Bones of Fore-limbs

Pectoral girdle

• Pectoral girdle is made of scapula, coracoid and clavicle.
• A cavity known as glenoid cavity occurs at the apex of the scapula.
• The humerus of the fore limb fits into this cavity.
• The clavicle is a curved bone connecting the scapular to the sternum.

Humerus

• Humerus is found in the upper arm.
• It articulates with the scapula at the glenoid cavity of the pectoral girdle and forms a ball and socket joint.

Ulna and radius

• These are two bones found in the forearm.
• The ulna has a projection called olecranon process and a sigmoid notch which articulates with the humerus.

Bones of hind limb

Pelvic Girdle

• The pelvic girdle consists of two halves fused at the pubic symphysis.
• Each half is made up of three fused bones:

• the ilium,
• ischium
• Each half has cup-shaped cavity for the acetabulum for articulation with the head of the femur.
• Between the ischium and pubis is an opening obturator foramen where spinal nerves, blood vessels and a tough inflexible connective tissues pass.
• The ilium, ischium and pubis are fused to form the innominate bone.

The Femur

• The femur is the long bone joining the pelvic girdle and the knee.
• The head of the femur articulates with acetabulum forming the ball and socket joint at the hip.
• The femur has a long shaft.
• At the distal end it has condyles that articulate with the tibia to form a hinge joint at the knee.
• The patella covers the knee joint and prevents the upward movement of the lower leg.

Tibia and Fibula

• The tibia is a large bone, and the fibula a smaller bone is fused to it on the distal part.
• In humans the tibia and fibula are clearly distinguishable.

Joints and Movement

• A joint is a connection between two or more bones.
• Joints provide articulation between bones making movement possible.
• However some joints do not allow any movement e.g. the joints, between bones of the skull.
• Movable joints are of three main types:

Gliding joint

• g., joints which occur between the vertebrae wrists and ankles.
• The ends of the bones that make the joint are covered with cartilage.
• The bones are held together by tough ligaments.

     Synovial joint

• The joint is enclosed by fibrous capsule lined by synovial membrane which secretes synovial fluid into the synovial cavity.
• The synovial fluid lubricates the joint.
• They are called synovial joints.
• They include hinge joint and ball and socket joint.