Classification of Skeleton
Skeleton can be classified into two groups, axial skeleton and appendicular skeleton.
Axial skeleton exists in the central axis of the body. It consist of skull, vertebral column, ribs and the sternum or chest bone.
Skull is formed by the cranium which encloses and protects the brain and facial bones that form the face.
- Facial BonesFacial skeleton consists of 14 bones, including 2 upper jaw bones (maxillary), 2 lower jaw bones (mandible), 2 cheek bones (zygomatic bones), 2 palate bones (palatine), 2 nasal bones, 2 lacrimal bones, 1 vomer bone, and 1 hyoid bone.
- Cranium Craniumconsist of 11 bones including 1 frontal bone, 2 pariental bones, 2 occipital bones, 2 sphenoid bones, 2 ehtmoid bones, and 2 temporal bones.
The vertebral column consist of separate bones or vertebrae attached to each other by invertebral disc.
Vertebral column consist of 33 vertebrae divided by five main regions, which are 7 cervical (nect) vertebrae, 12 thoracic (chest) vertebrae, 5 lumbar vertebrae, 5 fused sacral vertebrae, and 4 fused coccyx vertebrae.
Rib cage is formed by thoracic vertebrae, ribs, and chest bone. Rib cage protects the internal organs within it, such as lungs and heart. Twelve pairs of ribs attach to thoracic vertebrae and chest bone, except the lowest rib.
The ribs are divided into three types as follows
- 7 pairs of true ribs (costa spuria), each end of which attaches to chest bone.
- 3 pairs of false ribs (costa spuria), which attach to the true ribs.
- 2 pairs of floating ribs (costa fructuantes) which do not attach to any of chest bone nor true rib.
Chest bone is a flat bone with sword-like shape which is distinguished into head (manubrium sternum), and bulging bone (xiphoid process).
Appendecular skeleton is the skeleton that relates to movement. This skeleton consist of pectoral girdle and the upper skeleton of the limbs, and pelvic girdle with the lower skeleton of the limbs.
- 1. Pectoral Girdle and Upper Limbs
Pectoral girdle (pectoralis) is located on the both righ and left sides of the body. Every pectoral girdle consist of two clavicle bones and two scapula bones.
Upper limbs consist of 1 upper arm (humerus), 1 forearm (ulna) and 1 radius. Radius and ulna area called forearm.
The lower end of the two forearm relates with eight carpals, five metacarpals, and fourteen phalangees.
- 2. Pelvic Girdle and lower Limbs
Pelvic girdle is also located on both righ and left part of the body. When a baby is born, each of its hip bones consist of 3 separated bones, namely 2 ilium, 2 ischium, and 2 pubis. When the baby grow, the 3 hip bones fuse.
Lower limbs consist of 1 femur, 1 tibia, and 1 fibula. Upper leg/thigh (femur) is connected to tibia in knee region where kneecap (patella) is located. Tibia and fibula are also connected 7 tarsals, 5 metatarsals, and 14 phalanges. The largest tarsal is called calcaneus.
Test your self
1. what is the difference between bone and cartilage ?
2. What is the difference between axial skeleton and appendicular skeleton?
3. What do you know about epiphysis dist?