Welcome to your animated guide to the spinal cord and spinal nerves.
They are interconnected, but they serve distinct functions in our nervous system.
First, let’s talk about the spinal cord.
The spinal cord is a long, tubular structure made of nervous tissue that extends from the base of the brain down to the lower back, ending around the L1 or L2 vertebrae in adults.
Below the L1 – L2 vertebrae, the spinal cord nerves branch out into individual nerves that are contained in the thecal sac.
These nerves look like a “horse’s tail,” hence the name, and this section is called the cauda equina .
The spinal cord serves as a central communication highway, transmitting signals between the brain and the rest of the body.
Now, let’s look at spinal nerves.
There are 31 pairs of spinal nerves that emerge from the spinal cord.
Each pair is named after the region of the spine they come from: cervical, thoracic, lumbar, sacral, and coccygeal.
And each pair is numbered according to the spinal motion segment where it exits the spine.
Unlike the spinal cord, spinal nerves are part of the peripheral nervous system.
These nerves connect the central nervous system to the limbs and organs, allowing for sensory and motor functions.
Each spinal nerve is formed from two roots: the dorsal root and the ventral root.
The dorsal root carries sensory information from the body to the spinal cord. It brings information about touch, pain, and temperature from your skin to the spinal cord, where the information is then relayed to the brain.
The ventral root transmits motor commands from the spinal cord to the muscles. It sends commands from your spinal cord to your muscles, telling them to move.
Once the spinal nerves exit the vertebral column, they branch into smaller nerves that innervate specific areas of the body.
These branches are responsible for both sensory and motor functions, allowing you to feel sensations and control movements.
Each spinal nerve corresponds to specific areas of skin and muscle, known as dermatomes and myotomes. This means that if a spinal nerve is damaged, you may lose sensation or movement in the area it supplies.
In the lumbar spine, spinal nerves exit the spinal canal from the cauda equina. The five lumbar nerve roots, along with contributions from the sacral nerve roots, join together to form the sciatic nerve, which travels through the buttock and down the back of each leg.
The sciatic nerve is the largest and longest nerve in the human body.
The key takeaway to remember is that the spinal cord is the central structure that transmits signals between the brain and body, while spinal nerves are the peripheral extensions that connect the spinal cord to various body parts.
Together, they form a complex communication network essential for our daily functions.
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