Midbrain & Diencephalon

Lab 8

Midbrain (Mesencephalon)

Part of the brain responsible for vision, hearing, motor control, sleep/wake cycles, arousal, and temperature regulation

Diencephalon

Brain region including thalamus and hypothalamus that relays sensory and controls endocrine/autonomic functions

Midbrain vision role

Processes visual information

Midbrain hearing role

Processes auditory information

Midbrain motor control

Coordinates movement

Midbrain sleep function

Regulates sleep and wake cycles

Midbrain arousal

Controls alertness and consciousness

Midbrain temperature regulation

Helps maintain body temperature

Tectum

Dorsal part of midbrain involved in reflexes to visual and auditory stimuli

Superior colliculi

Visual processing and saccadic eye movements

Inferior colliculi

Auditory processing

Reticulospinal tract

Controls alertness and receives input from tectum

Tegmentum

Contains nuclei and tracts involved in movement and sensation

Red nucleus

Controls gait and motor coordination

Medial lemniscus

Carries somatosensory information from skin and joints

Reticular formation

Controls arousal, consciousness, motor coordination, serotonin production, and breathing

Cerebral aqueduct

Connects 3rd and 4th ventricles and allows cerebrospinal fluid flow

Cerebral aqueduct location

Between tectum and tegmentum

Periaqueductal gray

Involved in pain control (analgesia) and bonding

Crus cerebri

Contains corticospinal and corticobulbar tracts

Corticospinal tract

Controls voluntary movement of the body

Corticobulbar tract

Controls voluntary movement of the face

Substantia nigra

Produces dopamine and is involved in motor planning and learning

Substantia nigra location

Only basal ganglia structure outside the forebrain

Substantia nigra function

Motor control, learning, and addiction

Thalamus

Relay center for sensory and motor signals to the cerebrum

Thalamus function

Processes heat, cold, pain, pressure, vision, taste, and balance but not smell

Hypothalamus

Controls endocrine system via the pituitary gland

Hypothalamus function

Regulates hormones, homeostasis, and autonomic functions

Hypothalamus control

Controls eye movement and hearing responses

Thalamus exception

Does not process smell

Reticular formation neurotransmitter

Produces serotonin

Substantia nigra chemicals

Produces dopamine, melanin, and noradrenaline

Cerebral aqueduct size

Smallest ventricle in the brain

Superior colliculi function

Visual reflexes and eye movement

Inferior colliculi function

Auditory reflexes

Midbrain structure for vision reflex

Superior colliculi

Midbrain structure for hearing reflex

Inferior colliculi

Structure controlling alertness

Reticular formation

Structure for pain modulation

Periaqueductal gray

Structure for voluntary movement pathways

Crus cerebri