The human skeletal system includes all of the bones and joints in the body. Every bone is made up from many cells, protein fibers and minerals. The skeletal system of the human body is a scaffold that gives support and protection for the soft organs and tissues that make up the rest of the human body. The skeletal system also serves as a place for muscle attachment to allow movement at the joints. In the skeletal system, there is red bone marrow inside of the bones which is responsible for producing new blood for the body, making it vital for the health of the human body.
The bones of the human body are like a warehouse for the minerals iron and calcium as well as energy in the form of fat. Like other parts of the body, the skeleton grows with increasing age until it reaches maturity, which occurs around the age of 18 in women and 21 in men. Bone density may be lost with old age and actually cause the skeleton to shrink slightly. This is called osteoporosis and is more common in women than men.
How many bones are in the human body?
The skeletal system in an adult human contains 206 individual bones (babies are born with more bones, some of which fuse together as part of normal growth and development).The bones are arranged to form two major divisions: the axial skeleton and the appendicular skeleton.
The axial skeleton consists of the bones found along the midline of the body and has 80 bones, including the bones of the skull, hyoid, auditory ossicles, ribs, sternum and vertebral column.
The appendicular skeleton contains the 126 bones forming the appendages of the body, including the upper and lower limbs, pelvic girdle, and pectoral or shoulder girdle.
Types of bones in the human body
All of the bones in the human body can classified according to one of five types:
– Long bones are longer than they are wide and are the major bones of the limbs (e.g. humerus, femur, tibia, etc.).
– Short bones are as long as they are wide and often cubic or round in shape (e.g. tarsal bones, carpal bones).
– Flat bones can vary greatly in size and shape but are very thin along one axis (e.g. nasal bones, frontal and parietal bones in the skull, sternum).
– Irregular bones have a shape that does not fit with the patterns in any of the previous categories (e.g. vertebrae, jaw bones, hyoid).
– The last category is sesamoid bones, which are formed after birth inside of tendons that run across joints (e.g. patella, pisiform, some metacarpal and metatarsal).