Cranial Nerves: Descending nerves

Question 1

What are the divisions of the nervous system?

Answer 1

• Sympathetic (thoracolumbar)

* Parasympathetic (craniosacral)

Question 2

Where are the cell bodies of the sympathetic system located?

Answer 2

In the lateral horn of T1-L2 spinal cord segments

Question 3

Where are the cell bodies of the parasympathetic nervous system located?

Answer 3

In the brain stem or s2-4 spinal cord segments

Question 4

Where are the sympathetic ganglia located?

Answer 4

Close to the vertebral column

Question 5

Describe the sympathetic neurone chain

Answer 5

• Short pre-synaptic fibres (pre-ganglionic) emerge from the cord and pass to the sympathetic trunk in the white rami communicantes
• Long post synaptic fibres - after synapsing in a ganglion, fibres from the grey ramus communicantes join a spinal nerve
• Then it is distributed to the body wall

Question 6

Where do the sympathetic chains fuse?

Answer 6

At the ganglion impair, opposite the coccyx

Question 7

Sympathetic ganglia

Answer 7

• Superior cervical ganglion: C1- C4
• Middle cervical ganglion: C5, C6
• Inferior cervical ganglion: C7,C8
• Stellate ganglion is formed from the inferior cervical ganglion and T1 (C7,8)

Question 8

What are the symptoms of Horner’s syndrome?

Answer 8

• Ptosis
• Pupillary constriction
• Anhydrosis
• Flushing of the face

Question 9

Where are the parasympathetic ganglia located?

Answer 9

Close to the organ

Question 10

Which of the cranial nerves contain parasympathetic fibres?

Answer 10

• CN III oculomotor
• CN VII facial
• CN IX glossopharyngeal
• CN X Vagus

Question 11

What and where is the nucleus for oculomotor?

Answer 11

• In the Midbrain

* Autonomic nucleus - Edinger Westphall

Question 12

What are the afferents of the oculomotor nerve?

Answer 12

• From the cortex and pretectal nucleus bilaterally

Question 13

Describe the course of oculomotor

Answer 13

• In the interpeduncular fossa, it runs between the superior cerebellar and inferior cerebral arteries
• Runs in the lateral wall of the cavernous sinus
• Travels through the superior orbital fissure into the orbit

Question 14

Superior ramus of the oculomotor nerve

Answer 14

• Motor fibres to levator palpebra superioris

* Sympathetic fibres from the superior cervical ganglion to the same muscle

Question 15

Inferior ramus of the oculomotor nerve

Answer 15

• Parasympathetic fibres which synapse in the ciliary ganglion
• Post synaptic fibres join short ciliary nerves which run alongside the long ciliary nerves and ciliary artery, enter the eyeball and supplies the ciliary muscle and sphincter pupilla

Question 16

Describe the route of the impulse in the light reflex

Answer 16

• Optic nerve
• Optic tract
• Pretetal area: pretectal nucleus
• Edinger Westphal bilaterally
• Oculomotor nerve
• Ciliary ganglion
• Short ciliary nerves
• Pupillary constrictor

Question 17

Describe the results of injury to the oculomotor nerve

Answer 17

• No parasympathetic input for pupillary constriction - dilated pupil
• Loss of motor innervation to levator palpebral superioris - ptosis
• Loss of motor innervation to extra ocular muscles except superior oblique and lateral rectus - eye turns down and out

Question 18

Where and what is the nucleus of the facial nerve?

Answer 18

• Superior salivatory nucleus in the pons

Question 19

Where does the facial nerve exit the brainstem?

Answer 19

• Pontocerebellar angle

Question 20

Describe the course of the facial nerve

Answer 20

• Enters the internal acoustic meatus
• Parasympathetics are found in n.intermedius through the facial canal
• Greater petrosal nerve joins the deep petrosal in the foramen lacer to form the nerve of the pterygoid canal
• Synapses at the pterygopalatine ganglion

Question 21

What supplies the submandibular and sublingual salivary glands?

Answer 21

• The lingual nerve (branch of the facial) carries parasympathetic from the facial nerve, secretomotor supply to the submandibular glands

Question 22

Where and what is the nucleus of the glossopharyngeal nerve?

Answer 22

• Inferior salivatory nucleus

* In the medulla

Question 23

Where does the glossopharyngeal nerve leave the brainstem?

Answer 23

Posterior to the olive

Question 24

Which nerves pass through the jugular foramen (+vessel)?

Answer 24

• Glossopharyngeal
• Vagus
• Accessory nerve
(• Internal jugular vein)

Question 25

Describe the course of the glossopharyngeal nerve

Answer 25

• Inferior to the jugular foramen, gives off the tympanic nerve which forms the tympanic plexus giving off the lesser petrosal , synapses in the optic ganglion
• Post synaptic fibres join the auriculotemporal nerve and it innervates the parotid gland