The skeleton of an adult person is made up of 206 bones: 26 of them constitute the skull, 41 are in the face and 6 in the ear. It contains the smallest piece of bone, the stapes, which measures 2.6 to 3.5 millimeters. The hand and foot are articulated by 27 and 26 bones respectively, and the spine contains 34 vertebrae, although sometimes there is one less, due to the fusion of two pieces.
The skeleton of a baby is made up of 300 bones . As the child grows, some of these bones fuse until growth stops, usually by the age of 25, leaving the final figure of 206 bones.
The axial skeleton contains 80 bones , including the skull, spinal column, and rib cage. It forms the central structure of the skeleton, with the function of protecting the brain, spinal cord, heart and lungs.
The 126 remaining bones form the appendicular skeleton; They include the arms, legs, shoulder girdle, and pelvic girdle. The lower part of the appendicular skeleton protects the major organs associated with digestion and reproduction and provides stability when walking or running. The upper part allows a greater range of motion when lifting and carrying objects.
Classification of bones
– Long bones are found in the arms, legs, fingers, and toes. These bones are longer than they are wide and are cylindrical. They move when the muscles around them contract, and they are the most mobile parts of the skeleton.
– The short bones are found in the wrists and ankles and are almost equal in length, width and thickness.
– The flat bones make up the skull, shoulder blades, sternum, and ribs. These thin, curved bones protect internal organs and provide an anchor for muscles.
– Irregular bones are those located in the spinal cord and face that, due to their unique dimension, do not fit into any of the other categories.
– Sesamoid bones are found in the hands, wrists, feet, ears, and knees. These small, round bones are embedded in the tendons and protect them from the great pressure and force they encounter.
There are some variations between male and female skeletons. For example, the female pelvis is typically wider, thinner, and rounder than the male pelvis, according to Anatomy & Physiology .
What are bones made of?
Most bones are made up of several layers of tissue:
– periosteum : the thick membrane on the outer surface of the bone
– compact bone: the smooth, hard layer seen in the bones of a skeleton
– cancellous: spongy tissue within compact bone
– bone marrow: the gelatinous nucleus of bones that produces blood cells.
The process of bone development is called ossification and begins around the eighth week of embryonic development.
Curiosities about bones
The structure of the bones and joints of the human body is complex and fascinating. The bones come together like a massive puzzle and rely on a variety of muscles to move in the joints from the neck and jaw to the toes. Did you know…?
– The part of the body that contains the most bones is the hand. It is made up of a whopping 27 individual bones.
– Most of the red and white blood cells in the body are created in the bone marrow.
– The femur, located in the thigh, is the longest bone in the body.
– The stirrup, a stirrup-shaped bone located deep in the ear, is the smallest bone in the body.
– Bones store approximately 99% of the calcium in your body and are made up of approximately 25% water.
– Our skeleton is completely replaced every 10 years or so through remodel.
– There are two types of bone material: cortical, the hard type we think of when we imagine a skeleton, and trabecular, which is softer and more spongy and often found within large bones.
– Some bones are designed to support two to three times the body weight in force.
– Cartilage tissue does not have a regular blood supply and is not renewed, so cartilage injuries are permanent. Fortunately, they are also less common.
