Session 6- Autonomic Innervation of Head and neck

Question 1

what is a nucleus

Answer 1

collection of nerve cell bodies within the CNS

Question 2

what is a ganglion

Answer 2

collection of nerve cell bodies outwith the CNS; either relating to autonomic nerves

Question 3

properties of the ANS

Answer 3

part of the peripheral nervous system

controls body functions not under conscious control

maintains and fine tunes internal environment

Question 4

target tissues of ANS

Answer 4

smooth muscle
cardiac muscle
glands

Question 5

what is the autonomic outflow of the PNS

Answer 5

cranial- CN X IX VII III

Sacral- S2- S4 pelvic splanchnics

Question 6

SNS outflow from CNS

Answer 6

thoracolumbar outflow

T1-L2

Question 7

Where are the cell bodies of the sns

Answer 7

lateral horn of grey matter of spinal cord between T1 -L2

Question 8

what route do the preganglionic fibres of the sympahetic NS follow

Answer 8

blood vessels

Question 9

where are the cell bodies of the post ganglionic sympathetic nerves

Answer 9

superior cervical ganglion which is in close proximity to the common carotid

Question 10

once the sympathetic nerves enter the eye what are the target structures

Answer 10

dilator pulillae

eyelid- orbicularis occuli, levator palprebrae superiosis

Question 11

describe the route of the sympathetic innervation of Head and neck structres

Answer 11

1. originate from hypotahlamus
2. descends via brainstem into spinal cord
3. synapses on to cell body of 2nd order neurone- lateral horn of grey matter
4. exits at the the T1 & 2 leve; in thoracolumbar region of spinal cord
5. enters and ascends sympathetic chain
6. at superior cervical ganglion synapses onyo the 3rd order neurone - postganglionic
7. runs with common carotid artery and then along its terminal branches to reach target tissues-
   7a. branches to the eye and orbu=it run with internal carotid artery then into orbit via opthalmic artery and distal branches of Va
   7b. branches to sweat glands on face and neck run with branches of external carotid artery

Question 12

what is horners syndroe

Answer 12

miosis-one eye more constricted
ptosis
anhydrosis

Question 13

Why does interruption of sympathetic
innervation lead to partial ptosis and not a
complete or severe ptosis ?

Answer 13

Levator Palpebrae Superioris (LPS) contracts to elevate (retract) the upper eye lid

• Two muscle types within it with variable contributions to retraction
  
  • Skeletal muscle- majority contribution
  • Smooth muscle- smaller contribution

Question 14

effector tissues of SNS in head and neck

Answer 14

eye
eye lid
blood vessels
sweat glands

Question 15

which cranial nerves carry parasympathetic fibres from the brainstem

Answer 15

CN III VII IX X

Question 16

Descrivbe route of parasympathetic nerves to head and neck

Answer 16

1. arise from brainstem from parasympathetic nuclei
2. run with one of 4 CNs
3. parasympathetic ganglia
4. join on to branches CN V
5. target tissues

Question 17

what is the key parasympathetic nuclei to know

Answer 17

Edinger Westphal- the parasympathetic fibre that arises from here runs with CN III to the ciliary ganglia to the eye where it innervates the cilary muscle and sphincter pupillae muscle

Question 18

what does the cilary muscle do

Answer 18

alters shape of lens

Question 19

what does the sphincter pupillae muscle do

Answer 19

constrictor of the pupil

Question 20

what di teh afferent fibres do

Answer 20

sensory arm

optic nerve

Question 21

what do the efferent fibres do

Answer 21

motor arm

occulomotor nerve

Question 22

describe the puilary light reflex

Answer 22

LIGHT IN LEFT PUPIL

sensory afferent from left retina- CN II

some branches leae CN II to ente rmidbrain

connection with EDW nuclei- LEFT AND RIGHT

preganglionic parasympathetic fibres from EDW leave brainstem with CN III- left and right

Pre-ganglionic parasympathetics synapse in ciliary ganglion; become post ganglionic

reach sphincter pupilae muscle of the iris

Question 23

what is the direct light reflex

Answer 23

eye in which light shone

Question 24

consensual light reflex

Answer 24

opposite eye

Question 25

A patient presents with anisocoria. You shine light in the RIGHT eye. The RIGHT pupil does not constrict but the LEFT pupil does. You shine light in the LEFT eye; the LEFT pupil constricts, but the RIGHT pupil does not.

Where is the most likely lesion?

Answer 25

efferent limb- oculomotor nerve - right eye

Question 26

what 2 branches of CN VII that arise from petrous bone do parasympathetics run with

Answer 26

greater petrousal nerve

chordae tympani nerve

Question 27

route of parasympathetics that run with the CN IX

Answer 27

arise from brainstem and exit with CNIX -jugular foramen

CN IX splits into branches one being tympanic nerve- parasympathetics run with this nerve initially

then they exit middle ear as lesser petrousal nerve

synapse at otic ganglion

supplies parotid gland

Question 28

parasympathetic component of vagus nerve

Answer 28

Brainstem (medulla)
Parasympathetics exit
with other axons forming
CN X

Pre-ganglionic
parasympathetic fibres run
within CN X and its branches

Meet ganglion at or
in target tissue

Question 29

target tissues of parasympathetic fibres of CN X

Answer 29

• mucosal glands in pharynx/larynx and smooth muscle of oesophagus and trachea
• smooth muscle and mucosal glands within rest of resp tract and GI tract
• Heart