Question

What is the Upper limb? Briefly explain the parts of the the upper limb.

Answer 1

THE UPPER LIMB
Scapula

• It is a large, flat bone situated on the postero-lateral aspect of the chest wall, connected with the sternum by the clavicle and articulating with the humerus.

Side identification:

• • (a) The glenoid cavity lies on the lateral aspect of the bone,
  • (b) the bone tapers down towards the inferior side,
  • (c) the anterior surface is convex.

Clavicle:

• Lying on the anterior side almost horizontally at the root of the neck the clavicle articulates with the sternum on one hand and with the acromian process of the scapula on the other.

Humerus:

• It is the bone of the upper arm.
• It articulates with the scapula above and with the bones of the forearm below.
• The bone comprises expanded upper and lower extremities and a long shaft which is more or less cylindrical.
• The upper end presents the head, the greater and lesser tuberosities, the neck and the bicipital groove (inter tubercular sulcus).
• The shaft possesses three borders, viz., medial, anterior, and lateral a three surfaces, viz.. posterior, antero-lateral and antero-medial.
• The transversely expanded lower end comprises a pulley-shaped articular surface, termed the and a convex articular surface; termed the capitulum.
• It also presents medial epicondyle, lateral epicondyle, olecranon fossa, coronoid fossa and radial fossa.

Side identification:

• • (a) The rounded head is placed at the upper end of the bone,
  • (b) the head faces medially,
  • (c) the olecranon fossa lies on the posterior side of the bone.

Radius:

• It is the lateral bone of the forearm.
• The bone has two extremities and a shaft. The upper end presents a disc-shaped head, a neck and a tuberosity.
• The shaft has three borders, interosseous, anterior and posterior and three surfaces- anterior, posterior and lateral.
• The lower end comprises the styloid process on the lateral surface and the ulnar notch on the medial surface.
• The inferior surface of the lower end has a medial (quadrangular) and a lateral (triangular) articular area for articulation with the wrist bones.

Side identification:

• • (a) The lower end is much wider than the upper end,
  • (b) the shaft is concave forwards in its lower part,
  • (c) the ulnar notch is on the medial side.

Ulna:

• It is the medial bone of the forearm.
• It has a shaft, an upper end and a lower end or head.
• The upper end presents a deep notch; the trochlear notch; a beak shaped structure-the olecranon process; at the uppermost part of the bone-the coronoid process and the radial notch.
• The shaft has three borders, interosseous, posterior and medial and three surfaces, anterior, posterior and medial.
• The lower end or head is slightly enlarged and has a smooth articular surface and a prominent styloid process.

Side identification:

• • (a) The upper end is thick and hook like,
  • (b) the trochlear notch is directed forwards,
  • (c) the lateral border is thin and forms a sharp crest.

Skeleton of the hand:

• The skeleton of the hand comprises twenty-seven bones arranged in three groups-
• 1. The Carpus- is the proximal part consisting of eight small irregular bones arranged in two rows. proximal and distal.
  • The bones of the proximal row from the lateral to the medial side are (a) scaphoid (navicular), (b) lunate. (c) triquetral and (d) pisiform: the bones of the distal row are (e) trapezium, ( trapezoid, (g) capitate and (h) hamate.
• 2. The Metacarpus - They are five in number.
  • Each is a miniature long bone, comprising a shaft, a proximal base and a distal head.
• 3. The Phalanges - Each finger has three phalanges except the thumb which has only two.
  • Thus the phalanges are fourteen in number.
  • Each possesses a shaft, a head and a base.

Upper limb:

• The arm or upper extremity is the functional unit of the upper body.
• It consists of 3 sections, the upper arm, forearm, and hand.
• It extends from the shoulder joint to the fingers and contains 30 bones.
• It also consists of many nerves, blood vessels i.e. arteries and veins and muscles.