The Anatomy of the Central Nervous System (2024)

The central nervous system (CNS) consists of the brain and spinal cord. The CNS is the body and mind's control center. Like a central communication hub, it receives, processes, and responds to all types of sensory input. The CNS also controls voluntary muscle movements and motor functions.

"Nervous system" is an umbrella term for the bodily system in vertebrates consisting of nerves, ganglia, and receptor organs that can receive and interpret stimuli and transmit impulses to organs. Our nervous system has two main subdivisions: the central nervous system and the peripheral nervous system.

This article focuses on the system of nerve cells (neurons) contained within the cranium (skull) and spinal column that make up our central nervous system.

Discovery and Significance

Ancient Greeks such as Alcmaeon, Praxagoras, and Herophilus are credited with discovering and demonstrating the existence of the human body's nervous system millennia ago.

In the 1840s, a German physician and physiologist Emil du Bois-Reymond made groundbreaking discoveries about how nerves work that led to our current understanding of the anatomy and function of the central nervous system.

Our modern-day usage of the word "nervous" to describe someone who is anxious or easily alarmed originated centuries ago, when the term "nervous temperament" was used vaguely to describe disorders associated with the nervous system.

The central nervous system is a vital hub that facilitates everything we do, think, and feel as hom*o sapiens. It's responsible for learning, memory, and cognition. The CNS also controls muscles and supports coordinated movements, allowing people to perform daily activities necessary for survival. Without a central nervous system, it would be impossible for human beings—and every other mammal with a backbone—to exist as warm-blooded vertebrates.

Anatomy

The central nervous system includes neurons, which are information-carrying nerve cells of the brain and spinal cord. Cerebrospinal fluid (CSF) is a clear liquid with the consistency of water that surrounds the brain and spinal cord. CSF provides cushioning, protection, and nourishment to the central nervous system.

Cerebrospinal fluid is held within the meninges, the triple-layered fibrous covering of the central nervous system. The meninges has three distinct layers that surround the brain and spinal cord:

1. Pia mater: The delicate inner layer of the meninges closest to brain tissue
2. Arachnoid mater: The middle layer of the meninges
3. Dura mater: The durable outer layer of the meninges closest to the skull

Structure

The brain is encased and protected by the skull, which has eight cranial bones. The spinal cord is housed in the spinal column, which consists of 33 vertebrae bones.

Although the central nervous system's structure is divided into two main parts (brain and spinal cord), it has numerous subdivisions. The seven primary subdivisions of the central nervous system include the six brain regions (listed below) plus the spinal cord:

1. Cerebrum: The largest part of the brain responsible for thought, emotion, learning, speech, and planning movements
2. Cerebellum: The part of the brain responsible for keeping movements smooth
3. Diencephalon: Connects midbrain to the cerebrum, responsible for releasing hormones, regulating the sleep-wake cycle, managing automatic functions of living (such as breathing and heartbeat), memory, and emotions
4. Midbrain: Connects the medulla oblongata to the cerebellum and transmits information that allows us to see and hear; is also key in the movement of the eyes along with auditory and visual processing
5. Pons: Brain stem region that connects that brain and spinal cord to transmit information about hearing, taste, and motor function; also helps coordinate eye and facial movements, along with regulating rhythms of breathing and sleep-wake cycles
6. Medulla oblongata: The lowest portion of the brain stem that helps with functions like breathing, heart rate, swallowing, and tongue movement
7. Spinal cord: A long structure encased in the spine that runs down the back and transmits information between the brain and body
   

The central nervous system's structure is composed of two different tissue types: gray matter and white matter.

In the brain, white matter is buried beneath the gray matter. White matter tracts contain axons that act like communication cables between various gray matter structures in both hemispheres of the cerebrum and cerebellum. The cerebral and cerebellar cortices are made of gray matter.

In the spinal cord, the gray and white matter structure is reversed; gray matter is nestled inside the spinal cord's core, and white matter wraps around it (on the outside) like insulation.

Location

The central nervous system is comprises the brain and spinal cord, located in the skull and inside our backbone's vertebral canal, respectively. The brain stem is located at the base of the skull and top of the spine; it connects both organs of the CNS. Like a relay station, the brain stem facilitates bidirectional communication between the body and brain via the spinal cord.

Function

The central nervous system is like a central processing center. Its three main functions are:

1. Sensory function: Receive sensory input from every part of the body
2. Cognitive function: Process and respond to information using the brain's thinking capabilities and cognition
3. Motor function: Initiate voluntary movements by sending out motor signals via the spinal cord

Neurological Conditions

Neurological conditions associated with the central nervous system can be broken down into five categories, as follows:

• Degenerative disorders: Degenerative disorders are caused by a loss of neurons in the central nervous system. They include Alzheimer's disease,amyotrophic lateral sclerosis (ALS), ataxia, Huntington's disease, Lewy body dementia, multiple sclerosis (MS), Parkinson’s disease, spinal muscular atrophy (SMA)
• Functional disorders: Dizziness, epilepsy, headaches, migraine, trigeminal neuralgia
• Structural damage: Concussions, traumatic brain injury (TBI), spinal cord compression
• Infectious disease: Brain infection, encephalitis, meningitis
• Vascular issues: Brain aneurysm, brain bleed (hemorrhage), stroke, subdural hematoma, transient ischemic attack (TIA), vascular brain tumor

Nervous System Specialists

The following are specialists who deal with the nervous system:

• Neurologists are central nervous system specialists who treat conditions of the brain and spinal cord.
• Neurosurgeons perform surgery on the central nervous system.
• Neuroscientists conduct research and clinical trials related to the nervous system.

Summary

The central nervous system is important to everything we do as human beings. It's been observed since the times of Ancient Greece and is composed of seven main parts, each responsible for different key functions of daily living.

A Word From Verywell

Keeping our central nervous system functioning well is vital to our day-to-day lives and quality of life. Advances in neuroscience continue to shed light on how to optimize the brain's gray matter and white matter across the human lifespan.