DISSECTION OF THE DOG 143 



scapula and to the head of the humerus. Strengthening bands leave the base 

 of the coracoid process of the scapula and proceed to the tuberculum ma jus 

 and tuberculum minus of the humerus. It will be noticed that a mem- 

 branous ligament sti'etches from the acromion to the capsule. 



The capsule should be opened in order to allow investigation of the 

 synovial membrane down the intertubercular sulcus in connection with the 

 biceps tendon of origin. 



Articulatio cubiti. — The term ' elbow-joint,' strictly speaking, includes 

 three joints : the humero-radial articulation (articulatio humero-radialis), 

 the humero-ulnar articulation (articulatio humero-ulnaris), and the proximal 

 radio-ulnar articulation (articulatio radio-ulnaris proximalis). 



Capsula articularis. — The joint-capsule, surrounding all three components 

 of the elbow-joint, is strong in front where it is associated with the annular 

 radial ligament, but weak and room}' behind where it is supported by the 

 triceps and anconeus muscles. 



Ligamentum collaterale ulnare. — The ulnar collateral ligament springs from 

 the medial epicondyle of the humerus and divides into two parts. One limb 

 is attached to the border of the radius, while the other is connected with both 

 radius and ulna. 



Ligamentum collaterale radiale. — The radial collateral ligament leaves the 

 lateral epicondyle of the humerus and, like the ulnar ligament, divides into 

 two portions. One of these, the shorter and the stronger, ends on the lateral 

 part of the head of the radius. The other, longer, weaker and more diffuse, 

 joins the border of the ulna. 



Ligamentum annulare radii. — The radial annular ligament is essentially a 

 thickening of the joint-capsule on the flexor aspect of the articulation. Attached 

 to the lateral part of the head of the radius, it crosses over to unite with the 

 tendons of insertion of the brachial and biceps muscles by which it is fixed 

 to the ulna. From the middle of the ligament an offshoot, firmly adherent to 

 the capsule, proceeds in a proximal direction to the humerus. 



Membrana interossea antibrachii.— The interosseous membrane consists 

 of short fibres passing between the two bones of the forearm. 



Articulatio radio-ulnaris distalis. — The joint between the distal end 

 of the radius and ulna is enclosed in a joint-capsule which consists mainly 

 of ligamentous bands on the dorsal and volar aspects of the joint. 



Articulatio radio-carpea. — Uniting the bones of the forearm to the 



