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4.3 Axes of Movement
As mentioned previously, the shoulder girdle can be moved in several directions on the
chest wall. This ability, together with the large range of movement possible at the
shoulder joint (correctly called the glenohumeral joint), allows the arm to be moved
into many positions.
GLENOHUMERAL
JOINT
The combination of scapulothoracic and glenohumeral movement, make the shoulder
joint the most mobile in the body. The different axes of movements allow movements in
the coronal plane and the sagittal plane. In addition, rotation along the long axis of the
humerus is possible.
4.4 Types of Movement
 Flexion - swinging the arm forwards in the sagittal plane.
 Extension - swinging the arm backwards in the sagittal plane.
 Abduction - swinging the arm laterally in the coronal plane.
 Adduction - swinging the arm medially in the coronal plane.
 Internal rotation - rotation of the arm along its long axis so that the hand turns
towards the body.
 External rotation - rotation of the arm along its long axis so that the hand turns
away from the body.
 Circumduction - movements of the whole arm in a circle (a combination of flexion,
abduction, extension and adduction).
4.5 Muscles
When thinking of muscles controlling the shoulder joint, we must think of those which
move the shoulder girdle and those which move the glenohumeral joint. In addition, the
rotator cuff muscles also stabilise the glenohumeral joint while other muscles move it.
Muscle actions:
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Trapezius: rotates the scapula upwards and shrugs the shoulders.
Serratus anterior: stabilises the scapula to the chest wall and pulls it forwards.
Pectoralis major: flexes and adducts the glenohumeral joint.
Latissimus dorsi: extends and adducts the glenohumeral joint.
Deltoid: abducts the glenohumeral joint.
Rotator cuff: these four muscles stabilise the glenohumeral joint during movement
and when acting individually, can abduct, extend and rotate the joint.
TRAPEZIUS
SERRATUS ANTERIOR
PECTORALIS MAJOR
LATISSIMUS DORSI
DELTOID
ROTATOR CUFF
4.6 Examples of Muscle Activity
Muscle action around the shoulder can easily be observed on yourself. The action of
trapezius can be felt while shrugging the shoulders. During pull-ups the arm is being
extended and adducted on the body. The action of pectoralis major and the latissimus
dorsi is easily observed. The main abductor of the glenohumeral joint is deltoid. This
action is used when putting the arm into a jacket sleeve.
4.7 Nerve Supply
The general description of the nerve supply of the muscles of the limbs has been made
in Unit 2. The nerve supply to the upper limb comes from the neck region. The nerves
are distributed via the brachial plexus at the root of the neck and passed to their
appropriate muscle groups. The brachial plexus is a region where several nerves make
cross connections with each other. The major peripheral nerves of the upper limb are:
 the median nerve, which supplies the flexor muscles in the forearm and controls the
thumb,
Unit 3 - The Upper Limb 6
BRACHIAL PLEXUS
MEDIAN NERVE