Skeletal system

The skeleton is the bony framework of the body supporting the soft tissues and protecting the vital organs within the skull, rib cage and pelvis.
The 206 bones that comprise the adult human skeleton are usually divided for the purpose of study into two parts :

• the central axial skeleton , consisting of the bones of the skull, rib cage and the vertebral column, and
• the appendicular skeleton, consisting of the bones of the shoulders, arms, hips and legs.

The axial skeleton is designed primarily for the support and protection and therefore is quite rigid although the flexibility of the vertebral column allows it a certain
degree of movement.
The skull is made up of the bones of the cranium and the bones of the facial skeleton.
The cranium containing and protecting the brain consists of 8 bones united by immovable joints called sutures.
The bones of the face include 14 bones of which only the mandible is an independent and mobile one.

The trunk contains 12 pairs of ribs.
The first seven pairs extend from the vertebral column on the sternum, or breast bone.
The next 3 pairs are attached with cartilage to the sternum and the two pairs of floating ribs are unattached in front.
Together the ribs form the rib cage.

The vertebral column serving as the main supporting structure is composed of a number of separate bones, the vertebrae.
The 33 vertebrae can be divided into 5 regions according to where they are found :

• the 7 cervical vertebrae located in the neck,
• 12 thoracic vertebrae contained at the back of the chest,
• 5 lumbar in the small of the back and five sacral,
• 4 coccygeal fused together to form the sacrum and the coccyx, respectively.

The first two vertebrae are known as the atlas and the axis.
The appendicular skeleton consists of the bones of the extremities , as well as the bones of the shoulders and hips which attach the bones of the extremities to the axial skeleton.
As shown in the diagram, the shoulder is composed of the clavicle and the scapula.
The clavicle , or collarbone, is a thin bone forming the front os the shoulder.
It is attached medially to the sternum and laterally to the scapula.
The scapula , or shoulder blade, is a large flat bone located in the upper part of the back.
The arm contains only one large bone - the humerus.
The forearm is composed of two bones , the radius and the ulna.
Proximally, the radius articulates with the humerus and distally – with two of the carpal bones of the wrist and the ulna.
The wrist consists of eight carpal bones articulating with the metacarpals of the hand. The finger bones are known as phalanges.

The pelvic girdle is composed of the two large hip bone forming the sides and front, and the sacral and coccyheal vertebrae that form the back.
Analogically to the arm, the thigh also contains one bone.
It is the femur, the longest and the heaviest bone of the body.
The leg is composed of two bones, the tibia and fibula.
The bones of the ankle are known as the tarsals.
Five smaller tarsal bones and the five metatarsals from the remainder of the foot.
The toes, like the fingers , are composed of 14 bones referred to as phalanges.

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Bibliografia :
Ewa Donesch-Jeżo -English for Nurses
Ewa Donesch-Jeżo - English for Medical Students
Ewa Donesch-Jeżo -English for medical students and doctors