The human skeleton is made of individual or joined bones (such as the skull), supported and supplemented by a structure of ligaments, tendons, muscles, cartilage and other organs.

The skeleton is not unchanging; it changes composition over a lifespan. Early in gestation, a fetus has no hard skeleton; bones form gradually during nine months in the womb. At birth, all bones will have formed, but a newborn baby has more bones than an adult. On average, an adult human has 206 bones (according to Gray's Anatomy, but the number can vary slightly from individual to individual), but a baby is born with approximately 270 bones. The difference comes from a number of small bones that fuse together during growth, such as the sacrum and coccyx of the vertebral column. An infant is born with pockets of cartilage between particular bones to allow further growth. The sacrum (the bone at the base of the spine) consists of five bones which are separated at birth but fuse together into a solid structure in later years. Growing is usually completed between ages 12 and 14, at which point the bones have no pockets of cartilage left to allow more growth.

Not all bones are interconnected directly. There are 6 bones, the auditory ossicles (three on each side), in the middle ear that articulate only with each other. Another bone, the hyoid bone in the neck, does not touch any other bones in the body, and is supported by muscles and ligaments; it serves as the point of attachment for the tongue.

The longest and heaviest bone in the body is the femur and the smallest is the stapes bone in the middle ear. In an adult, the skeleton comprises around 20% of the total body weight.

Function

The most obvious function of bone is to support the body. It also the site of haematopoiesis, the manufacture of blood cells, that takes place in bone marrow (which is why bone marrow cancer is very often a terminal disease). It is also necessary for protection of vital organs. Movement in vertebrates is dependent on the skeletal muscles, which are attached to the skeleton by tendons. Without the skeleton to give leverage, movement would be greatly restricted. Bone also serves as a mineral storage deposit in which nutrients can be stored and retrieved.

A typical adult human skeleton consists of the following 206 bones, though a small portion of the human population have an extra bone, occurring in the form of an extra rib. (Numbers in bold refer to the diagram at right.)

Human Skeleton

In the skull (22):

Cranial bones:

• 1. frontal bone
• 2. parietal bone (2)
• 3. temporal bone (2)
• 4. occipital bone
• sphenoid bone
• ethmoid bone

Facial bones:

• 5. zygomatic bone (2)
• 6. superior and inferior maxilla
• 9. nasal bone (2)
• 7. mandible
• palatine bone (2)
• lacrimal bone (2)
• vomer bone
• inferior nasal conchae (2)

In the middle ears (6):

• malleus (2)
• incus (2)
• stapes (2)

In the throat (1):

• hyoid bone

In the shoulder girdle (4):

• 25. clavicle or collarbone (2)
• 29. scapula or shoulder blade (2)

In the thorax (25):

• 10. sternum
• 28. ribs (2 x 12)

In the vertebral column (26):

• 8. cervical vertebrae (7) incl. atlas & axis
• 14. lumbar vertebrae (5)
• thoracic vertebrae (12)
• 16. sacrum
• coccyx

In the arms (6):

• 11. humerus (2)
• 26. condyles of humerus
• 12. ulna (2)
• 13. radius (2)
• 27. head of radius

In the hands (54):

Wrist (carpal) bones:

• scaphoid bone (2)
• lunate bone (2)
• triquetrum bone (2)
• pisiform bone (2)
• Trapezium (bone) (2)
• trapezoid bone (2)
• capitate bone (2)
• hamate bone (2)

Palm or metacarpal bones:

• metacarpal bones (5 × 2)

Finger bones or phalanges:

• proximal phalanges (5 × 2)
• intermediate phalanges (4 × 2)
• distal phalanges (5 × 2)

• 15. pelvis (2)

In the legs (8):

• 18. femur (2)
• 17. hip joint (joint, not bone) (2)
• 22. greater trochanter of femur
• 23. condyles of femur
• 19. patella (2)
• 20. tibia (2)
• 21. fibula (2)

In the feet (52):

Ankle (tarsal) bones:

• calcaneus (heel bone) (2)
• talus (2)
• navicular bone (2)
• medial cuneiform bone (2)
• intermediate cuneiform bone (2)
• lateral cuneiform bone (2)
• cuboidal bone (2)

Instep bones:

• metatarsal bone (5 × 2)

Toe bones:

• proximal phalanges (5 × 2)
• intermediate phalanges (4 × 2)
• distal phalanges (5 × 2)

The infant skeleton has the following bones in addition to those above:

The sacral vertebrae (4 or 5), which fuse in adults to form the sacrum coccygeal vertebrae (3 to 5), which fuse in adults to form the coccyx ilium, ischium and pubis, which fuse in adults to form the pelvic girdle.

For a free evaluation of your treatment needs and cost, please contact us.

The information provided herein is not intended to be a substitute for professional medical advice.

Copyright © European Medical Tourist. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License.