Brain stem

Brain stem
Consists of three regions:
midbrain
Pons
medulla oblongata
Similar to spinal cord – deep gray matter surrounded by white tracts but contains embedded nuclei in the white matter.

Controls automatic behaviors necessary for survival (breathing, digestion, heart rate, blood pressure)
Provides the pathway for tracts between higher and lower brain centers
Associated with 10 of the 12 pairs of cranial nerves.

Midbrain
Located between diencephalon and pons
Midbrain structures include:
Cerebral peduncles – two structures that contain descending pyramidal motor tracts.
Cerebral aqueduct – hollow tube that connects the third and fourth ventricles
Various nuclei

Midbrain Nuclei

Nuclei that control cranial nerves III (oculomotor) and IV (trochlear).
Corpora quadrigemina - 4 domelike protrusions of dorsal midbrain.
2 Superior colliculi - visual reflex centers; coordinate head and eye movement when we follow a moving object (does not have to be a conscious decision).
2 Inferior colliculi - auditory relay centers between hearing receptors to sensory cortex.
Reflexive responses to sound – turn head toward sound