The Cranial Nerves Flashcards
Twelve pairs of nerves that are associated with the brain.
Cranial Nerves
Cranial Nerve I
Olfactory Nerves
Origin and Course of the Olfactory Nerve
Arise in olfactory epithelium of nasal cavity. Passes through cribriform plate of the ethmoid bone and synapses in the olfactory bulb. The olfactory tract terminates in the primary olfactory cortex.
Function of the Olfactory Nerve
Purely sensory; carries afferent impulses for sense of smell.
Cranial Nerve II
Optic Nerve
Origin and Course of the Optic Nerve
Arise in the retina of the eye. Passes through the optic canal of the orbit. Converges to form the optic chiasma. Synapses at the thalamus. The optic radiation fibers run to the primary visual cortex.
Function of the Optic Nerve
Purely sensory; carries afferent impulses for vision.
Cranial Nerve III
Oculomotor Nerve
Origin and Course of the Oculomotor Nerve.
Extends from the ventral midbrain and passes through the superior orbital fissure to the eye.
Function of the Oculomotor Nerve.
Chiefly motor neurons. Somatic motor fibers to inferior oblique; and the superior, inferior, and medial rectus muscles. Parasympathetic motor fibers to the sphincter pupillae and ciliary muscles. Sensory afferents from the skeletal muscles.
Cranial Nerve IV
Trochlear Nerve
Origin and Course of the Trochlear Nerve
Emerges from dorsal midbrain and enter the orbit through the superior orbital fissure.
Function of the Trochlear Nerve
Primarily motor nerves. Somatic motor fibers to superior oblique muscle, which passes through pulley-shaped trochlea.
Cranial Nerve V
Trigeminal Nerve
First Division of the Trigeminal Nerve
Ophthalmic Nerve (V1)
Origin and Course of the Ophthalmic Nerve
Run from face through superior orbital fissure to pons.
Function of the Ophthalmic Nerve
Sensory, conveys impulses from anterior scalp, upper eyelid, nose, nasal cavity mucosa, cornea, and lacrimal gland.
Second Division of the Trigeminal Nerve.
Maxillary Nerve (V2)
Origin and Course of the Maxillary Nerve
Runs from face through the foramen rotundum to the pons.
Function of the Maxillary Nerve
Sensory, conveys impulses from nasal cavity mucosa, palate, upper teeth, skin of cheek, upper lip, lower eyelid.
Third Division of the Trigeminal Nerve
Mandibular Nerve (V3)
Origin and Course of the Mandibular Nerve
Passes through skull via foramen ovale.
Function of the Mandibular Nerve
Sensory: Conveys impulses from anterior tongue, temporal region of the scalp, skin of the chin. Motor: muscles of mastication
Cranial Nerve VI
Abducens Nerve
Origin and Course of the Abducens Nerve
Leave inferior pons and enter the orbit via the superior orbital fissure.
Function of the Abducens Nerve
Motor fibers to the lateral rectus muscle. Sensory fibers from the same muscle.
Cranial Nerve VII
Facial Nerve
Origin and Course of the Facial Nerve
Runs from pons, enters temporal bone via the internal acoustic meatus, emerges through stylomastoid foramen, continues to lateral aspect of the face.
Function of the Facial Nerve
Mixed nerves. Chief motor nerves of the face. Sensory fibers of the same muscles. Parasympathetic motor impulses to lacrimal glands, nasal and palatine glands, and submandibular and salivary glands. Sensory impulses from taste buds of anterior two-thirds of the tongue.
Cranial Nerve VIII
Vestibulocochlear Nerve
Origin and Course of the Vestibulocochlear Nerve
Arise from hearing and equilibrium apparatus in the inner ear, passes through internal acoustic meatus to pons-medulla border.
Function of the Vestibulocochlear Nerve
Mostly sensory, vestibular division transmits impulses for sense of equilibrium, cochlear division transmits impulses for sense of hearing. Motor component adjusts the sensitivity of sensory receptors.
Cranial Nerve IX
Glossopharyngeal Nerve
Origin and Course of the Glossopharyngeal Nerve
Emerges from the medulla and leaves skull via jugular foramen.
Function of the Glossopharyngeal Nerve
Mixed nerve. Sensory motor fibers to and from stylopharyngeus, which elevates the pharynx during swallowing. Parasympathetic motor fibers to parotid glands. Sensory fibers conduct taste and general sensory impulses from pharynx and posterior tongue, chemoreceptor in carotid body which monitor O2 and CO2 levels and regulate respiratory function, baroreceptors of carotid sinus which monitor blood pressure.
Cranial Nerve X
Vagus Nerve
Origin and Course of the Vagus Nerve
Extends beyond the head and neck region. Emerges from the medulla, passes through skull via jugular foramen, descends into thorax and abdomen.
Function of the Vagus Nerve
Mix nerve. Mostly motor fibers. Parasympathetic motor fibers supply heart, lungs, and abdominal viscera. Sensory impulses from thoracic and abdominal viscera, aortic arch baroreceptors, carotid and aortic bodies, taste buds on the epiglottis, skin on external ear. Proprioceptor fibers from muscles of larynx and pharynx.
Cranial Nerve XI
Accessory Nerve
Origin and Course of the Accessory Nerve
Rootlets emerge from spinal cord. Pass along spinal cord and enter skull via foramen magnum, exit skull through jugular foramen.
Function of the Accessory Nerve
Mixed nerves. Motor fibers to trapezius and SCM muscles. Proprioceptor impulses from same muscles.
Cranial Nerve XII
Hypoglossal Nerve
Origin and Course of the Hypoglossal Nerve
Arise by series of roots from medulla and exit skull via hypoglossal canal to tongue.
Function of the Hypoglossal Nerve
Mixed nerve, primarily motor. Somatic motor fibers to intrinsic and extrinsic muscles of tongue. Proprioceptors from same muscles.
