Healthcare and Medicine Reference
In-Depth Information
The teres major muscle, which we included with the latis-
simus in the SFAL, is actually a crossover from the scapula
(and thus the DBAL) into the SFAL, with its distal attachment
on the anterior surface of the humerus (Fig 7.14).
The brachioradialis arises from the lateral intermuscular
septum and goes to the radius, thus making another connec-
tion from the SBAL to the DFAL (Fig. 7.40). The pronator teres
could be said to make the same kind of connection from the
DFAL to the SFAL.
Finally, the long pollicis muscles, abductor, and extensor
longus and brevis, build from the periosteum of the ulna to the
upper surface of the thumb, and could thus be said to connect
the DBAL to the SBAL.
Other connections among the lines are made by the arms
on a minute-by-minute basis to accommodate the varying
movements and strains placed on the shoulder-arm complex.
This does not, however, alter the basic value of the connec-
tions we have detailed in the four formal longitudinal myofas-
cial meridians of the arms.
Discussion 3
Arm and Leg Line comparison
The alert reader will notice that the four arm lines bear some
resemblance to four of the lines that course through the leg.
(A clinically useful correlate to the Spiral Line in the arm has
not been found.) Although the leg and the arm are functionally
different, the structural similarities beg for a comparison, and
the results are quite astonishing.
The correspondence between the arm and the leg in the
skeletal structure is unmistakable: a girdle arrangement close
to the axial frame (hip bone and scapula) is followed by a ball-
and-socket joint, one bone in the upper limb, a hinge, two
bones in the lower limb, three bones in the first tier of the outer
limb, four bones in the second tier, and five digits with fourteen
bones each.
Aside from the bony similarity (strange when one considers
that the arm and leg evolved at somewhat different times for
different purposes), the muscles also display interesting
correspondences, e.g. the hamstrings parallel the biceps, and
the abductors have often been termed the 'deltoid of the
hip'. 3
In spite of these obvious ties, the tracks of the myofascial
meridians spectacularly fail to fall in line as direct parallels
between arm and leg. On one level, the reason for this is
developmental: all the limbs bud straight out from the side of
the embryo, but in subsequent development, the legs rotate
medially on the trunk, while the shoulder rotates laterally. Thus
when we adopt the fetal position, the elbows and knees tend
to meet. You can demonstrate this for yourself by getting on
your hands and the balls of your feet, and then bending both
elbows and knees. The knees will go forward - maybe a little
out or in, depending on your patterns, but primarily toward
your arms. The elbows will bend in the opposite direction,
toward the legs - again, maybe more outward, depending on
your habit, but primarily toward your legs. Keep your hands
on the floor and try to turn your elbows around so they look
like knees to feel the impossibility of having your arms
approach a parallel position to the legs.
On another level, the lack of correspondence is testimony
to the malleability and plasticity of the fascial connections in
the body. The parallels in the bones remain; the parallels
in the muscles remain, but the longitudinal connections
through the fascia have changed with the times. The salaman-
der's sidewards extensions of the spine have a different set of
myofascial meridians from the loping forepaw and hind leg of
the dog or the bear, which is again different from the unique
upper limb of homo faber.
Our own leg is quite similar to the quadruped hindlimb, with
some allowances for the different attitude of the spine and hip,
but the structure and function of mobility in the front and back
lines, and stability in the inner and outer lines. The primate
arm, however, went through some decisive changes, presum-
ably during our ancestors' arboreal phase, which make its
longitudinal connections unique. It is thus a useful exercise
(though perhaps only to the anatomy nerds among us) to track
the differences in each section of the two limbs.
Comparing the hand and foot first, we can see easy paral-
lels side to side, but the front and back are reversed (Fig.
7.41A). The Deep Front Arm Line connects on the inside to
the thumb, as the Deep Front Line of the leg (yet to come, in
Ch. 9) connects to the inner arch and big toe. The Deep Back
Arm Line connects to the little finger as the Lateral Line con-
nects to the outer arch and 5th metatarsal.
The Superficial Front Line of the leg, which involves toe
and ankle extensors, corresponds easily to the Superficial
Back Arm Line, which contains finger and wrist extensors. The
Superficial Back Line of the leg, flexing the toes and ankle,
Fig. 7.40 The brachioradialis and pronator teres connect to the
radial periosteum, creating crossover links from the SBAL and
SFAL to the DBAL.
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