Neuroscience Anat (CN IX, X, XI, XII)

Question 1

RECALL:
State the structures that pass through
1. optic canal
2. superior orbital fissure
3. foramen rotundum
4. foramen ovale
5. internal acoustic meatus
6. jugular foramen
7. hypoglossal canal

Answer 1

State the structures that pass through
1. optic canal - CN II, ophthalmic A
2. superior orbital fissure - CN III, IV, V1, VI, ophthalmic V
3. foramen rotundum - CN V2
4. foramen ovale - CN V3
5. internal acoustic meatus - CN VII, VIII, labyrinthine A, labryinthine V
6. jugular foramen - CN IX, X, XI, IJV
7. hypoglossal canal - CN XII

Question 2

RECAP: CN IX - GLOSSOPHARYNGEAL NERVE
- State the sensory functions
- State the motor functions
- State the pathways involved

Answer 2

CN IX - GLOSSOPHARYNGEAL N
- Somatosensory = posterior 1/3 of tongue, ear and pharynx
- Special sensory = taste of posterior 1/3 of tongue
- Viscerosensory = carotid sinus
- Somatomotor = stylopharyngeus
- Visceromotor = parotid gland

SOMATOSENSORY:
glossopharyngeal G –> spinal nucleus of V –> thalamus –> sensory cortex

SPECIAL SENSORY
glossopharyngeal G –> nucleus of tractus solitarius –> thalamus –> sensory cortex

VISCEROSENSORY
glossopharyngeal G –> nucleus of tractus solitarius –> dorsal vagal nucleus –> visceral efferent pathway

SOMATOMOTOR
bilateral UMN supply –> nucleus ambiguus –> stylopharyngeus

VISCEROMOTOR
salivatory Nc –> otic ganglion –> parotid gland

Question 3

Recap: CN X - VAGUS NERVE
- State the sensory functions
- State the motor functions
- State the pathways involved

Answer 3

CN X - VAGUS NERVE
- Somatosensory = external ear, larynx
- Special sensory = taste for epiglottis
- Viscerosensory = distal organs (heart, lungs, digestive system)
- Somatomotor = all pharynx mucsles except stylopharyngeus, all palate muscles except tensor tympani, all larynx muscles, palatoglossus
- Visceromotor = distant organs

SOMATOSENSORY
External ear and larynx –> vagal ganglion –> spinal nucleus of V –> thalamus –> sensory cortex

SPECIAL SENSORY
Epiglottis –> vagal ganglion –> nucleus of tractus solitarius –> thalamus –> sensory cortex

VISCEROSENSORY
distal organs –> vagal ganglion –> nucleus of tractus solitarius –> thalamus –> sensory cortex

SOMATOMOTOR
bilateral UMN supply –> LMN supply (nucleus ambiguus) –> muscles

VISCEROMOTOR
bilateral UMN supply –> LMN supply (dorsal vagal nucleus) –> ____ ganglion –> target organs

Question 4

Recap: CN XI - SPINAL ACCESSORY NERVE
- State the sensory functions
- State the motor functions
- State the pathways involved

Answer 4

CN XI - SPINAL ACCESSORY NERVE
- No sensory function
- Somatomotor = trapezius, SCM

SOMATOMOTOR
Bilateral UMN supply –> spinal accessory nucleus –> muscles

Question 5

Recap: CN XII - HYPOGLOSSAL NERVE
- State the sensory functions
- State the motor functions
- State the pathways involved

Answer 5

CN XII - HYPOGLOSSAL N
- Somatomotor = all muscles in tongue except palatoglossus
- No motor functions

SOMATOMOTOR
bilateral UMN supply –> LMN (hypoglossus nucleus) –> muscles

Question 6

State the 2 viscerosensory reflexes. State the pathways involved.

Answer 6

(1) VISCEROSENSORY AFFERENT REFLEX
- carotid body and sinus
- 1st order neuron = inferior hypoglossus ganglion
- 2nd order neuron = nucleus of tractus solitarius

• aortic body and sinus
• 1st order neuron = inferior vagal ganglion
• 2nd order neuron = nucleus of tractus solitarius

(2) VISCEROSENSORY EFFERENT REFLEX
- preganglionic neuron = dorsal vagal nucleus
- postganglionic neuron = cardiac ganglion

• VISCERAL REFLEX FIBRES TRAVEL WITH PARASYMPATHETIC FIBRES