Musculoskeletal System

 

The musculoskeletal system consists of the bones, joints and muscles. There are 206 bones in the body and over 600 different muscles. The skeletal system includes all of the bones and joints in the body.

 

The skeleton is divided into two parts:

•  the axial skeleton (skull, spine, middle ear bones, hyoid bone, sternum and rib cage

• the appendicular skeleton (shoulder girdle, upper limb, pelvic girdle, lower limb).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The muscles are attached to the bones of the body and makeup about half of a person’s body weight. These muscles are individual organs made of skeletal muscle tissue, blood vessels, tendons, and nerves. Muscle is also located in the heart and other internal organs of the body.

 

The majority of skeletal muscles are attached to bones via tendons, tough bands of dense regular connective tissue.  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Functions of the muscles

1. Movement of other parts of the body.

2. Maintenance of posture and body position. 

3. Movement of substances inside the body e.g. blood, food

4. Generation of body heat e.g. shivering

 

Functions of the skeleton

1. Support

Acting as the framework of the body, the skeleton provides points of attachment for most skeletal muscles.

 

2. Protection

The skeleton provides protection for many of the major internal organs e.g. the skull protects the brain and the rib cage protects the heart and lungs

 

3. Assists Movement

The bones of the skeletal system will move when the attached skeletal muscles contract.

 

4. Storage of Minerals

Bone tissue stores minerals such as calcium which is required by the body for several functions including blood clotting, muscle contraction and the sending of nerve impulses. When levels are low in the body, bone tissue will release calcium into the blood.

 

5. Production of Blood Cells

Redbone marrow found in the sternum, ribs, spine and pelvis of an adult is responsible for the production of blood cells

 

6. Storage of Chemical Energy

The remaining bones in the adult body have yellow bone marrow, which consists mainly of adipose (fat) tissue which can be used for energy 

 

Joints

 

A joint (articulation) is located where two bones meet. They can be defined anatomically, ie. depending on what lies between the bones, or functionally, depending on the type of movement they produce.

 

Anatomical classification

1. Fibrous connective tissue joints

These types of joints are joined together by dense fibrous connective tissue

 

Examples: Joints between the skull bones, between the ulnar and radius, between the tibia and fibula

 

2. Cartilaginous joints

These types of joints are joined together by cartilage connective tissue

 

Examples: Sternocostal joints (between ribs and sternum), vertebral joints (discs),

symphysis pubis (pubic bones)

 

3. Synovial Joints

These types of joints are more complex. They consist of:

 

• Space between the bones which is filled with synovial fluid (filtrated blood), which is a viscous  (thick sticky), fluid the consistency of raw egg white

• Synovial membrane - a highly vascularised (many blood capillaries) membrane that 'squirts' fluid out of the capillaries into the space forming the synovial fluid

• Hyaline cartilage (also known as articular cartilage) with covers the ends of the bones. This is important because if the bone ends are forced together, if there was no cartilage the bone would get damaged causing bleeding (bone is highly vascularised, hyaline cartilage has no blood vessels therefore no bleeding)

• Ligaments that collectively form a joint capsule, holding the bones together

 

Some types of synovial joints;

• Hinge joints e.g. knee, elbow

• Ball and socket joints e.g. hip and shoulder

• Pivot joints e.g. Between atlas and axis of the

vertebral spine (top two neck vertebrae)

• Saddle joint e.g. thumb