This is how human beings would appear without flesh, organs, tissues and other internal
structures.
The human skeletal system has five functions: 1. Shape and support the body. 2. Allowing movement of the body. 3. Protection of tissues and organs from external shocks. 4. Storage of certain minerals like calcium.5. Production of blood cells.
The Human Skeleton is made of 206 individual bones and cartilages.These 206 bones are arranged in two major divisions:
Axial skeleton: It is made up of 80 bones; including the skull, Hyoid, Auditory Ossicles, Ribs, sternum and vertebral column. It contains the bones of the head and trunk of a human.
Appendicular skeleton: It is made up of 126 bones; includes, shoulder girdle and upper limbs and hip girdle and lower limbs. Functionally, it consists of the bones involved in locomotion and movement of objects in the environment.
Five types of bones in human body
1. Long bone: The femur or thigh bone is the longest and strongest bone of the human
skeleton.
2. Short bone: The smallest bone in the human body is located in the ear ossicles. They are found in the middle ear, and they are known as the ‘stapes’, the ‘incus’ and the ‘malleus’. Other examples are carpal and tarsal bones
3. Flat bones: Cranium (skull), sternum (breast plate), scapula (shoulder bone), ribs etc.
4. Irregular bones: Vertebrae
5. Sesamoid bones: Patella (knee cap). Complete human structure has two of these, one in each leg. It is found where there is considerable friction.
Joints: Bones are connected to other bones at joints. There are many different types of joints, including: fixed joints (such as in the skull), hinge joints (such as in the fingers and toes), and ball-and-socket joints (such as the shoulders and hips). Hinge joints allow movement in one plane, whereas ball-and-socket joints allow movement in all planes, as well as rotational movement around a central axis.
Skull: It consists of 8 cranial and 14 facial bones, including the mandible bone, which is the
movable jaw bone and forms a movable joint with the temporal bone of the skull.
Note that some of the bones exist in pairs. In that way, there are 6 types of cranial bones and 8 types of facial bones.
Cranial bones: provide protection of the brain. Inner surfaces attach to membranes that stabilize the position of the brain, blood vessels and nerves. Outer surface acts as an area of attachment of muscles that move the head in various ways.
Facial bones: Its functions include the protection and support of entry points of both digestive and respiratory systems, and also organs of senses i.e. vision, taste, smell, hearing and balance. It also allows attachment of muscles that impart facial expressions. It provides a firm support to the set of teeth and a mechanical framework for movement of jaws and contains organs such as eyes, ears, nose, mouth etc.
Hyoid bone: It lies below the mandible. It is the only bone in the body that does not join with any
other bone. It can be moved in any direction by the muscles attached to it. It holds up the tongue above it as well as the larynx below it. It forces the muscles that help to open the jaw.
Auditory Ossicles: The malleus, incus, and stapes are collectively known as auditory ossicles. Situated in the middle ear, they are the smallest bones in the human body. They are found in a small cavity inside the temporal bone. They serve to transmit and amplify sound from air, through the eardrum to the fluid-filled cochlea of the inner ear. The vibration of the eardrum is transmitted to the oval window of the inner ear by means of ossicles by a lever action. The lever is adjustable under muscle action and also attenuates (reduces the intensity of) loud sound for protection and prevention of damage to the ear.
Vertebral Column: The vertebral column extends from the head, down the back and to the pelvis. It consists of 26 separate bones called vertebrae, separated by strong pads of cartilage. Note that actually it is 33 vertebrae, but 5 are fused in Sacrum and 4 are fused in coccyx. Between each of these vertebrae are washer-like disks of flexible cartilage. The vertebral column holds the body upright. Many muscles in the body attach to the vertebral column, allowing the body to move freely. These include the muscles of the neck and shoulders, ribs, torso. The spinal cord lies inside the vertebral column.
Sternum: The sternum or breastbone is a thin bone of T shape located in the center of the chest. It protects the heart and lungs from injury and helps to stabilize the structure of ribcage.
Ribs: In the human body, there are 12 pairs of ribs that are attached to the thoracic vertebrae at the back of the body. The first 7 pairs are known as ‘true’ ribs because they join directly to the sternum at the front of the body by costal cartilages, whereas the eighth-to-tenth pairs of ribs, known as ‘false ribs’ connect to the sternum indirectly via the costal cartilages of the ribs above them. The last two pairs of ribs are called ‘floating ribs’ because they are not attached to the sternum.
The rib cage protects vital organs like heart and lungs. The flexible cartilage makes the breathing process easier. Between the ribs are intercostal muscles which play a part in the expansion and contraction of the chest cavity to allow breathing movements.
Pectoral Girdle and Upper Limb: It connects the upper limb (arm) to the axial system. It consists of the bones shown.
Pelvic Girdle and Lower Limb: It connects the lower limb (legs) bones to the axial system and consists of the bones as shown.
Differences in males and females: Males and females have slightly different skeletons, including a different elbow angle. Males have slightly thicker and longer legs and arms; females have a wider pelvis and a larger space within the pelvis, through which babies travel when they are born.
Zia Ahmed Khan email:khanziaahmed50@gmail.com