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. These parts include the:. Skip to content. Anatomy of the Spine Not what you're looking for?
Start New Search. About anatomy of the spine The human spine is a complex anatomic structure that is the scaffolding for the entire body.
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. Excess body weight, weak muscles, and other forces can pull at the spine's alignment:. The two main muscle groups that affect the spine are extensors and flexors. The extensor muscles enable us to stand up and lift objects. The extensors are attached to the back of the spine. The flexor muscles are in the front and include the abdominal muscles.
These muscles enable us to flex, or bend forward, and are important in lifting and controlling the arch in the lower back. The back muscles stabilize your spine. Something as common as poor muscle tone or a large belly can pull your entire body out of alignment. Misalignment puts incredible strain on the spine see Exercise for a Healthy Back. Vertebrae are the 33 individual bones that interlock with each other to form the spinal column.
The vertebrae are numbered and divided into regions: cervical, thoracic, lumbar, sacrum, and coccyx Fig. Only the top 24 bones are moveable; the vertebrae of the sacrum and coccyx are fused.
The vertebrae in each region have unique features that help them perform their main functions. Cervical neck - the main function of the cervical spine is to support the weight of the head about 10 pounds. The seven cervical vertebrae are numbered C1 to C7.
The neck has the greatest range of motion because of two specialized vertebrae that connect to the skull. The first vertebra C1 is the ring-shaped atlas that connects directly to the skull. The second vertebra C2 is the peg-shaped axis, which has a projection called the odontoid, that the atlas pivots around. 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 T The range of motion in the thoracic spine is limited. Lumbar low back - the main function of the lumbar spine is to bear the weight of the body. The five lumbar vertebrae are numbered L1 to L5. These vertebrae are much larger in size to absorb the stress of lifting and carrying heavy objects. Sacrum - the main function of the sacrum is to connect the spine to the hip bones iliac. There are five sacral vertebrae, which are fused together.
Together with the iliac bones, they form a ring called the pelvic girdle. Coccyx region - the four fused bones of the coccyx or tailbone provide attachment for ligaments and muscles of the pelvic floor. While vertebrae have unique regional features, every vertebra has three functional parts Fig. Each vertebra in your spine is separated and cushioned by an intervertebral disc, which keeps the bones from rubbing together.
Discs are designed like a radial car tire. The outer ring, called the annulus, has crisscrossing fibrous bands, much like a tire tread. These bands attach between the bodies of each vertebra. Inside the disc is a gel-filled center called the nucleus, much like a tire tube Fig.
Discs function like coiled springs. The crisscrossing fibers of the annulus pull the vertebral bones together against the elastic resistance of the gel-filled nucleus. The nucleus acts like a ball bearing when you move, allowing the vertebral bodies to roll over the incompressible gel. The gel-filled nucleus contains mostly fluid. At the junction of the pedicle and lamina on the right and left sides, bony protrusions project upward and downward, called the superior and inferior articular process.
These processes form facet joints zygapophysial joints with the adjacent upper and lower vertebrae. The articulating surfaces of these processes are covered with 1 to 2 mm thick hyaline cartilage. While the facet joints allow movements between adjacent vertebrae, their main function is to determine the direction of movement and limit excessive movement.
The facets also help carry loads, particularly during backward bending and twisting movements of the spine. A pair of intervertebral foramina bony openings are present between the pedicles of adjacent vertebrae.
These foramina provide a passage for the spinal nerve roots as they branch off the spinal cord or cauda equina and exit the vertebral column. Other nerves, lymph vessels, and arteries also pass through these foramina. The opening of the intervertebral foramina decreases from L1 to L5. These conditions may cause lower back pain, which may radiate to the legs sciatica if a spinal nerve is involved.
Read more about Causes of Lower Back Pain. Vertebrae in the Vertebral Column. You are here Conditions Spine Anatomy. Lumbar Vertebrae share pin it Newsletters.
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