Midbrain

Midbrain functions:

• Visual and auditory reflexes

• Motor control

• Arousal and consciousness

• Pathways connecting forebrain and spinal cord

part of midbrain: tectum structures

1. Corpora quadrigemina

2. Trochlear nerve (IV)

3. Cerebral aqueduct - of Sylvius

Superior Colliculi function

• Visual reflex center

• Processes visual signals

• Coordinates eye and head movements toward visual stimuli

Inferior Colliculi function

• Auditory reflex center

• Processes sound signals

• Sends auditory information to the thalamus, then to the auditory cortex

trochlear nerve (CN IV) functions

• Innervates superior oblique muscle

• Controls downward and lateral eye movement

• Only cranial nerve that exits dorsally

Tegmentum (ventral) structures

1. Red nucleus 2. Substantia nigra 3. Cerebral peduncles a) Corticospinal tract b) Corticobulbar tract c) Corticopontine tract 4. Oculomotor nerve (III)

red nucleus functions

• Motor coordination

• Helps control limb movement

• Communicates with cerebellum and motor cortex

Substantia Nigra Functions:

• Motor control

• Works with basal ganglia

Cerebral Peduncles Corticospinal Tract Functions

Voluntary movement of the body

Cerebral Peduncles Corticobulbar Tract Functions

Voluntary movement of cranial nerve muscles

Cerebral Peduncles Corticopontine Tract Functions

Communication between cerebral cortex and cerebellum

Oculomotor Nerve (CN III)

• Pupil constriction

• Lens accommodation

Controls most eye movements.

Cerebral Aqueduct

• Connects 3rd ventricle → 4th ventricle

• Allows cerebrospinal fluid (CSF) flow

Midbrain Reticular Formation

• Sleep-wake regulation

• Consciousness

• Pain modulation

• Visceral control

  • cardiovascular regulation

• Motor coordination