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Olfactory and Optic Cranial Nerves

Are not true cranial nerves because they are rostral to the brainstem and have no peripheral ganglia (edinger westphal-parasympathetic-constrict pupil)

Midbrain and Lower Medulla

Areas of the brainstem that are "stacked" like the spinal cord

Rostral Medulla and Pons

Areas of the brainstem in which the alar and basal plates are opened out beside each other instead of being stacked

Oculomotor Cranial Nerve (CN III)

Nerve that exits the midbrain anteriorly and moves the eye by supplying motor neurons to most of the extraocular muscles. Lies anterior to the PAG at the level of the superior colliculus (MLF carries fibers that interconnect extraocular nucleus so that the eyes move together and for connection with vestibular nucleus)

Nuclei of Oculomotor Cranial

MLF nucleus carries fibers (GSE & GVE) that interconnect extraocular nucleus so that the eyes move together and for connection with vestibular nucleus for coordinated head movement. The Edinger-Westphal nucleus is the autonomic component of this nerve (fibers pass with the nerve fibers through the red nucleus and form the nerve)

Cavernous Sinus

The sinus that all of the oculomotor neurons and trochlear nerve pass through (beside the sella turcica) in route to the superior orbital fissure and the orbit.

Parasympathetic Oculomotor Neurons

The preganglionic neurons continue to the ciliary ganglion in the orbit. The post-ganglionic neurons enter the eyeball to innervate the sphincter pupillae muscles of the iris and ciliary muscles

Trochlear Cranial Nerve (CN IV)

Only nerve that exits contralaterally at the posterior side of the brainstem. It supplies motoneurons (GSE) to the superior oblique muscle. Its nucleus site anteriorly to the PAG caudally to the inferior colliculus. After the nerve leaves the midbrain, it travels through ambient cistern and superior orbital fissure.

Trigeminal Cranial Nerve (CV V)

This nerve is a "mixed" nerve that has several different nuclei (mesencephalic, principal sensory, __________ motor, and spinal __________ nuclei).

Mesencephalic Nucleus of CN V

This structure is the only other cranial nerve nucleus in the midbrain (besides oculomotor nucleus). This nucleus helps in pressure and kinesthesis sensation from the mouth and lower face area. Only sensory neurons that have cell bodies with the CNS.

Principal Sensory Nucleus of CN V

Structure that provides most of the discriminative touch sensation of the face and sits in the lateral pontine tegmentum (continues with lamina III & IV)

Trigeminal Motor Nucleus of CN V

Structure that is medial to the chief sensory nucleus in the tegmentum of the pons. It provides motoneurons to the muscles of mastication and muscles of the ear (also digastric m). Input to the structure is both crossed and uncrossed, and is either from the corticobulbar tract, interneurons that receive corticobulbar input, or from other cranial nerve nuclei.

Trigeminal Motor Nucleus of CN V

This structure sends its motoneurons out the trigeminal nerve through the pontocerebellar angle to the middle cranial fossa. These neurons will exit via the foramen ovale (mandibular division). Only trigeminal input that does not house their cell bodies in the trigeminal ganglion.

Spinal Trigeminal Nucleus of CN V

This structure provides pain and crude touch sensation and sits in the medulla. Has three sections, the pars oralis (crude touch), pars interpolaris, and pars caudalis (from spinal cord/medulla junction to the obex).

Abducens Cranial Nerve (CN VI)

This nerve supplies GSE to the lateral rectus muscle. Its nucleus resides in the posterior pons, under the facial colliculus. It exits the at the pontomedullary junction then runs rostrally in the prepontine cistern, then the cavernous sinus, and through the superior orbital fissure.

Sensory Component of CN VII

This nerve is "mixed" nerve that has two sensory nuclei that receive facial input. It conveys taste (SVA) from the anterior 2/3 of the tongue (cell bodies in the geniculate ganglion) and synapses in the rostral solitary nucleus in the pons. Also has cuntaneous pain sensation (GSA) from around the ear and goes to the spinal trigeminal nucleus in the medulla (cell bodies also in the geniculate ganglion).

Rostral Solitary Nucleus

Structure that receives taste (SVA) from the facial (anterior 2/3 of tongue), glossopharyngeal (posterior 1/3 of tongue), vagus (throat).

Parasympathetic Component of CN VII

This component supplies GVE to the salivary and lacrimal glands. This nerves component roots in the superior salivatory nucleus of the pons.

Motor Component of CN VII

This component of a cranial nerve is rooted in the facial motor nucleus under facial colliculus in the caudal pons. It provides SVE to the face and courses anterolaterally to exit the junction of the medulla and the pons and then exits the skull via the internal accoustic meatus along with the vestibulocochlear nerve. Most fibers go to the geniculate ganglion, some go to pterygopalantine ganglion (mucous membranes and lacrimal gland), some go to the stapedius m, some go to the submandibular ganglion (salivary glands except parotid)

Facial Motor Nucleus

This structure provides facial motor (GVE) to facial expression mm (frontalis, orbicularis oris, orbicularis oculi, and buccinator).

Crossed Facial Motor Neurons

These fibers innervate all muscles of facial expression except the frontalis and the orbicularis oculi, which are ipsilaterally innervated.

Vestibulocochlear Facial Nerve (CN VIII)

This nerve has four SSA nuclei, the superior vestibular nucleus, the medial lateral inferior vestiular nuclei, and the cochlear nucleus.

Glossopharyngeal Cranial Nerve (CN IX)

This nerve emerges just below the pontomedullary junction at the post-olivary sulcus. The inferior salivatory nucleus (GVE) provides parasympathetic preganglionic fibers to this nerve. It innervates the larynx and pharynx.

Vagus Cranial Nerve (CN X)

This nerve emerges just below the pontomedullary junction at the post-olivary sulcus. Is rooted in the dorsal motor vagal nucleus (GVE) within the PAG. It provides parasympathetic preganglionic nerves to ultimately innervate all of the thoracic and most abdominal viscera. It innervates the larynx and pharynx.

Nucleus Ambiguus

This structure lies just medial to the spinal trigeminal nucleus in the rostral medulla. The branchial motoneurons originate within it which contribute motoneurons to both Cranial Nerves IX & X.

Accessory Cranial Nerve (CN XI)

This nerve is primarily motor, arising from the anterior horn of the cervical spinal cord. It ascends through the foramen magnum and exits the skull via the jugular foramen. It innervates the sternocleidomastoid and trapezius ispsilaterally.

Hypoglossal Cranial Nerve (CN XII)

This nerve only has motoneurons (GSE) that go to extrinsic and intrinsic muscles of the tongue. Is rooted in the hypoglossal nucleus, which lies inthe PAG of the medulla just laterally and anterior to the cerebral aqueduct (caudally) and lies near the midline and sulcus limitans (rostrally).

Medial Medullary Syndrome

Syndrome resulting in contralateral hemiparesis (corticospinal tract), loss of position sense and discriminating touch (medial lemniscus), and loss of ipsilateral tongue muscles (hypoglossal nerve, nucleus). Most often because of lesion to medullary branch of vertebral artery.

Lateral Medullary Syndrom (Wallenberg's)

Syndrome resulting in ipsilateral loss of pain and temperature sense in face(ALS), contralateral loss of pain and temperature sense in body (spinal trigeminal tract), diminished sense of touch in the body(), paralysis of larynx, pharynx, difficulty with phonation (dysarthria) and swallowing (dysphagia) (Nucleus Ambiguus). Due to lesion of posterior inferior cerebellar artery.

Horner's Syndrome

Syndrome resulting in unilateral partial ptosis, constricted pupils, and flushing face. Due to lesion of posterior inferior cerebellar artery.

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