6. ANS Of Head And Neck

Question 1

Describe the origin and route of sympathetics in the headend neck

Answer 1

1) preganglionic fibres arise from lateral horn T1/2 spinal segments of spinal cord…
2) ascend up thorax in sympathetic chain to synapse with 1 of 3 cervical ganglia (esp. superior cervical ganglion)…

3) post-ganglionic fibres hitchhike onto blood vessels forming sympathetic carotid plexus:
- ECA and its branches - sympathetics supply neck and face BV smooth muscle (vasoconstriction) and sweat glands (sweating)
- ICA - supply ICA itself and join CN III to superior tarsal muscle (eyelid retraction) or CN Va to dilator pupillae in iris (pupillary dilation)

Question 2

Describe the pathophysiology of Horner’ssyndrome

Answer 2

Unitalteral interuption of sympathetic plexus (eg due to pancoast tumour) causing:

1. Partial ptosis - paralysis of superior tarsal
2. Myosis - paralysis of dilator pupillae
3. Partial anhydrosis - loss of sweat gland innervation on ipsilateral side of face

Question 3

Which 4 cranial nerves carry parasympathetics

Answer 3

Occulomotor
Facial
Glossopharyngeal
Vagus

Question 4

Describe the course and functions CN III parasympathetics

Answer 4

• course: edinger westphal nucleus… CN III…ciliary ganglion… CN Va… eye: sphincter pupillae (SM) in iris and ciliary muscle
• functions:
  1. Pupil constriction
  2. Controls lens

Question 5

Describe the course and functions of the CN VII parasympathetics

Answer 5

Brainstem nucleus... CN VII (greater petrosal branch)... pterygopalatine ganglion... CN Vb... lacrimal and nasal mucosal glands.
                                      CN VII (chorda tympani branch)... submandibular ganglion... CN Vb... submandibular and sublingual glands.

Functions: tears and secretions

Question 6

Describe the course and functions of the CN IX sympathetics

Answer 6

Brainstem nucleus… CN IX nerve… otic ganglion… CN Vc… parotid gland

Functions: salivary secretion

Question 7

Describe the course and functions of the CN X parasympathetics

Answer 7

Course: brainstem nucleus… CNX and branches… carotid sheath… ganglia in target tissue… post-ganglionic fibres to:

• laryngopharynx and larynx glands
• oesophagus and trachea glands and SM
• heart
• respiratory and GI tract SM and glands