Clavicle

Shoulder girdle & thoracic cage

Definition: clavicle is a long bone that connects the trunk with upper limb. It is the anterior bone of shoulder girdle. It is also known as collar bone.

Shape: slender S-shape in appearance. It has double curvature of convex medially and concave laterally.

Functions: it support the shoulder and transmit the upper limb weight to the trunk through the sternum.

Site: lies horizontally at the junction of the front of the chest with front of the neck. Immediately above the first rib. It is subcutaneous throughout its whole extent.

Side determination:

1. Medial end: is bulky and quadrangular.
2. Lateral end: is flattened.
3. Superior surface: is smooth.
4. Inferior Surface: is rough at both ends & a groove for subclavius muscle at its middle third.
5. Anterior Curvature: is convex at its medial two-thirds & concave at its lateral one-third.

Superior surface of the clavicle

Inferior surface of the clavicle

General features: It consists of a shaft and two ends:-

• Shaft:

Lateral one-third	Medial two-thirds
Flattened from above downwards Consists of 2 borders: Anterior border- - It is concave forwards & show a rough area; deltoid tubercle Posterior border- - It is convex backwards Consists of 2 surfaces: Superior surface- - It is subcutaneous & smooth Inferior surface- - It shows 2 rough areas; conoid tubercle & trapezoid ridge	Rounded or quadrangular Consists of 4 surfaces: Anterior surface- - It is rough & convex forwards Posterior surface- - It is smooth & concave backwards Superior surface- - It is subcutaneous & rough on its medial part Inferior surface- - It has rough oval impression medially & subclavian groove in its intermediate third

• Ends:

Lateral end	Medial end
- Known as acromial end - Articulate with acromion process of scapula to form acromioclavicular joint - Flat shape (above downwards)	- Known as sternal end - Articulate with clavicular notch of menubrium -sterni to form sternoclavicular joint - Quadrangular or rounded shape

Acromial end of clavicle

Sternal end of clvicle

Particular features:

A) Muscles attachment:

Region	Specifically	Muscles
Anterior border	Medial third (rounded border)	Pectoralis major muscles
Posterior border	Superiorly, on the medial third	Sternocleidomastoid muscle (clavicular head)
Posterior border	Inferiorly, on the medial third	Sternohyoid muscle
Posterior border	Lateral third	Trapezius muscle
Superior surface & anterior border	Deltoid tubercle, anteriorly on the lateral third	Deltoid muscle
Superior surface	Posteriorly on the lateral third	Trapezius muscle
Inferior surface	Subclavian groove	Subclavius muscle

Superior surface of the clavicle

Inferior surface of the clavicle

B) Ligament Attachment: