Lecture 11- Autonomic innervation of the head and neck

Question 1

The autonomic (visceral) nervous system made up of

Answer 1

Sympathetic and parasympathetic nervous system

Question 2

autonomic (visceral) nervous system is part of

Answer 2

• of the peripheral nervous system
  
  • Central control from hypothalamus

Question 3

autonomuc nervous system controls

Answer 3

unconscious control

Question 4

examples of unconscious control

Answer 4

• Controls body functions not under conscious control e.g. vasoconstriction and pupil reflex (smooth muscle)
• Maintains and fine tunes internal environment
  
  • Accelerator and brake

Question 5

Neurone arrangement

*

Answer 5

pre-ganglionic autonomic neurone starts in the CNS and synapse with post ganglionic nerve either in the sympathetic chain or at the organ itself

Question 6

• Sympathetic neruones preganglionic nerves synapse with post ganglionic neurones in the

Answer 6

• vertical arrangement of autonomic ganglion

Question 7

paraympathetic neruones preganglionic nerves synapse with post ganglionic neurones in the

Answer 7

• Target tissue
  
  • Smooth muscle
  • Cardiac muscle
  • Glands (lacrimal, mucosal and salivary)

Question 8

Sympathetic

*

Answer 8

• Flight or flight
• Smooth muscles of blood vessels (constriction), eye lid (tarsal muscle) and iris (dilator pupillae)
  
  • Just not in resp and GI
• Sweat glands (NOT USUALLY SALIVARY)
• Arrector pili muscles (hair follicles)
• Decrease secretions from salivary and lacrimal glands (smaller volume but higher protein-more viscous)

Question 9

Parasympathetic

Question 10

• Parasympathetic and sympathetic leave the CNS in

Answer 10

discrete regions

Question 11

sympathetics leave the CNS via

Answer 11

thoracolumbar outflow

• All sympathetic nerves leaves the CNS from segments T1-L2 ONLY
• then enter sympathetic chain

Question 12

Parasympathetic leave the CSN via

Answer 12

Craniosacral outflow

• Cranial (4 cranial nerves)
• Sacral (S2-S4)
  
  • pelvic splanchnics

Question 13

nerve sthat come out of T1/T2 are

Answer 13

destined for head and neck

Question 14

thoracolumbar t1-T2 (sympathetic innervation to the head and enck) follow

Answer 14

routes of blood vessles (hitchhike on the exteranl surface of blood vessels)

Question 15

outline how thoracolumbar T1/T2 provide symapthetic innervation to the head an enck

Answer 15

1. Pre-ganglionic sympathetic nerves exit the spinal cord T1/T2
2. Joins the sympathetic chain (one on either side of the vertebral column)
3. Top 3 ganglion (cervical ganglion) at the top of the vertebral chain (in the neck)
   
   • Superior ganglion
   • Middle
   • Inferior
4. Superior cervical ganglion most important when thinking of head and neck
   
   • When the pre-ganglionic nerve meets the superior cervical ganglion we meet the cell body of the post-ganglionic sympathetic nerve
   • Post ganglionic sympathetic nerve will join the common carotid artery and follow the external carotid artery as it distributes branches across the face and the internal carotid artery as it runs through the base of the skull through the cavernous sinus and a branches into the orbit (think of the route of the carotid artery= route of sympathetic nerve)
   • Follows ophthalmic artery (branch of internal carotid) into the eye
     
     • To the smooth muscle of the eyelid
     • Pupil
   • Follows external carotid to the
     
     • Sweat glands of the forehead
     • Sweat glands of face

Question 16

think of the route of the carotid artery=

Answer 16

route of sympathetic nerve

Question 17

post ganglionic sympathetic nerve joins the

Answer 17

common carotid artery and follows the……

• external carotid artery as it distirbutes branches across the face
• internal carotid artery as it runs through the base of the skull through the cavernous sinus and branche sinto the orbit -carotid canal

Question 18

• Follows ophthalmic artery (branch of internal carotid) into the eye and innervates

Answer 18

• Small smooth muscle portion of the levator palpebrae superioris muscle which opens the eye called the superior tarsal muscle
• Pupil- ciliary muscles= pupil dilation

Question 19

The …………….is the only muscle involved in raising the superior eyelid- innervated by oculomotor CN III.

Answer 19

levator palpebrae superioris (LPS)

A small portion of this muscle contains a collection of smooth muscle fibres – known as the superior tarsal muscle. In contrast to the LPS, the superior tarsal muscle is innervated by the sympathetic nervous system.

Question 20

• Post ganglionic sympathetic fibres follows external carotid to the

Answer 20

• Sweat glands of the forehead
• Sweat glands of face

Question 21

the common carotid arteires and its branches and the lung apex

Answer 21

important relations to sympathetic nerves innervating head and neck

• A number of areas in the neck and body that if we have pathology it may manifest itself in signs in the face and the eye
• E.g. ptosis or partial ptosis, pupil constriction (miosis) à due to interruption to sympathetic innervation to the eye

Question 22

Why in Horner’s syndrome, is the ptosis only partial- compared to the more severe ptosis seen in an oculomotor nerve lesion?

Answer 22

• Smooth muscle (innervated by sympathetic nerve) part of the Levator Palpebrae Superioris Muscle (LPS), called the superior tarsal muscle, is only a small component LPS, which is innervated by the oculomotor nerve which uses skeletal muscle
• therefore if the sympathetic nerve has a lesion then only a small part of the LPS (superior tarsal) will be affected= partial pstosis

Question 23

full ptosis

Answer 23

• If you lose oculomotor nerve (and not sympathetic nerve), you would still get full ptosis due to the smooth muscle (superior tarsal) not being strong enough to open the eye

Question 25

Horner’s syndrome refers to a

Answer 25

Triad of symptoms produced by damage to the sympathetic trunk in the neck:

1. Partial ptosis (drooping of the upper eyelid) – Due to denervation of the superior tarsal muscle.
2. Miosis (pupillary constriction) – Due to denervation of the dilator pupillae muscle.
3. Anhidrosis (absence of sweating) on the ipsilateral side of the face – Due to denervation of the sweat glands.

Horner’s syndrome can represent serious pathology, such as a tumour of the apex of the lung (Pancoast tumour), aortic aneurysm or thryoid carcinoma.

Question 26

How would the pupil differ in a Horner’s syndrome compared to an oculomotor nerve lesions?

Answer 26

Horners (sympathetic lesion)- constricted pupil (miosis)

Oculomotor lesion- dilated pupil (mydriasis)

Question 27

Miosis in horners sundroem

Question 28

mydriasis in CN III lesion

Answer 28

dilated pupil

interruption to the parasymapthetic innervation (carried by mydriasis) to the constrictor muscle of the pupil, leaving unopposed sympathetic innervation to dilaotr muscle of pupil

Question 29

• Causes of Horners syndrome

Answer 29

• Sympathetic route comes from inside the chest?
  
  • Patients with apical lung cancer can have sympathetic interference e.g.
    
    • Pancoast tumour
  • Patients with anerysms or dissected blood vessels into the neck

Question 30

2 main ganglia (cell bodies of post ganglionic neurone) of the sympathetic innervation to the head and neck

Answer 30

top of sympathetic chain

• superior cervical ganglion (head)
• middle cervical ganglion (neck and chest)

Question 31

sympathetic nerve hitch hike on the

Answer 31

common carotid artery and then external and internal carotid artery

Question 32

sympathetic flight or flight response in the head and neck

Answer 32

pupillary dilation

assists eyelid retraction

vaso-constriction

sweating