Nervous System ELM 3 > Assisted Self Learning > Flashcards

Assisted Self Learning Flashcards

(57 cards)

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1
Q

What are the three purely sensory cranial nerves?

A
  • CrN 1 - Olfactory nerve
  • CrN 2 - Optic nerve
  • CrN 8 - Vestibulocochlear

These cranial nerves serve special senses.

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2
Q

What are the three purely somatic motor nuclei?

A
  • CrN 4 - Trochlear
  • CrN 6 - Abducens
  • CrN 12 - Hypoglossal

These cranial nerves control extraocular muscles and tongue movement.

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3
Q

Fill in the blank: The Olfactory nerve (I) is purely __________.

A

sensory

The sense of smell is relatively poorly developed in humans.

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4
Q

What is the pathway of the Olfactory nerve (I)?

A
  • Central processes form bundles of axons
  • Pass through cribriform plate
  • Synapse in the olfactory bulb
  • Converge on secondary sensory neurones

This enhances the sensitivity of the sense of smell.

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5
Q

What is the function of the Nucleus of tractus solitarius?

A
  • Taste
  • Visceral sensation

It receives input from cranial nerves VII, IX, X, and Cr XI.

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6
Q

What are the inputs to the Nucleus of tractus solitarius?

A
  • Cranial nerve VII (taste only)
  • Cranial nerve IX
  • Cranial nerve X
  • Cranial nerve Cr XI (taste & general visceral sensation)

This nucleus extends through most of the medulla.

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7
Q

True or false: The olfactory sensation is relayed through the thalamus.

A

FALSE

Olfactory sensation is the only form of sensation not relayed through the thalamus.

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8
Q

What are the clinical implications of olfactory nerve damage?

A
  • Anosmia
  • Rhinorrhea
  • Meningitis

Head injuries may tear olfactory nerves, leading to these conditions.

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9
Q

What does the Dorsal motor nucleus of vagus provide?

A

Motor output to the viscera

It includes parasympathetic preganglionics.

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10
Q

What is the function of the Nucleus ambiguus?

A

Motor to branchial skeletal muscles

It innervates muscles of the pharynx and larynx.

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11
Q

What are the general visceral sensations processed by the Nucleus of tractus solitarius?

A
  • Stretch
  • Chemoreception

These sensations are related to the viscera.

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12
Q

What is the function of the solitary nucleus?

A
  • Reflex responses to taste sensation
  • Salivation (salivatory nuclei)
  • Chewing, swallowing, moving food with tongue

Taste sensations come in along three cranial nerves and are projected bilaterally, making total loss rare.

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13
Q

Which cranial nerves are associated with taste sensations?

A
  • VII (Facial)
  • IX (Glossopharyngeal)
  • X (Vagus)
  • Cr XI

These nerves carry taste sensations from different regions of the tongue and throat.

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14
Q

What are the outputs from the solitary nucleus primarily responsible for?

A
  • Establishing direct reflexes with major visceral motor nuclei
  • Connections with brainstem centers for respiratory & cardiovascular control
  • General conscious awareness of visceral state

Projections go to the hypothalamus & cingulate gyrus.

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15
Q

What is the Dorsal Motor Nucleus of the Vagus responsible for?

A
  • Supplies preganglionic parasympathetic fibers to the viscera
  • Contains preganglionic nerve cells

It is the major autonomic motor nucleus of the brainstem.

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16
Q

What are the functions of the Nucleus Ambiguus?

A
  • Motor input to muscles of throat and larynx
  • Critical for swallowing and breathing

The nucleus extends throughout the medulla.

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17
Q

True or false: A stroke affecting one hemisphere will cause paralysis of critical muscles innervated by the nucleus ambiguus.

A

FALSE

Input to the motor neurons of nucleus ambiguus is roughly equal from both cerebral hemispheres.

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18
Q

What types of somatic sensory information are conveyed by the cranial nerves?

A
  • Discriminative sensation
  • Pain
  • Temperature

The trigeminal nerve is the main nerve involved, along with facial (VII), glossopharyngeal (IX), and vagus (X) nerves.

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19
Q

The trigeminal nerve has three divisions. Name them.

A
  • Ophthalmic
  • Maxillary
  • Mandibular

Each division carries sensory information from different regions of the face.

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20
Q

What is the primary sensory neuron location for the trigeminal nerve?

A

Trigeminal ganglion

The ganglion is located on the anterior surface of the petrous temporal bone.

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21
Q

What is the chief or pontine nucleus responsible for?

A
  • Discriminative sensation

Large diameter myelinated axons in CrN V terminate mostly in this nucleus.

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22
Q

What is the role of the mesencephalic nucleus?

A
  • Proprioception from jaw muscles

It extends from the rostral pons into the midbrain.

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23
Q

What is the function of the nucleus of the spinal tract?

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A
  • Pain and temperature sensation

It extends from the pons down into the cervical spinal cord.

24
Q

What is a notable clinical syndrome involving the trigeminal nerve?

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A

Trigeminal neuralgia

Characterized by sharp, lancinating pain in the face, usually in the maxillary or mandibular region.

25
What is the **corneal reflex**?
* Stimulus: Irritation of cornea * Afferents: Pain axons in the ophthalmic division of V * Efferents: To orbicularis oculi via CrN VII to close eyes ## Footnote It is a reflex connection involving the trigeminal and facial motor nuclei.
26
What is the **ventral trigeminothalamic tract** responsible for?
* Consciousness of sensation ## Footnote It runs close to the medial lemniscus and projects to the thalamus.
27
What happens if there is a **lesion** to the trigeminal nerve in the periphery?
Lose all modalities in that distribution ## Footnote Lesions to the brainstem may result in loss of pain but not other sensations.
28
What is the **major somatic sensory nerve** of the face?
Trigeminal nerve (V) ## Footnote It also has motor functions, innervating muscles of mastication and others.
29
List the **motor aspects** of the trigeminal nerve.
* Muscles of mastication * Muscles in the floor of the mouth * Tensor tympani ## Footnote The trigeminal nerve is primarily sensory but has significant motor functions.
30
Where is the **trigeminal motor nucleus** located?
Mid-pons ## Footnote It lies next to the chief sensory nucleus at the entry point of the Vth nerve.
31
What happens in a **LMN lesion** of the trigeminal nerve?
* Paralysis on the side of injury * Atrophy of jaw muscles * Jaw deviation on protrusion ## Footnote This occurs due to unopposed action of the intact side's protrusor muscles.
32
What is the **function** of the facial nerve (VII)?
Major motor nerve of the head ## Footnote It innervates muscles of facial expression and the scalp.
33
What are the **muscles innervated** by the facial nerve?
* Muscles of facial expression * Muscles of the scalp * Stylohyoid muscle * Platysma * Stapedius muscle ## Footnote The facial nerve has both motor and sensory functions.
34
What is the **clinical outcome** of a LMN lesion of the facial nerve?
* Flaccid paralysis of upper and lower face on the same side * Muscle atrophy ## Footnote This condition is often referred to as Bell's palsy.
35
What does the **hypoglossal nerve (XII)** control?
Intrinsic and extrinsic muscles of the tongue ## Footnote It is a purely somatic efferent nerve.
36
Where does the **hypoglossal nucleus** extend?
Throughout the medulla ## Footnote The rostral tip lies under the hypoglossal trigone in the floor of the IVth ventricle.
37
What is the effect of a **LMN lesion** on the hypoglossal nerve?
* Ipsilateral paralysis of the tongue * Atrophy of the tongue * Deviation towards the paralysed side ## Footnote This occurs due to unopposed action of the intact side's protrusor muscle.
38
What are the **cranial nerves** responsible for eye movement?
* Oculomotor nerve (III) * Trochlear nerve (IV) * Abducens nerve (VI) ## Footnote These nerves supply the extra-ocular muscles.
39
What is the **function** of the oculomotor nerve (III)?
* Supplies extra-ocular muscles * Responsible for pupillary constriction and accommodation ## Footnote It carries a preganglionic parasympathetic outflow.
40
What happens in a **LMN lesion** of the abducens nerve (VI)?
* Inability to direct the eye laterally * Diplopia (double vision) * Medial squint in affected eye ## Footnote This occurs due to weakness of the lateral rectus muscle.
41
What is the **location** of the trochlear nucleus?
Midbrain ## Footnote It is responsible for innervating the superior oblique muscle.
42
Where is the **trochlear nucleus** located?
In the midbrain, at the level of inferior colliculus ## Footnote The trochlear nerve has an unusual pathway as its fibres decussate before exiting from the brainstem.
43
What muscle does the **trochlear nerve** innervate?
Superior oblique muscle ## Footnote This muscle's action is strongest when the eye is directed medially.
44
What are the symptoms of an **LMN lesion** of the trochlear nerve?
* Blurred vision when the eye is directed medially and downwards * Difficulty walking downstairs or reading ## Footnote These symptoms are due to the impaired function of the superior oblique muscle.
45
What are the components of the **oculomotor nerve**?
* Somatic motor component * Parasympathetic component ## Footnote The somatic motor component controls eye movements, while the parasympathetic component is involved in pupil constriction and lens accommodation.
46
What does the **Edinger Westphal nucleus** contain?
Preganglionic parasympathetic neurones ## Footnote These fibres pass to the ciliary ganglion in the orbit.
47
What is the function of the **ciliary ganglion**?
* Sends postganglionic fibres to the pupillary constrictor muscle * Sends postganglionic fibres to the ciliary muscle ## Footnote Contraction of these muscles results in pupillary constriction and lens accommodation.
48
What are the two types of **pupillary reflexes**?
* Light reflex * Accommodation reflex ## Footnote The light reflex is more clinically significant as it tests brainstem integrity.
49
What happens during the **pupillary light reflex**?
* Pupil constricts in response to bright light * Constriction occurs in both the stimulated eye and the contralateral eye ## Footnote This reflex does not require cortical consciousness.
50
What might the **absence of a light reflex** indicate?
* Retinal blindness or lesion of the optic nerve * Lesion of the third nerve * Damaged brainstem ## Footnote Absence of the reflex is a poor prognostic sign.
51
What is the **pupillary accommodation reflex**?
* Accommodates the lens for close vision * Deviates both eyes medially * Constricts the pupil slightly ## Footnote This reflex is initiated by blurring of the visual field and is less clinically significant.
52
What are the symptoms of an **LMN lesion** of the oculomotor nerve?
* Eye directed laterally at rest * Very restricted eye movement * Severe diplopia * Severe droop of the eyelid (ptosis) * Fixed dilated pupil (mydriasis) ## Footnote These symptoms occur on the damaged side only.
53
What are the two major areas of **cortex** involved in control of eye movements?
* Frontal eye field * Occipital eye field ## Footnote The frontal eye field initiates voluntary movements, while the occipital eye field controls involuntary movements.
54
What does the **medial longitudinal fasciculus (MLF)** do?
Links cranial nerves III, IV, and VI ## Footnote It coordinates eye movements with head rotation.
55
What is the role of the **Paramedian Pontine Reticular Formation (PPRF)**?
Coordinates lateral gaze movements ## Footnote It receives input from the cortex and vestibular nuclei.
56
What happens if there is damage to the **frontal eye field**?
Gaze cannot be voluntarily directed to the opposite side ## Footnote The direction of gaze is fixed towards the side of the lesion.
57
What is the function of the **superior colliculus**?
* Locates retinal position of objects * Coordinates visual input with eye movement * Establishes protective reflexes ## Footnote Its ultimate importance in humans is unclear, and damage results in surprisingly little loss of function.
Nervous System ELM 3
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