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Topic

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Body of humerus

The shaft (body) of the humerus is the long cylindrical mid-portion of the humerus, extending between the proximal surgical neck and the distal supracondylar ridges. It is triangular in cross-section proximally and becomes more rounded distally.

On its anterolateral surface, the deltoid tuberosity marks the insertion of the deltoid muscle. The anteromedial surface gives attachment to part of the brachialis muscle. The posterior surface contains the radial (spiral) groove, which transmits the radial nerve and the deep brachial artery.

Laterally and medially, the shaft narrows into the lateral and medial supracondylar ridges, serving as attachment sites for forearm flexors and extensors.

Clinically, the shaft of the humerus is important because fractures here can injure the radial nerve, leading to wrist drop. It is also a key site for intramedullary nailing, plating, and orthopedic fixation.

Synonyms

  • Body of humerus

  • Corpus humeri

Function

  • Provides structural support for the upper limb

  • Serves as a lever arm for powerful upper limb muscles

  • Provides multiple muscle attachment sites:

    • Deltoid tuberosity (deltoid insertion)

    • Radial groove (accommodation of radial nerve and brachial artery)

    • Medial and lateral ridges (forearm flexor and extensor muscle origins)

  • Transmits mechanical forces from the shoulder to the elbow

MRI Appearance

T1-weighted images:

  • Cortical bone: low signal intensity

  • Bone marrow: intermediate signal depending on fat content

  • Muscle attachments appear as intermediate-to-low signal

T2-weighted images:

  • Bone cortex: dark (signal void)

  • Marrow: hyperintense in edema, tumor, or infection

  • Soft tissues clearly distinguished from cortical bone

PD-FS (Proton Density Fat-Suppressed):

  • Excellent for evaluating bone marrow edema, periosteal reaction, and subtle fractures

  • Fat suppression makes marrow pathology and soft tissue changes hyperintense

STIR:

  • Very sensitive for bone marrow edema, occult fractures, infection, and tumors

  • Suppresses fat to highlight subtle pathology in the humeral shaft

T1 Post-Gadolinium (contrast MRI):

  • Enhances soft tissue masses, marrow infiltration, and periosteal reaction

  • Differentiates between inflammatory and neoplastic lesions

  • Helpful for detecting osteomyelitis or tumor extension

MRI 3D Imaging (Non-contrast, high-resolution):

  • Provides detailed 3D mapping of cortical and marrow anatomy

  • Useful for surgical planning in fractures and oncologic resections

CT Appearance

Non-contrast CT:

  • Excellent for evaluating fractures, cortical bone integrity, and callus formation

  • Visualizes the radial groove, deltoid tuberosity, and supracondylar ridges

CT Post-Contrast:

  • Enhances soft tissue and vascular structures adjacent to the humerus

  • Used in cases of suspected tumor, infection, or vascular involvement

  • Multiplanar and 3D reconstructions assist in preoperative planning

MRI images

shaft of humerus anatomy MRI axial image -img-00000-00000

MRI images

shaft of humerus mri sag image

CT VRT 3D image

Shaft (Body) of humerus