List of bones of the human skeleton
The human skeleton of an adult consists of around 206 to 213 bones, and there are 300 bones in children, depending on the counting of sternum (which may alternatively be included as the manubrium, body of sternum, and the xiphoid process). It is composed of 300 bones at birth, but later decreases to 80 bones in the axial skeleton and 126 bones in the appendicular skeleton. Many small accessory bones, such as some sesamoid bones, are not included in this count. There are 20 major bones.
As a human ages, some of its bones fuse, a process which typically lasts until sometime within the third decade of life. Therefore, the number of bones in an individual may be evaluated differently throughout their life. In addition, the bones of the skull and face are counted as separate bones, despite being fused naturally. Some reliable sesamoid bones such as the pisiform are counted, while others, such as the hallux sesamoids, are not.
Individuals may have more or fewer bones than the average (even accounting for developmental stage) owing to anatomical variations. The most common variations include sutural (wormian) bones, which are located along the sutural lines on the back of the skull, and sesamoid bones which develop within some tendons, mainly in the hands and feet. Some individuals may also have additional (i.e., supernumerary) cervical ribs or lumbar vertebrae. Amputations or other injuries may result in the loss of bones. Complete bone fractures may split one bone into multiple pieces. Other genetic conditions may result in abnormally higher (e.g. polydactyly or conjoined twins) or lower (e.g. oligodactyly) counts of bones.
The axial skeleton, comprising the spine, chest and head, contains 80 bones. The appendicular skeleton, comprising the arms and legs, including the shoulder and pelvic girdles, contains 126 bones, bringing the total for the entire skeleton to 206 bones.
Spine (vertebral column)Edit
A fully grown adult features 26 bones in the spine, whereas a child can have 34.
- Cervical vertebrae (7 bones)
- Thoracic vertebrae (12 bones)
- Lumbar vertebrae (5 bones)
- Sacrum (5 bones at birth, fused into one after adolescence)
- Coccygeal vertebrae/Cordal (set of 4 bones at birth; some or all fuse together, but there seems to be a disagreement between researchers as to what the most common number should be. Some say the most common is 1, others say 2 or 3, with 4 being the least likely. It is counted as 1 in this article.
There are usually 25 bones in the chest but sometimes there can be additional cervical ribs in humans. Cervical ribs occur naturally in other animals such as reptiles.
There are 22 bones in the skull. Including the bones of the middle ear, the head contains 29 bones.
- Cranial bones (8)
- Facial bones (15)
- Middle ears (6 bones in total, 3 on each side)
There are a total of 64 bones in the arms.
- Upper arm bones (6 bones in total; 3 on each side)
- Lower arm bones (4 bones in total, 2 on each side) left bone
- Hand (54 bones in total; 27 in each hand)
- Metacarpals (10 bones in total; 5 on each side)
- Phalanges of the hand
Pelvis (pelvic girdle)Edit
- The sacrum and the coccyx attach to the two hip bones to form the pelvis, but are more important to the spinal column, where they are counted.
There are a total of 60 bones in the legs.
- Femur (2 bones)
- Patella or kneecap (2 bones)
- Tibia (2 bones)
- Fibula (2 bones)
- Foot (52 bones in total, 26 per foot)
- Metatarsals (10 bones)
- Phalanges of the foot