9 Pons and Midbrain

What are the two regions of the pons?

tegmentum (core), basilar pons

ventral portion of the pons

basilar pons (basis pontis)

The basilar pons contains three descending tracts. What are they?

corticospinal, corticobulbar, corticopontine

The basilar pons contains the transversely oriented _________ _________ and _________ __________

pontocerebellar tracts, pontine nuclei

The tegmentum (core) of the brainstem contains what _________ _______ pathways

ascending sensory

The tegmentum (core) of the brainstem contains _______ nerve nuclei, ______ _______ and periaqueductal ________ ________

cranial, reticular formation, gray matter

floor of the fourth ventricle due to its shape

rhomboid fossa

swelling on the floor of the 4th ventricle

facial colliculus

Facial colliculus is caused by CN ______ looping over the _________ nucleus.

VII, abducens

overlies the vestibular nuclei (balance + coordination of eye and head movements

vestibular area

groove in the floor of the 4th ventricle

sulcus limitans

The sulcus limitans separates _______ and ________ nuclei

motor, sensory

swelling on the dorsal surface of the medulla formed by the gracile nucleus

gracile tubercle

The abducens nerve (CN ______) supplies _______ _______fibers to the ________ ________ muscle, which abducts the eye (turns it laterally).

VI, somatic motor, lateral rectus

The facial nerve (CN _____) carries nerve fibers that control facial __________ and ________

VII, movement, expression

The facial nerve carries fibers involved in ________ to the ________ 2/3 of the tongue and producing ________ (lacrimal gland)

taste, anterior, tears

The facial nerve has small branches involved in moderating sensitivity to _______ _________ (stapedius muscle)

noise volume

Blood supply to the pons occurs in a ________ to __________ pattern from the ________ artery

medial, lateral, basilar

What are the 3 branches of the basilar artery that supply the pons?

paramedian, short circumferential, long circumferential

What are the four cranial nerves associated with the pons?

V (trigeminal), VI (abducens), VII (facial), VIII (auditory)

Pons proper is innervated by what?

CN V (trigeminal)

The pontomedullary junction is innervated by what?

CN VI (abducens), VII (facial), VIII (auditory)

What happens if CN V (trigeminal) is damaged?

ipsilateral alteration of pain, temperature, light touch on the face

What happens if CN VI (Abducens) is damaged?

ipsilateral weakness of abduction (lateral movement of the eye)

What happens if CN VII (facial) is damaged?

ipsilateral facial weakness

What happens if CN VIII (auditory) is damaged?

ipsilateral deafness

What is the smallest segment of the brainstem?

midbrain (2cm)

The midbrain (mesencephalon) is continuous with the _______ caudally

pons

The midbrain (mesencephalon) is continuous with the _________ rostrally

diencephalon

What two structures form the tectum (roof) of the midbrain?

superior colliculi, inferior colliculi

movement control center

Substantia nigra

Substantia nigra sends dopaminergic fibers to the ________

striatum

________ ________ is damaged in Parkinson's disease

Substantia nigra

Substantia nigra is damaged in ________ ________

Parkinson's disease

huge white masses; form the ventral surface (base) of the midbrain

Crus cerebri

What are the tracts of the crus cerebri?

corticopontine, corticobulbar and corticospinal (descending motor)

visual relay center

superior colliculus

auditory relay center

inferior colliculus

Decussation of the SCP is the site of crossing of axons which originated the nuclei of the ________; terminate in the ________ nuclei of the _________

cerebellum, motor, thalamus

The medial lemniscus changes orientation as it moves from ________ to _____ _____ ______ of the thalamus

medulla, ventral posteriolateral nucleus

What artery supplies the midbrain?

basilar artery

What three branches of the basilar artery supply the midbrain?

superior cerebellar artery (SCA), posterior cerebral artery (PCA), communicating artery

What are the two cranial nerves in the midbrain?

III (oculomotor), IV (trochlear)

What happens if CN III (oculomotor) is damaged?

eye is turned out and slightly down

What happens if CN IV (trochlear) is damaged?

eye is unable to look down when the eye is looking toward the nose

The cranial nerves are a set of ______ paired nerves that arise directly from the _______

12, brain

The first two cranial nerves (olfactory and optic) arise from the _________

cerebrum

The first two cranial nerves (_________ and _________) arise from the cerebrum

olfactory, optic

The remaining 10 cranial nerves emerge from the _________

brainstem

Names of cranial nerves relate to their __________; numerically identified in roman numerals (I-XII)

function

CN I

olfactory

Cn II

optic

CN III

oculomotor

CN IV

trochlear

CN V

trigeminal

CN VI

abducens

CN VII

facial

CN VIII

vestibulocochlear

CN IX

glossopharyngeal

CN X

vagus

CN XI

accessory

CN XII

hypoglossal

CN III – XII: arise from a specific part of the __________ (midbrain, pons or medulla), or from a ___________ between two parts

brainstem, junction

the trochlear nerve (IV) comes from the _________ side of the midbrain making it the ________ in intracranial length!

posterior , midbrain, longest

Where does the oculomotor (CN III) originate?

midbrain-pontine junction

Where does the trigeminal (CN V) originate?

pons

What three CNs originate from the pontine-medulla junction?

abducens, facial, vestibulocochlear (VI-VIII)

Where do the glossopharyngeal, vagus, and accessory nerves (IX-XI) originate?

Medulla oblongata - posterior to the olives

Where does the hypoglossal (XII) originate?

medulla oblongata - anterior to the olives

Brainstem neurologic syndromes are normally subdivided into ________ or _________ syndromes based on _______ ________ patterns and _________ found within those patterns.

medial, lateral, blood supply, structures

__________ involvement of long ascending/long descending tracts result in _________ sensory and motor deficits.

Unilateral, contralateral

Cranial nuclei and nerve involvement result in _________ motor/sensory deficits.

ipsilateral

The brainstem is between the _______ ________ and the ________

spinal cord, diencephalon

A specific part of the ventricular system is associated with each of the 3 regions: _________-third ventricle, cerebral aqueduct; _______-cerebral aqueduct, fourth ventricle; _________-fourth ventricle and central canal

midbrain, pons, medulla

CNs associated with the medulla

VIII-XII

CNs associated with the pons

V-VIII

CNs associated with the midbrain

III, IV

Major references structures on medulla cross section?

pyramidal decussation, olives, DCML, obex

Major references structures on pons cross section?

facial colliculus

Major references structures on midbrain cross section?

tectum, crus cerebri; nuclei: substantia nigra and red nucleus

The medulla is supplied by branches of the _________ artery system

vertebral-basilar

The pons and mesencephalon is supplied by branches of the ________ artery

basilar

unilateral deficit/involvement of tracts: ________ for long tracts; __________ for CNs (exception: CN IV)

contralateral, ipsilateral