The cord is segmentally organized. There are 31 segments, defined by 31 pairs of nerves exiting the cord. These nerves are divided into 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal nerve (Figure 3.2).
Why is the spinal cord divided into 31 segments?
The spinal cord is divided into 31 segments that send nerve rootlets out into the body through intervertebral foramen. Each segment of the spinal cord is associated with a pair of ganglia called dorsal root ganglia, which are situated just outside of the spinal cord and contain cell bodies of sensory neurons.
Are there 31 vertebrae?
In humans there are 31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. Each pair connects the spinal cord with a specific region of the body.
How are spinal cord segments named?
The numbers refer to the spinal segments by which each nerve is named C = cervical; T = thoracic; L = lumbar; S = sacral spinal cord segments (dermatome).
What is the shape of spinal cord?
The spinal cord is about 18 inches (45 centimeters) in length and is relatively cylindrical in shape. The cervical (neck) and lumbar (lower back) segments house the spinal cord’s two areas of enlargement. A fibrous band called the filum terminale begins at the tip of the conus medullaris and extends to the pelvis.
What are the segments of the spine?
What are the spine segments?
- Cervical (neck): The top part of the spine has seven vertebrae (C1 to C7). …
- Thoracic (middle back): The chest or thoracic part of the spine has 12 vertebrae (T1 to T12). …
- Lumbar (lower back): Five vertebrae (L1 to L5) make up the lower part of the spine.
What part of your spine controls your legs?
The nerves of the cervical spine go to the upper chest and arms. The nerves in your thoracic spine go to your chest and abdomen. The nerves of the lumbar spine then reach to your legs, bowel, and bladder. These nerves coordinate and control all the body’s organs and parts, and let you control your muscles.
How many pairs of spinal nerves do humans have?
In total, there are 31 pairs of spinal nerves, grouped regionally by spinal region. More specifically, there are eight cervical nerve pairs (C1-C8), twelve thoracic nerve pairs (T1-T12), five lumbar nerve pairs (L1-L5), and a single coccygeal nerve pair.
What part of the spine controls the heart?
Thoracic (mid back) – the main function of the thoracic spine is to hold the rib cage and protect the heart and lungs. The twelve thoracic vertebrae are numbered T1 to T12.
What part of the spine has no nerves?
Because the lumbar spine has no spinal cord and has a large amount of space for the nerve roots, even serious conditions—such as a large disc herniation—do not typically cause paraplegia (loss of motor function in the legs).
What part of spine controls feet?
Composed of five nerves that join at the lower part of the spine, the sciatic nerve extends down the back of each leg all the way to the toes and connects the spinal cord with the many of the muscles in the leg and foot.