Bones of Upper Limb

indexShoulder Girdle: It compromises the collar bone i.e. the clavicle and the Scapula. Together, they provide a mobile base to attach the upper limbs to the trunk.

The Clavicle:

  1. It acts as a strut to distance the scapula and upper limb from the chest wall.
  2. It forms the articulations with the sternum and with the acromion of the scapula.
  3. It transmits the forces to the axial skeleton
  4. It lacks marrow and ossifies in membrane.

The triangular scapula:

  1. It articulates with the humerus at the glenoid fossa.
  2. It possesses a prominent ridge on the posterior surface- the spine.
  3. It provides large, flat surfaces and roughened processes for muscle attachments
  4. It maintains a strong purchase on the chest wall.

The bones of the arms: Theses compromise the bone of the upper arm i.e. the humerus and the bones of the forearm- the radius and the ulna.

The humerus:

  1. It acts as a mobile lever to direct the forearm movement in any direction.
  2. It consists of a head, together with the neck and the shaft.
  3. It articulates with the radius at the rounded capitulum.
  4. It articulates with the ulna at the trochlea.
  5. It is often fractured at the ‘surgical neck’ below the anatomical head at the start of the shaft.

The Radius:

  1. It possesses a head, neck and a shaft.
  2. Head is a thick, disc like shape which articulates with the humerus.
  3. It articulates with the scaphoid bone and lunate carpal bones at its distal end.
  4. It is expanded at its distal end with an ulnar notch.
  5. It is often fractured by a fall on an outstretched hand i.e. Colle’s fracture.

The Ulna:

  1. It is not directly a part of the wrist joint.
  2. It possesses a head, neck and a shaft.
  3. It articulates with the humerus at the crescent-shaped trochlear notch.
  4. It possesses a beak-shaped process called the olecranon process at its proximal extremity which, in combination with the humerus, locks the extended elbow joint to prevent overextension.
  5. It articulates with the head of the radius at the radial notch.

The bones of the hand: These compromise eight small bones of the wrist i.e. the carpus and 19 bones of the fingers i.e. the metacarpals and phalanges.

The carpal bones:

  1. These are present distal to the wrist joint.
  2. These are pebble-like and arranged in two rows of four:
  • Scaphoid, Lunate, Triquetral, Pisiform in proximal row.
  • Trapezium, Trapezoid, Capitate, Hamate in distal row.
  1. These are transversely arched, creating a hollow.
  2. They provide a flexible but firm basis on which muscles can exert their action.
  3. They articulate distally with the metacarpal bones

The scaphoid bone is prone to fracture through fall on an outstretched hand.

The metacarpal Bones:

  1. They are five in number.
  2. They compromise a head, neck and a shaft.
  3. They articulate distally with the first row of phalanges.
  4. They are relatively immobile; only that of the thumb is truly mobile.

The Phalanges:

  1. They are the bones of the fingers and the thumb.

They function as a unit rather than as individual bones.

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