Practical 1 - station 2 - PNS Flashcards
What are the 12 cranial nerves?
Olfactory Optic Oculumotor Trochlear Trigeminal Abducent Facial Vestibulocochlear Glossopharngeal Vagus Accessory Hypoglossal
What is each cranial nerve for?
Olfactory - sensory smell
Optic - sensory sight
Oculomotor - motor eye movements (intrinsic and extrinsic)
Trochlear - motor eye movements
Trigeminal - 3 sensory branches to face, motor for mastication
Abducent - motor eye movement
Facial - motor facial expression, sensory taste and parasympathetic glands
Vestibulocochlear - sensory balance and hearing
Glossopharyngeal - tongue and pharynx
Vagus - parasymp to Gi tract, motor to palate, pharynx, larynx
Accessory - motor to SCM and trapezius
Hypoglossal - motor to tongue
Which cranial nerves are sensory?
Olfactory, optic, vestibulocochlear
Which cranial nerves are motor?
Hypoglossal, accessory, abducent, trochlear, oculomotor
Which cranial nerves are mixed?
Trigeminal, glossopharyngeal, vagus, facial
Which cranial nerves attach on to the forebrain?
Olfactory and optic
Where do most cranial nerves originate from?
Brainstem
What are the branches of the trigeminal nerve?
Opthalmic, maxillary, mandibular
What muscles are innervated by the mandibular branch?
Muscles of mastication - masseter, temporal, lateral and medial pterygoid
What are the branches of the facial nerve?
Temporal, zygomatic, buccal, marginal mandibular, cervical
What nerve allows taste of the anterior 2/3 of the tongue?
Chorda tympani
What nerve allows taste of the posterior 1/3 of the tongue?
Glossopharyngeal
What nerve allows general sensation of the oral cavity?
Trigeminal
Which blood vessels enter the carotid canal, jugular foramen and the foramen spinosum?
Carotid canal - internal carotid artery
Jugular foramen - ascending pharyngeal artery
Foramen Spinosum - Middle meningeal artery
How many spinal nerves are there in each section?
31 pairs in total 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
Which nerve allows tongue movements?
Hypoglossal innervates intrinsic and extrinsic muscles of the tongue
Which nerves are responsible for the gag reflex?
Initiation - glossopharyngeal (sensory)
Execution - vagus (motor)
What gland does the facial nerve supply?
Parotid
Which nerves supply the parotid, submandibular and sublingual glands?
Parotid - glossopharyngeal
Submandibular and sublingual - facial
Where does the vagus nerve travel in the neck?
Through the carotid sheath, inferior to IJV and common carotid
Right - anterior to subclavian and posterior to sternoclavicular joint
Left - inferior to common carotid and subclavian arteries, posterior to sternoclavicular joint
What does the vagus nerve give rise to in the neck?
Recurrent pharyngeal, superior pharyngeal, pharyngeal
Where does the vagus enter the abdomen?
Through oesophageal hiatus (opening in diagphragm)
What does the accessory nerve supply?
SCM and trapezium
What would accessory nerve palsy lead to?
Pain and weakness in shoulder
Droop shoulder
Weakness when lifting
Trapezius muscle atrophy
What does a spinal nerve divide into and where?
It emerges from the intervertebral foramen and divides into small dorsal ramus and large ventral ramus (both mixed)
What is different about ventral rami T2-T12?
They don’t converge to form plexi
Where are dermatomes C5,6,7,8, T5,12, L3,4,5, S1?
C5 - shoulder down arm C6 - thumb C7 - middle finger C8 - little finger T5 - below nipples T12 - pubis L3 - inner thigh L4 - knee L5 - big toe S1 - little toe
What is the difference between the roles of the afferent and efferent divisions of the PNS?
Afferent (sensory) - sensory receptors to CNS
Efferent (motor) - CNS to effector organs
What are the types of afferents?
Somatic - skin, joints, muscles
Visceral - organs
What are the 2 parts of the motor division?
Somatic - voluntary to skeletal muscle
ANS - involuntary to SM, cardiac, glands
What are the 3 divisions of the ANS?
Enteric - gut function
Sympathetic - 4F’s (flight, fight, fright, sex)
Parasympathetic - rest relaxation recuperation
Which nerves are involved in the parasympathetic and which in the sympathetic?
Para - craniosacral (cranial - oculomotor, facial, glossopharyngeal, vagus), S2-S4
Symp - T1-L2 (lumbosacral)
What do the cranial nerves do in parasympathetic control?
Oculomotor - pupil constriction
Facial - pupil constriction and salivary production
Glossopharyngeal - salivary production
Vagus - reduces heart rate and force of contraction and constricts bronchi SM
How do fibres get from the spinal nerves to the sympathetic trunk?
From the spinal cord ventral roots leave and become preganglionic sympathetic fibres which pass through white rami communicantes (myelinated) to the sympathetic trunk
Where does a sympathetic preganglionic axon synapse?
- paravertebral (in the same chain ganglion from the spinal segment that they arose from or higher or lower in the chain with postganglionic neurons)
- prevertebral (pass through the trunk and synapse along the abdominal aorta)
Which nerves synapse prevertebrally?
Splanchnic
Where are grey rami?
From the sympathetic trunk once synaptic contact has been established forming postganglionic neurons
What is the exception with some sympathetic preganglionics?
They project directly to the adrenal cortex (essentially is a postganglionic neuron) to release adrenaline directly into circulation
Pre and post ganglionic neurotransmitter of symp and para
Symp pre - Ach, post - Noradrenaline except at sweat glands
Para - pre - ach, post - Ach or NO or noradrenaline
