Cranial Nerves VI - XII

Question 1

CN VI function

Answer 1

Lateral rectus muscle (motor). GSE

Question 2

Which muscle moves the eye out (abducts laterally)

Answer 2

Lateral rectus

Question 3

What is the facial colliculus?

Answer 3

Fibers of I/L facial neurons wrapping around the abducens nucleus before exiting the brainstem

Question 4

Damage to the UMN or internal capsule of CN VI will result in?

Answer 4

No obvious deficits

Question 5

Damage to the left abducens nucleus will result in?

Answer 5

Loss of left (ipsilateral) eye abduction & right (contralateral) eye adduction–“lateral gaze policy”

Question 6

Damage to the left CN VI will result in?

Answer 6

Loss of left (ipsilateral) lateral rectus function; “Medial strabismus” causing diplopia and cross-eyed look

Question 7

Damage to the left medial longitudinal fasciculus will result in?

Answer 7

Left (ipsilateral) internuclear ophthalmoplegia: left medial movement deficits (only for coordinated medial/lateral movements). Purely medial movement (convergence will be unaffected)

Question 8

MLF interconnects nuclei of which cranial nerves?

Answer 8

Nuclei of CN 3, 4, 6. When right lateral rectus contracts (gaze right), then the left medial rectus will also contract (gaze right)

Question 9

Cranial nerves that all contain somatic and visceral sensory, visceral motor (parasympathetic), and branchial motor

Answer 9

CN 7, 9, 10

Question 10

Somatic sensory fibers of CN 7, 9, 10 enter ____ and then behave like ____

Answer 10

Spinal trigeminal tract, Trigeminal afferents

Question 11

Visceral sensory fibers of CN 7, 9, 10 enter ____ and terminate in ____

Answer 11

Solitary tract, Solitary nucleus

Question 12

CN VII function

Answer 12

Facial muscles, taste, and lacrimal/salivary glands (motor/sensory/autonomic). GSA, GSE (branchiomeric), GVE, GVA

Question 13

Corneal blink reflex connects to what structure?

Answer 13

Trigeminal tract

Question 14

Describe the sequence of corneal blink reflex

Answer 14

Sensory afferent in V1 –> spinal trigeminal nucleus –> via relays in RF –> B/L motor neurons of facial nucleus –> B/L orbicularis occuli

Question 15

Damage to the left CN 7 or facial motor nucleus will result in?

Answer 15

Left (ipsilateral) LMN damage (flaccid paralysis) Bell’s palsy

Question 16

Damage to the motor cortex or UMN of CN 7 will result in?

Answer 16

No obvious deficits for upper facial muscles. Paralysis of C/L lower facial muscles

Question 17

CN IX function

Answer 17

Pharynx (sensory/motor), taste and parotid gland (sensory/motor/autonomic). GSE (branchial), GVE, GSA, GVA

Question 18

Baroreceptors in the carotid sinus control?

Answer 18

Blood pressure

Question 19

Chemoreceptors in the carotid body control?

Answer 19

Blood gases, O2 and CO2

Question 20

Baroreceptors and chemoreceptors send information to where?

Answer 20

Hypothalamus and Reticular Formation (cardiovascular and respiratory reflexes)

Question 21

Which 3 cranial nerves enter the solitary tract and contribute to taste?

Answer 21

CN 7, 9, 10

Question 22

What is glossopharyngeal neuralgia?

Answer 22

Lesions of CN 9 can cause pain that begins in the posterior tongue/upper pharynx and radiate towards the ear. Attack may be set off by swallowing or talking. Requires pharmacological treatment or surgical lesion of spinal trigeminal tract

Question 23

Pain receptors in the pharynx, middle ear, and posterior 1/3 tongue send information to which structure in the PNS?

Answer 23

Inferior glossopharangeal ganglion

Question 24

Parotid gland (salivation) receives input from postganglionic parasympathetic neurons in which structure?

Answer 24

Otic ganglion

Question 25

In a normal individual, the gag reflex will elicit what response?

Answer 25

Bilateral elevation of pharynx

Question 26

Describe the gag reflex loop.

Answer 26

The afferent (sensory) of CN 9 and efferent (muscles) of CN 10. Tests both cranial nerves for function

Question 27

Lesions of the vagus nerve can result in what kind of autonomic problems?

Answer 27

Bilateral symptoms in thorax and abdomen

Question 28

CN 11 (accessory) function

Answer 28

SCM and trapezius (motor). GSE

Question 29

Damage of UMN before CN 11 crosses results in?

Answer 29

Bilateral weakness, most prominent on contralateral side (spastic paralysis)

Question 30

Where is the accessory nucleus located in the cervical region?

Answer 30

C1-C5

Question 31

Lesions of the accessory nucleus causes what kind of symptoms?

Answer 31

Produce dropped shoulder and inability to lift upper limb, problems with ipsilateral neck flexion (FLACCID PARALYSIS)

Question 32

CN 12 (hypoglossal) function

Answer 32

Muscles of tongue (motor) GSE; all intrinsics and most extrinsic muscles of the tongue

Question 33

Where is the hypoglossal nerve found on the brainstem?

Answer 33

Between pyramids and olives in the medulla

Question 34

Lesions of the hypoglossal nucleus produce what kind of symptoms?

Answer 34

Ipsilateral deficits: weakness and atrophy of tongue (tongue will deviate to the side of the lesion). Bilateral damage can produce difficulties in speaking and eating.

Question 35

Medial Medullary Syndrome (rostral medulla)

Answer 35

Caused by occluded anterior spinal artery or vertebral artery between pyramids. Results in C/L hemiparesis (due to damage of pyramid), C/L tactile and kinesthetic deficits (due to damage to medial lemniscus), I/L paralysis of intrinsic tongue muscles (due to damage of hypoglossal nucleus)

Question 36

Lateral Medullary Syndrome

Answer 36

Caused by occluded PICA or vertebral artery. Results in C/L body loss of pain and temp (damage to SThT), I/L face loss of pain and temp (damage to STrT), I/L paralysis of pharyngeal/laryngeal muscles (damage to nucleus ambiguus). Also problems with inferior cerebellar peduncle and vestibular nuclei (ataxia, vertigo, abnormal eye movements)

Question 37

How is Weber's Syndrome caused?

Answer 37

Lesion of cerebral peduncle in rostral midbrain caused by occluded posterior cerebral artery or posterior communicating artery

Question 38

How does Weber's syndrome present?

Answer 38

C/L spastic paralysis (corticospinal tract), I/L lateral strabismus, ptosis, and pupillary dilation (oculomotor). If lesion extends dorsally--C/L sensory deficits (STT and ML) and ataxis (superior cerebellar peduncles)