Neuroanatomy: Brain stem and cranial nerves

What are the parts of the brain stem

Midbrain, pons, medulla

What is contained within the brainstem that contributes efferent or receives afferent fibers from 9 of the cranial nerves

Cranial nerve nuclei

Which nuclei of the cranial nerves mediate voluntary movement of structures of the head and face

Efferent nuclei

What tract is used by the efferent nuclei of cranial nerves

Corticobulbar tract

What are the dorsal surface features of the midbrain

Superior and inferior colliculus

What is the function of the superior and inferior colliculus respectively

Vertical gaze, visual/orienting reflexes, and auditory pathways

What is formed by the superior and inferior colliculus

Tectum

What nerve emerges from the lower part of the midbrain

trochlear nerve

What are the dorsal surface features of the pons

Superior, middle, and inferior cerebellar peduncles

What do the cerebellar peduncles do

Connect cerebellum to the brain stem

What part of the ventricular system is present on the dorsal surface of the pons and medulla

4th ventricle

What prominent colliculus is found in the dorsal pons

Facial colliculus

What nucleus lies beneath the facial colliculus

Abducent nucleus

What are the dorsal surface features of the medulla

Obex and dorsal median sulcus

What is the point at which the dorsal surface of the medulla opens up to form part of the 4th ventricle

Obex

What are the ventral features of the midbrain

Interpeduncular fossa, cerebral peduncle

What tracts run within the cerebral peduncle

Corticospinal and corticobulbar tract

What are the ventral features of the pons

Basilar pons, basilar sulcus, middle cerebellar peduncle

The basilar sulcus is a shallow groove on the pons for which artery

Basilar artery

What fibers connect the pons with the cerebellum on the ventral surface

Pontocerebellar fibers

What cranial nerves will you not find attached to the brainstem

CN I and CN II

Which component of cranial nerves carries sensory information to the brain stem

Afferent components

Most somatosensory information from the face and anterior head is conveyed by what nerve

Trigeminal nerve

Which component of cranial nerves originate in cranial nerve nuclei and innervate muscles or visceral organs

Efferent components

Cranial nerve ulcer that innervate voluntary muscles are under control of which tract

Corticobulbar tract

Where does the corticobulbar tract originate

Cerebral cortex

Are cranial nerve nuclei unilateral or bilateral

Bilateral

What structures are found in the lower medulla cross sections

Nucleus of XII, pyramid, and spinal trigeminal nucleus

The nucleus of XII contains lower motor neurons that innervate what muscles

Tongue

What nucleus receives afferent CN V fibers carrying pain, temp, and some touch

Spinal trigeminal nucleus

What structures can bee seen in a mid-medulla cross section

Nucleus of XII, Dorsal motor nucleus of X, pyramid, spinal trigeminal nucleus, fourth ventricle, inferior olivary nucleus

Which nuclei is the source of most parasympathetic fibers of X to visceral organs

Dorsal motor nucleus of X

What structures can be seen in a cross section of the upper medulla

Pyramid, spinal trigeminal nucleus, nucleus of solitary tract, nucleus ambiguus, inferior olivary nucleus, vestibular nucleus, fourth ventricle, nucleus of XII, CN XII, dorsal motor nucleus of X, CN X, inferior cerebellar peduncle

What type of fibers are found in the nucleus ambiguus

Efferent/motor

What type of fibers are found in the nucleus of solitary tract

Afferent/Sensory

Which nucleus has a distinct appearance of a small dark patch surrounded by a circle of grey matter in the upper medulla

Nucleus of solitary tract

Where would you find the nucleus ambiguus

Halfway between the nucleus of solitary tract and inferior olivary nucleus

What nucleus provides motor innervation of the soft palate, pharynx, larynx, and upper part of esophagus via CN IX and X

Nucleus ambiguus

What structures can be seen in a cross section of the lower pons

Abducens nucleus, facial nucleus, pyramid, spinal trigeminal nucleus, vestibular nucleus, fourth ventricle, middle cerebral peduncle

The fibers of CN VII warp around which nucleus before exiting the brain

Abducens nucleus

What is formed by the wrapping of CN VII fibers around the Abducens nucleus on the dorsal pons

facial colliculus

Damage to the facial colliculus causes what condition

Bell's palsy

What structures can be seen on a cross section of the mid pons

Motor trigeminal nucleus, main sensory nucleus of trigeminal complex, pyramid, fourth ventricle

Damage to which nucleus ay cause weakness in chewing

Motor trigeminal nucleus

When the patient tries to protrude the mandible with damage to the motor trigeminal nucleus, which side will it deviate to

Towards the side of the lesion

Which cranial nerve is the primary somatic sensory nerve to most of the face, dura mater, and the scalp

CN V

What senses are carried by CN V from the face to the CNS

Pain, temperature, touch, pressure, proprioception, vibration

Where do afferent C V fibers synapse in the brain stem

Spinal trigeminal nucleus and main sensory trigeminal nucleus

What condition is associated with unilateral bouts of searing pain in the face

trigeminal neuralgia

Patients with what condition are at higher risk for trigeminal neuralgia

Multiple sclerosis

What is the most common intervention for trigeminal neuralgia after medications

Microvascular decompression

What structures can be seen in a cross section of the lower midbrain

Nucleus of trochlear nerve, mesencephalic nucleus of V, cerebral peduncle, inferior colliculus, cerebral aqueduct

Fibers of CN 4 with decussate where in the brain stem

Dorsal part of midbrain-pons junction

If the nucleus of IV is damaged on one side of the body, which superior oblique muscle is most likely paralyzed

Contralateral side

What structures can be seen in a cross section of the upper midbrain

Nucleus of III, mesencephalic nucleus of V, cerebral peduncle, superior colliculus, cerebral aqueduct

What is contained in the occulomotor nucleus that provides the parasympathetic fibers to CN III

Accessory occulomotor nucleus (Ediger-Westphal)

Damage to nucleus of III will cause what presentation

Eye in a down and out orientation with blown pupils

What is the name for an upper motor neuron pathway that allows for voluntary movement of the muscles of the face, head, neck, eyes, and shoulders

Corticobulbar tract

Which cranial nerves are a part of the corticobulbar tract

CN III, IV, V, VI, VII, X, XI, XII

What structures does the corticobulbar tract run through

internal capsule, cerebral peduncles, into brain stem

Which corticobulbar distributions are bilateral

Occulomotor, motor trigeminal, upper facial, ambiguus, spinal accessory (SCM)

What does it mean when a corticobulbar tract distribution is bilateral

Both sides of the brain will provide upper motor neurons that send the signals to the corticobulbar lower motor neurons

Damage to the corticobulbar tract on one side won't cause clinical symptoms to nuclei of which distribution type

Bilateral

Which corticobulbar distributions are ipsilateral

trochlear

What does it mean when a corticobulbar tract distribution is ipsilateral

The hemisphere of the brain will send signals to the same sided nuclei

Why will a contralateral deficit still be seen with damage to the trochlear corticobulbar distribution

The trochlear nerve decussates before emerging from the midbrain

Which corticobulbar distributions are contralateral

Abducens, spinal accessory (traps), lower facial, hypoglossal

What does it mean when a coticobulbar distribution is contralateral

The hemisphere of the brain will send signals to the opposite sided nuclei

Damage to the upper motor neurons on the contralateral side of the upper and lower facial divisions will cause what symptoms

Deficit in lower face because upper division is bilateral

Damage to the facial nerve after the upper and lower divisions of the facial nucleus will cause what symptoms

Deficit in upper and lower face