Anatomy of CNIX to CNXII

Question 1

Where do the bulbar nerves arise from?

Answer 1

The medulla oblongata

Question 2

What is Bulbar palsy and what causes it?

Answer 2

Arises from a lesion of the medulla or lesion of cranial nerve nuclei medulla
Signs are usually progressive e.g., difficulties swallowing, loss of speech, weakening of the tongue. Considered a variant of motoneuron disease.

Question 3

What is jugular foramen syndrome?

Answer 3

Refers specifically to paralysis to the cranial nerves passing through the jugular foramen, CNIX, CNX, CNXI

Question 4

What does glossopharyngeal nerve mean?

Answer 4

Nerve for the tongue and pharynx

Question 5

What are the 2 swellings in the glossopharyngeal nerve?

Answer 5

One is the superior (jugular) ganglion - just before it’s emergence from the foramen
Other is the inferior (petrous) ganglion - much larger and more constant

Question 6

What do the swellings of the glossopharyngeal nerve contain?

Answer 6

Ganglia so they contain cell bodies of afferents of the nerve

Question 7

What is the motor component of the glossopharyngeal nerve?

Answer 7

Banchiomotor fibres supply stylopharyngeus
Visceromotor (parasympathetic) fibres supply the parotid gland (via the optic ganglion)

Question 8

What is the sensory component of the glossopharyngeal nerve?

Answer 8

Viscerosensory fibres supply carotid body and carotid sinus (VSA)
Pharynx (around tonsillar part) and middle ear (GSA)
Special sensory (and general sensory) fibres supplied to posterior1/3G of the tongue (SSA)

Question 9

What fibre types does the glossopharyngeal nerve carry?

Answer 9

SVE, GVE, GVA, SVA, GSA

Question 10

What are the nuclei for glossopharyngeal?

Answer 10

Inferior salivatory nucleus, nucleus ambiguus, nucleus tractus solitarius

Question 11

What fibres come from or to the inferior salivatory nucleus?

Answer 11

Origin of pre-ganglionic parasympathetic efferent fibres for distribution to the optic ganglion. Will supply the parotid gland via the lesser superficial petrosal nerve.

Question 12

What fibres come from or to the nucleus ambiguus?

Answer 12

Efferent nerve fibres to the stylopharyngeus

Question 13

What fibres come from or to the nucleus tractus solitarius?

Answer 13

Visceral sensory fibres including taste fibres

Question 14

How does CNIX exit the cranial compartment?

Answer 14

Formed by 5/6 rootless which emerge from the side of the medulla in line with those which form the vagus nerve. Passes through the jugular foramen. Leaves the intracranial space in a separate sheath of dura mater (to X and XI), and occupies a groomer on the lower border of the petrous temporal bone.

Question 15

What does the inferior ganglion of CNIX communicate with?

Answer 15

The superior cervical ganglion, auricular branch of vagus nerve, superior ganglion of vagus nerve

Question 16

How do the somatic sensory fibres of CNIX distribute?

Answer 16

It is through the communication with the auricular branch of the vagus nerve that the somatic sensory fibres of glossopharyngeal nerve distribute.

Question 17

What are the branches of the glossopharyngeal nerve?

Answer 17

Sinus nerve, nerve to stylopharyngeus, tympanic branch, pharyngeal branches, lingual branch

Question 18

What does the sinus nerve supply?

Answer 18

Carotid sinus and carotid body

Question 19

What does nerve to stylopharyngeus supply?

Answer 19

Stylopharyngeus, tonsillar bud, pharynx, parts of the tongue

Question 20

What does the tympanic branch supply?

Answer 20

Tympanic plexus
Branch of this carries on to constitute the lesser superficial petrosal nerve

Question 21

What do the pharyngeal branches supply?

Answer 21

3/4 twigs which join with the the pharyngeal branches of the vagus and of the cervical sympathetic trunk on the middle constrictor muscle to form the pharyngeal plexus

Question 22

What does the lingual branch supply?

Answer 22

Provides afferent fibres for taste to the circumvallate papillae (SVA) and general afferent neurones to the mucous membrane of posterior 1/3 of the tongue.

Question 23

Test for CNIX

Answer 23

Test for CNIX function is the gag reflex - pharyngeal reflex. Consists of reflex pharyngeal constriction when the back wall of the oropharynx is touched by non-food substances. CNIX is the sensory limb of this reflex (CNX is the motor limb of this reflex). Swallowing has a voluntary element to it.

Question 24

What are the 2 motor nuclei of the vagus nerve?

Answer 24

Dorsal nucleus of vagus nerve - parasympathetic output to viscera
Nucleus ambiguus - branchial efferent motor fibres and preganglionic parasympathetic neurones that innervate the heart

Question 25

What are the sensory nuclei of CNX?

Answer 25

Nucleus solitarius - receives afferent taste information and primary afferents from visceral organs Spinal trigeminal nucleus - receives information about deep/crude touch, pain and temperature of the outer ear, the dura of the posterior cranial fossa and the mucosa of the larynx

Question 26

How does CNX leave the jugular foramen?

Answer 26

Contained in the same dural sheath as CNXI. Separated by a fibrous septum.

Question 27

How does CNX arise intracrnially?

Answer 27

By convergence of 8-10 rootlets which merge from the medulla in the groover dorsal to the inferior olive.

Question 28

Describe the superior sensory ganglion/jugular ganglion

Answer 28

Spherical swelling on vagus in the jugular foramen. Cell bodies are general somatic afferent component of the nerve.

Question 29

Describe the inferior sensory ganglion (nodose ganglion)

Answer 29

After exit from the foramen. Cell bodies are concerned with the visceral afferent component.

Question 30

What are the branches of the vagus nerve?

Answer 30

Meningeal branches, auricular branches whilst in jugular fossa In the neck: pharyngeal branches, laryngeal branches, cardiac branches

Question 31

What would damage to the right recurrent laryngeal nerve cause?

Answer 31

The vocal cord on that side (ipsilateral) is slightly adducted; symptoms are hoarse voices weak cough, risk of aspiration of fluids

Question 32

What would damage to the left recurrent laryngeal nerve cause (lower than right)?

Answer 32

May be affected in a bronchial or oesophageal carcinoma or enlarged mediastinal lymph nodes or become stretched over an aneurysm of the aortic arch.

Question 33

What do the motor modalities of CNX supply?

Answer 33

Intrinsic muscles of larynx and pharynx Muscles of the palate Smooth muscle - bronchi, digestive tract Secretomotor - thoracic and abdominal viscera

Question 34

What do the sensory fibres of CNX supply?

Answer 34

External ear, auditory canal, eardrum Pharynx and larynx Visceral sensation - thorax and abdomen

Question 35

What is the cranial division of accessory nerve CNXI.

Answer 35

Smaller root. Originates in the medulla from nuclei just below those of the vagus nerve.

Question 36

What is the spinal division of CNXI?

Answer 36

Larger root. Originates from the spinal cord, as 12 rootlets from upper cervical neural segments. Enters cranium via foramen magnum.

Question 37

Where do the 2 roots of CNXI split?

Answer 37

The 2 divisions combine near the jugular foramen. As they exit the jugular foramen, they split again. Cranial division joins the inferior ganglion of CNX to be distributed via pharyngeal and recurrent laryngeal nerves. Spinal division descends and leaves the cranium as CNXI via jugular foramen.

Question 38

What does CNXI supply?

Answer 38

Motor nerve supplying SCM a and trapezius.

Question 39

How to test for CNXI?

Answer 39

Inspect wasting of SCM and trapezius. Test for weakness. SCM - ask patient to rotate head against resistance Trapezius - shrug shoulder against resistance

Question 40

What is the nucleus of the hypoglossal nerve?

Answer 40

It’s somata constitute the hypoglossal motor nucleus.

Question 41

What does CNXII communicate with?

Answer 41

It communicates by numerous small branches with its inferior ganglion. Opposite the atlas it has communication with the superior cervical sympathetic ganglion Also opposite the atlas it is joined by a nerve derived from a loop between C1 and C2, which brings its sensory fibres from the meningeal branches and provide muscular fibres for the suprahyoid and infrahyoid muscles which are innervated through the superior ramus of the ansa cervicalis

Question 42

What do the terminal branches of CNXII distribute to?

Answer 42

Styloglossus, hyoglossus, genioglossus, intrinsic muscles of the tongue - completely motor Communicates with sensory branches of the lingual nerve

Question 43

What does damage to CNXII cause?

Answer 43

Causes dysarthria

Question 44

How do you inspect dysarthria?

Answer 44

Inspect by asking patient to protrude the tongue. Inspect for tongue wasting and fasciculations. In LMN lesions, the tongue deviates to the side of weakness.

Question 45

Brief course of hypoglossal nerve

Answer 45

Emerges from hypoglossal canal and is medial to ICA and IJV. Descends behind these vessels and passes posterior to the vagus.