Healthcare and Medicine Reference
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Fig. 7.41 (A) In the hand, the Deep Arm Lines correspond to the lateral and medial (Deep Front Line) lines of the foot, but the front and
back lines are reversed. (B) In the lower arm, the reversal of the front and back lines continue, but the medial line goes to the 'fibula' of
the arm, while the lateral line goes to the arm's 'tibia' - the ulna. (C) In the upper arm, the deep and superficial trade places - the
quadriceps and hamstrings of the front and back lines of the leg (SFL and SBL) correspond to the deeper lines of the arm - the biceps
of the DFAL and the triceps of the DBAL.
corresponds at this level to the Superficial Front Arm Line that
curls the fingers.
In the lower arm, these parallels continue, with the excep-
tion that the Lateral Line connects via the peroneals to the
fibula, while the Deep Back Arm Line connects to the tibia-
equivalent ulna (Fig. 7.41 B). In the leg, the Deep Front Line
connects to the weight-bearing tibia, while the Deep Front Arm
Line is tied inextricably to the more mobile radius. We can also
note that in the lower leg, only the gastrocnemius, popliteus,
and plantaris cross the knee; the rest of the foot-moving
muscles are confined to the lower leg, whereas many of the
muscles of both the SFAL and SBAL cross the elbow, though
they are not designed to affect it very much.
By the time we get to the upper arm and upper leg, most
of the parallels are spiraling out of control (Fig. 7.41C). We
find that at this level, the Superficial Front Line of the leg (pri-
marily the quadriceps) compares now with the Deep Back Arm
Line (triceps). The Superficial Back Line (biceps femoris and
the other hamstrings) now equates with the Deep Front Arm
Line (biceps brachii and its underlying compadres). The Lateral
Line of the leg (iliotibial tract) compares with the Superficial
Back Arm Line (lateral intermuscular septum), and the Deep
Front Line (adductor muscles and associated septa) compares
fairly easily to the Superficial Front Arm Line (medial intermus-
cular septum).
At the shoulder-to-hip level, the comparisons dim even
more, but the Lateral Line (abductors) clearly continues the
comparison to the Superficial Back Arm Line (deltoid). The
Deep Front Line of the leg - the psoas and other flexors -
might be compared with, strangely, the Superficial Front Arm
Line, in that the pectoralis major and latissimus dorsi, like the
psoas, both reach from the axial skeleton out across the ball
and socket to the proximal limb bone, though under greater
scrutiny the parallels begin to fade.
The Deep Back Arm Line (rhomboids to rotator cuff) can
be usefully compared with the quadratus lumborum to iliacus
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