Unit 12 - Cranial Nerves Flashcards
Where do cranial nerves originate
The inferior surface of the brain
How many pairs of cranial nerves are there
12
Mnemonic to remember cranial nerves:
oh (olfactory) once (optic) one (oculomotor) takes (trochlear) the (trigeminal) anatomy (abducens) final (facial) very (vestibulocochlear) good (glossopharyngeal) vacations (vagus) are (accessory) heavenly! (hypoglossal)
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The dendrites (and cell bodies) of olfactory neurons are positioned primarily within what
The axons of these specialized “chemoreceptors” pass through what to eventually make connections leading to the olfactory areas in the cerebral cortex of the temporal lobes
The mucosa which covers the superior nasal conchae and adjacent nasal septum
the cribriform plate of the ethmoid bone, bypass the thalamus
another purely sensory nerve, conducts impulses from the photoreceptors in the retina of the eye to the visual cortex within the occipital lobes of the cerebrum.
The Optic Nerve (CN II)
The optic nerves enter the optic foramen of the sphenoid bone and then converge to form the what
optic chiasm, just superior to the sella turcica and
pituitary gland
Nerve fibers that arise from the medial half of each retina do what at the chiasma
They cross to the opposite side of the brain
Nerve fibers that arise from the lateral half of each retina do what
Remain on the same side of the brain
The surgical removal of the pituitary gland is called
hypophysectomy
Most pituitary tumors cause changes in a person’s what and why?
vision, because the optic chiasm is essentially draped around the anterior pituitary.
If a pituitary tumor grows superiorly, it may exert sufficient pressure on the center of the optic chiasm to cause
“bitemporal hemianopia”, which is blindness in the
temporal field of vision in both eyes.
What typically travels along the optic nerve
Meninges
It, therefore, follows that the subarachnoid space, which contains cerebrospinal fluid, also travels along the optic nerve up to where the nerve merges with the
back of the eyeball.
Produces certain extrinsic and intrinsic movements of the eyeball
The Oculomotor Nerve (CN III)
The oculomotor nerve is primarily a motor nerve that originates in the _______ and passes to the eye via the _______
mesencephalon (midbrain), superior orbital fissure of the sphenoid bone
Innervates many of the outer (extrinsic) muscles that move the eye.
Innervates the internal (intrinsic) muscles that constrict the pupil or innervate muscles to change the shape of the lens for focusing.
The Oculomotor Nerve (CN III)
Pressure or trauma to this nerve can cause loss of function (“palsy”) on the same side of the head as the injury (“ipsilateral”).
A very small motor nerve that originates within the
mesencephalon (midbrain) and passes through the superior orbital fissure of the sphenoid bone to innervate one of the extrinsic muscles that controls downward and lateral movement of the eyeball
The trochlear nerve (CN IV)
It originates in the pons and exits the cranium through several foramina.
The sensory functions of this nerve are most extensive and are involved in sensations of touch, temperature, and pain from specific regions of the face.
The Trigeminal nerve (CN V)
Regions of the trigeminal nerve
1) Ophthalmic nerve branch (exits superior orbital fissure of sphenoid bone).
2) Maxillary nerve branch (exits foramen rotundum of sphenoid bone)
3) Mandibular nerve branch (exits foramen ovale)
An inherited condition, or successive sneezing induced by bright light, may be caused by close
association of optic nerve fibers and fibers of the maxillary nerve branch of the trigeminal nerve which supplies some sensory fibers to the nasal mucosa.
The “photic sneeze reflex”
dental anesthesia can be administered at the _____ to deaden the mandibular nerve that leads to the teeth of the lower jaw, while dental anesthesia administered near the _______ can deaden the maxillary nerve that leads to the teeth of the upper jaw.
mandibular foramen, foramen rotundum
Motor functions of the trigeminal nerve
Innervates muscles involved with chewing.
(a) Masseter
(b) Temporalis
(c) Medial and lateral pterygoids
A motor nerve that originates in the pons and passes
through the superior orbital fissure of the sphenoid bone to one of the extrinsic muscles of the eye that moves the eye laterally
Abducens (CN VI)
Its motor function is to innervate several muscles of facial expression (i.e. - epicranius, buccinators, obicularis oris, and platysma) and to stimulate several salivary glands (sublingual and submandibular glands).
Facial Nerve (CN VII)
Its sensory function is to receive impulses of taste from the anterior portion of the tongue and eventually convey them to the gustatory (taste) areas of the insula of the cerebral cortex.
Facial Nerve (CN VII)
