Location and Functions
The clavicle is a long bone that extends horizontally from the superior portion of the sternum to the acromion of the scapula (shoulder blade). Together, the clavicle and scapula make up the shoulder (pectoral) girdle.
The clavicle or collar bone has several important functions.
- First, anchored by muscles from above, it serves as a strut that extends laterally to support the scapula.
- The horizontally positioned clavicle holds the shoulder joint superiorly and laterally from the body trunk, allowing for maximal freedom of movement for the upper limb.
- The clavicle also transmits forces acting on the upper limb to the sternum and axial skeleton.
- Finally, it serves to protect the underlying nerves and blood vessels as they pass between the trunk of the body and the upper limb.
Clavicle Strut Function
The clavicle is divided into a rounded medial end, a flattened lateral end, and a central shaft. The medial end curves anteriorly and the lateral end curves posteriorly, which gives the bone an S-shaped appearance. The curves are best seen when the bone is viewed from above or below.
The clavicle articulates with two bones. Its medial (sternal) end articulates with the manubrium portion of the sternum to form the sternoclavicular joint. This joint is the only bony articulation between the pectoral girdle of the upper limb and the axial skeleton. This joint allows considerable mobility, enabling the clavicle and scapula to move in upward/downward and anterior/posterior directions during shoulder movements. The sternoclavicular joint is indirectly supported by the costoclavicular ligament (costo- = “rib”), which spans the sternal end of the clavicle and the underlying first rib. The lateral (acromial) end of the clavicle articulates with the acromion of the scapula, the portion of the scapula that forms the bony tip of the shoulder.
Along its inferior surface, the clavicle is roughed and bears several surface features. On the lateral side of the bone is the trapezoid line (or trapezoid ridge, or oblique), which runs forward and lateralward, and affords attachment to the trapezoid ligament. Medial to the trapezoid line is the conoid tubercle. This bump-like elevation is an attachment point for the conoid ligament. Together, the two ligaments form the coracoclavicular ligament, which connects the clavicle to the coracoid process of the scapula. A depression called the subclavian groove extends along the clavicle’s inferior shaft. It is an attachment site for the subclavius muscle, which originates on the first rib. On the medial part of the clavicle is the costal tuberosity (impression for costoclavicular ligament). This broad roughed surface extends more than 2 cm. in length and attaches the costoclavicular ligament, which connects the clavicle to the first rib.
Inferior Surface Features
Color and B/W Versions
(1125px X 750px)
There are some sex differences in the morphology of the clavicle. In women, the clavicle tends to be shorter, thinner, and less curved. In men, the clavicle is more massive and longer and has a greater curvature and rougher surfaces where muscles attach, features that are more pronounced in manual workers.
Access for free at – https://openstax.org/books/anatomy-and-physiology/pages/1-introduction
Reference: “The Pectoral Girdle“
Wikipedia, the free encyclopedia.
“The Clavicle” – https://en.wikipedia.org/wiki/Clavicle