Components and Functions of the Midbrain

Superior Colliculi

Subdivision: Gray matter, Tectum(roof)

Function: Integrate visual information with other sensory inputs; initiate reflex responses to visual stimuli

Inferior Colliculi

Subdivision: Gray matter, Tectum(roof)

Function: Relay auditory information to medical geniculate nuclei; initiate reflex responses to auditory stimuli

Red Nuclei

Subdivision: Gray matter, Walls and floor

Function: Subconscious control of upper limb position and background muscle tone

Substantia nigra

Subdivision: Gray matter, Walls and Floor

Function: Regulates activity in the basal nuclei

Reticular Formation(headquarters)

Subdivision: Gray matter, Walls and Floor

Function: Automatic processing of incoming sensations and outgoing motor commands; can initiate involuntary motor responses to stimuli; helps maintain consciousness(RAS)

Other nuclei/centers

Subdivision: Gray matter, Walls and Floor

Function: Nuclei associated with two cranial nerves (III,IV)

Cerebral Peduncles

Subdivision: White Matter

Function: Connect primary motor cortex with motor neurons in brain and spinal cord; carry ascending sensory information to thalamus