Human Anatomy Vol 1

(mdmrcog) #1
UPPER LIMB

b. Depression of the scapula (drooping of the shoulder).
It is brought about by gravity, and actively by the
lower fibres of the serratus anterior and by the
pectoralis minor.
It is associated with the depression of the lateral end,
and elevation of the medial end of the clavicle
(Fis. 10.2b).
Moverrrsrts (a) and (b) occff in inferolateral comParknert.
c. Protraction of the scapula (as in pushing and
punching movements). It is brought about by the
serratus anterior and by the pectoralis minor.
It is associated with forward movements of the lateral
end and backward movement of the medial end of
the clavicle (Fig. 10.2c).
d. Retraction of the scapula (squaring the shoulders) is
brought about by the rhomboids and by the middle
fibres of the trapezius.
It is associated with backward movement of the
lateral end and forward movement of the medial end
of the clavicle (Fig. 10.2d). Movements (c)and (d)
occur in superomedial compartment.
e. Lateral or forward rotation of the scapula round the
chest wall takes place during overhead abduction

of the arm. The scapula rotates around the coraco-
clavicular ligaments. The movement is brought about
by the upper fibres of the trapezius and the lower
fibres of the serratus anterior. This movement is
associated with rotation of the clavicle around its
long axis (Fig. 10.2e).
f. Medial or backward rotation of the scapula occurs
under the influence of gravity, although it can be
brought about actively by the levator scapulae and
the rhomboids (Fig. 1.0.2f).
Movements (e) and (f) occur in inferolateral compar-
tment.

Ligomenls of the Scopulo
The coracoacromiql ligament (seeFig.7.8): It is a triangular
ligament, the apex of which is attached to the tip of the
acromion, and the base to the lateral border of the
coracoid process.
The acromion, the coracoacromial ligament and the
coracoid process, together form the coracoacromial arch,
which is known as the secondary socket for the head of
the humerus. It adds to the stability of the joint and
protects the head of the humerus.

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Depression

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Retraction Glenoid cavity
facing downwards

(d) (e) (f)
Figs10.2a to f: Movements of the right shoulder girdle: (a) Elevation, (b) depression, (c) protraction, (d) retraction, (e) lateral
rotation of inferior angle, and (f) medial rotation of inferior angle

Lateral rotation
of inferior angle
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