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Manubrium of sternum

The manubrium is the broad, superior portion of the sternum, articulating with the clavicles and the first two costal cartilages. It lies at the level of T3–T4 vertebrae and joins the body of the sternum at the manubriosternal joint (sternal angle, angle of Louis), an important anatomical landmark for rib counting and thoracic measurements. The manubrium provides structural support to the thoracic cage, serves as a major attachment site for thoracic muscles, and protects underlying mediastinal structures, including the great vessels.

It has several important surfaces and borders:

  • Superior border: features the jugular (suprasternal) notch and clavicular notches

  • Lateral borders: articulate with the first costal cartilage and partly with the second costal cartilage

  • Inferior border: articulates with the body of the sternum at the manubriosternal joint

Synonyms

  • Upper sternum

  • Manubrium sterni

Function

  • Provides attachment for the clavicles (sternoclavicular joints)

  • Anchors the first two ribs, contributing to thoracic stability

  • Serves as a landmark for clinical assessment (sternal angle marks the level of the second rib and T4 vertebra)

  • Protects vital mediastinal structures such as the aortic arch, brachiocephalic veins, and trachea

  • Provides muscular attachment for the sternocleidomastoid, pectoralis major, and sternohyoid muscles

Arterial Supply

  • Supplied mainly by the internal thoracic arteries (anterior intercostal branches)

  • Additional contributions from perforating branches of the anterior intercostal arteries

Venous Drainage

  • Drains into the internal thoracic veins

  • Communicates with anterior intercostal venous plexuses

MRI Appearance

T1-weighted images:

  • Manubrium cortex appears as low signal intensity (hypointense)

  • Bone marrow shows intermediate to hyperintense signal depending on fat content

  • Useful for detecting bone marrow infiltration or fracture

T2-weighted images:

  • Cortical bone remains low signal

  • Bone marrow is variable (usually intermediate signal)

  • Edema or pathology (e.g., fracture, infection, tumor) appears hyperintense

STIR (Short Tau Inversion Recovery):

  • Cortical bone remains dark (low signal)

  • Marrow edema, infection, or tumor infiltration appear bright hyperintense

  • Excellent for detecting acute fractures or inflammatory changes

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal marrow enhances mildly and homogeneously

  • Pathological conditions (infection, metastasis, tumor) demonstrate heterogeneous or focal enhancement

CT Appearance

Non-contrast CT:

  • Manubrium appears as a dense cortical bone structure with internal trabecular pattern

  • Provides excellent visualization of fractures, sclerosis, or lytic lesions

Contrast-enhanced CT:

  • Used for evaluating adjacent soft tissue masses, mediastinal extension of pathology, or tumor invasion

  • Cortical detail remains unchanged but contrast delineates surrounding vascular and mediastinal structures

MRI images

Manubrium of sternum MRI coronal image -img-00000-00000

MRI image

Manubrium of sternum CT AXIAL image -img-00000-00000

CT images

Manubrium of sternum CT SAG image -img-00000-00000