Author: Adrian Rad, BSc (Hons) • Reviewer: Jana Vasković, MD
Last reviewed: November 03, 2023
Reading time: 23 minutes
Central nervous system anatomy
The central nervous system (CNS) is a division of the nervous system whose function is to analyze and integrate various intra- and extrapersonal information, as well as to generate a coordinated response to these stimuli. Put simply, the CNS is the supreme command center of the body.
The CNS consists of two organs which are continuous with each other; the brain and spinal cord. They are enveloped and protected by three layers of meninges, and encased within two bony structures; the skull and vertebral column, respectively. The brain consists of the cerebrum, subcortical structures, brainstem and cerebellum. The spinal cord continues inferiorly from the brainstem and extends through the vertebral canal.
While analyzing the information and preparing adequate body responses, the parts of the brain and spinal cord communicate with each other via many neural pathways. Once the final output is ready, they convey it to the rest of the body via nerves of the peripheral nervous system (PNS), which stem directly from them. More specifically, the brain gives off 12 cranial nerves that innervate the head, neck and thoracic and abdominal viscera, while the spinal cord gives off 31 pairs of spinal nerves. The spinal nerves complement the innervation of the viscera, as well as the remainder of the body that is not supplied by the cranial nerves (upper and lower limbs).
This article will introduce you to the anatomy and functions of the central nervous system.
The chief cells of the brain and spinal cord are the neurons, which receive and transmit neural impulses. Each neuron has a body which is its micro-command center, and it has a gray color when observed microscopically. The neurons possess two or more neural processes that stem from the body and relay the neural information. The neural processes are divided into short (dendrites) and long (axons). Most of the axons are ensheathed by a substance called myelin, which gives them a distinguishable white color.
The parts of neurons comprise what we call gray and white matter. The gray matter is made up of clusters of neuronal bodies, while the white matter is composed of their myelinated axons. The axons are not just randomly interwoven through the neural tissue, but rather are organized into bundles that connect certain parts of gray matter and carry the relevant impulses. In the CNS, these bundles are called pathways and tracts, while in the PNS they comprise nerves.
The distribution of gray and white matter is highly specific throughout the brain and spinal cord;
Overwhelmed by the task of learning all the parts of the brain? Help yourself with our brain anatomy quizzes and diagrams!
The cerebrum, or forebrain, is the most prominent part of the brain. It consists of two cerebral hemispheres interconnected by the corpus callosum. The surface of the cerebrum is highly irregular, being composed of sulci (ridges) and gyri (folds). The sulci and gyri increase the surface area of the cerebrum, providing it with the highest processing power and cognitive ability in the entire nervous system. Each hemisphere is composed of five regions called cerebral lobes: frontal, parietal, temporal, occipital and insular.
Each brain lobe carries a specific set of functions. This is why the entire cortex is mapped and divided into functional areas, such as motor cortex and sensory cortex. These areas of the cortex are further divided based on their level of function into primary, secondary and associative areas. These hierarchical subdivisions closely communicate with each other in order to process information and generate adequate body responses, either motor or sensory. Each lobe is outlined by specific sulci and is responsible for distinct functions. The most prominent sulcus is the central sulcus (of Rolando) which separates the precentral and postcentral gyri. They house the primary motor and primary somatosensory cortices, respectively. These are the regions where motor functions are initiated and sensations are detected. The grey matter surrounds the white matter of the cerebrum, which forms the bulk of the deep cerebral structures.
Learn more about the structure and function of the brain lobes with these study units:
The subcortical structures are a neural group of structures embedded deep within the brain. They include the diencephalon, basal ganglia, limbic system and pituitary gland.
The diencephalon is located deep within the white matter of the brain. It is a collection of four cerebral structures located on each side of the midline, bilaterally to the third ventricle of the brain. These include:
More information about the diencephalon is provided below.
The basal ganglia are a group of nuclear masses of grey matter spread out throughout the lower part of cerebrum, diencephalon and midbrain. These nuclei include the caudate nucleus, putamen, globus pallidus, substantia nigra and subthalamic nucleus. The caudate nucleus and putamen collectively form the striatum. The putamen and globus pallidus form the lentiform nucleus.
The basal ganglia are part of the extrapyramidal motor system. They communicate with the thalamus via direct, indirect and hyperdirect pathways to fine-tune motor skills.
To master the complex anatomy of the basal ganglia, take a look below:
The limbic system is a set of structures spanning the cerebrum, subcortex and brainstem. It consists of two divisions called the limbic cortex and deep limbic structures. The limbic cortex is formed by various cerebral sulci and gyri of the frontal, temporal and parietal lobes. The deep part of the limbic system is formed by the hippocampal formation, amygdala, diencephalon, olfactory cortex, basal ganglia, basal part of the cerebrum and brainstem.
The overall function of the limbic system is to control emotions, olfaction and homeostasis. One particular important structure of the limbic system is the hippocampal formation involved in long term memory and spatial navigation. In addition, the amygdala is the one responding to fear
