Human Anatomy Vol 1

Superomedial

compartment

lnterclavicular

ligament

Complete articular disc

Costoclavicular

ligament

I nferolateral com pa rtment

Fig. 10.1 : The sternoclavicular and acromioclavicular joints

Dissection^149 Arteries of Upper Limb

Acromioclavicular joinl

Acromion

Perforated articular disc

Conoid and hapezoid parts

of coracoclavicular ligamenl

There are two other ligaments associated with this

joint. The interclarsicular ligarrlerrl passes between the

sternal ends of the right and left clavicles, some of its

fibres being attached to the upper border of the

manubrium sterni (Fig. 10.1).

The costoclaaicular ligament is attached above to the

rough area on the inferior aspect of the medial end of

the clavicle. Inferiorly, it is attached to the first costal

cartilage and to the first rib. It consists of anterior and

posterior laminae.

Blood supply: Internal thoracic and suprascapular

arteries.

Neroe supply: Medial supraclavicular nerve.

Mooements: Movements of the sternoclavicular joint can

be best understood by visualizing the movement at the

lateral end of clavicle. These mov-ements are elevation/

depression, protraction/retraction and anterior and

posterior rotation of the clavicle. The anterior and

posterior rotation of clavicle is utilized in overhead

movements of the shoulder girdle.

D]SSECTION

Remove the muscles attached to the lateral end of

clavicle and acromial process of scapula. Define the

afticular capsule surrounding the joint. Cut through the

capsule to identify the intra-articular disc. Look for the

strong coracoclavicular ligament.

Feotules

The acromioclavicular joint is a plane synovial joint. It
is formed by articulation of srnall facets present:
i. At the lateral end of the clavicle.
ii. On the medial margin of the acromion process of
the scapula. The facets are covered with fibro-

cartilage. The cavity of the joint is subdivided by

an articular disc which may have perforation in it

(Fig. 10.1).

The bones are held together by a fibrous capsule and

by the articular disc. However, the mainbond of union

between the scapula and the clavicle is the

coracoclavicular ligament described below (Fig. 10.1).

Blood supply; Suprascapular and thoracoacromial

arteries.

Nense supply: Lateral supraclavicular nerve.

Moaements: See movements of shoulder girdle.

rococloviculor ligoment

The ligament consists of two parts-conoid and

trapezoid. The trapezoid part is attached, below to the

upper surface of the coracoid process; and above to the

trapezoid line on the inferior surface of the lateral part

of the clavicle. The conoid part is attached, below to

the root of the coracoid process just lateral to the

scapular notch. It is attached above to the inferior

surface of the clavicle on the conoid tubercle.

Movemenis of the Shoulder Girdle

Movements at the two joints of the girdle are always

associated with the movements of the scapula

(Figs 10.2a to f). The movements of the scapula may or

may not be associated with the movements of the

shoulder joint. The various movements of shoulder

girdle are described below.

a. Eleaation of the scapula (as in shrugging the

shoulders). The movement is brought about by the

upper fibres of the trapezius and by the levator

scapulae.

It is associated with the elevation of the lateral end,

and depression of the medial end of the clavicle. The

clavicle moves round an anteroposterior axis formed

by the costoclavicular ligament (Fig. 10.2a).

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