Skeletal system components

The skeletal system consists of approximately 206 bones, providing the body with structure and support. Let’s take a tour of various components that form the skeletal system.

Here’s the skull. It has 8 cranial bones that protect the brain. The facial skeleton has 14 bones that provide a framework for the eye sockets, jaws, and teeth. The facial bones provide the framework for the various structures of the face including the overlying muscles, fat and skin.

The vertebral column is composed of 24 individual vertebrae, along with two sets of fused bones called the sacrum and coccyx. In addition to providing support for the trunk of the body, the vertebral column protects the spinal cord. All together, there are 7 cervical, or neck vertebrae; 12 thoracic, or upper back, vertebrae; and 5 lumbar, or lower back, vertebrae.

The sacrum is composed of 5 fused bones, while the coccyx, or tailbone, is typically made up of 3 to 5 bones.

12 pairs of ribs form a protective cage for the heart, lungs, and other internal organs.

The first 7 ribs are called true ribs because they attach to the breastbone, or sternum. Ribs 8 through 12 are called false ribs, because they either attach indirectly, or, as in the case with ribs 11 and 12, float and don’t attach to the sternum at all.

Now let’s take a look at the pair of shoulder blades, or scapulae, and the collar bones, or clavicles. It is very important for the scapulae to be mobile, because they connect to the shoulder joint, which is the most movable joint in the body.

The bones of the upper limb include the humerus, which connects the shoulder with the elbow, the ulna, the radius, the wrist bones or carpals, the hand bones or metacarpals, and the finger bones or phalanges.

To complete our tour, let’s take a look at the pelvic girdle, knee, and foot.

The pelvic girdle is formed by a pair of hip bones. Each hip bone is comprised of 3 fused bones, the ilium, ischium, and pubis. The pelvic girdle connects with the femur or thigh bone at the hip joint. The femur is the longest bone in the body and is important for bearing the body’s weight while standing.

At the knee, the femur articulates with the tibia or shin bone. The fibula does not bear weight, but several muscles attach to it. The patella, or kneecap, is suspended within muscle tendons and glides over the femur and tibia when the knee bends.

And last, but certainly not the least, are the feet. The foot bones, which include the tarsals, metatarsals, and phalanges, are organized into a series of arches that allow the feet to support the body’s weight.

Review Date: 7/15/2024

Reviewed By: Frank D. Brodkey, MD, FCCM, Associate Professor, Section of Pulmonary and Critical Care Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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