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Show 240 MR. G. E. DOBSON ON CAPROMYS MELANURUS. [Apr. 1, inner border with the clavicular part of the pectoralis major), from nearly the whole outer border of the spine of the scapula; the fibres converging are inserted into the deltoid ridge of the humerus along with those of the clavicular part of the pectoralis major. Latissimus dorsi (fig. 1, l.d), arising from several dorsal and lumbar vertebras, divides behind the brachial vessels and nerves into two parts : one unites with the teres major muscle and, passing above the brachial nerves, is inserted with it into the humerus ; the other, a much smaller slip (l.d1), passes below the brachial nerves and is inserted by a broad fascial aponeurosis into the humerus under cover of the middle sternal part of the pectoralis major. The vessels and nerves of the arm, therefore, pass out between the insertions of this muscle, as Meckell noticed in Hyrax. Dorso-epitrochlearis is well developed, arising from the external surface of the latissimus dorsi, immediately before the tendon of the latter is formed. Biceps has two heads-a long one from the upper margin of the glenoid cavity, from which the main body of the muscle is derived, and a much smaller which arises by a tendon (common to it and the coraco-brachialis) from the coracoid process of the scapula. These two heads, uniting about the middle of the humerus, form a large muscular mass which is inserted by a strong tendon into the ulna, and by a narrow tendinous slip (which passes across the tendon of the brachialis anticus) into the adjacent margin of the radius. Coraco-brachialis arises, as above described, with the short head of the biceps from the coracoid process, and by a tendon .common to both, from which it separates at the lower margin of the tendon of the subscapularis muscle, and, forming a small muscular mass, is inserted into the lower third of the shaft of the humerus. Brachialis anticus arises, as usual, below tbe external tuberosity, and, winding round the humerus, forms a broad tendon which, passing between the two divisions of the tendon of the biceps, is inserted into the ulna. Palmaris longus and flexor carpi ulnaris arise together from the internal condyle and are inserted as usual. Flexor digitorum sublimis, which arises as usual, forms the three perforated tendons for the three middle toes; that for the outer toe is formed by the palmaris brevis. These tendons in passing into the manus arc covered by fascial arches, from which some of the fibres of the large lumbricales arising from the tendons of the flexor profundus also have their origin. Flexor digitorum profundus exhibits no peculiarity in its origin ; it is formed by a superficial, an internal, and two deep heads, which unite before crossing the carpus to form a very thick tendon, which gives off in the palm a slender filiform tendon to the rudimentary pollex, and four strong tendons to the four outer toes. Pronator radii teres, flexor carpi ulnaris, and flexor carpi radialis present no peculiarities. 1 ' Traits General d'Anatomie Compare^,' vi. p. 263. |
