The hollow spinal canal contains the spinal cord, fat, ligaments, and blood vessels. Under each pedicle, a pair of spinal nerves exits the spinal cord and pass through the intervertebral foramen to branch out to your body.
Surgeons often remove the lamina of the vertebral arch laminectomy to access the spinal cord and nerves to treat stenosis, tumors, or herniated discs. Seven processes arise from the vertebral arch: the spinous process, two transverse processes, two superior facets, and two inferior facets.
The facet joints of the spine allow back motion. Each vertebra has four facet joints, one pair that connects to the vertebra above superior facets and one pair that connects to the vertebra below inferior facets Fig. The ligaments are strong fibrous bands that hold the vertebrae together, stabilize the spine, and protect the discs.
The three major ligaments of the spine are the ligamentum flavum, anterior longitudinal ligament ALL , and posterior longitudinal ligament PLL Fig.
The ALL and PLL are continuous bands that run from the top to the bottom of the spinal column along the vertebral bodies. They prevent excessive movement of the vertebral bones. The ligamentum flavum attaches between the lamina of each vertebra.
The spinal cord is about 18 inches long and is the thickness of your thumb. It runs from the brainstem to the 1st lumbar vertebra protected within the spinal canal. At the end of the spinal cord, the cord fibers separate into the cauda equina and continue down through the spinal canal to your tailbone before branching off to your legs and feet.
The spinal cord serves as an information super-highway, relaying messages between the brain and the body. The brain sends motor messages to the limbs and body through the spinal cord allowing for movement. The limbs and body send sensory messages to the brain through the spinal cord about what we feel and touch. Sometimes the spinal cord can react without sending information to the brain.
These special pathways, called spinal reflexes, are designed to immediately protect our body from harm. Any damage to the spinal cord can result in a loss of sensory and motor function below the level of injury. For example, an injury to the thoracic or lumbar area may cause motor and sensory loss of the legs and trunk called paraplegia. An injury to the cervical neck area may cause sensory and motor loss of the arms and legs called tetraplegia, formerly known as quadriplegia.
Thirty-one pairs of spinal nerves branch off the spinal cord. Each spinal nerve has two roots Fig. The ventral front root carries motor impulses from the brain and the dorsal back root carries sensory impulses to the brain. The ventral and dorsal roots fuse together to form a spinal nerve, which travels down the spinal canal, alongside the cord, until it reaches its exit hole - the intervertebral foramen Fig. Once the nerve passes through the intervertebral foramen, it branches; each branch has both motor and sensory fibers.
The smaller branch called the posterior primary ramus turns posteriorly to supply the skin and muscles of the back of the body. The larger branch called the anterior primary ramus turns anteriorly to supply the skin and muscles of the front of the body and forms most of the major nerves. The spinal nerves are numbered according to the vertebrae above which it exits the spinal canal.
The 8 cervical spinal nerves are C1 through C8, the 12 thoracic spinal nerves are T1 through T12, the 5 lumbar spinal nerves are L1 through L5, and the 5 sacral spinal nerves are S1 through S5. There is 1 coccygeal nerve. The spinal nerves innervate specific areas and form a striped pattern across the body called dermatomes Fig. Doctors use this pattern to diagnose the location of a spinal problem based on the area of pain or muscle weakness.
For example leg pain sciatica usually indicates a problem near the L4-S3 nerves. The spinal cord is covered with the same three membranes as the brain, called meninges.
The inner membrane is the pia mater, which is intimately attached to the cord. The next membrane is the arachnoid mater. It provides several important functions, including: Protecting the spinal cord and nerves Structural support for the body, allowing us to stand upright. The spine supports about half the weight of the body. The spine above the sacrum consists of: Seven bones in the neck—the cervical spine 12 bones in the chest—the thoracic spine Five bones in the lower back—the lumbar spine The spinal column combines strong bones, unique joints, flexible ligaments and tendons, large muscles and highly sensitive nerves.
Some causes of spinal pain include: Irritation of the large nerves as they exit the bony confines of the spine leading to the arms and legs Irritation of the smaller nerves of the spine that involve innervate or supply the discs between the vertebrae, facets and ligaments Strain of the large muscles of the back that hold the spine upright Injuries to the bones, ligaments or joints Damage or disease to the discs that separate the vertebrae Abnormal movement between segments Tumors, infection, trauma, deformity or other spinal disorders The spinal column is made up of many parts, all designed to help the back move flexibly, support body weight and protect the spinal cord and nerves.
All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions. Not what you're looking for? Want More Information? Cedars-Sinai has a range of comprehensive treatment options. See Our Spine Program. Choose a doctor and schedule an appointment. These elements also provide sensations through the body via a complex interaction of the bones, ligaments and muscle structures of the back and the nerves that surround it.
The spine is composed of 33 bones, called vertebrae, divided into five sections: the cervical, thoracic, and lumbar spine sections, and the sacrum and coccyx bones. The cervical section of the spine is made up of the top seven vertebrae in the spine, C1 to C7, and is connected to the base of the skull.
The top two vertebrae are also know as the atlas and axis, which form the joint for connecting the skull to the spine. The cervical section is responsible for mobility and normal functioning of the neck, as well as protection of the spinal cord, arteries and nerves that travel from the brain to the body.
The thoracic section of the spine is located at chest level, between the cervical and lumbar vertebrae. The vertebrae in this section are labeled T1 to T12 and serve as attachments for the rib cage. The lumbar section is located between the thoracic vertebrae and the sacrum. The five lumbar vertebrae, labeled L1 to L5, are the main weight-bearing section of the spinal column. The sacrum is the section located at the base of the spine.
It does not have discs separating the vertebrae, because its five levels, S1 to S5, are fused together. The pelvis is connected to the spinal column at the sacrum section. The coccyx is at the very base of the spinal column and is made of four vertebrae that are fused together. The spine is normally a straight line when viewed from the back. If the spine curves to one side or the other, this indicates a condition named scoliosis.
However, the spine does have some normal, gradual curves when viewed from the side. The neck and lumbar sections of the spine have a lordotic curve, which means that they curve inward. These spinal curves help maintain balance while upright and support the weight of the head and upper body. However, too much curvature may cause spinal imbalance, causing spinal conditions that may result in pain or loss of mobility.
0コメント