Anatomy and physiology study guide: Anatomy of the Clavicle

Thursday, February 26, 2015

Anatomy of the Clavicle

Other names for Clavicle are:
Collar bone,Beauty bone

The shoulder is the most freely moveable joint in the body. The extreme range of its possible movements makes the shoulder joint susceptible to dislocation. One of the bones that meet at the shoulder is the clavicle, which is also known as the collarbone. The collarbone is long, curvy, and located at the root of the neck. One of the main functions of the collarbone is to hold the arms freely and supported, away from the trunk. Fractures of the collarbone are common. A fracture is easy to detect because the clavicle lies directly under the skin, making any deformity immediately visible. Symptoms of a fractured collarbone include tenderness, swelling, and an inability to move the arm because of pain. The victim may also have the desire to hold the arm against the chest to stabilize it. It is common practice to apply a sling to stabilize the fracture, allowing it to mend. Extreme fractures may require surgery to pin the collarbone back together.

Clavicle canbe divided into a cylindrical part called the shaft, and two ends – medial (sternal end) and lateral (acromial end).

Structure of the Clavicle
The clavicle consists of cancellous tissue, enveloped by a compact layer, which is much thicker in the intermediate part than at the extremities of the bone. 11

Functions of clavicle

The Clavicle allows the scapula to move freely on the thoracic wall due to the way in which it acts as a rigid support for the scapula and the arm. This gives the arm a higher range of movement.
The collar bone protects the neurovascular bundle that supplies the upper limb.
The Clavicle acts as a shock absorber by transmitting physical impacts from the upper limb to the axial skeleton.

Muscles and ligaments attached to clavicle

Lateral 1/3:
Trapezius muscle,
Deltoid Muscle,
Coracoclavicular ligament.

Medial 1/3:
Sternocleidomastoid muscle,
Pectoralis major muscle,
Subclavius muscle,
Costoclavicular ligament.

Ossification of the Clavicle
The clavicle is the first bone in the human body to ossify. The ossification process is of two types - intramembranous or dermal and endochondral. ; it is ossified from three centers—viz., two primary centers, a medial and a lateral, for the body, 53 which appear during the fifth or sixth week of fetal life; and a secondary center for the sternal end, which appears about the eighteenth or twentieth year, and unites with the rest of the bone about the twenty-fifth year.

Articulations of the Clavicle
The clavicle articulates with three bones: the sternum, the scapula, and the first rib. The sternal extremity forms an ovoid articular facet that sits in the clavicular notch of the manubrium. Just inferior to this facet is a smaller oval surface for articulation with the costal cartilage of the first rib. Laterally, an oval facet on the inferior aspect of the acromial extremity articulates with the acromion of the scapula.

Gender Variations of the Clavicle
Female clavicle is shorter, lighter, thinner, smoother, and less curved than in males . The lateral end of the clavicle is a little below the medial end in females whereas In males, the lateral end is either at the same level or slightly higher than the medial end.

Borders of the Clavicle
The anterior border is concave, thin, and rough, and gives attachment to the Deltoideus. The posterior border is convex, rough, thicker than the anterior, and gives attachment to the Trapezius.

Surfaces of the Clavicle

The medial two thirds of the shaft of the clavicle is rounded and has four surfaces.

The anterior surface- It is convex forwards,

gives origin to pectoralis major

The posterior surface- It is thickened and smooth,gives origin to sternohyoid muscle

The superior surface- This surface iss rough in its medial part.

The inferior surface- It has a rough oval impression at the medial end. It harbors a longtitudinal groove called subclavian groove in its lateral half,gives attachment to subclavius muscle

Ends of the Clavicle

Lateral (Acromial) End:articulates with with the acromian process of the scapula to form the acromioclavicular joint
Medial (Sternal) End:articulates with the clavicular notch of the manubrium sterni to form sternoclavicular joint