Human Anatomy Vol 1

UPPER LIMB

Digitations of serratus

anterior

Fig. 3.26: The serratus anterior

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The nerve to the serratus anterior is a branch of the

brachial plexus. It arises from roots C5, C6 and C7 and

is also called long thoracic nerve.

A*fi*r:s

1- Along with the pectoralis minor, the muscle pulls

the scapula forwards around the chest wall to

protract the upper limb (in pushing and punching

movements) (Fig. 3.27).

Pectoralis major

Pectoralis minor

Coracobrach ia lis

Medial wall of axilla formed

by serratus anterior

Scapulla pulled

foruvards around

the chest

(protraction)

of axilla

Subscapularis Scapula

I nfraspinatus

Fig. 3.27: Horizontal section through the axilla showing the

position of the serratus anterio.

2 The fibres inserted into the inferior angle of the

scapula pull it forwards and rotate the scapula so

that the glenoid cavity is turned upwards. In this

actiory the serratus anterior is helped by the trapezius

which pulls the acromion upwards and backwards

(see Frg. 70.6).

3 The muscle steadies the scapula during weight

carryrng.

4 It helps in forced inspiration.

A #drft-*ru * J F* cti*rfl *o"q

1 Paralysis of the serratus anterior produces 'winging

of scapula' in which the in{erior angle and the medial

border of the scapula are unduly prominent. The

patient is unable to do any pushing action, nor can

he raise his arm above the head. Any attempt to do

these movements makes the inferior angle of the

scapula still more prominent.

2 Clinicnl testing: Forward pressure with the hands

against a wall, or against resistance offered by the

examiner, makes the medial border and the inferior

angle of the scapula prominent (winging of scapula)

if the serratus anterior is paralysed (see Fig.2.12).

Mnemonics

Branches af any artery/nerve M-CAT

M-Muscular

C-Cutaneous

A-Articular

T-Terminal

Pectoralis major forms part of the bed for the

mammary gland 75% of lymph from mammary

gland drains into axillary, 25"h into parasternal and

5% into intercostal lymph nodes.

The sternocostal head of pectoralis major causes

extension of the flexed arm against resistance.

Pectoralis minor divides the axillary artery into

three parts.

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a

A 45-year-old women complained of a firm painless

mass in the upper lateral quadrant of her left breast.

The nipple was also raised. Axillary lymph nodes

were palpable and firm. It was diagnosed as cancer

breast.

o Where does the lymph from upper lateral

quadrant drain?

r What causes the retraction of the nippie?

drains arainly into the pectorai group of axillary