Healthcare and Medicine Reference
In-Depth Information
This leads us to an image that cannot be pressed very
hard without breaking, but is nonetheless useful to note.
Both superficial lines, front and back, are muscular
around the shoulder (traps, lats, pects and delts), fascial
septa in the upper arm, muscular flexors and extensors
in the lower arm, and fascial tendons in the wrist and
hand (DVD ref: Shoulders and Arm Lines, 14:35-15:17).
Both Deep Arm Lines are more fascial than their
superficial counterparts in the shoulder area (though
with stabilizing muscles like the rotator cuff, levator
scapulae, rhomboids, pectoralis minor and subclavius).
In the upper arm, these deep lines are highly muscular
with the triceps and biceps. In the lower arm, these deep
lines retreat to fascial stability along the bones, but in
the hand they blossom into muscularity with the thenar
and hypothenar muscles at the base of the hand.
This alternation generally corresponds to the alterna-
tion of joints in the arm between those of multiple
degrees of freedom, like the shoulder and radio-ulnar
joints, versus those with more limited, hinge-like motion,
e.g. the elbow and wrists. Again, the arm being designed
for mobility over stability, this idea requires a host of
qualifying adjectives and exceptions.
Fig. 7.32 The scapula is a roundhouse with many competing
vectors of pull.
Discussion 1
Scapular position and postural balance
The mobility of the scapula (as compared with the more fixed
hip bone) is crucial to the many services which our arms and
hands provide. The clavicle has limited movement, and func-
tions primarily to hold the arm away from the ribs in front (a
uniquely primate need, since most quadrupeds prefer the
shoulder joint close to the sternum under a proportionally
narrower rib cage).
While our clavicle is a fairly stable strut, our humerus, with
its rounded head, maintains the widest range of possibilities.
It is the scapula that must move the glenoid socket to keep
the peace between the two and manage the arm's shifting
positions while retaining some stability on the axial skeleton.
Finding the proper place for the scapula, a neutral position
where it has the most possibility to move in response to our
desires, is a worthy goal for manual and movement therapy.
Understanding the balance among the series of muscles
that surround the roundhouse of the scapula will help us in
this effort, especially concentrating on the scapular 'X'.
Looking at the human scapula from behind, we see the array
of vectors pulling it in nearly every direction (Fig. 7.32 or for
a more detailed explanation: DVD ref: Shoulders and Arm
Lines, 06:22-12:59).
Of these, four stand out in providing scapular stability and
determining postural scapular position, and these four form
an 'X'. One leg of this 'X' is formed by the rhombo-serratus
muscle, which we first saw in the Spiral Line (Ch. 5). While the
rhomboids and the serratus anterior work together in the SPL,
they work reciprocally as far as scapular position for the Arm
Lines is concerned (Fig. 7.33). The serratus protracts the
scapula interiorly and laterally; the rhomboids retract it supe-
riorly and medially. A chronically shortened ('locked short')
serratus will pull the scapula wide on the posterior rib cage,
causing the rhomboids to be strained ('locked long'). This
pattern frequently accompanies a kyphotic thoracic spine.
When the rhomboids are locked short, which frequently
accompanies a shallow thoracic curve (flat back), the serratus
will be locked long, and the scapula will rest closer to the
spinous processes.
Fig. 7.33 The reciprocal arrangement between the serratus
anterior and the rhomboids gives them a crucial role in setting the
postural position of the scapula along one leg of the scapular 'X'.
The other leg of the 'X' consists of the lower portion of the
trapezius, which pulls medially and interiorly on the spine of
the scapula, and the pectoralis minor, which pulls down and
in on the coracoid process, thereby pulling the scapula supe-
riorly and laterally (Fig. 7.34). This antagonistic relationship
most often appears with the pectoralis minor locked short and
the lower trapezius locked long, resulting in an anterior tilt of
the scapula on the ribs. Please note that this anterior tilt can
often be disguised by a posterior tilt of the rib cage, leaving
the appearance of a vertical scapula, but the underlying
pattern remains the same, and lengthening work on the pec-
toralis minor is required for both (Fig. 7.35).
Discussion 2
Though the lines we have described here are very logical, and
certainly work usefully in practice, the amount of rotational
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