CNSs

Central nervous systems (CNSs) are the principal processing centers of the nervous system in animals. In vertebrates, the CNS consists of the brain and spinal cord, where sensory information is integrated, motor commands are generated, and higher functions such as cognition, memory, and autonomic regulation are orchestrated.

Anatomy and organization

The brain is divided into major regions, including the cerebrum, cerebellum, and brainstem, each serving specialized roles in perception, movement, balance, and autonomic control. The spinal cord extends from the brainstem and transmits signals between the brain and peripheral nerves, while also coordinating reflexes. CNS tissue is protected by three meninges (dura mater, arachnoid, and pia mater) and cushions within the skull or vertebral column by cerebrospinal fluid. The blood-brain barrier isolates CNS tissue from most bloodborne substances, helping to maintain a stable environment.

Protection, circulation, and metabolism

CNS blood supply comes primarily from the internal carotid and vertebral arteries, delivering oxygen and nutrients. Venous drainage occurs through dural venous sinuses. Specialized glial cells support neurons, regulate extracellular ions, and form part of the metabolic infrastructure that sustains neural activity.

Development and function

In embryonic development, the CNS arises from the neural tube. Neurons and glia differentiate and form complex networks through synaptogenesis and plasticity. The CNS integrates sensory input, coordinates motor output, and supports higher-order processes such as language, planning, emotion, and learning.

Clinical relevance

CNS disorders include traumatic brain and spinal injuries, strokes, neurodegenerative diseases (e.g., Alzheimer’s, Parkinson’s), demyelinating conditions (e.g., multiple sclerosis), and CNS tumors. Diagnosis commonly uses imaging techniques such as MRI and CT, along with electrophysiological and laboratory assessments. Treatments aim to restore function, slow disease progression, or manage symptoms.