Veterinary Gross Anatomy-II

MUSCLES OF THE THORACIC LIMB-DOG

• The variations in the musculature of the dog is given below.
  • The posterior superficial pectoral is thin and narrow.
  • The anterior deep pectoral is feeble and terminates along with the posterior deep pectoral on the humerus.
  • The trapezius is thin and divided into cervical and dorsal portions.The right and left muscles meet on a fibrous raphe.
  • The omotransversarius is a well developed muscle arising from the spine of the scapula and maintains uniform thickness.
  • The brachiocephalicus is distinct in its division into two parts.
  • The serratus ventralis is highly developed muscle bearing no marks on the separation between serratus thoracis and serratus cervicis. It is a semicircular suspension starting from the third tro seventh cervical vertebra and first eight ribs and inserted to the cervical and thoracic angles of the scapula.It covers the most of the chest region.
  • The rhomboideus is very extensive.
  • The teres major is thicker.
  • The subscapsularis gives a glistening appearence.
  • The capsularis is absent.
  • The deltoideus is well developed and coracobrachialis is very small.
  • The biceps brachii is very prominent.
  • The triceps heads are marked by deposition of fat.There is an additional accessory head which arises from below the head of the humerus.
  • The brachioradialis is a consonant muscle of the forearm extending from the lateral epicondyle of the humerus and ending on the medial border of the radius.
  • The common digital extensor arises from the lateral epicondyle of the humerus as a single muscle and terminates by four tendons attaches to the third phalanges of the second to fifth digits.
  • The extensor of the first and second digits is a small muscle placed between the common digital and the lateral digital extensor.Arising from the shaft of the ulna,it terminates by joining the tendon of the common digital extensor and giving slips to the first and second digits.
  • The lateral digital extensor a is a muscle with double belly which is not common. It attaches to the third pahalanges of the third and the fourth digit and is called extensor of the third and fourth digits. The second one attaches to the third phalnx of the fifth digit.Both the tendons reach the third phalnx by joining with the tendon of the common digital extensor.
  • The extensor carpi obliquus is inserted to first metacarpal bone, abducting the first digit and manus.
  • The pronator teres helps in pronation.
  • The flexor carpi radialis tendon divides and terminates on the second and third metacarpal bones.
  • The flexor carpi ulnaris has two heads of originas humoral and ulanr which terminate on the accessory carpal.
  • The superficial digital flexor has single origin from the medial condyle of the humerus.Its muscular belly extends to the back of the carpus. Here,it is reinforced by slipd from the accessory carpal and the proximal sesamoid.The four bands into which it divides terminate on the second phalnes of the second to fifth digits.
  • The deep digital flexor presents the same heads. It has two attachments one of which terminates on the first digit and the other divides into four branches which are attached to the third phalanges of the second to fifth digits.In its course it passes through the tendon of the superficial digital flexor.
  • Palmaris longus joins thew deep digital flexor to the superficial flexor,originating from the middle of the radius and terminating behind the carpal.