How many vertebrae does a human have

Some causes of spinal pain include:. 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. 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.

Normal adult spines are positioned over the pelvis, so upright posture doesn't strain muscles. However, changes of spinal position can stress muscles and cause spinal deformity. If the spine is injured and unable to function properly, it can be very painful or even disabling. The spine is made of many parts that protect the spinal cord, facilitate movement and support the body. The spinal cord has nerve pathways that carry signals, such as pain, from the arms, legs, and the body to the brain.

Nerve roots are used to transmit information between the spinal cord and the other parts of the body, such as arms, legs and organs. The flat plates of the lamina create the outer wall of the vertebral canal and help protect the spinal cord. Discs separate the vertebrae. They are made of tough, elastic material that allows the spine to bend and twist naturally.

The spinous process protrudes from the back of each vertebra. Muscles and ligaments that move and stabilize the vertebrae attach to the spinous processes. Two transverse processes stick out of the sides of each vertebra. Muscles and ligaments that move and stabilize the vertebrae attach to the transverse processes. All of the above elements of the spinal column and vertebrae protect the spinal cord, which provides communication to the brain.

The spinal cord also transmits sensation and mobility in the body through interaction of ligaments, bones and muscle structures of the back and its surrounding nerves. The spinal cord ends at the L1 level, where it divides into many different nerve roots that travel to the lower body and legs. 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. This fluid is absorbed during the night as you lie down and is pushed out during the day as you move upright.

With age, our discs increasingly lose the ability to reabsorb fluid and become brittle and flatter; this is why we get shorter as we grow older. Also diseases, such as osteoarthritis and osteoporosis, cause bone spurs osteophytes to grow. Injury and strain can cause discs to bulge or herniate, a condition in which the nucleus is pushed out through the annulus to compress the nerve roots causing back pain.

On the back of each vertebra are bony projections that form the vertebral arch. The arch is made of two supporting pedicles and two laminae Fig.

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.