Veterinary Anatomy: Thoracic Limb Bones

Clavicle

is not articulated with the skeleton in the dog. It is located at the tendinous intersection of the brachiocephalicus muscle, and its medial end is attached to the sternal fascia by a distinct ligamentous band.

Scapula

is the large, flat bone of the shoulder joint. Its most dorsal part lies just ventral to the level of the free end of the spinous process of the first or second thoracic vertebra.

Acromion

The widened truncate distal end of the spine of the scapula is called the ___.

Supraspinous fossa

is bounded by the cranial surface of the scapular spine and the adjacent lateral surface of the scapula.

Infraspinous fossa

is in general triangular.

Dorsal border

sometimes called the vertebral border or base, extends between the cranial and the caudal angles.

Cranial border

is thin except at its extremities.

Scapular notch

Distally, the cranial border forms a concavity, __ , which marks the position of the constricted part of the bone.

Subscapular fossa

The large remaining part of the costal surface is the ___

Caudal border

is the thickest of the three borders and bears, just dorsal to the ventral angle, the infraglenoid tubercle (tuberculum infraglenoidale).

Glenoid cavity

___ receives the head of the humerus in forming the shoulder joint.

Humerus

is the bone of the arm, or brachium. Proximally it articulates with the scapula in forming the shoulder joint; distally it articulates with the radius and ulna in forming the elbow joint.

Head of humerus

is oval, being elongated in a sagittal plane.

Intertubercular groove

The articular surface of the head is continued distally by the ____

Neck of humerus

is distinct only caudally and laterally.

Body of humerus

or shaft, is the long, slightly sigmoid-shaped part of the humerus that unites the head and neck with the condyle.

Deltoid tuberosity

is the most prominent feature of the lateral surface of the humerus.

Greater tubercle

is the large craniolateral projection of the proximal extremity of the humerus.

Lesser tubercle

is a medially flattened enlargement of the proximal medial part of the humerus, the convex border of which does not extend as far proximal as the head.

Brachialis groove

the __ or musculospiral groove forms the smooth, flat to convex, lateral surface of most of the humerus.

Tuberosity for teres major

lies in the same transverse plane as the laterally located deltoid tuberosity.

Humeral condyle

is the entire sagittally rounded distal end of the humerus exclusive of the epicondyles.

Capitulum humeri

Small, lateral articular surface for articulation with the head of the radius.

Trochlea humeri

Pulley-shaped part that extends proximally into the adjacent fossae.

Olecranon fossa

Deep excavation of the caudal part of the humeral condyle.

Radial fossa

Fossa on the cranial surface of the condyle opposite the olecranon fossa.

Supratrochlear foramen

Foramen that allows communication between the radial and olecranon fossae.

Lateral epicondyle

Lateral prominence on the humeral condyle, caudoproximal to the lateral articular margin of the capitulum.

Medial epicondyle

Prominence on the medial side of the condyle, proximal to the medial border of the articular surface of the trochlea.

Radius

Main weight-supporting bone of the forearm, shorter than the ulna, primarily for muscle attachment.

Head of radius

Irregularly oval outline that extends transversely across the proximal end of the radius.

Neck of radius

Constricted segment of the radius that joins the head to the body.

Articular fovea

Concave surface that articulates with the capitulum and lateral part of the trochlea.

Articular circumference

Caudal, smooth, osseous band on the head for articulation with the radial notch of the ulna.

Radial tuberosity

Small projection that lies distally on the neck on the medial border and adjacent caudal surface of the radius.

Body of radius

Compressed shaft presenting two surfaces and two borders.

Trochlea of radius

Distal extremity of the radius and the most massive part of the bone.

Ulnar notch

Slightly concave and lipped surface on the lateral side of the trochlea that articulates with the ulna.

Styloid process

Wedge-shaped projection that extends distal to the main carpal articular surface.

Ulna

Longest bone in the body, divided into a body and two extremities, articulating with the humerus and radius.

Trochlear notch

Notch on the ulna that articulates with the humerus.

Olecranon

Includes the olecranon tuber, anconeal process, and proximal part of the trochlear notch, serving as a lever arm for extensor muscles.

Cranial surface of ulna

Rough and convex surface, both longitudinally and transversely.

Interosseous border

Border that extends proximally from the notch separating the distal extremity from the body of the ulna.

Caudal border of ulna

Smooth and concave border that tapers toward the head.

Medial border of ulna

Sharper and straighter than the lateral border.

Lateral border

Continues the wide, rounded, caudal border of the olecranon.

Forepaw

The skeleton of the ___ (manus) includes the bones of the carpus, metacarpus, phalanges, and certain sesamoid bones associated with them.

Carpus

Composed of seven bones arranged in two transverse rows, plus a small medial sesamoid bone.

Intermedioradial carpal bone

Located on the medial side of the proximal row, it is the largest of the carpal elements.

Ulnar carpal bone

The lateral bone of the proximal row.

Accessory carpal bone

A truncated rod of bone located on the palmar side of the ulnar carpal.

First carpal bone

The smallest carpal bone.

Second carpal bone

A small, wedge-shaped, proximodistally compressed bone.

Third carpal bone

Larger than the second carpal and has a large palmar projection.

Fourth carpal bone

The largest bone of the distal row.

Smallest bone of the carpus

A spherical sesamoid bone, about the size of a radish seed, located in the tendon of insertion of the m. abductor digiti I longus on the medial side of the proximal end of the first metacarpal.

Metacarpus

Refers to the region of the manus, consisting of five metacarpal bones that are each cylindrically shaped and enlarged at each end.

First metacarpal bone

Usually present, it is the shortest and most slender of the metacarpal bones.

Main metacarpal bones

Metacarpal bones II to V, which are irregular rods with a uniform diameter.

Metacarpals II and V

Shorter than III and IV and are four-sided, particularly at their base.

Metacarpals III and IV

More triangular at their base compared to II and V.

Digital skeleton

___ of the forepaw consists of five units, of which four are fully developed and one is rudimentary.

Dewclaw

The rudimentary first digit, which may be double in some breeds such as the St. Bernard.

Proximal phalanx

the ____ of each of the main digits, II to V, is a medium-length rod with enlarged extremities.

Middle phalanx

Present only in each of the main digits, there being none in digit I.

Distal phalanx

Approximately the same size in all four main digits.

Ungula process

The distal part of the distal phalanx, a laterally compressed cone that is shielded by the horny claw.

Ungual crest

A crescent-shaped shelf of bone under the root of the claw.

Sesamoid bones

On the palmar surface of each metacarpophalangeal joint of the main digits are two elongated, slightly curved sesamoid bones located in the tendons of insertion of the interosseus muscles.