Question

Compare the bones of the upper limbs with those of lower limbs. In what ways are the shapes and arrangements of the bones similar? How are they different? Why is this important?

Answer 1

Explanation:

Similarities of the shapes and arrangement of the upper limbs and the lower limbs bones:

1) The upper limbs and the lower limbs both have three segments which are upper segment, middle segment and the distal segment. In the upper limb we have the arm at the upper segment, forearm at the middle segment and  the hand at the distal segment. In the lower limb we have the thigh at the upper segment, the leg at the middle segment, and the foot at the distal segment.

2) The number of bones in the arm and forearm of the upper limbs is the same  as that of the thigh and leg in the lower limps. In the arm we have Single bone (i.e  humerus)  and in the forearm we two bones (i.e Radius  and Ulna), also in the thigh  we have single bone (i.e femur) and in the leg we have two bones (i.e Tibia and  Fibula).

3) Both the upper and the lower limbs  are fixed to the trunk by the pectoral and pelvic girdles respectively.

4) The number of compartments in the arm and forearm of the upper limbs is the same  as that of the thigh and leg in the lower limps. In the arm we have two compartments   and in the forearm we three compartments, also in the thigh  we have two compartments and in the leg we have three compartments.

5) The number of phalanges in both the upper and lower limbs are the same (i.e five phalanges in both).

The Differences between the upper limbs and the lower limbs bones:

Upper limbs:

1. Size: The upper limb is smaller and shorter.

2. Mobility: Less firmly attached to trunk and more mobile.

3. Function: Grasping and skilled movement

4. Segment: Arm, Forearm, Hand

5. Bones: arm (humerus), forearm (Radius  and Ulna) ,hand (carpals, metacarpals and  phalanges ).

6. Alignment of distal  parts : Aligned along  the axis of the  limb.

7. Position of  pollex/hallux in  anatomical position : Laterally placed

8. Position of flexor  surface/muscle:  Anteriorly/Posteriorly

9. Carrying angle: Present

Lower limbs:

1) Size: Larger and longer

2) Mobility: More firmly attached to trunk and less mobile

3) Functions: Weight bearing and locomotion

4) Segment: Thigh, Leg, Foot.

5) Bones: thigh (femur) , leg (Tibia and  Fibula) , foot (Tarsals,  Metatarsals and  Phalanges ).

6) Alignment of the distal parts: Placed at right  angle with the  axis of the limb.

7)  Position of  pollex/hallux in  anatomical position:   Medially  placed.

8) Position of flexor  surface/muscle:  Posteriorly Anteriorly .

9) Carrying angle: Absent.

Importance of the upper the limbs and the lower limbs:

The similarities and difference in the upper limbs and the lower limps are of importance so as to be able to perform their various functions effectively.

The main purpose of the upper limb is to move the hand around the body during the daily activities of humans such as grasping and skilled movement of the arm. The shoulder girdle provides a wide range of motion so that the hand can reach in all directions.

The bones of the lower limbs ( i.e thigh, leg and foot) are considerably larger and stronger than the bones of the upper limbs because the lower limbs bones support the entire weight of the body while walking, running, or jumping.