NEURO Lecture 8: Structure of Brain Stem

**make sure to look over last two slides, draw out, and the eye movements

Shape of brain stem

cylinder wider at the top

brainstem consists of

white matter (tracts) that consist of neurons

Shape of brain stem

cylinder wider at the top

brainstem consists of

white matter (tracts) that consist of neurons

brain stems three structures are

medulla oblongata (bulb), pons, and midbrain

brain stems location

basal portion of the occipital bone

brain stem controls

equilibrium, vital functions (BP, HR), eye movements, and other functions (posture/balance, walking symmetrically)

the medulla oblangata merges with

the spinal cord seamlessly to create the base of the brainstem (passes through the foramen magnum)

functions of the medulla oblangata

vital involuntary reflexes (swallowing, vomiting, sneezing, coughing, regulation of cardio and respiratory systems)

shape of medulla oblangata

continuous with the spinal cord and will widen gradually as it goes in the rostral direction

medulla oblangatas location

rests on the basilar portion of the occipital bone

junction between the spinal cord and medulla location

upper rootlet of the first cervical nerve

junction between the medulla and pons on the ventral surface

Pontomedullary sulcus

junction between the pons and medulla on the dorsal surface

line that passes between the caudal margins of the middle cerebellar peduncles

connects the cerebellum to the brainstem

cerebellar peduncles

caudal 2/3 of the medulla contains

the rostral continuation of the central canal of the spinal cord

Going rosturally, the central canal

shifts more dorsal and in the rostral medulla and it opens out into the fourth ventricle

the fouth ventricle is the widest at the level of the

pontomedullary junction

in the medulla, CSF flows from the

fourth ventricle to the subarachnoid space of the brainstem

Foramen lushka

CSF flows from the 4th ventricle to the subarachnoid space

foramen of monro

lateral ventricle and the third ventricle

the lateral walls of the rostral part of the 4th ventricle are made up of

superior and inferior cerebellar peduncles

connect the brian stem with the cerebellum

cerebellar peduncles

CN that comes out near the midline between the pons and pyramids of medulla & enters the orbit through the superior orbital fissure

abducens nerve CN 6

CN attatched to the brain stem at the caudal border of pons lateral to the abducens nerve

facial nerve CN 7

CN located lateral to the facial nerve at the caudal border of the pons

vestibularcochlear nerve CN 8

CN(s) attatched to the medulla along a line between the olive and the tuberculum cinereum

glossopharyngeal CN 9, vagus CN 10, accessory (cranial division) CN 11

CN that emerges along the ventrolateral sulcus between the pyramid and olive of medulla

hypoglossal CN 12

rounded brainstem region between the medulla and midbrain; two portions dorsal and basal

pons

function of pons

connects the cerebellum to the rest of the brain and to modify the respiratory output of the medulla

on ventral portion, shallow groove that runs along the midline

basilar sulcus

laterally, the pons merges into

middle cerebral peduncles

CN attached at the transition between pons and the peduncle

trigeminal nerve CN 5

three branches of the trigeminal nerve

opthalamic, maxillary, mandibular

Portion of pons that contains ALL ascending and descending tracts

dorsal portion (tegmentum) of pons

dorsal surface of pons is formed by

the floor of the fourth ventricle

in midbrain, on each side of the pons, column of white matter that consists of corticospinal, corticobulbar, and corticopontine fibers

basis pedunculi

deep depression in midbrain between the two basal pedunculi columns

interpeduncular fossa

CN that emerges from the side of interpeduncular fossa of the midbrain

oculomotor nerve CN 3

ventral surface of the midbrain extends from

pons to the mamillary bodies of the diencephalon

lateral surface of the midbrain is formed by

cerebral peduncle

cerebral peduncle contains

ALL FIBERS and basis pedunculi and some internal structures like the substantia nigra and tegmentum of the midbrain

dorsal surface of the midbrain bears four rounded elevations

two superior colliculi and two inferior colliculi

the colliculi make up the

tectum of the midbrain

colliculi for ocular movement/ sight vision

superior colliculi

colliculi for hearing/auditory

inferior colliculi

CN that emerges from the brain stem immediately caudal to the inferior colliculus: dorsal surface of midbrain ONLY

trochlear nerve CN 4