Human Anatomy Vol 1

UPPER LIMB

2 The anterior fibres are flexors and medial rotators of

the arm.

3 The posterior fibres are extensors and lateral rotators

of the arm.

Struclures under Cover of the Deltoid

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i. The upper end of the humerus.

ii. The coracoid process.

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Insertians of

i. Pectoralis minor on coracoid process.

ii. Supraspinatus, infraspinatus, and teres minor (on

the greater tubercle of the humerus) (Fig. 6.3).

iii. Subscapularis on lesser tubercle of humerus (Fig. 6.4).

iv. Pectoralis major, teres major and latissimus dorsi

on the intertubercular sulcus of the humerus

(Fig. 6.5).

Origin of

i. Coracobrachialis and short head of biceps brachii

from the coracoid process (Fig. 6.5).

ii. Long head of the biceps brachii from the supra-

glenoid tubercle.

iii. Long head of the triceps brachii from the infra-

glenoid tubercle.

iv. The lateral head of the triceps brachii from the upper

part of posterior surface of the humerus.

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i. Anterior circumflex humeral.

ii. Posterior circumflex humeral (Fig. 6.6).

Teres major

Triceps brachii

Fig. 6.3: The origin and insertion of the supraspinatus,

infraspinatus and teres minor muscles of right side

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Axillary (Fig.6.5).

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i. Musculotendinous cuff of the shoulder (Fi9.6.7).

ii. Coracoacromial ligament.

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All bursae around the shoulder joint, including the

subacromial or subdeltoid bursa (Fig. 6.8).

Intramuscular injections are often given into

the deltoid. They should be given in the middle

of the muscle to avoid injury to the axillary nerve

(Fig. 6.ea).

The deltoid muscle is tested by asking the patient

to abduct the arm against resistance applied with

one hand, and feeiing for the contracting muscle

with the other hand (Fig. 6.9b).

The axillary nerve may be damaged by dislocation

of the shoulder or by the fracture of the surgical

neck of the humerui. rn" effects produced aie:

a. Rounded contour of shoulder is lost; greater

tubercle of humerus becomes prominent

(Fig. 6.10a).

b. Deltoid is paralysed, with loss of the power of

abduction up to 90' at the shoulder.

c. There is sensory loss over the lower half of the

deltoid in a badge-like area calIed regimental

badge (Fig. 6.10b).

The tendon of the supraspinatus may undergo

degeneration. This can give rise to calcification and

even spontaneous rupture of the tendon.

In subacromial bursitis, pressure over the deltoid

below the acromion with the arm by the side

causes pain. However, when the arm is abducted

pressure over the same point causes no pain,

because the bursa disappears under the acromion

(Dawbarn's sign). Subacromial or subdeltoid

bursitis is usually secondary to inflammation of

the supraspinatus tendon (Fig. 6.11).

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Musculotendinous Cuff of lhe Shouldet or Rolotor Cuff

Musculotendinous cuff of the shoulder is a fibrous

sheath formed by the four flattened tendons which

blend with the capsule of the shoulder joint and

strengthen it. The muscles which form the cuff arise

from the scapula and are inserted into the lesser and

greater tubercles of the humerus. They are the

subscapularis, the supraspinatus, the infraspinatus and

the teres minor (Fig. 6.7). Their tendons, while crossing

the shoulder joint, become flattened and blend with