Session 6 Flashcards
(16 cards)
Autonomic (Visceral) Nervous System
Sympathetic and Parasympathetic Nervous System
• Part of the . – Central control is from hypothalamus
• Controls body functions not under conscious control
• Maintains and fine tunes internal environment: accelerator and brake
• Has a sequential two neurone arrangement and an associated ganglion – Pre ganglionic nerve → (autonomic) ganglion → post ganglionic nerve
• Target tissues are – Smooth muscle* – Cardiac muscle – Glands (lacrimal, mucosal and salivary)
*smooth muscle action is involuntary and frequently found in viscera (organs e.g. gastrointestinal and respiratory tract)
Sympathetic vs Parasympathetic
Sympathetic: “fight or flight”
• Smooth muscle of blood vessels, eye lid (tarsal muscle) and iris (dilator pupillae) • Sweat glands • Arrector pili muscles (hair follicles) • Decreases secretions from salivary and lacrimal glands (smaller volume but higher protein-more viscous)
Parasympathetic: “rest and digest”
• Smooth muscle of iris (sphincter pupillae) and muscle in ciliary body (controls thickness of lens) • Lacrimal glands (tears) • Salivary and mucosal glands • Smooth muscle of the respiratory and gastrointestinal tract
Autonomic Outflow from the CNS
Parasympathetic:’craniosacral outflow’ - Cranial (four cranial nerves)
- Sacral (S2-S4)- pelvic splanchnics
Sympathetic: ‘thoracolumbar outflow’ - Segments T1- L2 of spinal cord only - Cell bodies within lateral horn of grey matter of spinal cord
Sympathetic Innervation to Head and Neck
use panopto
Common carotid arteries (and its branches) and lung apex
important relations to sympathetic nerves innervating head and neck
Summary of Sympathetic Innervation to Head and Neck Structures: origin, ganglia, hitch-hikes, erector muscles, response
slide 11
Which cranial nerves “carry” parasympathetic fibres from the brainstem?
panopto
Parasympathetic Innervation to Head and Neck
Arise from brainstem from parasympathetic nuclei • Edinger Westphal • Superior salivary • Inferior salivary • Dorsal motor - > Hitch-hike on to one of 4 CNs • CN III • CN VII • CN IX • CN X - > Parasympathetic ganglia (4)• Ciliary • Submandibular • Pterygopalatine • Otic ->Hitch hike on to branches of CN V exception to this is CN X - > Target tissues • Smooth muscle (sphincter pupillae -pupil constrictor) & ciliary muscle (controls lens) • Lacrimal gland • Mucosal glands in nasal/oral mucosa/ resp. tract • Salivary glands
Parasympathetic: CN III Oculomotor
Brainstem (EWN) -> Parasympathetic fibres emerge with CN III fibres - > Ciliary ganglion->Hitch hikes on small branches from (CN Va))-> EyeCiliary muscle: alters shape of lens Sphincter pupillae muscle: constrictor of the pupil
Pupillary Light Reflexes
Light in left pupil
Sensory afferent from left retina (CN II)
Some branches leave CN II to enter midbrain and synapse in pre-tectal nucleus
Connection with EDW nuclei (left and right!)
Pre-ganglionic parasympathetic fibres from EDW leave brainstem with CN III (left and right
Pre-ganglionic parasympathetics synapse in ciliary ganglion; become post-ganglionic
Reach sphincter pupillae muscle of the iris
Direct light reflex - Eye in which light shone or
Consensual light reflex in opposite eye.
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
panopto
Parasympathetic: CN VII Facial
• Parasympathetic (pre-ganglionic) nerves exit brainstem with other axons forming facial nerve
• Parasympathetics reach target tissues via two branches of CVII that arise in petrous bone • Greater petrosal nerve • Chorda tympani nerve (also transmits special sense taste from anterior 2/3 tongue)
• Two associated parasympathetic ganglia • Pterygopalatine ganglion • Submandibular ganglion • These ganglia =area of synapse between pre-ganglionic parasympathetic nerves onto cell bodies of post-ganglionic nerves
• Post-ganglionic parasympathetics then run with distal branches of trigeminal (lingual nerve)
slide 33 lc 1
Parasympathetic: CN IX Glossopharyngeal
• Parasympathetic fibres arise from brainstem and exit with CN IX
• Exits through jugular foramen but at this point splits into no. of branches
• Tympanic nerve which supplies sensory to middle ear
• Parasympathetic fibres run with the tympanic nerve initially
• Then parasympatheticsexit middle ear as lesser petrosal nerve
• Synapses in otic ganglion (in infratemporal fossa)
• (Postganglionic parasympathetics then hitch hike on branch of CN Vc-auriculotemporal)
• Parotid gland
Route:
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
target 3:
oMucosal glands in pharynx/larynx and smooth muscle of oesophagus and trachea
o Smooth muscle and mucosal glands within rest of respiratory and gastrointestinal tract
o Heart
Summary of Parasympathetic Nervous System in Head and Neck - origin, hitch-hikes, ganglia, effector tissues, response
slide 27 lec 1
Parasympathetic Innervation to Head and Neck Structures (Image Summary)
slide 28 lec 1
Summary of cranial nerves and the foramen of the skull
Slide 35 block out answers
slide 35 lec 1 with answers
