DOI Page / Citation link:
https://doi.org/10.11588/diglit.20658#0056
42
ANATOMY.
Sect. II. The Situation and Uses of the several Muscles.
The various motions of the human body., and of every part, are performed by means of muscles.
These are distinct portions of flesh, capable of contraction and extension, and are divided into
voluntary and involuntary muscles.
The voluntary muscles are those which are entirely subject to the will ; as are all those upon
which the fingers hands arms legs, &c. depend for their motions.
Involuntary muscles do not depend on the will for their motions : such are the muscles of the
urinary bladder stomach intestines, &c. which act mereby by their own contraction, and without
any effort of the will. Some muscles depend partly on the will and act partly by their own in-
herent force, as those of respiration, and which are said to have a mixed motion.
Muscles owe their motions partly to the fibres of which they are composed and partly to the
nerves. Many hypotheses have been delivered concerning muscular motion, the particular merits
of which it is not necessary here to discuss. Suffice it to say that in action the muscular fibre
is shortened, and the muscle itself swells; but how these phenomena are produced has not yet
been satisfactorily declared. That operation by which the mind is enabled to impart motion to
the muscles is called the vis nervosa : this property is not inherent in the muscle, nor perpetual,
and is what is generally understood by the term muscular motion.
The voluntary muscles are distinguished by names founded on their size, figure, situation, use,
origin, insertion, or arrangement of their fibres. They are also distinguished generally ac-
cording to the situation of their fibres, insertion, use, &c. Thus if the fibres of a muscle be
placed parallel to each other, in a straight direction, the muscle is said to be rectilinear; if the
fibres cross each other they constitute a compound muscle; if they are disposed in the manner of
rays it is called a radiated muscle; or if they be placed obliquely with respect to the tendon,
like the feather of a pen, they form what is called apenniform muscle.
Some muscles act in opposition to each other, from whence they are called antagonists : thus
every extensor muscle has a flexor one for its antagonist, and vice versa. Those muscles which
concur in the same action are styled congeneres.
That end of a muscle which adheres to the more fixed part of the bone is usually called the
origin, and that which adheres to the more moveable part the insertion.
Each muscle contains two kinds of fibres, viz. one of a soft nature, red in colour, sensible, and
irritable, called fleshy fibres; the other kind called tendinous fibres are of a firmer texture, of a
white glistening colour, insensible, and without treatability or the power of contracting. The
former generally prevail in the belly or middle part of the muscle, and the latter at the extremi-
ties ; sometimes they are intermixed. If the tendinous fibres are formed into a round slender
shape they form what is called the tendon of the muscle; but when they are spread into a broad
flat surface the extremity of the muscle is called aponeurosis.
After the above general description of the muscles it will be sufficient to give only the name,
origin, insertion, and use of each, arranged according to their situation.
A Table
ANATOMY.
Sect. II. The Situation and Uses of the several Muscles.
The various motions of the human body., and of every part, are performed by means of muscles.
These are distinct portions of flesh, capable of contraction and extension, and are divided into
voluntary and involuntary muscles.
The voluntary muscles are those which are entirely subject to the will ; as are all those upon
which the fingers hands arms legs, &c. depend for their motions.
Involuntary muscles do not depend on the will for their motions : such are the muscles of the
urinary bladder stomach intestines, &c. which act mereby by their own contraction, and without
any effort of the will. Some muscles depend partly on the will and act partly by their own in-
herent force, as those of respiration, and which are said to have a mixed motion.
Muscles owe their motions partly to the fibres of which they are composed and partly to the
nerves. Many hypotheses have been delivered concerning muscular motion, the particular merits
of which it is not necessary here to discuss. Suffice it to say that in action the muscular fibre
is shortened, and the muscle itself swells; but how these phenomena are produced has not yet
been satisfactorily declared. That operation by which the mind is enabled to impart motion to
the muscles is called the vis nervosa : this property is not inherent in the muscle, nor perpetual,
and is what is generally understood by the term muscular motion.
The voluntary muscles are distinguished by names founded on their size, figure, situation, use,
origin, insertion, or arrangement of their fibres. They are also distinguished generally ac-
cording to the situation of their fibres, insertion, use, &c. Thus if the fibres of a muscle be
placed parallel to each other, in a straight direction, the muscle is said to be rectilinear; if the
fibres cross each other they constitute a compound muscle; if they are disposed in the manner of
rays it is called a radiated muscle; or if they be placed obliquely with respect to the tendon,
like the feather of a pen, they form what is called apenniform muscle.
Some muscles act in opposition to each other, from whence they are called antagonists : thus
every extensor muscle has a flexor one for its antagonist, and vice versa. Those muscles which
concur in the same action are styled congeneres.
That end of a muscle which adheres to the more fixed part of the bone is usually called the
origin, and that which adheres to the more moveable part the insertion.
Each muscle contains two kinds of fibres, viz. one of a soft nature, red in colour, sensible, and
irritable, called fleshy fibres; the other kind called tendinous fibres are of a firmer texture, of a
white glistening colour, insensible, and without treatability or the power of contracting. The
former generally prevail in the belly or middle part of the muscle, and the latter at the extremi-
ties ; sometimes they are intermixed. If the tendinous fibres are formed into a round slender
shape they form what is called the tendon of the muscle; but when they are spread into a broad
flat surface the extremity of the muscle is called aponeurosis.
After the above general description of the muscles it will be sufficient to give only the name,
origin, insertion, and use of each, arranged according to their situation.
A Table