Clavicle

Clavicle 

Synonames

Collar bone, Beauty bone.

Anatomical position

• It extends laterally and horizontally at the root of the neck

Side Determination 

1. Flattend end laterally.

2. Medial two-third of clavicle is convex anteriorly.

3. Rough area on the lateral side faces inferiorly.

Special Features 

• It is only long bone which lies horizontally.
• It has no medullary cavity (Bone marrow).
• It is the first bone to ossifies in the body ( second bone to ossifies Mandible).
• Almost whole clavicle visible through skin can be palpable.
• It has the only long bone which has two primary center of ossification.
• It has only long bone which ossifies in membrane.

General features of right clavicle (a) Superior aspect (b) Inferior aspect

Features

It has 2 ends (Medial or Sternal, Lateral or Acromial end) and a shaft.

Lateral end 

• It is flattend from above downwards.
• It articulate with the acromian process of scapula to form acromioclavicular joint.

Medial end

• It articulate with the sternum ( Manubrium sterni ) to form a joint which is called Sternoclavicular joint.
• It receives attachment of interaclavicular ligament.

Shaft

It is divided into two parts anatomically...

1. Lateral one-third of clavicle.

2. Medial two-third of clavicle.

Lateral one-third of clavicle

• It is flattend from above downwards.
• It has 2 surfaces ( Superior and Inferior ) and 2 borders ( Anterior and Posterior ).

Superior Surface

• It is subcutaneous.

Inferior Surface

• It has coroid tubercle and trapizoid ridge, which gives attachment to the coroid and trapizoid part of the coracoclavicular ligament.

Anterior Border

• It is concave anteriorly.
• It provide attachment to the deltoid muscle.

Posterior Surface

• It is convex backwards.
• It gives attachment to the trapizeus.

Medial two-third of clavicle

• It is quadrilateral in shape.
• It has 4 surfaces ( Anterior, Posterior, Superior and Inferior ).

Anterior Surface

• It is convex forwards.
• It receives attachment of clavicular head of pectoralis major.

Posterior Surface

• It is concave backwards.
• It related to the internal jugular vein, subclavian vein and brachiocephalic vein.
• Sternohyoid muscles originate from here.

Superior Surface

• The clavicular head of  sterno cleido mastoid originate from this surface.

Inferior Surface

• Several ligament attach on this surface like costoclavicular ligament and clavipectoral fascia.
• Nutrient foramen also present on this surface, nutrient artery of clavicle passes though it.

Attachment of the right clavicle (a) Superior aspect (b) Inferior aspect

Ossification

• It ossifies from 2 primary and one secondary center ( Primary center appear during 5-6th week of intrauterine life for for shaft. Secondary center appear in puberty).

Ossification 

Applied

• Most common fracture in this bone in road accident.
• Weight loss of a patient can be assist clavicle.