Cranial Nerves Lecture Flashcards
How is the CNS vs PNS?
Only the brain and spinal cord are ‘central’ nervous system*. Everything else is ‘peripheral’.
•* the olfactory and optic nerves (CN I and II) are considered extensions of the brain rather than specific ‘nerves’ so they are CNS structures.
What is the olfactory nerve (CN1) like?
Cribriform plate (ethmoid bone)
•Olfactory cortex (temporal lobe)
•Sensory only
•Provides sense of smell
•Dysfunction - altered/loss of sense of smell
What is the optic nerve like (CN 2)?
Optic canal (sphenoid bone)
•Visual cortex (occipital lobe)
•Sensory only
•Provides sense of sight
•Dysfunction - altered/loss of vision
What is the oculomotor nerve like?
Superior orbital fissure (sphenoid bone)
•Midbrain
•Motor and parasympathetics
•Motor supply to extra-ocular muscles (LPS, SR, IR, MR, IO), parasympathetics to the ciliary and constrictor pupillae muscles
•Dysfunction - eye rests in down and out position, ptosis and mydriasis (dilated pupil)
What is the pupillary light reflex?
What is the trochlear nerve like?
Superior orbital fissure (sphenoid bone)
•Midbrain
•Motor only
•Motor supply to one extra-ocular muscle (superior oblique)
•Dysfunction - eye is unable to look down whilst adducted
What is the trigeminal nerve like?
Superior orbital fissure (sphenoid bone)
•Pons
•Sensory only
•Sensation from the upper 1/3 of the face
•Dysfunction - altered/absent sensation
What is the corneal reflex?
What is the trigeminal nerve?
Foramen rotundum (sphenoid bone)
•Pons
•Sensory only
•Sensation from the middle 1/3 of the face
•Dysfunction - altered/absent sensation
What is the trigeminal nerve like?
V3 - Foramen ovale (sphenoid bone)
•Pons
•Sensory and motor
•Sensation from the lower 1/3 of the face, motor to the muscles of mastication, motor to the tensor tympani, motor to some suprahyoid strap muscles
•Dysfunction - altered/absent sensation and weakness in mastication
What is the abducens nerve like?
Superior orbital fissure (sphenoid bone)
•Pons
•Motor only
•Motor supply to one extra-ocular muscle (lateral rectus)
•Dysfunction - eye is unable to abduct
What is the facial nerve like?
Internal auditory meatus, then stylomastoid foramen (temporal bone)
•Pons
•Motor, sensory and parasympathetic
•Motor supply to the muscles of facial expression and stapedius, sensation from the ear canal, parasympathetics to the SM and SL salivary glands and lacrimal gland, and taste from the anterior 2/3 of the tongue.
•Dysfunction - weakness/paralysis of facial muscles, reduced salivation
What is the vestibulocochlear nerve like?
Internal auditory meatus (temporal bone)
•Pons
•Sensory only
•Provides sense of balance and hearing
•Dysfunction - vertigo or tinnitus or deafness
What is the glossopharyngeal nerve like?
Jugular foramen (temporal/occipital bone)
•Medulla
•Motor, sensory and parasympathetic
•Motor to stylopharyngeus muscles, sensation from the pharynx and posterior 1/3 of tongue, sensation from carotid baroreceptors, parasympathetics to parotid salivary gland, taste from posterior 1/3 tongue
•Dysfunction - loss of gag reflex, reduced salivation
What is the vagus nerve like?
Jugular foramen (temporal/occipital bone)
•Medulla
•Motor, sensory and parasympathetic
•Motor to muscles of the soft palate, pharynx and larynx, sensation from the ear canal, taste from the epiglottis, parasympathetics to thoracic and abdominal organs.
•Dysfunction - loss of gag reflex, absent rise of soft palate, weak or absent cough/swallow, loss of parasympathetics to thoracic/abdominal organs
