Brain Anatomy Overview

Overview

This lecture provides an introductory overview of the main anatomical structures of the brain and their basic functions.

Brain Stem

• The brain stem is divided into the medulla oblongata, pons, and midbrain (from inferior to superior).
• The medulla oblongata connects the brain to the spinal cord and controls vital functions like heart rate and breathing.
• The pons sits above the medulla and below the midbrain.
• The midbrain includes the cerebral peduncles (front) and the corpora quadrigemina (back), which are four bumps called the superior and inferior colliculi.
• The tectum is the "roof" of the midbrain; it houses the corpora quadrigemina.
• Nuclei in the brainstem control basic functions such as respiration, consciousness, and house cranial nerve nuclei.

Cerebellum

• The cerebellum ("little brain") is located behind the brainstem.
• It is responsible for coordination, balance, and muscle tone.
• The cerebellum has many connections with the brainstem.

Diencephalon

• The diencephalon sits above the midbrain and includes the thalamus, hypothalamus, and pineal gland.
• The thalamus relays sensory and motor signals to the cerebral cortex.
• The hypothalamus, below the thalamus, regulates homeostasis and endocrine functions.
• The pineal gland is involved in regulating sleep patterns.

Cerebral Hemispheres

• The brain has right and left cerebral hemispheres responsible for higher functions like thinking, memory, language, and movement.
• Each hemisphere has an outer cortex (gray matter, up to six layers) and inner white matter.
• The neocortex has six layers and is responsible for conscious thought and language; areas with fewer than six layers are called allocortex.

Major Sulci and Lobes of the Brain

• The central sulcus separates the frontal and parietal lobes.
• The lateral sulcus separates the temporal lobe from the frontal and parietal lobes.
• The frontal lobe handles decision making, problem solving, and planning.
• The parietal lobe processes sensory information.
• The temporal lobe handles memory, language, emotion, and hearing.
• The occipital lobe, at the back, is primarily responsible for vision.

Key Terms & Definitions

• Brain stem — Structure connecting brain to spinal cord; controls vital functions.
• Medulla oblongata — Lowest part of the brain stem; manages autonomic functions.
• Pons — Middle part of brain stem; relays information.
• Midbrain — Upper brain stem; involved in vision, hearing, and motor control.
• Tectum — Roof of midbrain housing sensory structures.
• Cerebellum — "Little brain" behind brainstem; coordinates movement.
• Diencephalon — Brain region including thalamus and hypothalamus.
• Thalamus — Relay center for sensory and motor signals.
• Hypothalamus — Controls homeostasis and hormones.
• Pineal gland — Regulates sleep cycles.
• Cerebral cortex — Outer gray matter layer of cerebrum.
• Sulcus (pl. sulci) — Groove on the brain surface.
• Gyrus (pl. gyri) — Ridge on the brain surface.

Action Items / Next Steps

• Review diagrams of brain anatomy, focusing on locations and names of major structures.
• Prepare for a tutorial on the grooves, ridges, and functions of additional cortical areas.