Major brain parts and their functions

Author: Scott A. Sheffield MS

Last update: Nov 1st, 2022

The adult brain is divided into the cerebrum, diencephalon, cerebellum, and brainstem.

Lateral and midsagittal views of the brain show the anatomical boundaries of these major brain divisions.

• Making up most (80-85%) of the brain are the right and left hemispheres of the cerebrum.

• Beneath the convoluted surface of the cerebrum lies a thin layer of gray matter (cerebral cortex), which performs many higher level functions.
• Sensations are imaged and interpreted, movements are planned, memories are stored and retrieved, and complex judgments are made.
• Underneath the large cerebrum is the much smaller diencephalon. Most of this region consists of the right and left thalamus.

• Many neurons synapse here so that sensory and motor information can be correctly routed to the cerebrum for further processing.
• Inferior to the thalami is the hypothalamus.

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• This area regulates several involuntary functions, such as water balance, appetite, and body temperature.
• Additionally, the hypothalamus is involved in the sensation of primitive emotions and regulation of hormones released from the anterior pituitary gland.

• Inferior to the cerebrum is the second largest division of the brain called the cerebellum.

• Like the cerebrum, the cerebellum made up of two, highly convoluted hemispheres.
• The cerebellum coordinates ongoing muscular movements and helps maintain proper posture, equilibrium, and muscle tone.
• The fourth major division of the adult brain is called the brainstem (or brain stem), which lies anterior to the cerebellum and inferior to the diencephalon.

• At its superior end is the midbrain(or mesencephalon).

• One of the functions of this area is to control reflex tracking movements of the head, neck, and eyes based on stimuli received from the eyes and ears.
• Inferior to the mesencephalon is a knob-like pons.

• Most of the pons consists of ascending and descending tracts of axons (white matter).
• However, it also contains several small nuclei (= gray matter).
• Some of these nuclei help the cerebrum communicate with the cerebellum (relay center), and others help regulate breathing movements.
• The pons also gives rise to several of the cranial nerves.
• The inferior portion of the brainstem is called the medulla oblongata, and it spans the distance from the pons to the spinal cord.

• Because of its location, much of the medulla oblongata is made up of the same nerve fiber tracts that run through the spinal cord.
• Many of the sensory tract neurons synapse here so that information can be relayed to higher brain centers for processing.
• Nuclei in the medulla oblongata are involved with five of the cranial nerves, and they also control many of the body’s vital (heart rate, blood pressure, & breathing) and non-vital (sneezing & coughing) visceral activities.

Overview:

Interactive quiz with the parts of the brain