Topic overview

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Structurally, the central nervous system (CNS) consists of the brain and spinal cord, while the peripheral nervous system (PNS) includes cranial and spinal nerves. Functionally, sensory (afferent) pathways carry input toward the CNS, and motor (efferent) pathways carry output to effectors. The somatic nervous system directs voluntary skeletal muscle movement; the autonomic nervous system regulates involuntary smooth muscle, cardiac muscle, and gland activity through sympathetic and parasympathetic branches. In the spinal cord, gray matter supports cell-body processing and white matter contains myelinated axons involved in transmission. The lesson also introduces the functions of major CNS regions, from spinal reflexes and brainstem vital functions to cerebellar coordination and cortical cognition.