Bone
The skeleton consists of approximately 206 bones.
The axial skeleton consists of the spine, ribs and skull.
The appendicular skeleton consists of the upper and lower limbs the pelvic and shoulder girdles.
Cancellous bone makes up about 20% of the human skeleton virtual support and flexibility without the weight of compact bone.
Compact bone is dense bone that is solidly filled with organic substance leaving only a tiny spaces.
Bone Classification
Long Bones – long bones have a greater length than width and consist of a shaft with normally two extremities. they contain mostly compact bone in their diaphysis and more cancellous bone in their emphasis. these bones normally act as levers. some examples of long bones include the humerus femur fibula tibia metacarpals, metatarsals and phalanges.
Short Bones – short bones are normally about as long as they are wide. they are usually cancellous which gives them strength and reduced weight. Some examples of short bones are tarpals and carpals.
Flat bones – flat bones are thin cancellous bone between two compact layers. they provide protection and large areas for muscle attachment. Some examples of flat bones are the scapular, sternum and ilium.
Irregular – Irregular bones form very complex shapes and cannot be classified within the previous groups. Two examples of a regular bones are the calcaneus or the heel bone and vertebrae.
Sesamoid – Sesamoid bones develop within particular tendons at a site of friction or tension. they serve to improve leverage and protect the joint from damage. An example of a sesamoid joint is the Patella or knee cap.
Functions of the Skeleton
Support – One function of the skeletal system is to provide a framework for the body which gives it shape. Without this framework we would just be a heap on the floor.
Protection – The skeletal system protects vital organs from external damage. For example, the skull gives protection to the brain and the rib cage protects the heart and lungs.
Attachment for Skeletal Tissue – the bones provide surface’s which enables the attachment of soft tissues. For instance, muscles and ligaments attach to bones which then enable movement to occur.
Blood Cell Production – certain bones contain bone marrow which produces red blood cells white blood cells and platelets. the bones that support blood cell production all the pelvis, sternum, humerus and femur.
Storage – The bones also store several minerals such as calcium and phosphorus to be released when required.. Therefore it’s important to ensure good nutrition as an athlete. starvation and low calorie diets can in fact lead 2 the loss of minerals from the bones if it’s not consumed via the diet.
Describe the 3 different types of joints found in the skeletal system, their location, structure and movement available: fixed, slightly moveable, synovial. Expand further on synovial joints and describe each of the 6 synovial joints, with examples of where they can be found: ball and socket, hinge, pivot, gliding, condyloid, saddle.
Types of Joint
There are three types of joint which all have different types of movement.
Fibrous – these are a moveable and interlocking bones such as the plates of the skull.
Cartilaginous is a slightly movable bone brought together by ligaments search as the vertebrae.
Synovial joints are freely movable and are the most common types which have the following characteristics:
- ends of the bone are covered with hyaline cartilage
- they are stabilised by ligaments
- surrounded by a fibrous capsule and a capsule is lined by a synovial membrane that secretes synovial fluid as lubrication
Synovial Joints
Ball and Socket
The bowl and socket joint allows for almost any movement in any direction. Think of your shoulder and hip joint.
Hinge Joint
A hinge joints allows for flexion and extension such as the Patella and elbow joint.
Pivot Joint
Pivot joints allow for rotation around an axis. the neck and forearms have pivot joints. In the neck the Atlas rotates around the axis. in the four arms the radius and all the twist around each other.
Gliding Joint
Gliding joints allow to bones to slide past each other such as the inter carpal an midtarsal joints.
Condyloid/ Ellipsoid
This joint is similar to a ball and socket. It allows the same type of movement but to a lesser magnitude such as the metacarpophalangeal joints (knuckles).
Saddle
A saddle joint allows for movement back and forth and up and down but does not allow for rotation doctor ball and socket joint an example would be a carpometacarpal joint or better known as the thumb.