The skeleton of the body is composed of 223 bones of various sizes and shapes which give firm but flexible support to the soft tissues, muscles and organs. They also form cases for protection of viscera or contained structures.
The bony framework of the body includes the bones of the head, the bones of the trunk, the bones of the lower and upper limbs.
The skeleton of the head is the skull. It consists of the cranium, which surrounds the delicate brain, and face. The cranium is formed by eight bones: the frontal bone, two parietal bones, two temporal bones, the occipital bone in the back, the ethmoid bone behind the nose and the sphenoid bone. The face consists of fourteen bones including the maxilla (upper jaw), mandible (lower jaw) and two zygomatics (cheek-bones). The bones of the skull form one large cavity, called the cranial cavity, and some smaller ones: the oral cavity, the nasal cavity and two orbits holding the eyeballs.
The bones of the trunk include the spinal column, the ribs and the breastbone. The vertebral column forms the central axis of the body. It contains the spinal marrow or spinal cord. The spine consists of 32 – 34 small bones termed the vertebrae. The vertebrae are grouped under the names cervical, thoracic, lumbar, sacral and coccygeal according to the region in which they lie. The cervical vertebrae, seven in number, are the smallest ones. Twelve thoracic vertebrae have large bodies. Together with 12 pairs of ribs and the breastbone they form the chest (thorax). The lumbar vertebrae, 5 in number, are the strongest and the largest vertebrae in the spinal column. They have oval bodies. The sacrum consists of 5 fused vertebrae. The coccyx is formed by 2 - 5 vertebrae.
The upper and lower limbs are constructed after a common type. Each extremity includes a girdle, which connects it to the trunk. The upper limb is attached to the trunk by the shoulder girdle, which consists of the collar-bone (or clavicle) in front and the shoulder-blade (or scapula) behind. The upper arm has one bone – the humerus; the forearm contains the radius and the elbow bone (or ulna). In the framework of the hand and wrist we have twenty–seven bones: 8 carpals, 5 metacarpals and 14 phalanges. The lower limb is attached to the trunk by the pelvic girdle. The adult pelvis is composed of three pairs of fused bones: the ilium, ischium and pubis. The thigh has only one bone – the femur, the leg includes two bones: the shin-bone (tibia) and fibula; and the foot is subdivided into a tarsus consisting of 7 bones, metatarsus – 5 bones, and phalanges, which are 14 in number.
The bones of the skeleton are connected together by the joints or by the cartilages and ligaments. The bones consist of organic and inorganic substances.
31. Match the Latin and English medical terms:
1. cervix a) backbone
2. clavicle b) limb
3. sternum c) skull
4. scapula d) upper jaw
5. cranium e) collar-bone
6. thorax f) neck
7. maxilla g) breastbone
8. vertebral column h) thigh bone
9. coccyx i) lower jaw
10. ulna j) cheek-bone
11. tibia k) chest
12. extremity l) shoulder-blade
13. femur m) shin-bone
14. zygomatic n) elbow bone
15. mandible o) kneecap
16. patella p) tailbone
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