Spinal cord and Spinal nerves [Video]

@sciencemadeeasyy

The brain and spinal cord are surrounded and enveloped by the three layers of protective membranes called meninges. They provide support, cushioning, and protection for the central nervous system (CNS) against mechanical injury and trauma. The three layers of the meninges, from outermost to innermost, are the dura mater, arachnoid mater, and pia mater.

The cross-section of the human spinal cord reveals its internal structure, which consists of gray matter and white matter arranged in a distinctive pattern. Here’s a description of the main features you would observe in a cross-section of the human spinal cord:

Gray Matter:
Located centrally within the spinal cord, forming an H or butterfly shape.
Composed of neuron cell bodies, dendrites, unmyelinated axons, and glial cells.
It contains various nuclei responsible for integrating and processing sensory and motor information.

The gray matter is organized into regions called horns:
Dorsal (posterior) horns: Contain sensory nuclei that receive incoming sensory information from the peripheral nervous system.

Ventral (anterior) horns: Contain motor nuclei that send motor commands to muscles via the peripheral nervous system.

Lateral horns: Contain autonomic nuclei involved in regulating involuntary functions such as heart rate and digestion.

White Matter:
Surrounds the gray matter and forms the outer region of the spinal cord.
Composed primarily of myelinated axons, which appear white due to the myelin sheath.
Organized into columns or tracts that carry sensory and motor information between the spinal cord and the brain.

Central Canal:
Located centrally within the gray matter.
Filled with cerebrospinal fluid (CSF), which provides cushioning and support for the spinal cord.
Functions in the circulation and exchange of nutrients and waste products within the spinal cord.

Spinal Nerves:
Extend from the lateral aspects of the spinal cord, formed by the fusion of dorsal and ventral nerve roots.
Spinal nerves carry both sensory and motor information between the spinal cord and specific regions of the body.
The number of spinal nerves corresponds to the number of spinal cord segments, which typically number 31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
This description provides an overview of the major structures and organization of the human spinal cord as seen in a cross-section.

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