Human Anatomy Vol 1

Spines T1-T12

Fig. 5.4: The trapezius muscle and latissimus dorsi

Addilionol Feolures of Muscles of lhe Bock

US

1 Developmentally the trapezius is related to the
sternocleidomastoid. Both of them develop from
branchial arch mesoderm and are supplied by the
spinal accessory nerve.
2 The principal action of the trapezius is to rotate the
scapula during abduction of the arm beyond 90'.
Clinically the muscle is tested by asking the patient
to shrug his shoulder against resistance (Fig. 5.5).

BACK

Medial branch

Transverse section of

spinal cord

Trunk

Ventral ramus (intercostal nerve)

Grey ramus communlcans

Sympathetic ganglion

A large number of structures lies immediately under

cover of the trapezius. They are shown in Figs 5.6 to

5.8 and are listed below.

A. Muscles

L Semispinalis capitis.

2 Splenius capitis.

3 Levator scapulae (Fig.5.6).

4 Inferior belly of omohyoid.

5 Rhomboid minor.

5 Rhomboid major.

7 Supraspinatus.

8 Infraspinatus.

9 Latissimus dorsi.

10 Serratus posterior superior.

B. Vessels

1 Suprascapular artery and vein

2 Superficial branch of the transverse cervical artery

(superficial cervical) and accompanying veins

(Figs 5.7 and 5.8).

3 Deep branch of transverse cervical artery (dorsal

scapular) and accompanying veins.

C. rres

1 Spinal root of accessory nerve.

2 Suprascapular nerve.

3 C3, C4 nerves.

4 Posterior primary rami of C2-C6 and T1-T12 pierce

the muscle to become cutaneous nerves.

D. Bursa

A bursa lies over the smooth triangular area at the root

of the spine of the scapula.

Anterior cutaneous branch

Fig. 5.3: Typical thoracic spinal nerve. The ventral primary ramus is the intercostal nerve

Superior nuchal

line

Trapezius

Clavicle

Acromion

Scapula

Rhomboid

major in triangle

of auscultation

Latissimus dorsi

Ear

Ligamentum

nuchae'

Spine C7

TI

E

o

o

e

f

oE

oo

@