Veterinary Gross Anatomy

BONES OF THE PECTORAL LIMB

• Pectoral girdle and shoulder region : Scapula, Coracoid and Clavicle.
• Arm : Humerus
• Forearm : Radius and Ulna
• Manus : Consisting of
  • Carpus: A number of small bones called carpals arranged in the domestic mammals in two rows.
  • Metacarpus: Typically consisting of five bones designated only by numbers 1 to 5, but showing considerable modifications in different animals.
  • Digits: These form the terminal parts of the limbs and usually correspond to the number of the fully developed metacarpals. These are also designated by numbers 1 to 5. Each digit is composed of a number of bones arranged serially called the phalanges. The number of phalanges may vary (from 1 to 5) within the species and also in different digits of the same species.

Modifications in different animals

It should be noted that in all animals, there are considerable modifications in the number present and the extent of development of the various bones as compared with the typical pattern. Significant modifications are noted in the domestic animals to be studied (i.e. ox, sheep, goat, horse, pig, dog, rabbit and fowl). They are

• The absence of a typical pectoral girdle and only scapula being well developed in all the mammals, (all three bones are present in the fowl).
• Ulna is being reduced and fused to radius in ox and horse.
• Extensive modifications in the bones of the manus, (i.e.) carpus, metacarpus and digits, with two well developed digits in the ox, sheep, goat, pig and only one in the horse but five (first reduced) in the dog and three in the fowl.
• For specific bones present in each species, refer details given in the descriptions of corresponding regions.

(Note: In this course, the anatomy of the ox, is given with significant differences and special features if any, are mentioned briefly for horse, pig, dog, rabbit and fowl.)