| OCR Text |
Show 1870.j MR. J. B. PERRIN ON BALAENOPTERA ROSTRATA. 815 it gave off a tendon to the index digit. From this tendon an additional one was given off" to the dorsal carpal fascia and the base of the middle metacarpal bone. Besides these it gave off three other tendons respectively to the second, third, and fourth digits. This muscle presented a few differences from the corresponding one described by Carte and Macalister, namely:- 1. It attained a humeral attachment, whereas Macalister's specimen had only a radio-ulnar attachment. 2. Its indicator tendon gave off an additional slip to the metacarpus. 3. It was well developed, Macalister's specimen being a mere rudimentary fasciculus. The flexor muscles are three in number-namely, flexor carpi ulnaris, flexor sublimis digitorum, and flexor profundus digitorum. The flexor carpi ulnaris (fig. 2, Fix. Carp. UI.) arose from the olecranon, its ventral aspect, and was inserted into the ventral border of the lower end of the ulna. The flexor sublimis digitorum (fig. 2, Fl. I.) was a small and bi-penniform muscle, occupying the interval between the ulnar and radial divisions of the profundus flexor. It arose from the distal end of the humerus, immediately below the insertion of the latissimus dorsi, and behind the aponeurosis from the masto-humeral. Its muscular fibres soon terminated in a long slender tendon, which passed downwards in the interval between those of the deep flexor tendons. Opposite the lower end of the radius it divided into two tendons: the radial tendon was short, and joined a corresponding tendon from the ulnar portion of the deep flexor; the ulnar tendon was also short, and terminated in the palmar carpal fascia. Between the divisions the radial tendon of the ulnar portion of the deep flexor passed, forming a rudimentary condition of perforatus and perforans. The flexor profundus digitorum (fig. 2, Fix. Rad. Digt., Fix. UI. Digt.) consisted of two distinct portions, separated by the flexor sublimis. The ulnar portion was fan-shaped, arising by fleshy fibres from the anterior surface of the distal end of the humerus, from the adjoining surface of the ulna and its olecranon, from the upper part of the shaft of the ulna and the strong fascia which covered it. It terminates in a strong flat tendon, fully half an inch wide, about the middle of the shaft of the ulna, and opposite the lower end of that bone divided into four tendons. The radial one passed through the two divisions of the flexor sublimis, joining the radial one, already described, to be inserted into the radial tendon of the deep flexor. The three remaining tendons were prolonged to the distal extremities of the phalanges of the second, third, and fourth digits respectively, imbedded in aponeurotic canals. The radial portion of the deep flexor was much smaller than the preceding: it arose from the upper two-thirds of the anterior surface of the shaft of the radius, and from the membrane occupying the interosseous groove. Its fleshy fibres terminated in a strong tendon, which was joined opposite the carpus by the conjoined tendon formed by the radial divisions of the sublimis and ulnar portion of the deep flexor tendons. The resulting tendon was finally inserted into the distal extremity of the first digit. |
