Зображення сторінки
PDF
ePub
[ocr errors]
[ocr errors]
[ocr errors]

Quadrumana, than in Man, thus enabling the muscles to continue their action as finger-benders when the hand itself is flexed. The fasciculus of the flexor profundus' which sends the tendon to the last phalanx of the thumb, is more distinctly a flexor longus pollicis' in Apes than in lower Quadrumana. In the Aye-aye it adheres to the supplementary carpal and fascia on its way to the thumb, and thus opposes both the last phalanx and the 'pad' at the base of the thumb in the act of grasping. The 'flexor brevis,' the abductor,' the adductor,' and 'opponens pollicis' are present in the Chimpanzee and Gorilla, as are likewise the extensor longus' and extensor brevis.' In the Orang these muscles begin to be confounded; in most lower Quadrumana they are blended together. The homologue of the 'extensor indicis' of Man bifurcates and sends a tendon to both the index and medius digits; the homologue of the extensor minimi digiti likewise splits and sends a tendon also to the annularis; so that, while in Man the index and minimus only have two extensor tendons, all four fingers (iv) have them in most Quadrumana. The hand is thereby the stronger as a suspensor of the body from a bough.

[ocr errors]
[ocr errors]
[ocr errors]

The ectogluteus' is feebly developed compared with that in Man: the Gorilla, though receding far in this respect, recedes the least. The homologue of the 'gracilis' is relatively larger in all Quadrumana than in Man, and its insertion is extended lower down the leg. In Stenops the vastus externus contributes a fasciculus to the rectus femoris; in Chiromys it is as distinct as in higher Quadrumana. But here the mesogluteus exceeds the ectogluteus in size, although the latter is supplemented in the Gorilla by fleshy fasciculi from the ischial tuberosity, which spread their insertions from that of the ectogluteus down the femur to the internal condyle, apparently representing the adductor magnus. In both Orang and Chimpanzee a muscle from the outer border of the ilium to near the acetabulum is inserted into the under and outer part of the great trochanter and rotates the thigh inwards.' The gastrocnemii have a greater length and minor breadth and thickness of the fleshy part: the soleus rises from the fibula exclusively, and joins the gastrocnemii low down.

§201. Muscles of Bimana.-The myologies of Anthropotomy reduce the need of noticing human muscles here to some comparison with those of highest Apes, bringing out the ordinal characteristics of the limbs, and to the illustration of those giving expression to the face and reflecting the action of the organ that marks Man's place in Creation as the type of a distinct sub-class. Scansorius,' Trail, xxxv ̈*. Invertor femoris,' xxxIV". p. 68.

1

23

Figures 23 and 24 give a view of the superficial muscles and tendons of the fore-arm and hand of a full-grown male Gorilla and Man of correct relative size. The portion of the triceps is seen in the Gorilla at 2"; in Man at 5', in whom the origins of the carneous fibres of that part from behind the inter-muscular septum are continued lower down the humerus. The brachialis anticus' is seen at 4, fig. 23, and 17, fig. 24. This muscle is not so completely differentiated from the deltoid and supinator longus in the Gorilla as in Man, nor so individualised as a single muscle: its two portions being more distinct. The biceps, fig. 23, 3, maintains in Man more of its full fleshy character to the sending off of the tendon, 3', to the rough posterior margin of the tuberosity of the radius, gliding over the anterior smooth surface of that process with an intervening 'bursa.' The aponeurosis, 3", sent off to the fascia of the fore-arm crosses the pronator teres.' This muscle, 8, fig. 24, is attached to the outer side of the radius below the middle of the bone in the Gorilla, but rather above it in Man. The double origin, viz. from the inner humeral condyle and the coronoid process of the ulna, is better defined in Man, fig. 23, 6. The palmaris longus,' fig. 23, 8, arising as a distinct muscle in Man from the inner humeral condyle, is a fasciculus, 5, of the 'flexor carpi ulnaris' (3, fig. 24) in the Gorilla; but, as this muscle is subject to variation, and sometimes absent in Man, it may show analogous inconstancy in the Gorilla. The flexor carpi ulnaris is inserted into the pisiforme in both Man and Ape, but the Muscles of the fore-arm and hand, fleshy and tendinous parts are better defined,

[graphic]
[ocr errors]

Man.

and the latter relatively longer and more slender in Man, fig. 23, 9. The flexor carpi radialis arises in Man, fig. 23, 7, from the inner condyle, from the antibrachial fascia and septa continued therefrom between the pronator teres, 6, and palmaris longus, 8; but in the Gorilla, fig. 24, 4, it derives a considerable accession of

fibres directly from the radius, and its tendon is shorter and much

[ocr errors][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small]

thicker than in Man. In both it passes through a pulley provided by the trapezium to its insertion into the base of the metacarpal of the index. The tendon of the supinator longus in the Gorilla, fig. 24, 4', is also shorter and thicker, and is not crossed, as in Man, by the extensors of the metacarpal and first phalanx of the pollex (fig. 23, 11 and 12) before its insertion into the styloid process of the radius. Part of the carneous mass of the flexor sublimis digitorum is seen at 13, fig. 23, and 6', fig. 24. External to this a greater proportion of the flexor profundus appears in the Gorilla, fig. 24, 6, than in Man, fig. 23, 15. The flexor longus pollicis, fig. 23, 14, expends its force in the Gorilla, fig. 24, 20, upon both the pollex and index, furnishing tendons to the distal phalanx of each, but the largest and most direct being that to the index. There are modifications of minor

[graphic]

importance in the origin of this muscle which tend to give it a

[ocr errors]

character of being part of the system of the flexor profundus' in the Gorilla.

The relations of the tendons of the superficial and deep flexors to each other and to the digits are much alike in Man and Ape, but the tendons are relatively broader, and their restraining and strengthening sheaths and bands stronger in the Gerilla; those formed by the oblique decussating ligamentous fasciculi, as in the mid-finger of fig. 23, are more distinctly shown in Man than in the Ape. The muscles acting on the metacarpal and first phalanx of the pollex-fig. 24, 22, abductor,' ib. 24, flexor brevis, ib. 25, adductor are longer and more slender in the Gorilla. The abductor in Man is shown at fig. 23, 17. In the Gorilla the abductor minimi digiti' is shown at fig. 24, 10; the 'flexor brevis' at 11; the tendon of the flexor profundus at 13; that of the flexor sublimis' at 6'. Two of the lumbricales' are shown at 14 and 28, and one of the interossei at 27, fig. 24. The carneous part of the common extensor of the fingers is continued to the wrist in the Gorilla ; three strong tendons go to the second, third, and fourth digits, and a fourth, less strong, to the fifth digit. This digit also receives the tendon of an extensor minimi digiti, and the index a small tendon of an indicator' which is more completely blended with that of the ordinary extensor, besides being more feeble, than in Man. The extensors of the metacarpal, first and last phalanges of the pollex, are present in the Gorilla, but of smaller size than in Man.

In the Gorilla the portion of the biceps cruris derived from the ischiadic tuberosity, and inserted, fig. 25, 4, into the outer part of the head of the tibia, is more distinct than in Man from that, ib. 5, derived from the femoral linea aspera and inserted into the head of the fibula, and which expands, 5', upon the cnemial fascia. The external gastrocnemius, fig. 25, 7, continues longer distinct from the internal, and both present longer but narrower and thinner carneous portions than in Man. The soleus, ib. 8, arises exclusively from the fibula and is much narrower than in Man, where it also derives fibres from the oblique line of the tibia and from the middle third of its internal border. The margins of the tendon of the soleus first unite with those of the gastrocnemius, the middle part continues distinct to near the calcaneum. The plantaris has not been met with in the Gorilla. The peroneus longus, fig. 25, 9, has a longer carneous and shorter but thicker tendinous part in the Gorilla than in Man: the course and insertion of the tendons are the same. The peroneus brevis,

[ocr errors]

25

[ocr errors]

ib. 19, very closely repeats the characters of that muscle in Man. The tibialis anticus,' fig. 25, 17, commences by a broader and more fleshy origin, but gradually decreases as it descends, not swelling out into the well-marked belly,' as in Man: the tendon divides more distinctly and deeply to be inserted into the metatarsal of the hallux and the entocuneiform bone. The extensor longus digitorum, with the same relations at its origin to the tibialis anticus and peroneus longus as in Man, divides, after passing under the annular ligament, into three, instead of four tendons; the innermost of which subdivides to supply the second and third toes. The extensor longus hallucis sends its tendon to the last phalanx of the hallux, as in Man. The short extensor of the toes, ib. 20, also sends off a strong fasciculus, 20', the tendon of which acts. upon the proximal phalanx of the hallux. Three other fasciculi send tendons to the second, third, and fourth toes.

[graphic]
[ocr errors]

The long flexors of the toes are distinguished in the Gorilla, as in lower Quadrumana, by their relative position at the back of the leg. The one toward the inner or tibial side sends its tendon through a strong ligamentous synovial sheath behind the inner malleolus to the sole, where it divides into three chiet tendons which are connected with those of the 'flexor accessorius.' In fig. 26, the divisions of the long tibial flexor, 1, are cut and reflected; a goes to the fifth toe; 4 is

Muscles of the leg and foot, Gorilla. I".

the perforated tendon of the fourth toe, 4', reinforced by carneous

« НазадПродовжити »