Human Skeleton
Thehuman skeletonis the internal framework of the body. It is composed of around 270 bones at birth -- this total decreases to around 206 bones by adulthood after some bones get fused together.The bone mass in the skeleton reaches maximum density around age 21. The human skeleton can be divided into the axial skeleton and the appendicular skeleton. The axial skeleton is formed by the vertebral column, the rib cage, the skull and other associated bones. The appendicular skeleton, which is attached to the axial skeleton, is formed by the shoulder girdle, the pelvic girdle and the bones of the upper and lower limbs.
The human skeleton performs six major functions; support, movement, protection, production of blood cells, storage of minerals, and endocrine regulation.
The human skeleton is not as sexually dimorphic as that of many other primate species, but subtle differences between sexes in the morphology of the skull, dentition, long bones, and pelvis exist. In general, female skeletal elements tend to be smaller and less robust than corresponding male elements within a given population. The human female pelvis is also different from that of males in order to facilitate childbirth.Unlike most primates, human males do not have penile bones.
Skeletal Divisions
Axial skeleton
The axial skeleton (80 bones) is formed by the vertebral column(32--34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length), a part of the rib cage(12 pairs of ribs and the sternum), and the skull(22 bones and 7 associated bones).
The upright posture of humans is maintained by the axial skeleton, which transmits the weight from the head, the trunk, and the upper extremities down to the lower extremities at the hip joints. The bones of the spine are supported by many ligaments. The erector spinae muscles are also supporting and are useful for balance.
Appendicular skeleton
The appendicular skeleton (126 bones) is formed by the pectoral girdles, the upper limbs, the pelvic girdle or pelvis, and the lower limbs. Their functions are to make locomotion possible and to protect the major organs of digestion, excretion and reproduction.
Functions
The skeleton serves six major functions: support, movement, protection, production of blood cells, storage of minerals and endocrine regulation.
List of bones
Spine (vertebral column)
A fully grown adult features 26 bones in the spine, whereas a child can have 33.
- Cervical vertebrae(7 bones)
- Thoracic vertebrae(12 bones)
- Lumbar vertebrae(5 bones)
- Sacral vertebrae(5 bones at birth, fused into one after adolescence)
- Coccygeal vertebrae
Chest (thorax)
Various bones of the human skeletal system.
There are usually 26 bones in the chest but sometimes there can be additional cervical ribs in humans. Cervical ribs occur naturally in other animals such as reptiles.
- Hyoid(1)
- Sternum(1)
- Ribs(24, in 12 pairs)
- Cervical ribs are extra ribs that occur in some humans.
Head
There are 22 bones in the skull. Including the bones of the middle ear, the head contains 28 bones.
- Cranial bones(8)
- Occipital bone
- Parietal bones(2)
- Frontal bone
- Temporal bones(2)
- Sphenoid bone(sometimes counted as facial)
- Ethmoid bone(sometimes counted as facial)
- Facial bones(14)
- Nasal bones(2)
- Maxillae(upper jaw) (2)
- Lacrimal bone(2)
- Zygomatic bone(2)
- Palatine bone(2)
- Inferior nasal concha(2)
- Vomer
- Mandible(1)
- Hyoid bone(1)
- Middle ears(6 bones in total, 3 on each side)
- Malleus(2)
- Incus(2)
- Stapes(2)
Arm
There are a total of 64 bones in the arm.
- Upper arm bones (6 bones in total; 3 on each side)
- Humerus(2)
- Pectoral girdle(shoulder)
- Scapula(2)
- Clavicles(2)
- Lower arm bones (4 bones in total, 2 on each side)
- Ulna(2)
- Radius(2)
- Hand(54 bones in total; 27 in each hand)
- Carpals
- Scaphoid bone(2)
- Lunate bone(2)
- Triquetral bone(2)
- Pisiform bone(2)
- Trapezium(2)
- Trapezoid bone(2)
- Capitate bone(2)
- Hamate bone(2)
- Metacarpals(10 bones in total; 5 on each side)
- Phalanges of the hand
- Proximal phalanges(10 bones in total; 5 on each side)
- Intermediate phalanges(8 bones in total; 4 on each side)
- Distal phalanges(10 bones in total; 5 on each side)
Pelvis (pelvic girdle)
The pelvis (or hip bone) is made up of three regions that have fused to form two coxal bones. They are:ilium, ischium, and pubis
- 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.
Leg
There are a total of 60 bones in the legs.
- Femur(2 bones)
- Patella or kneecap (2 bones)
- Tibia(2 bones) Also called shin bone
- Fibula(2 bones)
- Foot(52 bones in total, 26 per foot)
- Tarsus
- Calcaneus or heel bone (2 bones)
- Talus(2 bones)
- Navicular bone(2 bones)
- Medial cuneiform bone(2 bones)
- Intermediate cuneiform bone(2 bones)
- Lateral cuneiform bone(2 bones)
- Cuboid bone(2 bones)
- Metatarsals(10 bones)
- Phalanges of the foot
- Proximal phalanges(10 bones)
- Intermediate phalanges( 8 bones)
- Distal phalanges( 10 bones)
Axial skeleton = 80 Skull =22 Vertebral Coloumn = 26 Ribs = 12 Fore limb = 60 Hind limb = 60
- Patella
- Pisiform bone
- Fabella
- Sesamoids in the first and second metacarpal bones
- Sesamoids in the first metatarsal bone
- Lenticular process of the incus
- For bones that are present variably in different people, see Accessory bone
References
https://en.wikipedia.org/wiki/Human_body
https://en.wikipedia.org/wiki/Human_skeleton
https://en.wikipedia.org/wiki/List_of_bones_of_the_human_skeleton