Support refers to a skeleton. A rigid skeleton supports the soft part of the body. It raises the body from the ground and maintains the shape of the body during moment.
It’s the ability to move from place to place. Locomotion involves coordination between the nerves, muscles and skeleton system. Muscles used for locomotion are attached to the skeleton thus called skeleton muscles.
Moments refers to the change in position of one part of the body in relation to another part. The skeleton works with muscles which are attached to it to produce movements and many bones of the skeleton act as levers.
Functions of human vertebrate skeleton
The skeleton is the frame work of the body: it supports the softer tissues and provides points of attachment foe the most parts of skeletal muscles.
The skeleton provides mechanical protection for many of the body’s internal organs, reducing risk of damage to them.
- Assisting movement
skeletal muscles are attached to bones; hence as the associated muscles contract they cause bones to move.
- Storage of minerals
Bone tissues store several minerals, including calcium and phosphorus. When required, bone releases minerals into the blood.
- Production of blood cells
Production of blood cells. The red bone marrow of some bones like vertebrae ribs.
A synovial joint at a ball and socket joint
The skeletal movements of the body are produced by contraction and shortening of muscles. Skeletal muscles are generally attached by tendons to bones, so when the muscles shorten, the attached bones move. These movements of the skeleton occur at joints, or articulations, where one bone meets another.
A Joint location is at which 2 or more bones make contact. It is constructed to allow movement and mechanical support.
Moveable joint (synovial) are:
- Ball and socket joint
- Hinge joint
Synovial joints: Movement at joint could cause friction. The synovial joint is adapted to reduce friction.
- Move like a hinge of a door
- Move one in one plane
Ball and socket joint
- Rounded head of one bone fix into a cup shaped socket another
- Move in all planes
- Provide a greater flexibility
E.g. hip bone
The skeleton of the forearms
Scapula: the bone that connects the humerus with the collar bone
Humerus: This long bone is essential for movement and support of the arm. The humerus exists on both arms and thus accounts for 2 bones of the human body.
Radius: The radius is the bone of the forearm or lower arm, extending from the elbow to the wrist. This bone is relatively long and curved, extending parallel to the ulna.
Ulna: the ulna is the third and final bone of the arm. This bone runs parallel to the radius
Action of antagonistic muscles of forearm
- Antagonist and agonist muscles often occur in pairs, calledantagonistic pairs. As one muscle contracts, the other relaxes.
- Agonist muscles are those we typically associates with the movement itself, and thus sometimes referred to as primary movers.
- Antagonist muscles are act as opposing muscles to agonists, usually contracting as a means of returning the limb to its original, resting point.
- Limb muscles are usually arranged in pairs having opposite effect at the movement.
- Alternative contraction and relaxation of this pairs bring opposite effect at the movement to the bone at the joint. These muscles re called antagonistic muscles.
- Muscles which cause bending of the arm at the joint re called flexor muscles. The extensor muscles work in opposite direction to straighten the joint.
Comparison of the bending and straightening of the arm
|Bending of arm||Straightening of arm|
|Biceps contract||Biceps relax|
|Triceps relax||Triceps contract|
|Arm is pulled upward||Arm is pulled downward|
|Arm is raised and bends||Arm is lowered and straightened|
|Ulna and radius pull closer to humerus||Ulna and radius pull away to humerus|
Comparison of the bending and straightening of the upper leg
|Bending of leg||Straightening of leg|
|Flexor contract and become shorter and thinner||Extensor contract and become shorter and thicker|
|Extensor relax||Flexor contract|
|Knee joint flexes||Knee joint extends|
|Tibia and fibula pull closer to femur||Tibia and fibula away from femur|