Brain Anatomy | Princeton Brain, Spine & Sports Medicine (2024)

About the Human Brain

Anatomy & Function

The brain is arguably the most important organ in the human body. It controls and coordinates actions and reactions, allows us to think and feel, and enables us to have memories and feelings-all the things that make us human.

While the brain only weighs about three pounds, it is a highly complex organ made up of many parts. Years of scientific study have made it possible for scientists to identify the various areas of the brain and determine their specific functions. The following information provides a brief description of some of the major parts of the human brain.

The Cranium: Covering of the Brain

The brain is protected by a bony covering called the cranium. The cranium and the bones of the face make up the skull. Inside the cranium, the brain is surrounded by three layers of tissue called the meninges. The meninges include:

• Pia mater: The layer closest to the surface of the brain
• Arachnoid membrane: The middle layer of tissue
• Dura mater: The outer-most layer

The Cerebrum: Front Part of the Brain

The largest part of the brain, located in the front, is called the cerebrum. The cerebrum is responsible for:

• Movement
• Body temperature
• Touch
• Vision
• Hearing
• Judgment
• Reasoning
• Problem solving
• Emotions
• Learning

The cerebrum is made up of the right and left cerebral hemispheres. The hemispheres are connected at the bottom and have a deep groove running between them. In general, the right cerebral hemisphere controls the left side of the body, and the left cerebral hemisphere controls the right. The right side is involved with creativity and artistic abilities. The left side is important for logic and rational thinking.

The cerebral hemispheres are divided into lobes (broad regions of the brain). Each lobe is responsible for a variety of bodily functions. Frontal lobes are involved with personality, speech, and motor development. Temporal lobes are responsible for memory, language and speech function. Parietal lobes are involved with sensation, while the occipital lobes are the primary vision centers.

The surface of the cerebrum appears wrinkled and is made up of deep grooves (called sulci) and bumps or folds (called gyri). The outer part of the cerebrum is called gray matter and contains nerve cells. The inner part is called white matter and contains connections of nerves.

The Brainstem: Middle of the Brain

The brainstem is located in front of the cerebellum. Think of the brainstem like a computer hard-drive. It is the body’s main control panel and is responsible for conveying messages between the brain and other parts of the body. The cerebrum, the cerebellum and the spinal cord are all connected to the brainstem. The brainstem has three main parts: the midbrain, the pons and the medulla oblongata.

The brain stem controls these vital body functions:

• Breathing
• Consciousness
• Cardiac function
• Involuntary muscle movements
• Swallowing
• Eye and mouth movement
• Sensory relay (pain, heat, noise, etc.)
• Hunger

The Cerebellum: Back of the Brain

Behind the cerebrum at the back of the head lies the cerebellum. In Latin, cerebellum means “little brain,” but the cerebellum actually contains more nerve cells than both hemispheres combined. The cerebellum is primarily a movement control center, responsible for:

• Voluntary muscle movements
• Fine motor skills
• Maintaining balance, posture & equilibrium

Unlike the cerebrum, the left cerebellum controls the left side of the body, and the right cerebellum controls the right side of the body.

Other Key Parts of the Brain

Ventricular System

The brain is not a solid organ. Instead, there are fluid-filled cavities within the brain called ventricles. The ventricles provide nourishment to the brain. The ventricular system produces and processes cerebrospinal fluid, a clear, watery substance flowing around the brain to cushion and protect it.

Cranial Nerves

The brain also contains 12 pairs of cranial nerves. Each is responsible for specific body functions.

• Olfactory nerve: Sense of smell
• Optic nerve: Vision
• Oculomotor: Eye movement, eyelid opening
• Trochlear: Eye movement
• Trigeminal: Facial sensations & chewing
• Abducens: Eye movement
• Facial: Taste & facial expressions
• Vestibulocochlear: Hearing & balance
• Glossopharyngeal: Taste & swallowing
• Vagus: Swallowing & taste
• Accessory: Neck & shoulder muscles
• Hypoglossal: Tongue movement

Learn More About the Brain

To learn more about the anatomy and function of the brain, take advantage of these reputable resources:

• Brain Facts
• The Brain From Top to Bottom
• American Association of Neurological Surgeons

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