CBSE Class 11-science Answered
Give an account on appendicular skeletal system of a human being
Asked by jayantvatsa2005 | 19 Feb, 2018, 09:34: PM
Expert Answer
Appendicular skeleton comprises of limb bones and girdles. Limb bones are again divided into bones of forelimbs and bones of hindlimbs. Girdles comprises of pectoral girdle and pelvic girdle
Limb Bones
- There are two pairs of limbs—a pair of forelimbs and a pair of hind limbs.
- Each fore limb is made of 30 bones.
- Bones of the forelimbs are
Bone |
Region |
Number |
Humerus |
Upper arm |
1 |
Radius |
Forearm |
1 |
Ulna |
Forearm |
1 |
Carpals |
Wrist |
8 |
Metacarpals |
Palm |
5 |
Phalanges |
Fingers |
14 |
- Each hind limb is made of 30 bones.
- Bones of the hind limbs are
Bone |
Region |
Number |
Femur |
Thigh |
1 |
Tibia |
Shank |
1 |
Fibula |
Shank |
1 |
Tarsals |
Ankles |
7 |
Metatarsals |
Instep |
5 |
Phalanges |
Toes |
14 |
Patella |
Fingers |
1 |
Pectoral Girdle
- The pectoral girdle is formed of two identical halves.
- Each half of the girdle consists of the following bones — scapula and clavicle.
- Scapula:
- The scapula is also called the shoulder bone.
- It is the flat, triangular bone located at the back of the thorax.
- It has a slightly elevated ridge called the spine.
- The spine projects as a flat, expanded process called the acromion.
- Below the acromion is a cup-shaped cavity called the glenoid cavity.
- The glenoid cavity articulates with the humerus of the forelimbs.
- Clavicle:
- It is also called collar bone.
- It is a rod-shaped bone extending between the neck and the shoulder.
Pelvic Girdle
- It is made of two coxal bones.
- Each coxal bone comprises three bones—ilium, ischium and pubis.
- At the point where all the three bones fuse is a depression called the acetabulum. The head of the femur articulates with the acetabulum.
A line of fusion called the pubic symphysis is observed where the two halves meet
Answered by Sivanand Patnaik | 20 Feb, 2018, 08:39: AM
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