Anatomy of the Central and Peripheral Nervous System

The human brain is a complex organ consisting of four main parts — the cerebrum, the cerebellum, the diencephalon, and the brainstem. The cerebrum …

Deep inside the human brain are the hollow fluid-filled cavities called ventricles. There are two lateral ventricles, one in each cerebral hemisphere. …

The cerebrum is the largest part of the brain. It is divided into two cerebral hemispheres. The outer area of each hemisphere — the cerebral cortex …

Each cerebral hemisphere has three basic regions. The outermost region is called the cerebral cortex. It is a 2 to 4 mm thick layer of gray matter …

The cerebral cortex has three functional areas — the motor, sensory, and association areas. The motor areas, located in the frontal lobe, control …

Association areas are regions of the cerebral cortex that do not have a specific sensory or motor function. Instead, they integrate and interpret …

The diencephalon is situated above the brainstem, concealed by the cerebral hemispheres. It is majorly made up of three paired structures — the …

The thalamus consists of several groups of paired nuclei, each acting as a relay station to channel the information from specific brain parts into the …

The hypothalamus receives somatic and visceral inputs and controls various physiological activities. It consists of several nuclei organized into four …

The cerebellum is positioned inferior to the posterior part of the cerebrum. As seen in the posterosuperior view, a thin median structure called the …

The brainstem comprises three regions—the midbrain, pons, and medulla oblongata. The midbrain is situated below the diencephalon and has two bulging …

The medulla oblongata is a critical region of the brainstem. It contains several nuclei having vital functions. The lateral side of each pyramid has a …

The limbic system is a functional brain region consisting of specific parts of the diencephalon and cerebrum. The limbic lobe of the cerebral cortex …

The reticular formation is a complex network of gray and white matter spread across the core of the brainstem. It is roughly divided into three paired …

Inside the vertebral column is the slender and tubular structure called the spinal cord. It is shorter than the vertebral column, with a length of about …

In the transverse section of the spinal cord, the gray matter is surrounded by the white matter. The dorsal median sulcus and the ventral median fissure …

The spinal cord helps relay sensory and motor information between the brain and the PNS. The sensory receptors in the skin detect somatic sensory stimuli, …

The peripheral nervous system consists of nerves, ganglia, and sensory receptors. Each nerve has an outermost connective tissue layer called the …

The cranial nerves are 12 pairs of nerves originating directly from the brain and brainstem. These nerves are a part of the peripheral nervous system …

The olfactory nerve is a sensory nerve, that emerges from the olfactory bulb and innervates the receptors for the sense of smell. The optic nerve is …

The facial nerve emerges from the pons and innervates the facial muscles, lacrimal glands, tongue, and salivary glands. It is a mixed nerve that controls …

Spinal nerves are mixed nerves that originate from the spinal cord. A typical nerve begins as dorsal roots having sensory fibers and ventral roots …

A plexus is an axon network of the anterior rami of nerves from different spinal regions, except for thoracic nerves T2 to T12, which form the intercostal …

The lumbar, sacral, and coccygeal plexuses serve the lower body. The lumbar plexus is mainly composed of the first four lumbar spinal nerves, that branch …

The brain is wrapped by three membranes called meninges. The outermost cranial dura mater has the periosteal layer adhering to the inner skull surface and …

The cerebrospinal fluid, or CSF, is a colorless liquid surrounding the brain and spinal cord. It comprises water, blood plasma, proteins, glucose, and …