The Appendicular Skeleton

EFE Veterinary Science

Development of the Long BoneDevelopment of a long bone, schematic. 1, Cartilage model with perichondral membrane (arrow); 2, intramembranous ossification of diaphysis; 3, 4, endochondral (primary) ossification of diaphysis, replaces cartilage; 5, beginning of medullary cavity (arrow); 6, epiphysial ossification centers appear; 7, endochondral (secondary) ossification of epiphyses 8, narrow epiphysial cartilages (arrows) separate the diaphysis from epiphyses: these and the articular cartilages are all that remain of the cartilage model (1); note circumferential growth of diaphysis by removal (−) and addition (+) of compact bone; 9, mature bone consisting of articular cartilage, spongy bone, and compact bone; the epiphysial cartilages have disappeared.

The Forelimb

The Scapula

Left scapula of the dog; lateral (A), ventral (B), and medial (C) views. Distal end (D) of left feline scapula. Left equine scapula (E). 1, Cranial angle; 2, spine; 2 , tuber of spine; 3, ′supraspinous fossa; 4, infraspinous fossa; 5, neck; 6, supraglenoid tubercle; 7, acromion; 7 , 7″, hamate ′and suprahamate processes of acromion; 8, infraglenoid tubercle; 9, caudal angle; 10, facies serrata; 11, coracoid process; 12, glenoid cavity; 13, scapular cartilage.

ShoulderLeft shoulder (A) and elbow (B) joints of the dog. The drawings on the left are lateral views, those on the right medial. 1, Scapula; 2, joint capsule opened to expose biceps tendon; 3, tendon of infraspinatus; 4, infraspinatus bursa; 5, humerus; 6, joint capsule, stretched by pulling bones apart; 7, tendon of coracobrachialis; 8, tendon of subscapularis, reflected ventrally; 9, biceps tendon emerging from intertubercular groove; 10, stump of extensor carpi radialis and common digital extensor; 11, lateral collateral ligament; 12, annular ligament of radius; 13, radius; 14, ulna; 15, joint capsule; 16, stump of ulnaris lateralis; 17, common stump of carpal and digital flexors; 18, stump of pronator teres; 19, biceps; 20, brachialis; 21, medial collateral ligament.

Humerus

Left humerus of the dog; caudal (A) and cranial (B) views. C, Distal end of right feline humerus; cranial view. Cranial (D) and lateral (E) views of left equine humerus. 1, Greater tubercle; 1 , 1″, ′cranial and caudal parts of greater tubercle; 2, head; 3, lesser tubercle; 3 , cranial part of lesser ′tubercle; 4, teres (major) tuberosity; 5, deltoid tuberosity; 6, lateral supracondylar crest; 7, olecranon fossa (with supratrochlear foramen in dog); 8, medial epicondyle; 9, condyle; 10, lateral epicondyle; 11, radial fossa; 12, groove for brachialis; 13, intertubercular groove; 13 , ′intermediate tubercle; 14, supracondylar foramen

ElbowLeft shoulder (A) and elbow (B) joints of the dog. The drawings on the left are lateral views, those on the right medial. 1, Scapula; 2, joint capsule opened to expose biceps tendon; 3, tendon of infraspinatus; 4, infraspinatus bursa; 5, humerus; 6, joint capsule, stretched by pulling bones apart; 7, tendon of coracobrachialis; 8, tendon of subscapularis, reflected ventrally; 9, biceps tendon emerging from intertubercular groove; 10, stump of extensor carpi radialis and common digital extensor; 11, lateral collateral ligament; 12, annular ligament of radius; 13, radius; 14, ulna; 15, joint capsule; 16, stump of ulnaris lateralis; 17, common stump of carpal and digital flexors; 18, stump of pronator teres; 19, biceps; 20, brachialis; 21, medial collateral ligament.

Radius and Ulna

Left ulna (A) and left radius (B) of the dog. In sequence from the left: cranial view of the ulna, craniolateral and cranial views of the radius and ulna, and caudal view of the radius alone. Cranial (C) and lateral (D) views of fused left radius and ulna of the horse. 1, Olecranon; 2, anconeal process; 3, trochlear notch; 4, 4 , lateral and medial ′coronoid processes; 5, distal articular facet for radius; 6, lateral styloid process (with facet for the ulnar carpal bone in the dog); 6 , distal end of ulna incorporated within ′radius; 7, articular facet for ulna; 8, medial styloid process; 9, circumferential facet; 10, radial tuberosity; 11, interosseous space.

Carpus

Left carpal joint of the dog, palmar view. 1, Ulna; 2, radius; 3, accessory carpal; 4, lateral collateral ligament; 5, distal ligaments of accessory carpal; 6, palmar carpal ligament; 7, flexor retinaculum; 8, medial collateral ligament; the arrow is in the carpal canal.

Carpus

The bones of the carpal skeleton in the carnivores (Car), horse (eq), cattle (bo), and pig (su), schematic. Roman numerals identify the metacarpal bones; Arabic numerals, the distal carpal bones. R, Radius; U, ulna; a, accessory carpal bone; i, intermediate carpal bone; r, radial carpal bone; u, ulnar carpal bone.

Manus

Right manus (human hand; A) of horse (B) and ruminant (C), palmar views. The Roman numerals number the rays. 1, Radius; 2, ulna; 3, metacarpal; 4, 5, 6, proximal, middle, and distal phalanges; 7, carpal bones; 8, rudimentary metacarpal V; 9, accessory carpal bone; 10, rudimentary metacarpals II and IV (medial and lateral splint bones); 11, axis in line with ray III (mesaxonic), in C paraxonic.

Species Comparison

Hindlimbs of bear, dog, and horse (from left to right) illustrating plantigrade, digitigrade, and unguligrade postures.

Digits

Right manus (human hand; A) of horse (B) and ruminant (C), palmar views. The Roman numerals number the rays. 1, Radius; 2, ulna; 3, metacarpal; 4, 5, 6, proximal, middle, and distal phalanges; 7, carpal bones; 8, rudimentary metacarpal V; 9, accessory carpal bone; 10, rudimentary metacarpals II and IV (medial and lateral splint bones); 11, axis in line with ray III (mesaxonic), in C paraxonic.

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Manus (Dog)

Skeleton of the right manus of the dog, lateral (A) and dorsal (B) views. The Roman numerals identify the metacarpal bones. 1, Radius; 2, ulna; 3, accessory carpal; 4, ulnar carpal; 5, radial carpal (intermedioradial in the dog); 5 , intermediate carpal; 6, 7, first and fourth of the distal ′row of carpal bones; 8, sesamoid bone; 9, proximal sesamoid bones; 9 , ridged articular ′surface of equine metacarpus III, articulates with proximal sesamoid bones (not shown); 10, dorsal sesamoid bone; 11, 12, 13, proximal, middle, and distal phalanges; 13 , claw; 14, axis of ′manus.

Forelimb Muscles

Muscular suspension of the thorax between the forelimbs (dog). 1, Scapula; 2, humerus; 3, radius and ulna; 4, sternum; 5, pectoralis profundus (ascendens); 6, serratus ventralis; 7, trapezius; 8, rhomboideus.

Forelimb Muscles

Superficial muscles of the shoulder and arm. 1, Sternocephalicus; 2, 2 , ′brachiocephalicus: cleidocervicalis and cleidobrachialis; 3, omotransversarius; 4, superficial cervical lymph node; 5, 5 , cervical and ′thoracic parts of trapezius; 6, deltoideus; 7, latissimus dorsi; 8, 8 , long and lateral ′heads of triceps; 9, pectoralis profundus (ascendens); 10, accessory axillary lymph node.

Forelimb Muscles

Intrinsic muscles of the left shoulder and arm of the dog, lateral (A) and medial (B) views. 1, Rhomboideus; 2, teres major; 3, supraspinatus; 4, 4 , scapular and ′acromial parts of deltoideus; 5, latissimus dorsi; 6, 6 , 6″, long, ′lateral, and medial heads of triceps; 7, brachiocephalicus; 8, brachialis; 9, subscapularis; 10, coracobrachialis; 11, tensor fasciae antebrachii; 12, biceps.

Forelimb Muscles

Muscles of the left forearm of the dog, lateral (A) and medial (B) views. 1, Extensor carpi radialis; 2, common digital extensor; 3, lateral digital extensor; 4, ulnaris lateralis; 5, flexor carpi ulnaris; 6, extensor carpi obliquus; 7, extensor retinaculum; 8, carpal pad; 9, biceps; 10, superficial digital flexor; 11, flexor carpi radialis; 12, pronator teres; 13, radius; 14, deep digital flexor; 15, flexor retinaculum.

The Hindlimb

Species Differences

The Hip

Schematic transverse section through the left hip joint of a dog. The femur has been drawn in relief. 1, Gluteus medius; 2, acetabulum, connected to the femoral head by the ligament of the head of the femur; 2 , fibrous rim (labrum) of acetabulum; 2″, transverse ′acetabular ligament; 3, femur; 4, biceps; 5, rectum; 6, vagina; 7, urethra; 8, obturator forame 9, pelvic floor.

Femur

Left femur of the dog, cranial (A), caudal (B), and lateral (C) views. Cranial (D) and lateral (E) views of left equine femur. 1, Head; 1 , fovea; 2, neck; 3, greater trochanter; 3 , 3″, cranial and ′ ′caudal parts of greater trochanter; 4, lesser trochanter; 4 , third trochanter; 5, trochanteric ′fossa; 6, trochlea; 6 , enlarged proximal end of medial trochlear ridge; 7, supracondylar ′tuberosities; 7 , supracondylar fossa; 8, 8 , lateral and medial condyles; 9, intercondylar fossa; ′ ′10, patella; 11, sesamoid bones (in gastrocnemius); 12, extensor fossa; 13, fossa for popliteus.

StifleLeft stifle joint of the dog, cranial view (A-C). The extent of the joint capsule is shown in B. The patella has been removed in C. D shows the crossing of the cruciate ligaments in a medial view. E is a caudal view. 1, Femur; 2, sesamoids in gastrocnemius; 3, patella; 4, extensor groove; 5, tibial tuberosity; 6, fibula; 7, tibia; 8, patellar ligament; 9, tendon of long digital extensor passing through extensor groove; 10, medial meniscus; 11, medial collateral ligament; 12, lateral femoropatellar ligament; 13, lateral collateral ligament; 14, trochlea; 15, caudal cruciate ligament; 16, cranial cruciate ligament; 17, lateral meniscus; 18, stump of 9; 19, popliteus tendon; 20, meniscofemoral ligament.

Tibia and Fibula

Left tibia and fibula of the dog, lateral (A), cranial (B), and caudal (C) views. Cranial (D) and lateral (E) views of left equine tibia and fibula. 1, Tibial tuberosity; 2, 2 , lateral and medial ′condyles; 3, extensor groove; 4, intercondylar eminence; 5, fibula; 6, 6 , medial and lateral ′malleoli; 6″, lateral malleolus in the horse (representing distal end of fibula); 7, cochlea.

Tarsus (Hock)

The bones of the tarsal skeleton in the carnivores (Car), horse (eq), cattle (bo), and pig (su), schematic. Roman numerals identify the metatarsal bones, Arabic numerals the distal tarsal bones. Tib., Tibia; F, fibula; T, talus; C, calcaneus; c, central tarsal bone.

Pes

Skeleton of right pes of the dog, lateral (A) and dorsal (B) views. Dorsal (C) view of left equine tarsus. Roman numerals identify the metatarsal bones. 1, Tibia; 2, fibula; 2 , lateral malleolus; 3, ′calcaneus; 3 , sustentaculum ′tali; 3″, calcanean tuber (point of hock); 4, talus; 5, central tarsal; 6, fourth tarsal; 7, first, second, and third tarsal bones in distal row; 7 , third tarsal in the ′horse; 8, proximal sesamoid bones; 9, dorsal sesamoid bones; 10, 11, 12, proximal, middle, and distal phalanges; 12 , claw.′

Hindlimb Muscles

Muscles of the left canine leg, lateral (A) and medial (B) views. 1, Biceps; 2, semitendinosus; 3, peroneal nerve; 4, gastrocnemius; 5, tibialis cranialis; 6, peroneus longus; 7, lateral deep digital flexor, 7 , tendon of the smaller medial deep digital flexor; 8, superficial digital flexor; 9, long ′digital extensor; 10, peroneus brevis; 11, extensor brevis; 12, tendon of lateral digital extensor; 13, interossei; 14, tibia; 15, popliteus.

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