CLAVICLE
1.Clavicle is a long bone and it supports the shoulder so that the arm can swing clearly away from the trunk.
2.The bone has a cylindrical part called the shaft, and two ends, lateral and medial
SIDE DETERMINATION
1.the lateral end is flat and the medial end is large and quadrilateral.
2.the shaft is slightly curved, so that it is convex forward in its medial two-thirds and concave forward in its lateral one-third.
3.The inferior surface is grooved Longitudinally in its middle one-third.
PECULIARITIES OF THE CLAVICLE
1.It is the only long bone that lies horizontally.
2.It is subcutaneous throughout.
3.It is first bone to start Ossifying.
4.There is no medullary cavity.
5.It is the only bone which has two primary centres of Ossification
6.It is occasionally pierced by the middle Supraclavicular nerve.
FEATURES
SHAFT
The shaft is divisible into the lateral one-third and the medial two-thirds.
The lateral one-third of the shaft is flattened from above downwards. It has two borders, anterior and posterior. The anterior border is concave forwards. The posterior border is convex backwards. This part of the bone has two surfaces, superior and inferior. The superior surface is subcutaneous and the inferior surtace presents an elevation called the conoid (Greek cone) tubercle and a ridge called the trapezoid ridge.
The medial two-thirds of the shaft is rounded and is said to have four surfaces. The anterior surface is Convex forwards. The posterior surface is smooth. The superior surface is rough in its medial part. The inferior surface has a rough oval impression at the medial end. The lateral half of this surface has a longitudinal subclavian groove, The nutrient foramen lies at the lateral end of the groove.
Lateral and Medial Ends
1. The lateral or acromial (Greek peak of shoulder) end 1s flattened from above downwards. It bears a tacet that articulates with the acromion process ot the Scapula to form the acromioclavicular joint
2.The medial or sternal end is quadrangular and articulates with the Clavicular notch of the Manubrium sterni to form the sternoclavicular joint.
The articular surface extends to the interior aspect, for articulation with the first costal cartilage.
ATTACHMENTS
1.At the lateral end, the margin of the articular surface for Its acromioclavicular joint gives attachments to the joint capsule.
2.At the medial end, the margin of the articular surface for the sternum gives attachment to:
A. Fibrous capsule of sternoclavicular joint all around
B. Articular disc POSTEROSUPERIORLY.
C. Interclavicular ligament superiorly.
3.lateral one-third of shaft
A. The anterior border gives origin to the deltoid.
B. The posterior border provides insertion to the Trapezius.
C. The conoid tubercle and trapezoid ridge give attachment to the conoid and trapezoid parts of the coracoclavicular ligament.
4.Medial Two-third of the shaft
a. Most of the anterior surface gives origin to the pectoralis major.
b.Half of the rough superior surface gives origin to the Clavicular head of the STERNOCLEIDOMASTOID.
C. The oval impression on the inferior surface at the medial end gives attachment to the costoclavicular ligament
d. The subclavian groove gives insertion to the subclavius muscle. The margins of the groove give attachment to the clavipectoral fascia.
e. The posterior surface close to medial end gives origin to sternohyoid muscle.
f. The subclavian vessels and cords of brachial plexus pass towards the axilla lying between the inferior surface of the clavicle and upper surface of first rib. Subclavius muscle acts as a cushion.
The nutrient foramen transmits a branch of thesuprascapular artery.
OSSIFICATION
CLINICAL ANATOMY
