Characteristics of human bones
Sternum or breast bone
(i) The flat, narrow bones located in the centre of the anterior thoracic wall (15 cm in length).
(ii) Composed of three parts: manubrium, body and xiphoid process.
(iii) The body or middle portion gives attachment to the ribs.
(iv) The xiphoid process is the tip of bone that gives attachment to the diaphragm.
(i) There are 12 pairs of ribs which give support to the thoracic cavity
(ii) The ribs increase in length from 1st to 7th and then decrease in length up to 12th
(iii) 1st 7 pairs of ribs are directly attached to the sternum by costal cartilage called true ribs (vi) Rest of the ribs are not directly attached or not attached to the sternum called false ribs.
(i) Consists of one clavicle and one scapula
(ii) Scapula or shoulder blade is a flat triangular shaped bone lying on posterior chest wall superficial to the ribs and separated from them by muscles
(iii) At lateral angles there is a shallow articular surface which with the head of the humerus forms the shoulder joint
(iv) Clavicle or collar bone is a long bone which has a double curve v. It only provides the bony link between upper limb and axial skeleton.
(i) It is the bone of upper arm
(ii) The head articulates with scapula, forming shoulder joint
(iii) Distal to the head there are two roughened projections of bone, the greater and lesser tubercles and between them there is a deep groove that is called intertubercular sulcus, occupied by one of the tendons of biceps muscle
(iv) The distal end of bone presents two surfaces that articulate with radius and ulna to form elbow joint.
Radius and ulna
(i) Radius is a long bone that is composed of head, neck, radial tuberocity, shaft and styloid process
(ii) Interosseous membrane is present between radius and ulna
(iii) Radius and ulna are articulated with each other by proximal and distal redicualr joint
(iv) Ulna is composed of trochlear notch, coronoid process, shaft and styloid process.
Carpal or wrist bone
(i) There are 8 carpal bones, arranged in two rows of four: proximal row: scaphoid, lunate, triquetrum, pisiform; distal row: trapezium, capitate, trapezoid and hamate
(ii) These bones together allow a certain amount of movement between them
(iii) The bones of proximal row are associated with the wrist joint and distal row form joints of metacarpal bones.
Metacarpal bones or bones of hands
(i) There are five bones form the palm of the hand
(ii) They are numbered from the thumb side inwards
(iii) The proximal ends articulate with the carpal bones and distal ends with the phalanges.
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