autonomic nerves in the head and neck /orbits part 2 (A21) Flashcards
(46 cards)
1
Q
organs of the head and neck
A
- skin
- blood vessels
- brain
- eyes
- glands
- trachea
- oesophagus
2
Q
components of the organs of the head and neck supplied by the nervous system
A
- skin (sympathetic innervation of arterioles/veins, sweat glands and erector pili muscles)
- blood vessels 9all of the bodies arterioles receive sympathetic innervation)
- brain (the brain is insensitive therefore no somatic sensory innervation and has no motor function as it is not a muscle)
- eyes (the anterior surface is sensitive to touch/somatic sensory innervation via CNVa, and the smooth muscle of the iris involved in pupil diameter/the smooth muscle associated with the lens involved in focusing = somatic motor)
- glands eg. sweat glands of the skin, major and minor salivary glands, lacrimal gland, mucous glands of the airway and GI tract all receive sympathetic innervation
- trachea is similar to the larynx in that it is supplied by somatic sensory as it is sensitive to inhaled stimulants
- oesophagus (there is a mid oesophageal transition from striated muscle that receives somatic motor innervation, to smooth muscle that receives autonomic innervation)
3
Q
how do sympathetic nerve fibres get from the CNS/central nervous system to organs of the head and neck and what are the neurotransmitters involved in synapse
A
- preganglionic fibres travel from the CNS to the CERVICAL part of the sympathetic chain (ganglion=synapse between axon of preganglionic neurone and cell body of postganglionic fibre) where they synapse (involving acetylcholine)
- postganglionic fibre travels from ganglion to organ where it synapses (neurotransmitter involved = noradrenaline)
4
Q
neurotransmitter (s) involved in sympathetic nervous system synapse
A
- acetylcholine (synapse between preganglionic fibre and ganglion)
- neurotransmitter (synapse between postganglionic fibre and organ)
5
Q
cervical part of the sympathetic chain
A
- contains:
- > superior
- > middle
- > and inferior cervical sympathetic ganglia
6
Q
how do the preganglionic sympathetic nerve fibres from the spinal cord reach the ganglion of the cervical part of the sympathetic chain
A
-they exit the spinal cord in T1 spinal nerve -> travel upwards in the sympathetic chain -> synapse in one of the cervical sympathetic ganglia (cervical part of sympathetic chain has superior, middle and inferior cervical sympathetic ganglia)
7
Q
how do the post ganglionic sympathetic nerve fibres get from the cervical part of the sympathetic chain to the organs of the head and neck
A
- the internal and external carotid nerves postganglionic sympathetic nerve fibres within nerves coming from the superior cervical sympathetic ganglion travel to the surface of the carotid arteries to be carried to the skin and organs in the head and neck
- > the internal carotid nerve travels from superior cervical sympathetic ganglion to the surface of the internal carotid artery
8
Q
carotid peri-arterial plexuses
A
- the internal and external carotid nerves postganglionic sympathetic nerve fibres within these nerves give rise to plexuses on the carotid arteries
- the plexuses are made up of:
- > postganglionic sympathetic fibres carried by all branches of externernal carotid artery (on the surface of the artery) to be distributed to all extra-cranial structures eg. facial and scalp skin, salivary glands, mucous glands, smooth muscle etc
- > postganglionic sympathetic fibres carried into the cranial cavity on the internal carotid artery to be distributed via its branches (including ophthalmic artery to the orbit/eye) and also the deep petrosal nerve follows this artery
9
Q
branches of the external carotid artery
A
- ascending pharyngeal artery
- superior thyroid artery
- lingual artery
- facial artery
- occipital artery
- posterior auricular artery
- maxillary artery
- superficial temporal artery
10
Q
how do parasympathetic nerve fibres get from the CNS/central nervous system to organs of the head and neck and what are the neurotransmitters involved in synapse
A
- preganglionic fibres travel from the CNS to the parasympathetic ganglion (synaps between axon of preganglionic neurone and cell body of postganglionic fibre where they synapse (involving acetylcholine)
- postganglionic fibre travels from parasympathetic ganglion to organ where it synapses (neurotransmitter involved = acetylcholine)
11
Q
neurotransmitter (s) involved parasympathetic nervous system synapse
A
-acetylcholine (synapse between preganglionic fibre and ganglion AND synapse between postganglionic fibre and organ)
12
Q
parasympathetic nerve synapse/ parasympathetic ganglions
A
- preganglionic parasympathetic nerve fibres travel via cranial nerves III (oculomotor), VII (facial), IX (glossopharyngeal) and X (vagus) to the specific parasympathetic ganglia where they synapse:
- in the head and neck:
- > CN III (oculomotor nerve) synapses at the ciliary ganglion (eye)
- > CN VII (facial nerve) synapses at the pterygopalatine ganglion AND at the submandibular ganglion
- > CN IX (glossopharyngeal nerve) synapses at the otic ganglion (parotid)
- in the enteric system/GI tract:
- the presynaptic fibres directly synapse on other thoracic/abdominal viscera and the postsynaptic fibres will synapse on the organs
- > CN X (vagus nerve) preganglionic parasympathetic fibres synapse onto postganglionic neurons with short axons in ganglia within the walls of the organs of the chest and upper abdomen eg. heart and lungs
- > sacral spinal nerves carry preganglionic parasympathetic fibres to organs of the lower abdomen, pelvis and perineum
13
Q
ganglion
A
-contains cell bodies of the post synaptic fibres and is where the pre synaptic fibres synapse
14
Q
sacral spinal nerves
A
carry preganglionic parasympathetic fibres to organs of the lower abdomen, pelvis and perineum
15
Q
what ganglion do parasympathetic fibres carried in CNIII (oculomotor nerve) synapse at
A
ciliary ganglion (eye)
16
Q
what ganglion (s) do parasympathetic fibres carried in CN VIII (facial nerve) synapse at
A
pterygopalatine ganglion AND submandibular ganglion
17
Q
what ganglion do parasympathetic fibres carried in CN IX (glossopharyngeal nerve) synapse at
A
otic ganglion (parotid)
18
Q
where do parasympathetic fibres carried in CN X (vagus nerve) synapse
A
-preganglionic parasympathetic fibres synapse onto postganglionic neurons with short axons in ganglia within the walls of the organs of the chest and upper abdomen eg. heart and lungs
19
Q
blushing mechanism (caused by sympathetics)
A
- blush region = skin of the face, ears and neck (upper body)
- due to the sympathetic supply onto the skin (there is no parasympathetic supply to skin)
- sympathetic vasodilator fibres to the facial vein and its tributaries cause blushing
- possible ‘blush reaction’ takes place all over body but is only visible in the ‘blush region’ this is because facial skin has more blood vessels per unit volume and vessels are wider and nearer the surface
- postganglionic fibres from superior cervical sympathetic ganglion travel via the external carotid nerve to the external carotid plexus -> plexus fibres follow the facial artery to reach the facial vein
20
Q
autonomic supply to the eyes (sympathetic functions)
A
- > open eyes wider (to see danger and get escape route)
- > get more light into eyes (to see danger and escape route)
- > focus on far objects (to see danger and escape route)
21
Q
autonomic supply to the eyes (parasympathetic functions)
A
- > allow orbicularis oculi to work (involved in shutting eyes)
- > get less light into eyes (if its too bright or when asleep)
- > focus on near objects (eg. to see a needle and thread)
22
Q
mechanism of opening eyes wider (route of postganglionic sympathetic fibres to levator palpebrae superioris)
A
- postganglionic sympathetic fibres reach levator palpebrae superioris via: the superior cervical sympathetic ganglion -> internal carotid nerve -> internal carotid plexus -> fibres on ophthalmic artery and its branches to the orbital structures
- > levator palpebrae superioris contains skeletal and smooth muscle and attaches to the superior tarsal plate
23
Q
autonomic nervous systems involvement in controlling the amount of light you get into the eye
A
- increasing amount of light:
- > the iris has associated radial smooth muscle (dilator pupillae)
- > the sympathetics dilate the pupil (in fight or flight response in order to see danger/escape route)
- > sympathetic nerve fibres reach the orbit via the internal carotid plexus and then the ophthalmic artery
- decreasing the amount of light:
- > the iris has associated circular smooth muscle (sphinctor pupillae)
- > the parasympathetics constrict the pupil (rest and digest) in order to decrease the amount of light eg. when you are asleep
- > parasympathetic nerve fibres reach the eye via CN III (oculomotor nerve)
24
Q
autonomic nervous systems involvement in focusing on near or far objects (parasympathetics)
A
- > ciliary muscle relaxes as a result of decreased parasympathetic supply (has no parasympathetic activity), this tightens the ligament and the lens flattens to focus on distance
- parasympathetics allow you to focus on near objects (eg. needle and thread)
- > parasympathetics to smooth muscle or ciliary body
- > ciliary muscle contracts (parasympathetics) causing the liament to relax and lens flattens out to focus on close object eg. needle and thread
- > parasympathetic nerve fibres reach the eye via CN III (oculomotor nerve)
25
how do sympathetic fibres reach the orbit
-ophthalmic arteries carry sympathetic fibres into the orbit for levator palpebrae superioris and also for the ciliary nerves
26
how do parasympathetic fibres reach the orbit
- preganglionic parasympathetic fibres in branch from CN III (oculomotor nerve) synapse at the ciliary ganglion
- >ciliary nerves carry postganglionic fibres to smooth muscle of the eye
27
ciliary nerves
-ciliary nerves carry postganglionic fibres to smooth muscles of the eye (parasympathetic AND sympathetic)
28
parasympathetic secretomotor supply to the lacrimal gland
- basal and reflex tears
- afferent limb of the reflex is CNVa (ophthalmic division of trigeminal)
- efferent limb is parasympathetic
- the parasympathetic fibres are derived from CN VII (facial nerve)
- >cutting CNVa will stop reflex tears but not emotional tears (the brain emotional centres produce parasympathetic stimulation of the lacrimal gland)
- basal/reflex and emotional tears are all produced by efferent action potentials in parasympathetic axons that travel in CN VII (facial nerve), then in branches of CN Vb (maxillary division of trigeminal nerve) -> then in the lacrimal branch of Va (ophthalmic division of the trigeminal nerve) to reach the lacrimal gland
29
basal tears
- flow all the time
| - lubricate the eye and clear dust
30
reflex tears
- stimulation:
- >mechanical
- >chemical
- afferent limb of the reflex is CNVa (ophthalmic division of trigeminal)
- efferent limb is parasympathetic
- the parasympathetic fibres are derived from CN VII (facial nerve)
- >cutting CNVa will stop reflex tears but not emotional tears
31
emotional tears
- happy, sad or frightened tears
| - the brain emotional centres produce parasympathetic stimulation of the lacrimal gland
32
parasympathetic route to the lacrimal gland
-basal/reflex and emotional tears are all produced by efferent action potentials in parasympathetic axons that travel in CN VII (facial nerve), then in branches of CN Vb (maxillary division of trigeminal nerve) -> then in the lacrimal branch of Va (ophthalmic division of the trigeminal nerve) to reach the lacrimal gland
33
sympathetic nervous systems supply to lacrimal gland and involvement in producing tears
-the sympathetic nervous system is not directly involved in stimulating or inhibiting secretion from the lacrimal gland, but will supply arterioles in the gland, hence theoretically reducing the glands capacity to produce tears
34
autonomic supply to salivary glands
- parasympathetic secretomotor nerve supply to produce saliva
- sympathetic system reduces H20 content by vasoconstriction in the glands (causing sticky saliva/dry mouth)
35
major salivary glands
- become active at meal times
- >parotid (serous - greatest volume)
- >submandibular (mucous)
- >sublingual (mixed)
36
type of secretion from parotid gland
- serous
| - largest volume
37
type of secretion from submandibular gland
mucous
38
type of secretion from sublingual gland
mixed (mucous and serous)
39
minor salivary glands
- continually active
- >in mucosa of the lips (labial mucosa)
- >in mucosa of the cheeks (buccal mucosa)
- >in mucosa of the palate (palatal mucosa)
40
parasympathetic secretomotor supply to the parotid gland
-CN IX (glossopharyngeal nerve)
41
parasympathetic secretomotor supply to sublingual and submandibular glands
-CN VII (facial nerve) travels through internal acoustic meatus -> CNVII then exits cranial cavity at stylomastoid foramen ->preganglionic parasympathetic secretomotor fibres travel in the chorda tympani (branch of the facial) and join with the lingual nerve (branch of CNVc) to the submandibular ganglion where they synapse before supplying the submandibular and sublingual glands
42
CNVII
- enters internal acoustic meatus
- exits cranial cavity at stylomastoid foramen
- CN VII somatic motor fibres go to supply muscles of facial expression
- chorda tympani = branch of CNVII (preganglionic parasympathetic secretomotor fibres)
43
ciliary ganglion detailed summary
- The ciliary ganglion is located within the bony orbit. It is situated anteriorly to the superior orbital fissure, between the lateral rectus muscle and the optic nerve.
- >Pre-ganglionic fibres: The ciliary ganglion is supplied by fibres from the Edinger-Westphal nucleus (associated with the oculomotor nerve).
- >Post-ganglionic fibres: The parasympathetic fibres leave the ganglion via the short ciliary nerves. These fibres continue into the orbit to innervate structures of the eye.
- >Target Organs: The post-ganglionic fibres from the ciliary ganglion innervate the sphincter pupillae (contracts the pupil) and the ciliary muscles (accommodates for near vision).
- >In addition, two sets of nerve fibres pass through the ciliary ganglion without synapsing (Sympathetic nerves from the internal carotid plexus that innervate the dilator pupillae muscle and Sensory fibres from the nasociliary nerve/ branch of the ophthalmic division of the trigeminal nerve that innervate the cornea, ciliary body and iris)
44
pterygopalatine ganglion detailed summary
- The pterygopalatine ganglion (also known as sphenopalatine) is the largest of the four parasympathetic ganglia. It is located within the pterygopalatine fossa – a space located inferiorly to the base of the skull, and posteriorly to the maxilla.
- >Pre-ganglionic fibres: The pterygopalatine ganglion is supplied by fibres from the superior salivatory nucleus (associated with the facial nerve). These fibres travel within the greater petrosal nerve and the nerve of the pterygoid canal to reach the ganglion.
- >Post-ganglionic fibres: The parasympathetic fibres leave the ganglion by hitch-hiking on branches of the maxillary nerve (derived from the trigeminal nerve).
- >Target organs: The post-ganglionic fibres from the pterygopalatine ganglion provide secretomotor innervation to lacrimal gland, mucous glands of posterosuperior nasal cavity, nasopharynx, and the palate.
- >Sympathetic fibres from the internal carotid plexus and sensory branches from the maxillary nerve pass through the pterygopalatine ganglion without synapsing.
45
submandibular ganglion detailed summary
- The submandibular ganglion is located inferiorly to the lingual nerve, from which it is suspended.
- >Pre-ganglionic fibres: The ganglion is supplied by fibres from the superior salivatory nucleus (associated with the facial nerve). These fibres are carried within a branch of the facial nerve, the chorda tympani. This nerve hitch-hikes along the lingual branch of the mandibular nerve to reach the ganglion.
- >Post-ganglionic fibres: Fibres leave the ganglion and travel directly to the submandibular and sublingual glands.
- >Target Organs: Secretomotor innervation to the submandibular and sublingual salivary glands.
- >Sympathetic fibres from the facial artery plexus pass through the submandibular ganglion. They are thought to innervate glands in the base of the oral cavity.
46
otic ganglion detailed summary
- The otic ganglion is located inferiorly to the foramen ovale, within the infratemporal fossa. It is medial to the mandibular branch of the trigeminal nerve.
- >Pre-ganglionic fibres: The ganglion is supplied by fibres from inferior salivatory nucleus (associated with the glossopharyngeal nerve). Parasympathetic fibres travel within a branch of the glossopharyngeal nerve, the lesser petrosal nerve, to reach the otic ganglion.
- >Post-ganglionic fibres: The parasympathetic fibres hitchhike along the auriculotemporal nerve (branch of the mandibular division of the trigeminal nerve) to provide secretomotor innervation to the parotid gland.
- >Target Organs: The post-ganglionic fibres from the otic ganglion provide innervation to the parotid gland.
- >Sympathetic fibres from the superior cervical chain pass through the otic ganglion. They travel with the middle meningeal artery to innervate the parotid gland
