It only remains for us to give a summary view of the muscles, extrinsic and intrinsic, concerned in the motions of the hand. These motions are flexion, extension, adduction or motion ulnad, abduction or motion radiad. First, the flexors of the wrist are six. 1. Flexor longus pollicis ; 2 and 3, flexor sub limis et profundus ; 4, palmaris longus ; 5, flexor carpi radians; 6, flexor carpi ulnaris. The extensors are six. 1, Extensor communis; 2, indicator ; 3, extensor secundi internodii pollicis ; 4 and 5, extensores carpi radiales longior et brevior; 6, extensor carpi ulnaris. The last three of the extensors as well as the last three of the flexors act directly on the wrist; the others act first on the phalanges. These also are the muscles that, in extreme flexion and extension, call into play the motion that exists between the two rows of the carpus, the two former extending, the three latter flexing the second row upon the first.
The adductors are five. 1, Extensor carpi ulnaris ; 2, extensor communis ; 3, flexor carpi ulnaris; 4, sublimis; 5, profundus.
The abductors are also five. I and 2, Ex tensores ossis metacarpi et primi internodii pollicis ; 3 and 4, extensores carpi radiales longior et brevior ; 5, flexor carpi radians.
The following table is intended to exhibit at one view the motions of which the lingers are capable, and the muscles which effect them.
The movements of the fingers are 1. _Flexion performed by nine.
Flexor longus pollicis.
Flexor sublimis.
Flexor profundus.
Three internal lumbricales.
Three interossei interni.
2. Extension by eight.
Three extensores pollicis.
Extensor communis.
Indicator.
Three internal dorsal interossei.
3. Adduction by seven.
Three adductor, flexor brevis, and oppo nens pollicis.
Abductor utinimi digiti.
Three interossei, viz. posterior indicis, posterior medii, posterior annularis.
4. Abduction by eleven.
Abductor pollicis.
Adductor et opponens minimi digiti. Four lumbricales.
Four interossei, viz. abductor indicis, prior medii, prior annularis, interosseus au ricularis.
We thus see that the hand is furnished with no less than thirty-three muscles, each capable of acting either singly or in conjunction with others. The most powerful of these are the flexors and opposers, both performing actions, as we have seen, peculiarly adapted for the pre hension and retention of bodies.
But there is yet another function in which they are the chief agents, and of which the hand is the principal organ, that of touch, which may be regarded as a kind of sentinel by which we ascertain the nature of bodies ; which without seeing warns the hand from too closely embracing what may prove hurtful to itself, or admonishes it to handle gently those delicate objects that would be destroyed by too rude a grasp. In the blind this sense, by con stant exercise, becomes so perfect as in a great measure to compensate for the loss of sight. But by the combination of these two functions the hand is indeed rendered an organ worthy of, and admirably suited to the mind of man. With the one he plans, while through the other he performs and executes all that administers to the pleasures, the comforts, and the conve niences of life, and that establishes his superi ority in the creation.
( F. T. illWougall.)