U1, L4 A&P232

The brainstem is similar to the spinal cord but contains

embedded nuclei

Functions of the brain stem

• Controls automatic behaviors necessary for survival

• Provides the pathway for tracts between higher and lower brain centers

• Associated with 10 of the 12 pairs of cranial nerves

the brainstem contains three regions called

• medulla oglongata

• pons

• midbrain

Midbrain structures include

• Cerebral peduncles – two structures that contain descending pyramidal motor tracts

• Cerebral aqueduct – hollow tube that connects the third and fourth ventricles

• Corpora quadrigemina – four domelike protrusions of the dorsal midbrain (superior and inferior colliculi)

• Superior colliculi – visual reflex centers

• Inferior colliculi – auditory relay centers

• Substantia nigra – functionally linked to basal nuclei

• Red nucleus - part of descending motor pathways

• (Call Courtney Cause She Is Super Reliable)

Fibers of the pons connect

the brain and the spinal cord, and relay impulses between the motor cortex and the cerebellum.

Ascending sensory tracts and nuclei as well as descending motor (corticospinal) tracts lay within

the medulla

Crossover (decussation) of the corticospinal fibers occurs at this level forming pyramids.

ascending sensory tract and descending motor tract

Some of the centers found in the medulla oblongata are

▪ Cardiovascular control center

▪ Respiratory centers

▪ Centers for other reflexes are located here: vomiting, hiccupping, swallowing, etc

Cardiovascular control center

adjusts force and rate of heart contraction, and diameter of the vessels

Respiratory centers

control rate and depth of breathing

the cerebellum provides

precise timing and appropriate patterns of skeletal muscle contraction

Cerebellar activity occurs

subconsciously.

The cerebellum consists of two hemispheres connected by the

vermis that rest on the cerebellar peduncles

what makes up the cerebellar cortex

• Gray matter

• scattered nuclei

• internal white matter fill the rest of the structure.

Cerebellar peduncles are three paired fiber tracts that connect the cerebellum to the brain stem

• the superior peduncles connect to the midbrain

• the middle peduncles connect to the pons

• the inferior peduncles connect to the medulla

The cerebellum receives impulses that initiate

voluntary muscle contraction

Proprioceptors and visual signals…

“inform” the cerebellum of the body’s condition.

The cerebellar cortex calculates

the best way to perform a movement.

A “blueprint” of coordinated movement is sent to

the cerebral motor cortex

The cerebellum plays a role in

• language and problem solving

• It recognizes and predicts sequences of events.