Appendicular Skeleton
Dr. R. Menaka
.......................................................................................................................................................................................
The appendicular skeleton includes the bones of forelimb and hind limb. The bones of forelimb consists of shoulder girdle (scapula, coraccoid and clavicle), humerus (arm bone), radius and ulna (fore arm region), carpals (small bones), metacarpals and phalanges. The shoulder girdle is well developed in man and birds. In domestic animals the scapula is well developed and coracoid and clavicle either rudimentary or absent.
Scapula of Ox:
The scapula (shoulder blade) is a flat bone and extends from 3 to 4th thoracic spine to the distal end of first rib.
It presents
a. Two surfaces- Lateral surface and medial surface
b. Three borders- Anterior border (cranial border) ; posterior border (caudal border) and dorsal border
c. Three angles- Cranial angle; caudal angle and distal angle
a. Two surfaces-
Lateral surface: The lateral surface is divided into two unequal halves by a scapula spine. The scapular spine is attached with trapizeus muscle. The spine has pointed at its terminal part known as acromian process. The superior one is smaller and known as supraspinous fossa, which is covered by supraspinatus muscle. The inferior part is known as infraspinatus fossa, which is covered by infraspinatus muscle.
Medial surface: The medial surface has a shallow fossa at the middle, known as subscapular fossa, whcih accommodates subscapulairs muscle.Upper part of this surface has rough areas which gives attachment with serratus cervicis and serratus thoracis muscles.
b. Three borders-
Anterior border- thin and convex
Posterior border- thick and convex
Dorsal border- rough and attached with scapular cartilage
c. Three angles-
Distal angle- It presents the glenoid cavity and tuber scapulae. The glenoid cavity is articulated with the head of humerus. The tuber scapula is situated at the cranial aspect of the glenoid cavity. Biceps brachii muscle originates from the tuber scapulae. The coracoid process is small projection from the medial aspect of the tuber scapulae and this process gives the origin of coraco-brachialis muscle.
Scapula of Horse:
The subscapular fossa is deep
The glenoid notch is deep and distinct
The acromian process is absent
The tuber scapula is larger and further placed away from the glenoid cavity
Scapula of Dog:
The lateral surface of the scapula is divided into two equal halves
The acromian process is extended up to the level of glenoid cavity
The subscapular fossa presents few rough lines
Scapula of Pig:
The acromian process is rudimentary
The glenoid notch is absent
Scapula of Rabbit:
Acromian process is broad and continues backward in the form of a projection, known as metacromian process.
Coracoid process is well developed