Agriculture Reference
In-Depth Information
There are cranial antebrachial muscles that extend the
carpus and muscles that extend the digits. As for the
caudal antebrachial muscles, those attached to the carpal
bones fl ex the carpus, whereas the muscles attached to
the phalanges fl ex the digits.
There is only one muscle in the metacarpal region,
which is mostly tendinous. Its name is the interosseous
muscle. It plays the role of suspensory apparatus for the
digits.
The muscles of the thoracic limb from the lateral and
from the medial perspectives are illustrated in Figure
6.15 and Figure 6.16 .
the ventral aspect of the lumbar vertebrae inside of the
abdominal cavity, whereas the ventral muscles contribute
to the ventral and lateral walls of the abdomen. The func-
tion of the dorsal abdominal muscle is to fl ex the thoraco-
lumbar vertebrae, whereas the function of the ventral
abdominal muscles is to support the weight of the abdomi-
nal viscera (internal organs within the abdominal cavity)
and to act in respiration, defecation, micturition (the act of
urination), and parturition (birth). There are four ventral
abdominal muscles: the external and internal abdominal
obliques, the transversus abdominis, and the rectus abdom-
inis muscles. The aponeurosis of the external abdominal
oblique is also involved in the passage of the spermatic
cord from the abdominal cavity to the scrotum (see the
Reproductive System), in the descent of testicles, and in
the suspensory apparatus of the udder (see the Mammary
Gland). Due to the considerable weight of the abdominal
viscera, an additional structure helps in supporting them.
This is the tunica fl ava abdominis, or the yellow tunic,
because it has abundant elastic fi bers in its texture fi bers
that give a yellow appearance. The tunica fl ava is attached
fi rmly to the ribs and surrounds the ventral abdominal
muscles. It contributes also to the suspensory apparatus of
the mammary gland (see the Mammary Gland). This
elastic structure is necessary to suspend the abdominal
organs in a passive way and to prevent the abdominal
muscles from being under constant load (and fatigue).
T
HE
M
USCLES
OF
THE
P
ELVIC
L
IMB
Two terms, propulsion and rearing, should be explained
here. Propulsion is the action of driving or propelling the
body forward, whereas rearing is the action of pulling
the body off the ground with the pelvic limbs still on the
ground.
The muscles of the pelvic limb consist of the muscles
of the rump, the muscles of the thigh, the muscles of the
crus, and one muscle of the metatarsal region.
The muscles of the rump function as abductors and
extensors of the thigh. One of them is also a propulsor, and
helps in the action of rearing.
There are three groups of muscles of the thigh: cranial,
caudo-lateral, and medial muscles. As function, the cranial
muscles are extensors of the crus by means of the patella.
As function, the caudolateral muscles are the most power-
ful muscles of the body, and they perform fl exion and
extension of the crus, are propulsors, and act in rearing.
The rearing is a very important act for the goats, as brows-
ers, who in search for food reach considerable heights in
trees (bipedal stand) to access leaves. As to function, the
medial muscles of the thigh are all adductors. At the
ventral aspect of the coxal bones, a paired muscle origi-
nates from the so-called symphiseal tendon, involved in
the suspensory apparatus of the udder (see the Mammary
Gland).
Similar to the antebrachial muscles, the muscles of the
crus can be grouped into cranial and caudal muscles. Some
cranial muscles are fl exors of the tarsus, and some
are extensors of the digits. There are two subgroups of
caudal muscles: superfi cial and deep. The superfi cial
muscles are either extensors of the tarsus, or fl exors of the
digits (only one muscle). One deep muscle is a fl exor of
the crus, while the others are fl exors of the digits. The
muscles of the pelvic limb are illustrated in Figure 6.17
and Figure 6.18. There is an interosseous muscle in the
pelvic limb, too.
T
HE
M
USCLES
OF
THE
T
HORACIC
L
IMB
There are specifi c muscle actions that should be introduced
before covering the muscles. The fl exion is that action
which reduces the angle between two bones in their long
axis. The extension is opposite to the fl exion (increases the
angle). The adduction is the movement toward the median
plane. The abduction is opposite to adduction (movement
away from the median plane).
The muscles of the shoulder, the muscles of the arm, the
muscles of the forearm, and the muscles of the metacarpal
region are grouped by position and function, as follows:
There are lateral and medial muscles of the shoulder. As
function, the lateral muscles are extensors and abductors
of the arm. The medial muscles are adductors and fl exors
of the arm.
There are cranial and caudal muscles of the arm.
As function, the cranial muscles are fl exors of the
forearm, whereas the caudal muscles are extensors of
the forearm.
The muscles of the forearm are disposed on the cranial
and on the caudal aspects of the radius and ulna, and
both groups have two different functions.
