Functions of Pectoral girdle
❖ It is strong enough to support the weight of quadruped animals
❖ Serves as shock absorber when an animal land to the end of a
jump
Femur is a long bone found in the thigh between the hip and the knee
Figure; 7.5: the femur
The adaption of femur to its role includes;
❖ Presence of the condyles which articulate to allow movement in
one plane.
❖ It has a strong shaft bone that offers support of the body weight.
❖ It has a large round head which articulates with the acetabulum of
the pelvic girdle to allow flexible movement of the leg.
❖ The long bone provides a large surface area for attachment of thigh
muscles.
Functions of the femur
❖ Supports the upper part of the body
❖ Its shaft provides surface for attachment of thigh muscles
Tibia and fibula, these are skeleton of the lower hind limb. The tibia is
ventral while fibula is dorsal.
❖ Provides surface for attachment of leg muscles
❖ Supports the body weight
Figure; 7.6: (a) Tibia and fibula
(b) Femur and Tibia of grasshopper
Pelvic girdle is made up of two halves of bones known as pubic bones.
Each half comprises three bones namely pubis, ilium and ischium. The
pubic bones of each side join in the middle ventrally at the pubic
symphysis. The ilium is fused to the sacrum of the vertebral column on
each side. On the outer edge of each half, is a depression called
acetabulum which articulates with the head of the femur to form the ball
and socket hip joint.
Functions of the Pelvic girdle
❖ Supports the weight of the body from the vertebral column
❖ Protects and supports the organs in the lower body such as urinary
bladder and reproductive organs
❖ Protects the developing foetus in pregnant women.
Figure;7.7: The Pelvic girdle
The major functions of human skeleton
❖ Support
Skeletons provide a strong framework that maintains the shape of
the body. The skeleton supports the weight of the body against
gravitational force. It raises up the body above the ground for
efficient movement. Moreover, the skeleton provides attachment
for many organs
❖ Locomotion
The skeleton provides attachment for the muscles of the body. The
skeleton and the muscles operate as levers where the skeleton
provides an attachment base for the muscle and the muscle pulls
the skeleton to enhance locomotion.
❖ Protection
The skeleton protects delicate internal organs against mechanical
damage and injuries.
❖ Synthesis of red blood cell
❖ Storage of mineral salts
Joints
Joint is the area in the skeletal system where two or more bones meet.
They hold the skeleton together to support movement. Usually tendons
join muscles to the bones and ligaments join the bones to each other.
Types of joints, there are two main types of joints,
(i)
Immovable (fixed) joints these are joints that do not allow any
movement of the body parts in any direction. They are made up of a
thin layer of connective tissue between the bones which holds bones
firmly in position. They provide strength and support for the body as
well as protection of delicate structures which cannot withstand any
kind of deformation.
Examples of Immovable (fixed) joints
• Suture found in the skull
• Joints found in the pelvic girdle
(ii)
Movable joints,
Movable joints these are the joints that allow movements of body
parts. Some joints allow only a small degree of movement while
others allow a wide range of movement of body parts. Articulating
bone surfaces are covered by cartilage and are separated from each
other by synovial cavity containing synovial fluid. Joints with
synovial fluid are referred to as synovial joints
Examples of movable joints
❖ Joint between the ulna and radius
❖ Joints in the vertebral column
❖ Joints in the wrist and ankle
❖ Ball and socket joints found on the shoulder and the hip.
❖ Hinge joint which allows movement in only one plane and is found
on the elbow and the knee.
Adaptations of joints to movement
❖ Friction in movable joints is prevented by synovial fluid
❖ dislocation is prevented by ligaments which hold the bones
together.
❖ Joints which support weight are provided with cushion. The
cushion absorbs compression caused by weight. Cushioning effect
in the joint is provided by discs of cartilage.
❖ The cushion also prevents strain and knocking of bones against
each other.
❖ Most bones have surface area for attachment of muscles which aid
in movement.
Muscles
Muscle is a contractile tissue specialized for relaxation and contraction to
bring about movement and locomotion. The muscles are attached to bones,
and are composed of many elongated cells called muscle fibres which are
able to contract and relax.
Muscles act as the ‘engine’ that the body uses to propel itself. Although
they do not work in the same way as a car engine, muscles do the same
function as done by a car engine. They turn energy into motion. It would
be impossible to do anything without muscles.
Types of muscles, there are three types of muscles
(iii)
What type of joint formed at W and Z respectively
(iv)
Why are the surfaces at W and Z smooth
(v)
What is the difference between the joint formed at W and Z and
that at Z
Note; the specimen L was femur
