Healthcare and Medicine Reference
In-Depth Information
Position the arm out to the side, as in Figure 7.2A, and
arrange it so that the palm faces forward and the olec-
ranon of the elbow points down to the floor. The Super-
ficial Front Arm Line (SFAL - Fig. 7.2B) is now arrayed
along the front of your arm - palmar muscles, lower arm
flexors, intermuscular septum, and pectoralis major. The
Superficial Back Arm Line (SBAL - Fig. 7.2D) is arrayed
along the back side of the arm - trapezius, deltoid,
lateral intermuscular septum, extensors.
Rotate your arm medially at the shoulder (no prona-
tion allowed), so that the palm faces the floor and the
olecranon of the elbow points back, as in Figure 7.2C. In
this position, the Deep Front Arm Line (DFAL - Fig.
7.2A) is arrayed along the front - thenar muscles, radius,
biceps, and (under the major) pectoralis minor. The
Deep Back Arm Line (DBAL - Fig. 7.2C) is arrayed along
the back side of the arm - the hypothenar muscles, the
ulna, the triceps, the rotator cuff, and (under the trape-
zius) the rhomboids and levator scapulae.
Keeping these 'sight lines' in mind when analyzing
movement, especially movements where the arm plays
a supporting role, will help distinguish which lines are
being employed - and perhaps over-employed - in a
movement. Overuse of a particular line 'downstream'
(distally) will often precede strain injuries 'upstream'
(proximally) in the given line.
Table 7.1 Arm Lines: myofascial 'tracks' and bony
'stations' (Fig. 7.2)
Bony stations
Myofascial tracks
A. Deep Front Arm Line
3rd, 4th and 5th ribs 1
2
Pectoralis minor,
clavipectoral fascia
Coracoid process 3
4
Biceps brachii
Radial tuberosity 5
6
Radial periosteum,
anterior border
Styloid process of radius 7
8
Radial collateral
ligaments, thenar
muscles
Scaphoid, trapezium 9
Outside of thumb 10
B. Superficial Front Arm Line
Medial third of clavicle, costal 1
cartilages, thoracolumbar
fascia, iliac crest
2
Pectoralis major,
latissimus dorsi
Medial humeral line 3
4
Medial intermuscular
septum
Medial humeral epicondyle, 5
6
The Deep Front Arm Line
Flexor group
7
Carpal tunnel
The DFAL (Fig. 7.4) begins muscularly on anterior
aspects of the 3rd, 4th and 5th ribs with the pectoralis
minor muscle (Fig. 7.5). This muscle is actually
embedded in the clavipectoral fascia (Fig. 7.6A) that runs
underneath the pectoralis major from clavicle to armpit,
and includes both the pectoralis minor and the subcla-
vius muscles, with connections to the neurovascular
bundle and lymphatic tissues in this area (Fig. 7.6B
and DVD ref: Shoulders and Arm Lines, 29:56-32:28).
The entire clavipectoral fascia, nearly as large as the
pectoralis major, constitutes the initial track of this
line; the pectoralis minor, however, provides the chief
contractile structural support to the scapula from this
complex, while the smaller subclavius tethers the
clavicle. 1
The distal station for the pectoralis minor muscle is
the coracoid process, a nub of the scapula which projects
forward under the clavicle like a thumb or a 'crow's
beak' (from whence it gets its name). Two other muscles
proceed out to the arm from here, the short head of the
biceps brachii and the coracobrachialis (Fig. 7.5). There
is clearly a myofascial continuity between the pectoralis
minor and both these more distal muscles (Fig 7.7), but
by our Anatomy Trains rules, this connection would
seem to be out of the running, at least in a relaxed stand-
ing posture, due to the radical change of direction from
the pectoralis minor in this position. When the arms are
outstretched, however, at the horizontal or anywhere
above (as in a tennis forehand), and especially in any
hanging position (as in a swinging monkey or in a chin-
up), these myofascial units link into a connected line
(see Fig. 2.2, p. 66).
Palmar surface of fingers 8
C. Deep Back Arm Line
Spinous process of lower 1
cervicals and upper thoracic,
C1-4 TPs
2
Rhomboids and levator
scapulae
Medial border of scapula 3
4
Rotator cuff muscles
Head of humerus 5
6
Triceps brachii
Olecranon of ulna 7
8
Ulnar periosteum
Styloid process of ulna 9
10
Ulnar collateral ligaments
Triquetrum, hamate 11
12
Hypothenar muscles
Outside of little finger 13
D. Superficial Back Arm Line
Occipital ridge, nuchal 1, 2, 3
ligament, thoracic spinous
processes
4
Trapezius
Spine of scapula, acromion, 5
lateral third of clavicle
6
Deltoid
Deltoid tubercle of humerus 7
8
Lateral intermuscular
septum
Lateral epicondyle of humerus 9
10
Extensor group
Dorsal surface of fingers 11
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