Autonomic Supply of Head and Neck Flashcards
Which neurotransmitter is released by the post-ganglionic neurone in sympathetic vs parasympathetic transmission?
Sympathetic: adrenaline or NA
Parasympathetic: Ach
Describe the length, location and receptor involved in the pre and post- ganglionic fibres of the SNS
Pre-ganglionic fibres originate within the grey matter of the spinal cord. These synapse with the post-ganglionic neurone which has its sympathetic ganglia located next to the vertebral column (ontop of one and another, creates a chain). Thus the length of the pre-ganglionic fibre of the SNS is short. The NT released is ACh which binds to nicotinic receptors.
The post-ganglionic neurone is long and synapses at the effector organ. In the SNS the NT released by the post-ganglionic neurone is Adrenalin or NA which binds to adrenergic receptors.
Describe SNS innervation to the Adrenal gland
With the adrenal gland, the SNS pre-ganglionic fibres go directly to the adrenal medulla.
This stimulates the chromafin cells, which are responsible for releasing Adrenaline or NA directly into the bloodstream
What is meant by ‘cranial’ and ‘sacral’ outflow of the PNS?
Cranial outflow originates from brainstem: cranial nerves
Sacral outflow: forms the pelvic nerves which innervate various organs incl the ureter, bladder, prostate, anal sphincter etc…
At which vertebral levels do sympathetic and parasympathetic nerves exit the CNS?
Sympathetic: T1-L2 (the sympathetic chain extends up to near the skull base)
Parasympathetic: exits via cranial nerves + S2-S4
Describe the length, location and receptor involved in the pre and post- ganglionic fibres of the PNS
Pre-ganglionic fibres originate within the brainstem and are long in length.These synapse with the post-ganglionic neurone which has its ganglia located either next to or on the effector organ, hence the length of the post-ganglionic fibres of the PNS is short.
The NT released at both is ACh. At the pre-ganglionic neurone ACh binds to nicotinic receptors and at the post ganglionic neurone ACh binds to muscurinic receptors
Give 4 SNS and PNS effects in the body
What are the 4 parasympathetic ganglia in the head and their associated cranial nerves?
Which structures do they innervate?
1) Ciliary ganglion: receive fibres from the oculomotor nerve (midbrain) → innervate the iris to constrict the pupil and the ciliary muscle for vision accommodation
2) Pterygopalatine ganglion: receive fibres from the facial nerve (pons) → innervate the mucosal glands of nose/palate and lacrimal gland
3) Submandibular ganglion receive fibres from the facial nerve (pons) → innervate submandibular and sublingual glands for salivary secretion
4) Otic ganglion: receive fibres from glossopharyngeal nerve (medulla) → innervate the parotid salivary glands for salivary secretion
Where are the ciliary ganglion located?
Where do the sympathetic vs parasympathetic outflow come from?
Orbital cavity (lateral to the optic nerve)
Sympathetic: come from superior cervical ganglion via the plexus on the opthalmic artery
Parasympathetic: come from the occulomotor nerve (CN III)
Where are the pterygopalatine ganglion located?
Where do the sympathetic vs parasympathetic outflow come from?
Lies in the pterygopalatine fossa (connected to maxillary nerve by small branches)
Sympathetic: come from superior cervical ganaglion on the ICA
Parasympathetic: come from the facial nerve (CN IV)
Where are the submandubular ganglion located?
Where do the sympathetic vs parasympathetic outflow come from?
Suspended from the lingual nerve by small branches
Sympathetic: comes from superior cervical ganglion along the facial artery
Parasympathetic: comes from the facial nerve (CN VII) via its chorda tympani branch
Where are the otic ganglion located?
Where do the sympathetic vs parasympathetic outflow come from?
Motor branches from what specific nerve pass through this ganglion WITHOUT synapsing?
Located within the infratemporal fossa
Sympathetic: come from superior cervical ganglion along the MMA
Parasympathetic: come from the glossopharyngeal nerve (CN IX)
Motor branches from the maxillary nerve (C V3) pass through the otic ganglion but do NOT synaps
Describe the sensory, motor and PNS innervation of the Vagus nerve
Sensory: laryngopharynx and ear
Motor: muscles of the pharynx and larynx
PNS: Heart, lungs and GIT
What can be said about the vagus nerve ganglia compared to CN III, VII and IX?
The vagus nerve does not have discrete ganglia associated with it because it extends beyond the head and neck
List 3 abnormal features seen in the image (incl which side of the face is affected?
What syndrome does this indicate and what causes it?
Assymetry of the face (patients Right affected):
- *Ptosis**: droppy eyelid
- *Miosis**: pupil contriction
- *Anhidrosis**: cheek dryer (less shine): indicates absence of sweating
Diagnosis: Right Horner’s syndrome caused by damage to the sympathetic post-ganglionic fibres that supply the SM portion of the upper eyelid
Which circulation (ant, middle, post) does a stroke most commonly occur in?
Give 2 common presentation features
Middle circulation resulting in hemiplegia and problems with speech
What 3 structures will a stroke of the posterior circulation affect?
1) Occipital cortex (impt for vision)
2) Cerebellum (impt for balance and co-ordination)
3) Brainstem (impt for SNS outflow)
List 4 symptoms of a posterior stroke circulation?
Weakness, sensory loss, vertigo, diplopia, dysarthria, visual field defects, dysphagia
Which acronym is used for detecting strokes?
What is the downside of the test
Face arm speech test (FAST)
It is less sensitive for posterior circulation strokes
Briefly explain what Syringomyelia is and state which SNS neurone tends to be affected?
Give 4 symptoms:
Cavity in the spinal cord, called a syrinx, which expands and elongates over time
Affects the 1st order neurone
Symptoms:
- Chronic pain
- Weakness
- Sensory disturbance - classic
- sparing dorsal columns
- Disturbances in the ANS
Describe the pathway of the following SNS fibres to the face:
- first order neurones
- second order neurones
- third order neurones
First: Hypothalamus ➞ midbrain + pons ➞ terminates in spinal cord at T1
Second: Exit spinal cord at T1 ➞ enter + ascend through cervical sympathetic chain ➞ synapse in superior cervical ganglion at level of carotid bifurcation (C3-4)
Third: Exit superior cervical ganglion ➞ travels along with ICA and ECA
- pupillomotor fibres carried with the ICA
- fibres related to sweating of face, carried with the ECA
Where are pancoast tumours located?
Which sympathetic fibres tend to be affected and why?
Give 3 symptoms:
Located at the apex of the lung
Affects the 2nd order neurons (sympathetic fibres as they exit the cord at T1, and ascend to the superior cervical ganglion)
Symptoms:
- Bovine cough (if recurrent laryngeal nerve affected)
- Shoulder/arm pain (brachial plexus located close)
- Oedema (many near by vessels)
How does the sympathetic and parasympathetic influence vision?
Sympathetic
- dilation of the pupil (dilator papillae muscles)
Parasympathetic
- constricts the pupil (constrict papillae muscle)
- accommodation vision (ciliary muscles round up the lens for near vision- CN III)
Which glands are stimulated by the parasympathetic and sympathetic system?
Sympathetic
- secretions from sweat glands
Parasympathetic
- saliva production (parotid, submandibular, sublingual)
- mucous production from glands in oral cavity and hard palate
- tear production from lacrimal gland
