Session 4 Flashcards
(18 cards)
Describe the differences of cranial nerves compared to other parts of the peripheral nervous system
Relate to the brainstem (except two which arise from the brain)
Arise at irregular intervals from the cns rather than segments
What is the brainstem?
Adjoins the brain to the spinal cord - location of majority of cranial nerve nuclei. Consists of the midbrain, pons and medulla
What are the 12 cranial nerves and where do they originate from?
CNI/Olfactory nerve. CNII/Optic nerve. CNIII/Oculomotor nerve. CNIV/Trochlea nerve. CNV/Trigeminal nerve. CNVI/Abducens nerve. CNVII/Facial nerve. CNVIII/Vestibulomotor nerve. CNIX/Glossopharyngeal nerve. CNX/Vagus nerve. CNXI/Accessory nerve. CNXII/Hypoglossal nerve. On occasion oliver tries to anally finger various girls - vaginas are history.
2244 from forebrain, midbrain, pons and medulla.
What is the type of each cranial nerve?
SSMMBMBSBBMM. Some say marry money but my brother says big brains matter most. The 3 purely sensory nerves are special sensory (as opposed to general sensory).
Describe the route, function, testing and any further points of the olfactory nerve (CNI)
Passes from olfactory mucosa through holes in the cribiform plate to olfactory bulbs to then become the olfactory tract. Sense of smell. Not formally tested - test one nostril at time. Head injury can sheer the nerves, loss of smell (anosmia).
Describe the route, function, testing and any further points of the optic nerve (CNII)
Retina -> optic canal -> optic chiasm -> optic tract. Vision. Visual tests. Pituitary tumours can cause visual loss.
Describe the route, function, testing and any further points of the oculomotor nerve (CNIII)
Midbrain -> superior orbital fissure (SOF) -> orbit. Innervates 4/6 ocular muscles and levator palpebrae superioris. Motor and autonomic (parasympathetic to pupil). Test eye movements and pupillary light reflex. Presents with double vision, ptosis and down and out eye and maybe blown pupil. Lesion can be caused by cavernous sinus thrombosis, aneurysms or raised intercranial pressure.
Describe the route, function, testing and any further points of the trochlea nerve (CNIV)
Midbrain -> SOF. Supplies superior oblique muscle. Eye movements. Tested by eye movements. Subtle eye deviation, Diplopia (double vision) worse on downward gaze. Damaged by head injury or raised ICP.
Why is the trochlea nerve the longest cranial nerve?
It arises from the dorsal aspect of the brainstem
Describe the route, function, testing and any further points of the trigeminal nerve (CNV)
Pons to V1/opthalmic - SOF to orbit, V2/maxillary - foramen rotundum to pterygopalatine fossa, V3/mandibular - foramen ovale to infratemporal fossa. Muscles of mastication (mandibular) and main sensory of the face. Test functions to test nerve. The mental (V3) and infra-orbital nerves (V2) can be damaged in face fractures (mental and infraorbital foramen).
Describe the route, function, testing and any further points of the abducens nerve (CNVI)
Pons -> cavernus sinus -> SOF -> orbit. Innervates lateral rectus. Test by eye movements. Easily stretched in raised ICP.
Describe the route, function, testing and any further points of the facial nerve (CNVII)
Pons -> internal acoustic meatus (IAM)->petrous part of temporal bone -> stylomastoid foramen. Muscles of facial expression, taste to anterior 2/3 tongue and parasympathetic fibres to lacimal and salivary glands. Bell’s palsy, close to vestibulocochlea nerve.
Describe the route, function, testing and any further points of the vestibulocochlear nerve (CNVIII)
Pons - > IAM -> terminates in petrous part of temporal bone. Hearing and balance. Tested by rinne’s and weber’s. Tinnitus, acoustic neruoma (benign tumour of nerve).
Describe the route, function, testing and any further points of the glossopharyngeal (CNIX)
Medulla -> Jugular foramen. Mainly sensory. Sensation of soft palate, tonsils and oropharynx. Taste to posterior 1/3 tongue. Autonomic to parotid gland. Carries sensory afferents from the carotid body and carotid sinus. Stylopharyngeus muscle. Test by testing gag reflex.
Describe the route, function, testing and any further points of the vagus nerve (CNX)
Medulla -> jugular foramen -> carotid sheath. Sensory to laryngopharynx, larynx. Muscles of soft palate, pharynx, larynx. Parasympathetic to thoracic and abdominal viscera. Test by swallow, cough, gag reflex. Injury to recurrent laryngeal branch causes hoarseness.
Describe the route, function, testing and any further points of the accessory nerve (CNXI)
Medulla -> jugular foramen. Supplies sternocleidomastoid and trapezius. Shrug shoulders. Vulnerable at posterior triangle. Has a spinal and cranial root. Cranial part joins vagus nerve and becomes indistinguishable.
Describe the route, function, testing and any further points of the hypoglossal nerve (CNXII)
Medulla -> hypoglossal canal. Muscles of the tongue. Damage leads to atrophy and weakness of ipsilateral side.
What passes through the cavernous sinus?
O TOM CAT
O TOM - lateral wall. CNIII, CNIV, CNV1, CNV2
CA - internal carotid artery, CNVI in middle of sinus
T - crossover point
