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AAAC27 21/5/05 10:45 AM Page 62
27 The osteology of the upper limb

Medial (sternal) end

Facet for acromion
Trapezoid line

Tubercle for costo- Conoid tubercule
clavicular ligament
Fig.27.1
The upper and lower surfaces of the left clavicle

Fig.27.2
X-ray of a fractured clavicle

The clavicle (Fig. 27.1) • The clavicle articulates laterally with the acromion process of the
• The clavicle is the first bone to ossify in the fetus (6 weeks). scapulaathe acromioclavicular joint. The coracoclavicular ligaments
• It develops in membrane and not in cartilage. secure the clavicle inferolaterally to the coracoid process of the
• It is subcutaneous throughout its length and transmits forces from the scapula. This ligament has two componentsathe conoid and trapezoid
arm to the axial skeleton. ligaments which are attached to the conoid tubercle and trapezoid line
• The medial two-thirds are circular in cross-section and curved con- of the clavicle, respectively.
vex forwards. The lateral third is flat and curved convex backwards. • The clavicle is the most commonly fractured bone in the body. The
• The clavicle articulates medially with the sternum and 1st costal car- weakest point of the bone is the junction of the middle and outer thirds
tilage at the sternoclavicular joint. The clavicle is also attached medi- (Fig. 27.2).
ally to the 1st rib by strong costoclavicular ligaments and to the
sternum by sternoclavicular ligaments.

62 Upper limb