Manubrium of sternum

At a glance

English

Manubrium of sternum

Latin (TA2)

Manubrium sterni

System

Bone

Region

Thorax

Side

Single, on the midline

Muscles on it

Sternocostal head of pectoralis major

About the manubrium of sternum

The manubrium is the top and widest piece of the sternum. Its name is Latin for a handle, the sternum as a whole having once been likened to a short sword with the manubrium as its grip. It is roughly four-sided, broad above and narrowing towards its lower edge, and lies in front of the upper part of the chest at about the level of the third and fourth thoracic vertebrae. It is thicker than the rest of the sternum, especially between the clavicular facets.

The upper border has a shallow central dip, the jugular or suprasternal notch, easily felt in the midline at the root of the neck between the inner ends of the clavicles. Flanking it, an oval clavicular notch, angled up and out, takes the inner end of the clavicle at the sternoclavicular joint, with an articular disc in between. Each side border has a rough hollow into which the first costal cartilage is directly fused, and below it a half-facet that combines with one on the body of the sternum to hold the second costal cartilage. The lower border is covered by a thin layer of cartilage and meets the body at the manubriosternal joint.

The front surface gives origin to pectoralis major and to the sternal head of sternocleidomastoid; the back surface gives origin to sternohyoid and sternothyroid and faces the great vessels in the superior mediastinum, including the left brachiocephalic vein and the arch of the aorta and its branches. The superior sternopericardial ligament tethers the fibrous pericardium to its back.

The joint with the body forms the sternal angle, a ridge that marks the second costal cartilage and is used for counting ribs. The manubrium is where force from the shoulder girdle reaches the trunk, so it carries every load passed through the clavicle.

Function and supply

Function

Links the shoulder girdle and the first pair of ribs to the front of the chest, giving the only bony attachment of the upper limb to the trunk.

Nerve supply

Not innervated as a muscle is; the periosteum and joints are supplied by anterior cutaneous branches of the upper intercostal nerves, and the clavicle region by the supraclavicular nerves.

Blood supply

Perforating and sternal branches of the internal thoracic arteries, which run down just lateral to the sternum behind the costal cartilages.