2 mains sources of the pharyngeal arch mesenchyme core?
A
- Mesoderm
2. Neural crest
6
Q
What 4 things does the pharyngeal arch mesenchyme core give rise to?
A
- Muscle (brachial muscles)
- Cartilage element
- Artery
- Cranial nerve
7
Q
What are ill defined “segments” of paraxial mesoderm in the head region rostral to somites also called?
A
Somitomeres
8
Q
Describe the movement of Paraxial mesoderm & what it forms?
A
Migrates into pharyngeal arches & elsewhere to form mostly muscle tissue of the head (& some connective tissue/bone)
9
Q
Describe the movement of the neural crest cells & what they form?
A
Ventral flow around placodes & into pharyngeal arches, giving rise to mesenchyme, ganglia & nerves
10
Q
What are Ectodermal Placodes?
A
Thickening of ectoderm that help give rise to sensory neurons/ganglia
11
Q
What are the major blood vessels derived from the pharyngeal arches (aortic arch)?
A
- 1st & 2nd Aortic arch: 2nd disappear, 1st is maxillary artery
- 3rd Aortic arch: common & proximal internal carotid artery
- 4th Aortic arch: right subclavian artery, left aortic arch
- 5th Aortic arch: disappear
- 6th Aortic arch: right pulmonary, left pulmonary & forms the ductus arteriosus
12
Q
What bones of the head, face & neck do lateral plate mesoderm give rise to (mesenchymal)?
A
Laryngeals
13
Q
What bones of the head, face & neck do paraxial mesoderm give rise of (mesenchymal)?
A
- Parietal
- Pet. temporal
- Occipitals
14
Q
What muscles come from the cranial somitomeres of 1st pharyngeal arch (“mandibular arch”)?
A
- Mastication
- Ant. belly of digastric
- Mylohyoid
- Tensor tympani
- Tensor veli palatini
15
Q
What are the skeletal structures from the 1st pharyngeal arch (“mandibular arch”)?
A
- Maxilla
- Zygomatic bone
- Mandible
- Malleus
- Incus
16
Q
What are the nerves derived from the 1st pharyngeal arch (“mandibular arch”)?
A
- Skin of the face supplied by V1, V2, V3
- Trigeminal V3 muscles of mastication
17
Q
What muscles come from the cranial somitomeres of 2nd pharyngeal arch (“hyoid arch”)?
A
- Facial expression
- Stylohyoid
- Stapedius
- Post. belly of digastric
18
Q
What are the skeletal structures from the 2nd pharyngeal arch (“hyoid arch”)?
A
- Stapes
- Styloid process
- Stylohyoid ligament
- Lesser horn of hyoid, upper part body of hyoid
19
Q
What is the nerve derived from the 2nd pharyngeal arch (“hyoid arch”)?
A
Facial VII
20
Q
What arteries comes from 2nd pharyngeal arch?
A
Hyoid & stapedial arteries
21
Q
What muscle comes from the cranial somitomeres of 3rd pharyngeal arch?
A
Stylopharyngeus
22
Q
What skeletal structure comes from the 3rd pharyngeal arch?
A
Greater horn of hyoid, lower part body of hyoid
23
Q
What is the nerve derived from the 3rd pharyngeal arch?
A
Glossopharyngeal IX
24
Q
What muscles come from the somites of 4th & 6th pharyngeal arches?
A
- All muscles of pharynx (4th) except stylopharyngeus
- All muscles of palate (4th) except tensor veli
- Cricothyroid (4th)
- All larynx muscles (6th)
25
What are the skeletal structure from the 4th & 6th pharyngeal arches?
- Epiglottis
- Laryngeal cartilages
- Thyroid
- Cuneiform corniculte
- Arytenoids
26
What nerve is derived from the 4th & 5th pharyngeal arches?
- Vagus X
| - Superior laryngeal branch supplies 4th arch
27
What does paraxial mesoderm give rise to in the head, neck & face?
- All voluntary muscles
- Arteries,
- Neurocranium
- Meninges
- Dorsal skin
28
What does the neural crest give rise to in the head, neck & face?
- Pharyngeal arch skeleton
- Viscerocranium
- Glandular connective tissue
- Parts of neurocranium, teeth
29
What does Ectodermal Placodes & Neural Crest form in the head, neck & face?
Cranial neurons of sensory ganglia (V, VII, IX, X) & sensory apparatus (eyes/nose)
30
What does the 1st pharyngeal pouch develop into (internal endoderm)?
Primitive tympanic cavity
31
What does the 2nd pharyngeal pouch develop into (internal endoderm)?
Palatine tonsil/tonsillar fissure
32
What does the 3rd pharyngeal pouch develop into (internal endoderm)?
Parathyroid (inferior) & thymus (migrates)
33
What does the 4th pharyngeal pouch develop into (internal endoderm)?
Parathyroid gland (superior) & Ultimobranchial body (calcitonin producing parafollicular (C) cells of thyroid)
34
What can happen during migration of thymus, parathyroid glands & ultimobranchial body?
- Thymus can remain in neck (ectopic thymus)
| - Inferior parathyroids can be variable in position (ectopic parathyroid)
35
What does the 1st pharyngeal cleft give rise to?
- DORSAL PART: external auditory meatus & external tympanic membrane
- DEEPEST PART: tympanic membrane
36
What happens to the 2nd, 3rd & 4th pharyngeal clefts?
Lose contact with exterior forming cervical sinus, the sinus usually disappears
37
What are the pharyngeal cleft anomalies?
Cysts (adults) & fistulas/sinuses (children) anterior to sternocleidomastoid
38
What are key controllers of rostrocaudal patterning in the head?
HOX genes
39
What is the hindbrain region that neural crest cells migrate from called?
Rhombomeres
40
What provides guidance cues for sensory cranial nerves growing back from ganglia?
Expression of transcription factor OTX & HOX genes to migrate to pharyngeal arches
41
What do local patterns of endoderm signals do to neural crest cells?
Specifies mesenchymal expression pattern & arch characteristics
42
What pharyngeal arch is affected in Treacher Collins Syndrome (autosomal dominant)?
Failure of formation/apoptosis of neural crest cells & migration into 1st/2nd pharyngeal arches
43
What protein is defected in Treacher Collins Syndrome (autosomal dominant)?
Treacle (TCOF1 gene)
44
What are the signs & symptoms of Treacher Collins Syndrome (autosomal dominant)?
- Abnormal eye shape
- Micrognathia
- Conductive hearing loss
- Underdeveloped zygoma
- Malformed ears
45
What is the physiology behind Di George Syndrome?
3rd & 4th pouches fail to develop & thymus & parathyroids are defective
46
What are the signs & symptoms of Di George Syndrome (CATCH-22)?
- Cardiac abnormality
- Abnormal facies
- Thymic aplasia
- Cleft palate
- Hypocalcaemia
47
What is holoprosencephalon spectrum?
Congenital brain malformation of incomplete separation of the 2 hemispheres
48
What gene is mutated in holoprosencephalon spectrum?
Sonic Hedgehog (SHH)
49
What are the signs of inadequate SHH function?
- Narrowing & Fusion
| - Cyclopia
50
What are the signs of excess SHH function?
- Widening structures duplicated
| - Diprosopus
51
What is Craniosynostosis syndromes (Apert & Crouzon syndromes)?
1+ fibrous sutures in infant skull prematurely fuses by ossifying
52
What 3 genes are often mutated in Craniosynostosis syndromes?
1. FGFR's
2. TWIST transcription factor
3. EPHRIN-B1
53
What are the anterior & posterior structures of the eyeball?
- Ant: Cornea, Iris, Lens, Conjunctiva
| - Post: Retina/optic disc
54
What are the connections in the vision pathway?
- Optic nerve
- Chiasm
- Optic tract
- Lateral Geniculate Nucleus (LGN)
- Radiation
55
Describe Trachoma infection of the eye?
- Caused by Chlamydia
| - 4th major cause of blindness in the world
56
What are the 3 most common causes of world visual impairment?
- Uncorrected refractive error: URE (42%)
- Cataract 33%
- Glaucoma 2%
57
What are the 3 most common causes of world blindness?
- Cataract 51%
- Glaucoma 8%
- Age related macular degeneration (AMD) 5%
58
What are the 6 layers of the cornea?
1. Epithelium
2. Bowman's membrane
3. Stroma
4. Descemet's membrane
5. Endothelium
6. Tear film
59
What is the role of endothelium in the cornea?
Keeps the cornea clear
60
What are the 3 layers of the tear film?
1. Oily LIPID outer layer to reduce evaporation
2. AQUEOUS middle layer containing lysozymes & antibodies
3. MUCIN layer containing glycoprotein (lubricates for good coverage)
61
What are the 3 functions of the tear layer?
1. Wash eye debris
2. Provide dissolved O2 to cornea external epithelium
3. Lubrication
62
What does the cornea provide for the eye?
Major light focusing element of the eye- 40D of "fixed" power
63
What can side effect happen during cataract surgery?
Corneal oedema
64
How is the whole eye ball refraction (60D) split up?
1. Cornea: 40D
| 2. Lens: 20D
65
What is the equation for dioptric power of the eye?
Power= 1/focal length
66
What is the equation for power of the cornea in air & under water?
Power= (n2-n1)/r
67
What happens during lens accommodation when focusing on close objects?
Ciliary muscles contract to slacken zonule fibres
68
What is the "near triad" for lens accommodation?
1. Miosis
2. Convergence
3. Accommodation
69
What is Presbyopia?
Failure to accommodate when you are older due to lends hardening, main type of URE
70
What is Myopia?
Short-sightedness, growing epidemic in industrialised regions esp. Asia & associated with retinal detachment
71
What is Hypermetropia?
Long-sightedness, associated with squint & lazy eye (amblyopia) & cute closed angle glaucoma
72
How do you correct Myopia?
To stop image focusing before the retina, use a concave lens
73
What are the 2 different types of cataract surgeries?
1. Small incision cataract surgery (SICs)
| 2. Phacoemulsification surgery
74
What does the anterior & posterior chamber of the eyeball contain?
Aqueous humor
75
What are the 4 different layers in the retina?
1. Outer nuclear
2. Plexiform
3. Ganglion cell
4. Outer nuclear
76
Where does information from rods & cones go?
Converge to ganglion cells in ganglion cell layer of retina
77
What do lateral & amacrine cells in the plexiform layer of retina do?
Provide initial processing of visual signal
78
Describe characteristics of Rods?
- High convergence
- One type (vision in greyscale)
- Very light sensitive
- Widespread distribution in retina
- Broad spectral sensitivity
79
Describe characteristics of Cones?
- Low convergence
- 3 types (blue, green, red)
- Only 1/30th the sensitivity of rods
- Concentrated in macula
- Narrow spectral sensitivity
80
Where are rods most numerous in the retina?
Peripherally
81
Where are cones most numerous in the retina?
Fovea
82
What range of wavelength is visible light?
400-700nm
83
Photoreceptors are depolarised in the ____ & hyperpolarised in the ____?
- Dark
| - Light
84
At our eyes most sensitive wavelength, how many photons of light can they detect?
5
85
What protein is found in all rods & cones?
Retinal (derived from Vit A)
86
What is Retinal protein bound to under unstimulated conditions?
Opsin protein
87
What are 3 colours with rod retinal binding an opsin called?
Rhodopsin
88
What happens when light hits retinal?
Changes conformation & appears bleached
89
When is the retina metabolically more active?
When asleep
90
Describe Cone fatigue?
- Staring at specific colour for 2 long, cells that detect that frequency of light will fatigue
- After image is result of photoreceptors not being "in balance"
- As photoreceptors become less tired (10-30sec) after image disappears
91
What is Emmert's Law?
Things the same size on the retina appear a different size depending on the distant you are viewing hem & how far away you "think" you are viewing them
92
Whats the difference between "ON" or "OFF" bipolar cells?
- "ON" neurotransmitter release in light
| - "OFF" is opposite
93
What do Horizontal & Amacrine cells do?
Connect bipolar cells & allow for summation of information to allow detection of edges & contrast
94
Where does the visual information go?
Convergence from photoreceptors --> Bipolar cells --> Ganglion cell --> BRAIN
95
How does the ganglion cell transfer retinal information to the brain?
Optic nerve --> Chiasm --> Optic tract
96
What is the lateral geniculate nucleus (LGN)?
- Part of thalamus
- Major relay station for sensory info
- Sends info to occipital lobe
97
What is the optic nerve?
- Collection of all ganglion cells
- Exits back of eye through hole in sclera
- Head can be see at back of eye (optic disc)
98
What can cause total blindness of the right eye?
Complete lesion of right optic nerve
99
What can chiasmal lesions cause?
Bitemporal hemianopia
100
What does lesion of the left optic tract cause?
| least common site
Right homonymous hemianopia
101
What does lesion of inferior optic radiations in temporal lobe cause?
Right homonymous superior quadrantanopia
102
What visual defect does lesion of the left hemisphere cause?
- Right homonymous hemianopia
| - Pupillary light reflex is not impaired if it is beyond the tract
103
What visual defect does lesion of the left occipital lobe cause?
Right incomplete homonymous hemianopia
104
What 2 things can cause chasmal lesions & what fibres are most vulnerable?
1. Pituitary tumour- decussating fibres
| 2. Craniopharyngioma- posteriorly crossing fibres
105
What is evolved to allow creation of stereovision (3D)?
Chiasma
106
What could be used to assist in stereovision if chiasma was not evolved?
Corpus callosum
107
In quadrantanopias what does damage to posterior lobe cause according to "PIST"?
Inferior visual field loss
108
In quadrantanopias what does damage to temporal lobe cause according to "PIST"?
Superior visual field loss
109
When is bilateral lower quadrantanopia (lower visual field loss) most common?
Premature babies
110
What happens to brain growth in the last 3-4months of gestation?
"Flowering" of dendritic tree occurs
111
How many synapses are being created every second?
14 million
112
What are the characteristics of vascular ischaemic damage in "watershed areas" of premature baby's brain?
Peri-ventricular leucomalacia (PVL)
113
Describe children's visual problems who have cerebral palsy & PVL?
Children with spastic diplegia can have difficulty with talks involving lower field
114
What hemianopia affects reading english the most?
Right homonymous hemianopia
115
How many layers does the lateral geniculate nucleus have?
6
116
What layers in the lateral geniculate nucleus does information from the ipsilateral eye go to?
LGN layers 2, 3 & 5
117
What layers of the lateral geniculate nucleus does information from the contralateral eye go to?
LGN layers 1, 4 & 6
118
What layers of the lateral geniculate nucleus receive signals that travel by the magnocelluplar pathway?
LGN layers 1 & 2
119
What layers of the lateral geniculate nucleus receive signals that travel by the parvocellular pathway?
LGN layers 3, 4, 5 & 6
120
What are line of Gennari?
Myelinated fibres running from LGN to synapse in layer 4 of the "striate" cortex
121
What are the 4 function of the occipital lobe?
1. Relay station
2. Retinotopic map
3. Neural tuning is present
4. Specific populations of cells respond to: colour, spatial frequency, orientation
122
What is the striate cortex?
Main receiving area for visual signals from LGN, divided into 6 layers- 1 (nearest the surface) to 6 (deepest)
123
Describe the layers of striate cortex area V1?
- Superficial: cytochrome oxidase bolbs
| - Deep: Ocular dominance columns (right & left eye)
124
What is the right side of the temporal lobe for?
Faces & route finding
125
What is the left side of the temporal lobe for?
Words & shapes
126
What is Prosopagnosia?
Loss of face recognition
127
What is Topographic agnosia?
Loss of route finding
128
What is alexia?
Inability to read words
129
What is the pupillary light reflex?
Controls diameter of the pupil in response to intensity of light that falls on retinal ganglion cells of the retina in back of the eye, assisting in adaptation to various levels of lightness/darkness
130
What is the scalp?
Skin & subcutaneous tissue from superior nuchal line of occipital bone to supraorbital margins of frontal bone, extends over temporal fascia to zygomatic arch
131
Describe the 5 layers of the "SCALP"?
1. Skin: outermost
2. Connective tissue: subcutaneous rich in neurovascular
2. epicranial Aponeurosis: suturing to close wounds
3. Loose connective tissue: separates scalp proper (1st 3 layers) from pericranium & calvaria
4. Pericranium: external periosteal
132
What does the skin of the scalp contain?
- Hair follicles, sweat & sebaceous glands
| - Thickest over occipital bone
133
What does the epicranial aponeurosis of the scalp contain?
- Tendon & muscle of occipitofrontalis
| - Prevents superficial wounds from gaping
134
What does loose connective tissue of the scalp contain?
Spaces susceptible to distension with fluid or infection spread (eyelids, root of nose)
135
Whats the clinical significance of the layers of the scalp?
Between aponeurosis & pericranium there are potential spaces for accumulation of fluid (blood) or spread of infection
136
Why can fluid/infection spread to eyelids or root of nose?
Frontal belly of occipitofrontalis inserts into skin & subcutaneous tissue NOT BONE
137
How can scalp infections spread to intracranial structures?
Via emissary veins
138
What is the cutaneous/sensory nerve supply of the scalp?
- CN V1: supraorbital, supratrochlear
- CN V2: zygomaticotemporal
- CN V3: auriculotemporal
- Cervical nerve C2: greater & lesser occipital
- Cervical nerve C3: 3rd occipital
- Cervical nerve C2 & C3: great auricular
139
Describe the Ramsay Hunt Syndrome?
```
- Varicella zoster virus
reactivation in
geniculate ganglion (CN VII)
- Erythematous, vesicular rash in & around external auditory canal
- Otalgia & acute facial palsy
```
140
What its the cutaneous & motor innervation of auricle & external acoustic meatus?
- Cutaneous: superficial same as scalp, deep CN VII & CN X
- Motor: CN VII
141
Describe the characteristic symptoms of reactivation of varicella zoster virus in trigeminal ganglion (shingles)?
- CN V1 distribution
| - Erythematous, vesicular, crusting rash & burning sensation, conjunctivitis, keratitis & uveitis
142
What is Hutchinson's sign?
Cutaneous involvement of tip of nose (external nasal branch of nasociliary nerve)
143
What is the arterial supply to the scalp?
Internal (anterior) & external (lateral & posterior) carotid
144
Where do the veins of the scalp drain into?
External jugular vein, except occipital vein that drains to internal jugular
145
What is the clinical consequence of scalp arterial anastomoses?
Lie superficially & can lead to profuse bleeding when lacerated
146
What is the anterior & posterior lymphatic drainage of the scalp?
- ANT: pre-auricular & parotid nodes
| - POST: mastoid & occipital nodes drain to deep cervical
147
What are the 4 muscles of mastication (1st pharyngeal derivatives)?
1. Temporalis
2. Masseter
3. Medial pterygoid
4. Lateral pterygoid
148
What is the motor innervation of the muscles of mastication?
Motor root of CN V that emerges with CN V3 (anterior trunk except medial pterygoid that comes from main trunk)
149
Describe the location of Temporalis muscle?
- From temporal fossa & fascia
- Inserts at mandible coronoid process (medial surface) & anterior border/ramus of mandible
- Fan shape
150
What motion does the temporalis muscle provide?
Retract & elevate mandible (assists in closing mouth)
151
Describe the location of the Masseter muscle?
- From inferior border of zygomatic arch & maxillary process of zygomatic bone
- Inserts at angle & lateral surface of mandible ramus
152
What motion does the Masseter muscle provide?
Elevate the mandible (powerful)
153
Describe the location of the medial pterygoid muscle?
- From medial surface of lateral plate of pterygoid process & pyramidal process of palantine bone & tuberosity of pyramidal process of maxilla
- Inserts to medial surface of mandible near angle inferior to mandibular foramen
154
What motion does the Medial Pterygoid muscle provide?
Elevate the mandible & assist with lateral movements
155
Describe the location of the lateral pterygoid muscles?
- From roof of infratemporal fossa & crest of wing of sphenoid bone & lateral plate of pterygoid process
- Inserts at condylar process of mandible, capsule of TMJ & articular disc
156
What motion does the lateral pterygoid muscle provide?
- Protrude mandible
- Assist medial pterygoid with lateral movements
- Depress mandible
157
What are the 5 muscles of fascial expression?
| derived from 2nd pharyngeal arch
1. Buccinator
2. Orbicularis oris
3. Orbicularis oculi
4. Occipitofrontalis
5. Platysma
158
What are the 5 muscles of facial expression innervated by?
Branches of CN VII
159
Describe the location of Buccinator muscle?
- From posterior alveolar processes of maxilla/mandible & from pterygomandibular raphe
- Merge with orbicularis oris
160
What motion does the Buccinator muscle provide?
- Press cheeks against molar teeth
- Works with tongue to keep food between occlusal surfaces of teeth & out oral vestibule
- Smiling
161
Where is the parotid duct located?
On top of masseter before piercing buccinator en route to oral cavity
162
Why is the buccal fat pad larger in infants?
Reinforce cheeks & inhibit cheek collapse during feeding
163
Describe the location of the Orbicularis oris muscle?
- From buccinator/surrounding muscles & medial mandible/maxilla
- Inserts into mucous membrane of lips
164
What motion does the orbicularis oris provide?
- Close &/or protrude lips
- With buccinator & tongue keeps food between occlusal surfaces of teeth
- Assists in whistling
165
Describe the location of the Platysma muscle?
- From subcutaneous tissue of infra & supraclavicular regions
- Inserts at base of mandible, merges with orbicularis oris, skin of cheek & lower lip, angle of mouth
166
What motion does the Platysma muscle provide?
- Tense skin of inferior face/neck
| - Depress mandible
167
Describe the location of the 2 bellies of the Occupitofrontalis muscle?
- FRONTAL belly: epicranial aponeurosis & the skin/subcutaneous tissue of eyebrows & forehead
- OCCIPITAL belly: lateral 2/3 superior nuchal line & epicranial aponeurosis
168
What motion does the Occupitofrontalis muscle provide?
- Retract scalp (occipital belly)
- Wrinkle forehead
- Elevate eyebrows (frontal belly)
169
Describe the location of the 2 parts of the Orbicularis oculi muscle?
- PALPRBRAL from medial palpebral lig & into lateral palpebral raphe
- ORBITAL from nasal part of frontal bone, frontal process of maxilla & medial palpebral lig & inserts into skin around orbit
170
What motion does the orbicularis oculi provide?
- Close eyelids gently (involuntary or blinking reflex in palpebral part)
- Tightly close eyelids (voluntary orbital part)
171
What are the 4 dilator muscles which insert into angle of mouth (modiolus)?
1. Levator anguli oris
2. Zygomaticus major
3. Risorius
4. Depressor anguli oris
172
What are the 3 dilator muscles which insert into upper or lower lips?
1. Levator labii superioris
2. Zygomaticus minor
3. Depressor labii inferioris
173
What muscle flares the nostrils?
Levator labii superioris alaeque nasi
174
What 2 muscles wrinkles skin over dorsal of the nose?
1. Procerus
| 2. Transverse part of nasalis
175
What are the 3 muscles of facial expression that are related to the ear?
1. Superior auricular
2. Anterior auricular
3. Posterior auricular
(ALL SUPPLIED BY CN VII)
176
What is the lymphatic drainage of the ear muscles of facial expression?
Via parotid, mastoid & deep cervical nodes
177
List the 6 layers of the eyelids?
1. Skin
2. Connective tissue
3. Muscle (orbicularis oculi)
4. Orbital septum
5. Tarsus
6. Conjunctiva
178
What are the spaces between eyelids called?
Palpebral fissure
179
Describe the orbital septum?
Anterior border of orbit continuous with periosteum
180
What is preseptal cellulitis?
Infection of skin/subcutaneous tissue anterior to orbital septum
181
What are the clinical consequences of orbital cellulitis?
- Infection posterior to orbital septum
- Pain on eye movements that are restricted & proptosis (bulging of the eye)
- Threatens vision & risk of infection spread to cavernous sinus/meninges/brain
182
What is Conjunctivitis (pink eye)?
Inflammation of membrane covering posterior surface of the eyelid & eyeball
183
What is the sensory innervation of the eyelids?
CN V1 & V2
184
What is the vascular supply of the eyelids?
- External & internal carotid arteries
| - Veins following arteries
185
What is the lymphatic drainage of the eyelids?
Parotid nodes
186
Where is the majority of the blood supply to the face from?
External carotid artery (branch of ophthalmic) with some from internal carotid artery
187
What 2 places can the facial pulses be felt?
1. Facial artery at inf border of mandible
| 2. Transverse facial artery ant to auricle
188
What is the venous drainage of the face?
- FACIAL vein into Internal jugular vein
| - TRANSVERSE FACIAL vein drains upper face
189
Describe the danger triangle of the face?
- No valves in external facial veins
- Blood flows in both directions
- Deep veins drain to cavernous sinus
- Skin infections here may spread as intracranial infections
190
Name 3 means of lymphatic drainage of the face?
1. Pre-auricular & parotid
2. Submandibular
3. Submental
191
What is the innervation of the Medial Pterygoid muscle?
MAIN TRUNK of CN V3
192
What are the 3 functional groups of the basal nuclei?
1. Input nuclei: inputs from cortex & thalamus
2. Intrinsic nuclei: relay info between input & output nuclei
3. Output nuclei: send info to thalamus
193
What 2 structures are associated with the input nuclei function of the basal nuclei?
1. Caudate nucleus
| 2. Putamen
194
What 3 structures are associated with the intrinsic nuclei function of the basal nuclei?
1. Globus Pallidus (external)
2. Subthalamic nucleus
3. Substantia nigra (pars compacta)
195
What 2 structures are associated with the output nuclei function of the basal nuclei?
1. Globus Pallidus (internal)
| 2. Substantia nigra (pars reticulata)
196
List the 5 subcortical structures of the basal nuclei?
1. Caudate nucleus (includes nucleus acumbens)
2. Putamen
3. Globus Pallidus
4. Subthalamic nucleus
5. Substantia nigra
197
What 3 basal nuclei structures make up the neostriatum/striatum/corpus striatum?
1. Caudate nucleus
2. Putamen
3. Globus Pallidus
198
What are the 3 functions of the basal nuclei?
1. Refinement & initiation of motor output (Motor loop)
2. Emotional & reward aspects of motor output (limbic)
3. Influence on behaviour & learning (behavioural loop)
199
What problems can lesions in the basal ganglia cause?
Problems "getting going"- ataxia
200
What happens in the direct pathway in basal ganglia for movement?
"The accelerator"- medial Globus Pallidus acts as a brake to movement
201
List the 4 steps involved in the direct pathway of basal ganglia for movement?
1. Cerebral cortex excited neostriatum with glutamate
2. Neostriatum inhibits Globus Pallidus medial lobe with GABA
3. Medial lobe inhibits thalamus (GABA), but as its activity is reduced the thalamus activity increases
4. Results in increased cerebral stimulation & increased movement
202
What happens in the indirect pathway in basal ganglia for movement?
"The brake"- medial Globus Pallidus acts like a brake
203
List the 6 steps involved in the indirect pathway of basal ganglia for movement?
1. Cerebral cortex excites neostriatum with glutamate
2. Neostriatum inhibits Globus Pallidus lateral lobe with GABA
3. Lateral lobe inhibits subthalamic nucleus (GABA), it is inhibited so the subthalamic nucleus activity rises
4. Subthalamic nucleus increases normal excitation of medial lobe of Globus Pallidus which increases activity
5. Results in increased inhibition of thalamus & reduction in cerebral stimulation
6. Reduced movement
204
Where is dopamine produced?
Substantia nigra (pars compacta)
205
Cortical activity is influenced by direct & indirect pathways ______?
Simultaneously
206
How does dopamine modulate the movement system in basal ganglia?
Depends on what dopamine receptor they join with, can inhibit the indirect pathway or excite the direct pathway- both INCREASE movement
207
Why are clinical signs of basal ganglia lesions contralateral to the side of lesion?
Basal ganglia doesn’t cross, but the corticospinal tract crosses to the contralateral side and basal ganglia modulates the motor cortex
208
What does TRAP stand for in Parkinsonism disease (hypokinetic disease)?
- Tremor
- Rigidity
- Akinesia
- Posture
209
What is the physiology behind Parkinson's disease (hypokinetic disease)?
Progressive degeneration of the dopaminergic neurons of the substantia nigra
210
How does a loss of dopamine lead to hypokinesia?
1. Decrease in direct pathway activity (decreased movement)
| 2. Increase in the indirect pathway activity (decreased movement)
211
What are the 2 places targeted for deep brain stimulation for Parkinson's disease?
1. Globus Pallidus medial lobe (internal)
| 2. Subthalamic nucleus
212
Describe the hyperkinetic disorder called Hemiballismus?
| lesion of indirect pathway
- Lesion of subthalamic nucleus
- No stimulation of globus pallidus (internal)
- Violent projectile movement of limb contralateral to lesion
213
Describe the physiology behind the hyperkinetic disorder called Chorea?
(lesion of indirect pathway)
- Lesion of striatum (putamen)
- Initially, loss of GABAergic cells that project to globus pallidus (external)
- Later, stratal cholinergic cells begin to die
214
What are the clinical signs of Chorea (hyperkinetic disorder)?
Rapid, involuntary & purposeless jerks of irregular & variable location on body
215
What is Huntington's chorea due to?
Excessive CAG repeats on chromosome 4
216
Describe the hyperkinetic disorder called Athetosis?
- Lesion in Globus Pallidus
| - Spontaneous & often continuous writhing movements of a hand, arm, neck or face
217
Describe the hyperkinetic disorder called Wilson's disease?
- Lenticular degeneration due to copper accumulation
| - Dystonia & tremor
218
Describe the hyperkinetic disorder called Dystonia?
- Lesions in lentiform nucleus
| - Increased/sustained muscle contractions, twisting of trunk/extremities & abnormal postures
219
What makes up the Lentiform nucleus?
Putamen & Globus Pallidus
220
Describe the cause of Huntington's disease (basal ganglia disease)?
- Mutation causing malformed protein: Huntingtins
- Loss of enkephalinergic & GABAergic neurons in neostriatum, leading to decrease in activity of the indirect pathway (increased movement)
221
What 4 things is Huntington's disease characterised by?
1. Wildly flailing limbs & contorted posture
2. Reduced ability to saccade
3. Abnormal emotional responses (later stages)
4. Reduced cognitive ability (later stages)
222
What is the average life expectancy of Huntington's disease after onset of symptoms?
15yrs
223
What is death of Huntington's diseased patient usually due to?
Respiratory infections
224
What syndrome is also thought to be a hyperkinetic disease of the basal ganglia?
Tourette's Syndrome
225
Describe the axes of the orbit?
- Medial walls almost parallel
- Lateral walls at 90o
- Bases anterolaterallly
- Apices posteromedially
226
What does the tendinous ring of the orbit give rise to?
4 recti muscles
227
What nerves pass through the superior orbital fissure "LFTSNIA"?
- Lacrimal nerve CN V1
- Frontal nerve CN V1
- Trochlear nerve IV
- Superior branch of CN III
- Nasociliary nerve CN V1
- Inferior branch of CN III
- Abducens nerve VI
228
What lies within the optic canal?
- Optic nerve (CN II)
| - Central retinal artery & vein (end/terminal artery)
229
What are the contents of the orbit?
- Extraocular muscles
- Eyelids & lacrimal apparatus
- Retrobulbar fat
230
What is the Orbicularis Oculi muscle innervated by?
Temporal & Zygomatic branches of CN VII
231
What can malfunctions of the orbicularis oculi muscle lead to?
Sagging of lower eyelid, leakage of tears & dry eyes with the potential for corneal ulceration
232
What is the clinical consequence of the meninges & subarachnoid space extending from skull along CN II to sclera?
Raised intracranial pressure can therefore slow retinal venous drainage via the central retinal vein causing papilloedema
233
What is the clinical significance of the central retinal artery?
If occluded due to transient causes (amaurosis fugax) it can lead to painless temporary loss of vision in affected eye
234
What does the tarsal plate of the eyelid contain?
Tarsal (meibomian) glands that lubricate the lids (cyst)
235
What does the eyelashes of the eyelid contain?
Ciliary (sebaceous) glands (sty)
236
Describe the lacrimal apparatus & route of tears?
- Tears gather in lacrimal caruncle
| - Drain via puncture --> canaliculi --> lacrimal sac --> nasolacrimal duct --> inferior nasal meatus
237
List the extraocular muscles from superior to inferior?
- Superior oblique
- Levator palpabrae superioris
- Superior rectus
- Medial rectus
- Lateral rectus
- Inferior oblique
- Inferior rectus
238
What eye movement does the superior rectus provide?
Pulls eye upwards
239
What eye movement does the inferior rectus provide?
Pulls eye downwards
240
What eye movement does the medial rectus provide?
Pulls eye medially
241
Where does the inferior & superior rectus pass?
Posteriorly & medially
242
What gaze renders the rectus eye muscles efficient & oblique eye muscles inefficient?
Divergent gaze (distally forwards & slightly lateral)
243
What are the extra ocular muscles dependent upon?
- Direction of the gaze
- Position of eye
- Action of other muscles
244
What eye movements does the superior oblique provide?
Pulls back of eye upwards & medially, turning eye inferiorly & laterally
245
What eye movements does the inferior oblique provide?
Turns eye superiorly & laterally
246
How many axes of movement/diretions can the eyes do?
3
247
What muscles control left & right eye to look right?
- RIGHT EYE: lateral rectus
| - LEFT EYE: medial rectus
248
What nerve supplies the lateral rectus?
CN VI (abducens)
249
What is the side effect in the eyes when there is injury to the right CN VI?
Diplopia when looking right & eye would not abduct fully
250
What can lack of synchronous movements of the eyes cause?
Double vision (diplopia)
251
What muscles help to make the left & right eye look upwards & right?
- RIGHT EYE: inferior oblique turns eye superolaterally
| - LEFT EYE: superior rectus turns eye superiorly & medially
252
What muscles help to make the left & right eye look directly superiorly?
For BOTH EYES: superior rectus & inferior oblique
253
What muscles help to make the left & right eye look downwards & right?
- RIGHT EYE: superior oblique turns eye inferolaterally
| - LEFT EYE: inferior rectus turns eye inferiorly & medially
254
What muscles help to make the left & right eye look directly inferiorly?
For BOTH EYES: inferior rectus & superior oblique
255
What gaze renders the rectus eye muscles inefficient & oblique eye muscles efficient?
Convergence gaze
256
How are the eye muscles clinically assessed?
"H" test & testing muscles in their most efficient position will show any weakness
257
When looking laterally, what muscles can elevate & depress the eye?
Superior & inferior recti
258
When looking medially, what muscles can elevate & depress the eye?
Superior & inferior obliques
259
What happens in the eye "H" test if there is a CN VI lesion?
Lateral rectus will not work, giving obvious signs
260
What happens in the eye "H" test if there is a CN III lesion?
Pupil signs & eye movements will be limited, lateral rectus & superior oblique take over, so eye will look downwards & outwards
261
What nerve supplied the superior oblique?
CN IV (trochlear)
262
What is a clinical sign of injury to CN IV?
Patient cannot look medially & inferiorly so therefore struggle to walk downstairs / read a book
263
Where does the ophthalmic artery branch from?
Internal carotid artery
264
What 3 structures does the ophthalmic artery supply?
1. Eye
2. Part of nasal cavity
3. Forehead
265
Describe the venous drainage of the orbit & how its important clinically?
Supra & infraorbital veins anastomose with superficial veins of face & forehead, therefore infections may spread to cavernous sinus
266
What 3 pathologies could cause internal acoustic meatus narrowing?
1. Acoustic neuroma
2. Mastoiditis
3. Paget's disease
267
What are the clinical signs of tumours in internal acoustic meatus & at cerebellopontine angle?
They impinge upon CN VII & VIII giving ipsilateral facial signs (possibly effect CN V)
268
What can fractures of the cranial base affect?
- Ear
- Eye
- Nose
- Petrous temporal bone
- Orbit
- Cribriform plate
269
Describe the external structure of the ear?
Auricle & external acoustic meatus of cartilage & bone leading sound waves to tympanic membrane
270
Describe the middle structure of the ear?
Ossicles mechanically transmitting sound, connected to pharynx by auditory tube
271
Describe the internal structure of the ear?
Semi- circular canals (motion) & cochlea (hearing) converting mechanical signals to electrical carried by CN VIII
272
What groove lies posterior to petrous temporal bone & mastoid process?
Groove for sigmoid venous sinus
273
What apparatus lies within the petrous temporal bone?
Vestibulocochlear apparatus
274
Describe the structure of the auricle in the external ear?
Elastic cartilage for support & "catching" sound & funnelling it into the external acoustic meatus
275
What is the external acoustic meatus lined by?
Skin with hairs containing ceruminous glands (modified sweat glands) that secrete ear wax
276
What needs to be done to the sinuous course of the external acoustic meatus during examination?
Straightened for examination of tympanic membrane by pulling ear superiorly, posteriorly & slightly laterally
277
What nerve supplies the internal surface of tympanic membrane & middle ear?
CN IX
278
Describe the structure of the tympanic membrane?
- Held within temporal bone by fibrocartilaginous ring
- Lies at angle, facing downwards & anteriorly
- External skin, then a thin fascia & then
mucous membrane internally
279
What is used to examine the tympanic membrane?
Otoscope
280
What does the tympanic cavity extend superiorly to?
Epitympanic recess
281
Where does the tensor tympani arise & attach?
| CN V3 via nerve to medial pterygoid
Within canal of petrous temporal bone above auditory tube & attaches to handle of malleus
282
Where does the Stapedius (CN VII) arise & attach?
Within pyramid & attaches to neck of stapes
283
What does loss of Stapedius function cause?
Hyperacusis
284
What do both Tensor tympani & stapedius muscles prevent?
Excessive movement of the ossicles
285
Describe the route of the auditory tube?
From medial wall of middle ear to nasopharynx (sensation by CN IX)
286
Describe the auditory tube?
Bony canal but then tube is cartilaginous lying between petrous temporal bone & greater wing of sphenoid
287
What does the cartilage of the auditory tube give origin to?
Levator & tensor palati that pull tube open for pressure equalisation of the middle ear (swallow while ascending in aeroplane)
288
What is the clinical significance of the position of tubal tonsil?
Swelling may obstruct the tube causing otitis media (middle ear infection)
289
The tubal tonsil & cartilage cause ________ in the nasopharynx?
Elevation
290
What can chronic middle ear infection (otitis media) cause?
Damage ossicles causing conductive deafness & these may even spread to mastoid air cells or beyond
291
Describe the anatomical relations of the middle ear?
- Thin bony roof between middle ear & middle cranial fossa (infection)
- Chorda tympani lies deep to upper portion of tympanic membrane
292
Describe the inner ear structure?
Bony labyrinth containing membranous labyrinth, perilymph & endolymph
293
What lies lateral to the inner ear?
Narrow box-like cavity of middle ear
294
What do the cochlear & vestibular aqueducts allow?
Membranous labyrinth to connect with subarachnoid space for reabsorption of peri & endolymph
295
Describe the vestibular part of CN VIII in the inner ear bony labyrinth?
Leaves semicircular canals, utricle & saccule of labyrinth & it has cell bodies clustered in ganglia in internal acoustic meatus
296
What is the cochlear part of CN VIII derived from?
Organ of Corti in the cochlea
297
Describe the anterior & posterior chambers of the eyeball?
- Separated by iris
- Communicate via pupil
- Contain aqueous humour
298
Describe the layers of the eyeball?
- Sclera forms outer fibrous layer (replaced by the cornea anteriorly)
- Then the vascular choroid layer before the innermost retina
299
What does the choroid continue as in the anterior segment of the eyeball?
Ciliary body which forms a supportive ring around the lens & iris
300
What happens when the ciliaris muscle in the anterior segment of the eyeball contracts?
(parasympathetic, CN III, Edinger-Westphal nucleus)
Ring shrinks, suspensory ligaments relax, & lens becomes rounded (accommodation for close vision)
301
What 2 muscles does the iris have?
1. Sphincter pupillae (parasympathetic, CN III, Edinger-Westphal nucleus)
2. Dilator pupillae (sympathetic)
302
What secretes aqueous humour?
Ciliary body
303
How is the aqueous humour reabsorbed?
By scleral venous sinus (canal of Schlemm)
304
What results in Glaucoma?
Excess pressure: drugs that constrict the pupil may ‘pull’ the venous sinus open & help
305
Describe the optic disc from an ophthalmoscopic view?
- ‘Entry’ of optic nerve & central retinal vein with artery which is an end/terminal artery (obstruction= blindness)
- Lacks photoreceptors & often referred to as the ‘blind spot’
306
Describe the clinical macula from an ophthalmoscopic view?
Corresponding to the anatomical fovea centralis which is the region of greatest visual sensitivity (thinnest retina)
307
Describe the retina from an ophthalmoscopic view?
- Anteriorly retina is non-optic but optic posterolaterally
| - Inner neural layer may separate (detached retina)
308
How to the rods in the retina look from an ophthalmoscopic view?
Dim light, not colour
309
How do the cones in the retina look from an ophthalmoscopic view?
Bright light & colour
310
What gives rise to the fibres of the optic nerve (CN II)?
Receptors in the retina
311
What can strokes damaging the optic radiation/occipital cortex result in?
Loss of upper/lower parts of appropriate visual field= QUADRANTANOPIA
312
What is the origin of foramen ceacum?
Midline thyroid
313
Describe the development of the tongue?
- Swellings develop (lateral lingual x2, tuberculum impar, copula, epiglottal)
- 1st arch body of the tongue
- Tissue of 3rd arch overgrows 2nd arch
- Terminal sulcus becomes junction between 1st & 3rd arch mesenchyme
314
What is the general sensation of the anterior 2/3 of the tongue, derived from the 1st arch?
Trigeminal (V)
315
What is the general sensation of the posterior 1/3 of the tongue, derived from 3rd arch?
Glossopharyngeal (IX)
316
What is the general sensation of the epiglottis/root, derived from 4th arch?
Vagus (X)- superior laryngeal nerve
317
What is the nucleus of tractus solitarius in the brainstem for?
Taste
| VII ant 1/3 tongue, IX post 1/3 tongue, X epiglottis
318
What is the commissural nucleus in the brainstem for?
Cardiovascular reflexes
| IX carotid sinus/body, X aortic arch & viscera
319
What is the hypoglossal muscle derived from?
Somites
320
Where does the thyroid originate from?
Foramen caecum caudal to the tuberculum impar (foregut endoderm origin), then migrates anteriorly
321
What is the tract of thyroid migration marked by?
Thyroglossal duct (connects thyroid with tongue)
322
What can cause Thyroid dsygenesis (abnormal development)?
Mutations in transcription factors PAX8 & TITF1 (expressed as bud descends)
323
What do follicular cells secrete?
Triiodothyronine & Thyroxine
324
Where are calcitonin producing parafollicular cells derived from?
4th pouch (ultimobranchialbody)
325
Describe a Thyroglossal cyst?
- Remnant of thyroglossal duct
- Close to midline, most found in hyoid bone region
- Moves upwards on tongue protrusion
326
What % of Thyroglossal cysts are associated with the hyoid bone?
80%
327
What pharyngeal arch are the facial prominences from?
1st arch
328
Describe the development of the face?
- Around stomodeum
- Maxillary prominences grow ->> midline
- Nasal pits form surrounded by medial/lateral prominences
10th week
329
How is the upper lip formed?
By Maxillary prominences & fusion of Medial nasal prominences (philtrum)
330
What is the 4th & 6th pharyngeal arch innervation?
- 4th superior laryngeal
| - 6th recurrent laryngeal
331
What innervates the frontonasal prominence?
Trigeminal nerve
332
What is the primary development of the palate?
Maxillary process fusion (1st arch) --> Intermaxillary segment forms philtrum/4 incisors/primary palate
333
What is the secondary development of the palate?
- Maxillary process --> palatine shelf
- Palatine shelf flips “above” tongue
- Fusion in midline and with nasal septum
334
Where is cleft lips & cleft palates more/less prevalent in the World?
- More in asia
| - Less in africa
335
What type of cleft lip is most common?
Unilateral
336
What % of cleft lip cases also have a cleft palate?
Over 50%
337
What are the associated defects for cleft lips & cleft palates?
- SYNDROMIC: Treacher Collins & Van der Woude
| - Many genes identified as affected in these syndromes (coding & non-coding regions)
338
What is it called when cleft lips & cleft palates are not associated with other defects?
NON SYNDROMIC
339
List the environmental causative factors for cleft lips & cleft palate?
- Maternal age
- Medications antiepileptic agents /corticosteroids,
- Smoking, Alcohol during pregnancy
- Maternal illness
- Maternal diabetes
- Lack of dietary folic acid
340
List the genetic causative factors for cleft lips & cleft palate?
- Aberrant gene variants are inherited from mother or father
| - Inheritance is variable, often not strictly Mendelian probably because of environmental factors
341
What are the 2 gene mutations identified for cleft lips & cleft palates?
1. PHF8 mutated in Siderius X-linked mental retardation
codes histone lysine demethylase
2. IRF6 mutated in Van der Woude syndrome
342
List the negative effects cleft lips & palates have on people?
- Difficulty feeding
- Hearing problems “glue ear”, ear infections
- Speech problems
- Dental anomalies
- Social & psychological issues
343
How can cleft lips & palates be corrected?
- Surgery from 2-6 months
| - Further operations to improve speech & correct bone growth
344
What is the purpose of the oval window of the cochlea during transmission of sound waves?
Acts as a pressure release
345
What do we mean by cognition?
The acquisition, retention & use of information that allows successful behaviour in our complex & changing environment
346
What 6 concepts does cognition encompass?
1. Perception (not the same as sensation)
2. Attention
3. Memory & learning
4. Emotion & social cognition
5. Symbolic representations (language etc.)
6. Reasoning & problem solving
347
What do primary areas receive?
Unprocessed modality data, association areas (also called higher-order areas) & sub-cortical components function to determine the perceptual qualities of the modality
348
What does the integration of modal qualities from higher-order cortex with themselves & from other sensory modalities allow for?
Appreciation of music, detection of danger, integration of other peoples behaviour
349
What is used to determine what is happening & where its happening?
Combination of processed sensory perceptions (vision, temp, sound)
350
What do sub-cortical structures & association fibres do to the information?
Move it through association cortices for processing & integration to become either a reflex or cognitive state
351
Describe the 3 steps to multi-sensory integration for motor output?
1. Sensory info about environs & body project to primary cortical areas (visual, somatosensory, auditory)
2. Processed & unprocessed info then passed to sensory association areas in parietal & temporal lobes for integration
3. Integrated info shared with supplementary motor cortex (processing info about intent in association with other frontal lobe areas) & thence to the pre- & motor cortex to make sensory input into planned integrated motor events
352
What is the McGurk Effect?
Visual sensory information is interpreted & is dominant over auditory processed information (fooled senses)
353
What is Synaesthesia?
Combo of sensory experiences from 1 sensory domain with those from another, or the mixing of 2 modalities of the same sensory domain (seeing colour come out a muscical instrument)
354
What is the most commonly studied Synaesthesia?
Colour-graphemic synaesthesia where specific black & white shapes are perceived in colour
355
What are the 2 areas in the brain for speaking works?
1. Primary motor cortex
| 2. Broca's area
356
What are the 2 areas in the brain for hearing words?
1. Auditory cortex
| 2. Wernicke's area
357
What hemisphere is dominant for speech in most people (Wada test)?
Left hemisphere
358
What way does the brain work to say written words?
Visual info passed to Wernicke's area via angular gyrus, & so on to Broca’s area etc.
359
How can Aphasia (inability to understand or produce speech) occur?
When the link between 2 areas (the arcuate faciculus) is damaged, & is typified by reduced ability to repeat spoken words
360
How does the brain work for the basis of hearing, understanding & repeating spoken words?
1. Afferent info arrives at auditory cortex & Wernicke’s area (left temporal lobe)
2. Wernicke's area comprehends words & passes the info to Broca’s area for sentence construction & syntax
3. Broca’s area stimulates motor cortex to control the lips & tongue etc.
361
What is Wernicke's aphasia?
- Speech fluent but nonsensical
- Wrong or invented words
- Comprehension lost
- Here's other people speak gibberish
362
What is Broca's aphasia?
- Also known as motor/non-fluent aphasia
- Difficulty speaking (stuttering to find the right word)
- Patients aware they are making little sense
- No problem responding to the spoken/written word
363
What is the function of Broca's area?
Motor programs for generation of language & sentence construction
364
What is the function of Wernicke's area?
Language comprehension
365
How are Broca's & Wernicke's areas linked?
Arcuate faciculus
366
What side of the brain is able to contribute to emotional content of language?
Right side
367
What does dysfunction of right side of the brain near Broca's & Wernicke's areas cause?
Aprosodias- robotic or monotonic speech patterns
368
What do congenitally deaf patients with damage approximating to left brain language centres show?
Signing deficits & comprehension deficits
369
What dominant hemisphere do most right handed people have (95%)?
Left hemisphere
370
What dominant hemisphere do most left handed people have?
Right hemisphere
371
Where is language produced & speech comprehended in the brain?
Dominant side of the brain (mostly the left)
372
How do you perform a Wada test?
| now normally achieved using fMRI
- 1 side of brain is anaesthetized via appropriate internal carotid & subject is tested for speech
- If the dominant side remains awake, speech is unaffected
373
When can split brain patients not verbally identify objects & why?
1. When felt behind the screen with left hand as its controlled by right brain
2. Seen with only left visual field was it cannot communicate with right brain
374
How can the right brain communicate in split brain patients?
Independently by drawing (visual task) or holding up fingers (if the hidden task was counting)
375
Describe Positron emission tomography (PET) for testing cortical function?
- Requires a cyclotron
- Poor spatial resolution
- Can localise a neurotransmitter system
376
Describe how & why MRI can be used to test cortical function?
Variations in hydrogen density provide the tone of the image
377
Describe how & why fMRI can be used to test cortical function?
- Imaging blood flow based on amount of haemoglobin /oxyhaemoglobin detected within an area
- As neural activity increases so does requirement for glucose & blood flow
378
What are meningitis symptoms in babies?
- Tense/bulging soft spot on their head
- Refusing to feed
- Irritable when picked up, with a high pitched or moaning cry
- Stiff body with jerky movements, or else floppy & lifeless
379
What is the definition of encephalitis?
Inflammation of the brain
380
What is the definition of Sepsis?
- Whole-body inflammation
| - Systemic inflammatory response syndrome (SIRS)
381
What is the blood-cerebrospinal fluid (CSF) barrier?
- Similar barrier at arachnoid membrane & in ventricles
| - Breach by infectious agents causes meningitis
382
What 3 ways can pathogens cross the brain barriers resulting in a typical inflammatory response associated with infection?
1. Growing across & infecting cells comprising barrier
2. Passive transfer in intracellular vacuoles
3. Carriage across in infected white blood cells
383
What are the lab investigations to confirm meningitis?
- BLOOD: culture, NAAT, glucose, FBC, U&E, clotting
| - CSF: white cell count, gram stain, Ziehl-Neelsen stain, India ink, NAAT
384
What are the 4 commonest bacteria which cause meningitis?
1. Neisseria meningitidis
2. Haemophilus influenzae
3. Streptococcus pneumoniae
4. Mycobacterium tuberculosis
385
What are the 3 commonest viruses which cause meningitis?
1. Enteroviruses
2. Herpes simplex 1 & 2
3. Paramyxovirus
386
What is the commonest fungus which causes meningitis?
Cryptococcus neoformans
387
What are the 3 commonest protozoa which cause meningitis?
1. Amoebae
2. Naegleria
3. Acanthamoeba
388
What are the 5 virulence factors of bacterial meningitis?
1. Anti-phagocytic polysaccharide capsule 2. Endotoxin
3. IgA protease
4. Outer membrane proteins (OMPs)
5. Pili (fimbriae)
389
Describe the effect on CSF with bacterial meningitis?
- Turbid appearance
- Polymorphs
- Increased protein
- Reduced glucose
- Gram negative stain
- Neutrophilia
390
Describe the effect on CSF with viral meningitis?
- Clear appearance
- Lymphocytes
- Slight increase in protein
- Normal glucose
- Normal white cell count
391
What 3 pathogens commonly cause bacterial meningitis in neonates?
1. Escherichia coli
2. Group B Streptococcus
3. Listeria monocytogenes
392
What 2 pathogens commonly cause bacterial meningitis in <5yrs old?
1. Neisseria meningitidis 2. Haemophilus influenzae
393
What pathogen commonly causes bacterial meningitis in young adults?
Neisseria meningitidis
394
What 2 pathogens commonly cause meningitis in older people?
1. Streptococcus pneumoniae
| 2. Listeria monocytogenes
395
What 2 pathogens commonly causes meningitis in immunosuppressed people?
1. Mycobacterium tuberculosis
| 2. Cryptococcus neoformans
396
What are the possible complications with bacterial meningitis?
- Sepsis
- Intellectual deficit
- Deafness
- Arthritis
- Skin necrosis
397
How do you treat suspected meningococcal infection?
- IV/IM Penicillin (by GP on pre-admission)
| - IV Ceftriaxone (on admission)
398
List the 6 different vaccines available for bacterial meningitis?
1. MenC (meningococcal group C)
2. Hib (Haemophilus influenzae type B)
3. BCG (Mycobacterium tuberculosis)
4. Strep. Pneumoniae (pneumonococcal)
5. MenB (meningococcal group B)
6. Men ACWY (quadrivalent)
399
How should you notify when you have a patient who is positive for meningitis?
1. Reference Laboratories
2. Public Health Action
3. Public Awareness
400
Describe Viral meningitis?
- Milder disease than bacterial but more common
- NAAT is diagnostic tool
- Identify in faeces, urine, CSF, serology
- No specific treatment
- Aciclovir (herpes)
- Use of vaccination (polio)
401
Describe Tuberculous meningitis?
- Frequently associated with miliary TB
- Usually develops when Rich focus discharges contents in sub-arachnoid space
- Acid-fast bacilli in CSF smear
- CSF NAAT & culture
- Treatment: rifampicin, isonazid, pyrazinamide, ethambutol
- Vaccine: BCG
402
What is usually the origin for encephalitis?
Viral (through blood or neurons)
403
What is primary encephalitis?
First exposure to virus results in virus directly
| affecting brain / spinal cord
404
What is secondary encephalitis?
Virus first infects another part of body, then affects CNS when reactivated
405
What are the signs of cerebral dysfunction in encephalitis?
- Abnormal behaviour
- Seizures
- Altered consciousness - Nausea
- Vomiting
- Fever
406
Describe the development of a brain abscess?
- Begin as diffuse inflammation of brain matter progressing to focal lesion
- From pia mater suppuration
407
How are brain abscesses diagnosed?
Culture from aspirated pus (visualised by MRI or CT scans)
408
What are the 3 predisposing factors for brain abscesses?
1. Otitis media
2. Mastoiditis
3. Sinusitis
409
What 2 different oral-nasopharyngeal microbiota can cause brain abscesses?
1. Aerobic (S. aureus, Strep. milleri)
| 2. Anaerobic (Bacteroides sp., Fusobacterium sp.)
410
What 2 are the different causes of brain abscesses in the immunocompromised?
1. Protozoa (Toxoplasma gondii)
| 2. Fungi (Candida sp., Nocardia sp., Aspergillus sp.)
411
What are transmissible spongiform encephalopathies (TSE's)?
Prion diseases
412
What 2 ways can Transmissible Spongiform Encephalopathies (TSEs) affect humans?
1. Creutzfeldt-Jakob disease (CJD)
| 2. New variant Creutzfeldt-Jakob disease (nvCJD)
MD4001
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