What is Human Skeleton? As we know that Human skeleton is a tough and rigid framework of the body which includes a skull, vertebrae, ribs, sternum, pectoral girdle and appendages (forelimbs), and pelvic girdle and appendages (hind limbs). Let’s discuss in detail various parts of the human skeleton are as under;
PARTS OF HUMAN SKELETON
Human skeleton can be divided into two parts:
1) Axial Skeleton
2) Appendicular Skeleton
The axial skeleton includes the skull, the vertebrae, and the ribs and the sternum.
Skull; It is made up of a cranium and facial bones:
Cranium: The cranium consists of eight bones, 4 unpaired and 2 paired which protect the brain. Parietal and Temporal are paired bones, whereas Frontal, Occipital, Sphenoid and Ethmoid are unpaired bones.
Facial bones: There are 14 facial bones of which 6 are paired and 2 unpaired. The paired facial bones are Maxilla, Zygomatic, Nasal, Lacrimäl, Palatine and inferior concha, The unpaired facial bones are Mandible and Vomer.
Vertebral column extends from skull to the pelvis to form the backbone, which protects the spinal cord. Normally the vertebral column has 4 curvatures, which provide more strength than the straight column. The vertebral column consists of 33 vertebrae. The vertebrae are named according to their location in the body, viz., cervical thoracic, lumbar and pelvic.
Cervical Vertebrae: These are seven vertebrae which lie in the neck region. The first two cervical vertebrae are Atlas vertebra and vertebra.
Thoracic Vertebrae: There are twelve thoracic vertebrae located in the thoracic region.
Lumbar vertebrae: There are five vertebrae in the lumbar region.
Sacrum: Sacrum is formed by the fusion of anterior five vertebrae present in the pelvic region,
Coccyx: Coccyx is formed by the fusion of four posterior vertebrae present in the pelvic region.
Rib Cage; It is composed of twelve pairs of ribs that articulate with the thoracic vertebrae. Ten of them connect anteriorly with the sternum, either directly or through the costal arch. The lower two pairs. of ribs are called “floating ribs” because they do not attach with the sternum. The rib cage provides support for a semi-vacuum chamber called the “Chest cavity”.
The appendicular skeleton consists of pectoral girdle and appendages (fore limbs), and pelvic girdle and appendages (hind limbs).
PECTORAL GIRDLE AND FORE LIMBS
i) Pectoral girdle: Pectoral girdle attaches the arms to the trunk. It comprises scapula, suprascapula and clavicle. The clavicle connects scapula with the sternum.
ii) Fore limb: The fore limb consists of humerus, radius, and ulna, 8 Carpals, 5 Metacarpals and 14 Phalanges.
Humerus forms ball and socket joint with the scapula, while at distal end humerus forms hinge joint with radius and ulna. The radius and ulna at their distal end form multistage joint with eight wrist bones called carpals. Five metacarpals form the framework of a palm of the hand. Five rows of the phalanges are attached to the metacarpals. They support the fingers.
PELVIC GIRDLE AND HIND LIMB
i) Pelvic girdle: Pelvic girdle attaches the hind limb to the vertebral column. It consists of two coxal bones. Each is formed by the fusion of three bones ilium, ischium and pubis. The pelvic girdle supports the pelvic region.
ii) Hind Limb; The hind-limb consists of One Femur, 2 Tibia + Fibula, 8 Tarsals, 5 Metatarsals and 14 Phalanges.
Femur is the proximal bone which forms a hip joint (ball and socket joint), with the hipbone. At the distal end, the femur forms knee joint with the proximal end of two parallel bones called tibia and fibula. The distal end of the tibia and fibula form a joint with tarsals, which are also distally attached with five metatarsal bones of the ankle. Five rows of the 14 phalanges of the toes are attached with metatarsals.