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→Structures of the Proximal Forelimb and Shoulder
==Structures of the Proximal Forelimb and Shoulder==
==Structures of the Proximal Forelimb and Shoulder==
===[[Forelimb - Anatomy & Physiology#Scapula|Scapula]]===
===Scapula===
[[File:Cambridge Natural History Mammalia Fig 025.png|thumb|right|150px|Canine Scapula, Cambridge Natural History Mammalia Fig 025, Frank E. Beddard, 1902]]
[[File:Cambridge Natural History Mammalia Fig 025.png|thumb|right|150px|Canine Scapula, Cambridge Natural History Mammalia Fig 025, Frank E. Beddard, 1902]]
The scapula is the bone found at the most proximal region of the forelimb and provides articulation between the limb and the trunk. The scapula is a flat bone that lies laterally over the thoracic region but does not directly articulate with the ribs and is instead held in place by the '''pelvic girdle'''. Therefore the canine forelimb does not have a direct link with the trunk but instead the scapula provides an anchoring point for a ''synsarcosis'', or arrangement of muscles facilitating the carriage of the weight of the body onto the forelimb.
The scapula is the bone found at the most proximal region of the forelimb and provides articulation between the limb and the trunk. The scapula is a flat bone that lies laterally over the thoracic region but does not directly articulate with the ribs and is instead held in place by the '''pelvic girdle'''. Therefore the canine forelimb does not have a direct link with the trunk but instead the scapula provides an anchoring point for a ''synsarcosis'', or arrangement of muscles facilitating the carriage of the weight of the body onto the forelimb.
The scapula itself is flat and in the canine is roughly rectangular with a point at the distal end where there is an articulation with the humerus. The medial surface of the scapula is generally flat with small prominences facilitating the attachment of muscles including the subscapularis muscle (found within a shallow fossa) and the serratus ventralis. In the dog the caudal border of the scapula is thickened, particularly towards the distal extremity where the suprascapular nerve passes. Also at the distal end of the scapula but on the cranial aspect is the ''supraglenoid tubercule'' which projects cranially to the articulation with the humerus. This tubercle also gives rise to the muscular attachment of the biceps brachii.
The scapula itself is flat and in the canine is roughly rectangular with a point at the distal end where there is an articulation with the humerus. The medial surface of the scapula is generally flat with small prominences facilitating the attachment of muscles including the subscapularis muscle (found within a shallow fossa) and the serratus ventralis. In the dog the caudal border of the scapula is thickened, particularly towards the distal extremity where the suprascapular nerve passes. Also at the distal end of the scapula but on the cranial aspect is the ''supraglenoid tubercule'' which projects cranially to the articulation with the humerus. This tubercle also gives rise to the muscular attachment of the biceps brachii.
===[[Forelimb - Anatomy & Physiology#Clavicle|Clavicle]]===
===Clavicle===
In canines the clavicle is not strictly a bony structure and is instead reduced to a fibrous area of tissue within the brachiocephalicus muscle. In some older canines the clavicle may be visible on radiographs.
In canines the clavicle is not strictly a bony structure and is instead reduced to a fibrous area of tissue within the brachiocephalicus muscle. In some older canines the clavicle may be visible on radiographs.
===[[Forelimb - Anatomy & Physiology#Humerus|Humerus]]===
===Humerus===
The humerus represents the first part of the limb that is a free appendage, i.e. it does not have any firm attachment to the trunk. The humerus is a long bone that has a large articular head which articulates with the glenoid cavity of the scapula (see above). This articular head is slightly offset via a neck to facilitate articulation. The head itself has two processes, the ''greater tubercle'' which is found laterally and the ''lesser tubercule'' that is found medially. These tubercules are seperated by an intertubercular groove across which the biceps tendons run. The lateral tubercule forms the anatomical landmark of the point of the shoulder and in canines this can be readily palpated.
The humerus represents the first part of the limb that is a free appendage, i.e. it does not have any firm attachment to the trunk. The humerus is a long bone that has a large articular head which articulates with the glenoid cavity of the scapula (see above). This articular head is slightly offset via a neck to facilitate articulation. The head itself has two processes, the ''greater tubercle'' which is found laterally and the ''lesser tubercule'' that is found medially. These tubercules are seperated by an intertubercular groove across which the biceps tendons run. The lateral tubercule forms the anatomical landmark of the point of the shoulder and in canines this can be readily palpated.
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At approximately one third distally along the humerus are two musclar attachment processes; the teres (major) tuberosity and the deltoid tuberosity. The deltoid tuberosity runs laterally along the humerus and is joined to the greater tubercule via a ridge which can be palpated in canines. The teres tuberosity is on the medial aspect and is much less prominent. The distal aspect of the humerus articulates with the radius and ulna and to facilitate this articulation there are condyles on the lateral and medial aspects. In canines these condyles are divided into the '''trochlea notch''' which articulates with the ulna and the '''capitulum''' laterally for the radius. The groove of the trochlea notch forms the ''olecranon fossa'' which receives the anconeal process of the ulna allowing articulation of the joints. Proximal to the articular surfaces are epicondyles with the medial epicondyle being larger than the lateral. The medial epicondyle gives rise to the flexor muscles of the carpus and digits. The smaller lateral epicondyle gives rise to the extensor muscles of the carpus and digit. The epicondyles also facilitate the attachment of the collateral ligaments around the joint.
At approximately one third distally along the humerus are two musclar attachment processes; the teres (major) tuberosity and the deltoid tuberosity. The deltoid tuberosity runs laterally along the humerus and is joined to the greater tubercule via a ridge which can be palpated in canines. The teres tuberosity is on the medial aspect and is much less prominent. The distal aspect of the humerus articulates with the radius and ulna and to facilitate this articulation there are condyles on the lateral and medial aspects. In canines these condyles are divided into the '''trochlea notch''' which articulates with the ulna and the '''capitulum''' laterally for the radius. The groove of the trochlea notch forms the ''olecranon fossa'' which receives the anconeal process of the ulna allowing articulation of the joints. Proximal to the articular surfaces are epicondyles with the medial epicondyle being larger than the lateral. The medial epicondyle gives rise to the flexor muscles of the carpus and digits. The smaller lateral epicondyle gives rise to the extensor muscles of the carpus and digit. The epicondyles also facilitate the attachment of the collateral ligaments around the joint.
===[[Forelimb - Anatomy & Physiology#Radius|Radius and Ulna]]===
===Radius and Ulna===
The radius and ulna provide the connection between the proximal forelimb to the bony structures of the distal limb. In canines the ulna is caudal to the radius proximally and then becomes lateral to the radius distally. In canines the ability to pronate or supinate the limb is restricted and is only possible to approximately 45 degrees.
The radius and ulna provide the connection between the proximal forelimb to the bony structures of the distal limb. In canines the ulna is caudal to the radius proximally and then becomes lateral to the radius distally. In canines the ability to pronate or supinate the limb is restricted and is only possible to approximately 45 degrees.
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