Human Anatomy Vol 1

Middle fibres of trapezius

UPPER LIMB

Fig. 5.9: Rotation of the scapula during abduction of the arm

beyond 90 degrees, brought about by the trapezius and the

serratus anterior muscles

Lotissimus Dolsi

1 This is the only muscle which connects the pelvic

girdle and vertebral column to upper limb. It

possesses extensive origin and narrow insertion.

2 The latissimus dorsi develops in the extensor

compartment of the limb. Thereafter, it migrates to

its wide attachment on the trunk, taking its nerve

suppty (thoracodorsal nerve) along with it (lata =

wide).

3 The latissimus dorsi is tested clinicallyby feeling the

contracting muscle in the posterior fold of the axilla

after asking the patient to cough.

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Triangle of auscultation is a small triangular interval

bounded medially by the lateral border of the trapezius,

laterally by the medial border of the scapula, and

inferiorly by the upper border of the latissimus dorsi.

The floor of the triangle is formed by the 5th and 7th

rib, and 6th intercostal space (ICS), and the rhomboid

major. This is the only part of the back which is not

covered bybigmuscles. Respiratory sounds of apex of

lower lobe heard through a stethoscope are better heard

over this triangle on each side. On the left side, the

cardiac orifice of the stomach lies deep to the triangle,

and in days before X-rays were discovered the sounds

of swallowed liquids were auscultated over this triangle

to confirm the oesophageal tumour (Fig. 5.4).

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Lumbar triangle of Petit is another small triangle

surrounded by muscles. It is bounded medially by the

lateral border of the latissimus dorsi, laterally by the

posterior border of the external oblique muscle of the

abdomen, and inferiorly by the iliac crest (which forms

the base). The occasional hernia at this site is called

lumbar hernia (Fig. 5.6).

After completing the dissection of the back, the limb

with clavicle and scapula is detached from the trunk.

Dissection

For detachment of the limb, muscles which need to be

incised are trapezius, levator scapulae, rhomboid minor

and major, serratus anterior, latissimus dorsi and

sternocleidomastoid.

The sternoclavicular joint is opened to free clavicle

from the sternum. Upper limb with clavicle and scapula

are removed en bloc.

Trapezius is a shrugging muscle supplied by spinal

root of XI nerve.

Trapezius with serratus anterior causes 90'-180'

of abduction at shoulder joints.

shoulder

. \,Vhy was the biopsy advised?
. \AIhy is he not able is shrug his shoulder?

he is unable to shrug his sh der.

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MULTIPLE CHOICE AUESTIONS

1. Boundaries of triangle of auscultation are not c. Upper border of latissimus dorsi
   formed by one of the following structures: d. Upper border of teres major
   a. Lateral border of trapezius 2. Boundaries of lumbar triangle of Petit are formed
   b. Medial border of scapula by all except: