Before we proceed to a general enumeration of the muscles, we must premise, that the most fixed point is styled its origin, the more moveable its insertion. In the motion, however, of limbs, the peculiar muscles are not exclusively employed, since some distant ones are exerted to fix the part from which the muscles originate. In other circumstances the fixed point becomes occasionally, though in a less degree, the moveable; and for this reason we have styled the origin the most fixed point. In some instances, the part from which the muscle originates is equally moveable with that into which it is inserted.

Muscles of the Head. The forehead is wrinkled and drawn upwards, as are also the eyebrows, by a broad thin muscle, occipito frontalis, which rises at the back part of the skull, and, covering the head, runs down the forehead, to be inserted into the skin of the eyebrows.

The eyebrows are drawn towards each other, and the skin of the forehead pulled down and made to wrinkle, as in frowning, by a pair of small muscles, corrugatores supercilii, which rise from the root of the nose, and are inserted into the inside of the eyebrows.

The ear is moved by eleven small muscles. The first three are called common, because they move the whole ear. The next five are termed proper, and only move the parts to which they are connected; while the other three are internal, to move the small bone situated within the ear.

The eyelids are closed by a muscle, which, rising from the inner angle of the orbit or cavity in which the eye is embedded, covers the under eyelid, then surrounds the outer angle, and passing over the upper eyelid, descends to be inserted, by a short, round tendon, near to its origin, orbicularis palpebrarum.

The eye is opened by a muscle, which, rising from the inner and upper part of the socket, is inserted into the upper eyelid, to draw it upwards, levator palpebrae superioris.

The eyeballs are carried through all their motions by six small slender muscles to each. They arise from the bottom of the socket, and are inserted into the outer coat of each eyeball at different points. Four of these move the eye upwards or downwards, to the right and to the left; while the two remaining muscles give oblique directions to the eye, at the same time protruding it; and all acting in quick succession, enable the ball of the eye to describe a complete circle. See Oculus.

The nose is affected by several small muscles of the face, but only one muscle on each side is proper to it. This muscle straightens the nostrils, and corrugates the skin of the nose, corrugator naris.

The mouth and lips are moved by nine pair of muscles, levator labii superior is alaeque nasi; levator anguli oris; zygomaticus major; buccinator; depressor labii superioris alaeque nasi; depressor anguli oris; depressor labii inferioris; levator labii itiferioris; orbicularis oris; which, arising from the contiguous bones of the face, are inserted into the lips and angles of the mouth: and from the termination of these muscles a tenth is formed, which surrounds the mouth like a sphincter, and closes it, by drawing the lips together. It is from the actions of these muscles on the mouth, particularly at its corners, that the emotions of the mind are expressed, and the predominance of particular feelings in characters is indelibly stamped: unless in those individuals whom nature has gifted with an unimpressible dulness of character, or in whom the more delicate lines are tilled up by too great fatness.

The lower jaw has four pair of muscles for pulling it upwards, as in manducation, viz. two pair seen upon the outside of the face, and two pair concealed by the angles of the jaw. The first pair arise from the sides of the skull, above the temples, whence they are called temporal muscles, temporalis; and then descending under the bony bridges of the cheek bone, are inserted into the lower jaw near its ends. The second pair arise, at each side, from the under edge of the bony bridge, and descending along the cheek, are inserted into the angle of the lower jaw, masseter. These four muscles act powerfully in pulling the jaw upwards, and when we bite, may be felt swelling out in the flat part of the temple, and upon the back part of the cheek. The other two pair of muscles arise from the base of the skull, and are inserted into the lower jaw internally, for enabling this bone to move from side to side, the more effectually to grind the food, pterygoideus internus and externus. The lower jaw is pulled downwards by muscles, which extend between it and the bone of the tongue, and which also serve to raise the throat upwards.

Muscles of the Neck. The neck is covered with numerous and complicated muscles: those on the fore part or throat extend some between the head and upper part of the trunk, latissimus colli and mastoideus: others between the lower jaw and the os hyoides; more between this bone and the cartilages of the throat; while numerous other small muscles are situated between these cartilages and the trunk; and also about the root of the tongue and the back part of the mouth. Their names are sufficiently descriptive of their situations, viz. omo-hyoideus; sterno-hyoideus; hyo-thyroideus; ster-no-thyroideus; crico-thyroideus; digastricus; stylo-hy-oideus; mylo-hyoideus; genio-hyoideus; genio-glossus; hyo-glossus; lingualis; stylo-glossus; stylo-pharyn-gtaeus; circumflexus; palati; levator-palati; palato-pharyngaus; constrictor isthmi faucium; azygos uvulae; constrictor pharyngis superior, medius et inferior; crico-arytanoideus lateralis et posticus; arytaenoideus obli-quus et transversus; thyreo-arytaenoideus; arytaeno-epiglottideus; and thyreo-epiglottideus. Their uses are, viz. to bend the head forwards; to open the mouth by pulling the lower jaw downwards; and to move the parts concerned in deglutition and speaking.

The muscles on the back part of the neck are rather portions of the great muscles, which cover the back, than distinct bundles of fibres; but, having some of their extremities fixed to the back part of the skull, and also to the hinder portion of the spine of the neck, are intended to move those parts, drawing them backwards and sideways.