Skeletal System

Skeletal System

Figure: Skeletal system

The axial skeleton lies along the longitudinal axis of the body. It supports and protects the organs of the head, neck, and truck. It includes a skull, ribs , sternum and vertebral column.
The appendicular skeleton is associated with the appendages. It consists of 2 girdles, the pectoral and pelvic girdle, and the limb bones.

The ribs are thin, flat, and curved bones hat form a protective cage around the organs in the upper body. Ribs are comprised of 24 bones arranges in 12 pairs. The first 7 ribs are attached directly with the sternum and are called true ribs. The 8th, 9th, and 10th are attached to the rib above each. These are called vertebronchondral ribs or false ribs. The last two (11th and 12th) ribs remain free anteriorly and are called floating ribs.

Vertebral column

The vertebral column is called the backbone or spine. It is curves, vertical rod about 70 cm long. It consists of a row of 33 movable, articulated, ring-like bones, the vertebrae.
The vertebral are grouped into five groups :

Cervical vertebrae – 7 in number, present in the neck, first cervical vertebrae is called atlas; second cervical vertebra is known as an axis. The atlas supports the head. The axis has a peg-like process called the odontoid process.
Thoracic vertebrae- 12 in number present in the chest. Thoracic vertebrae much are larger and stronger than cervical vertebrae. They articular with ribs.
Lumbar vertebrae – 5 in number, present in the abdomen. They are the largest and strongest in the vertebral column. The process is short and thick. The spinous processes are thick and broad, and project posteriorly.
Sarcasm- the 5 sacral vertebrae are fused in the adult. These form one structure called the sacrum. Sacrum lies between the innominate bones of the pelvic girdle. The sacrum is shorter in females and wider than the male sacrum.
Coccyx – the four coccygeal vertebrae are fused to form a curved triangular bone called the coccyx. In the female, the coccyx points inferiorly, but in the male, it points anteriorly. It is called a vestigial tail.

Figure: Vertebral column

Each pectoral girdle consists of two bones : one clavicle and one scapula. The scapula, also is known as the shoulder blade, consists of a sharp ridge, the spine projects s a flattened and expanded process called the acromion. This process articulates with the clavicle. At the one end of the superior of the scapula is a projection of the anterior surface called the coracoid process, o which the tendons of the muscle attached. At the point, the superior and lateral borders of the scapula meet, there is the lateral angle which presents a shallow articular surface called the glenoid cavity into which the head of the humerus is articulated.
The pelvic girdle, also known as the hip girdle, is composed of two coxal bones. Each coxal bone consists of 3 separate parts : the ilium, ischium, and the pubis. On its outer surface, it has a deep depression called the acetabulum, which, with the spherical head of the femur, forms the hip joint. The pelvic girdle differs between men and women.