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Humerus

The humerus is the long bone of the upper arm, extending from the shoulder to the elbow. It articulates proximally with the scapula at the glenohumeral joint and distally with the radius and ulna at the elbow joint.

Proximal humerus: The rounded head fits into the glenoid cavity of the scapula. The anatomical neck separates the head from the tubercles. The greater and lesser tubercles serve as attachment points for the rotator cuff muscles. The intertubercular groove transmits the tendon of the long head of the biceps brachii. The surgical neck is a common fracture site.

Shaft: The diaphysis has a cylindrical proximal portion and a triangular distal portion. The deltoid tuberosity is located laterally for insertion of the deltoid muscle. The radial groove runs obliquely along the posterior surface, transmitting the radial nerve and profunda brachii artery.

Distal humerus: This widens to form articular and non-articular parts. The capitulum articulates with the head of the radius, and the trochlea articulates with the ulna. Above them are the radial fossa, coronoid fossa, and olecranon fossa. The medial and lateral epicondyles serve as muscle attachment sites.

Clinically, the humerus is a frequent site of fractures, dislocations, metastatic lesions, and bone tumors. Knowledge of its anatomy is vital for trauma surgery, joint replacement, and orthopedic imaging.

Synonyms

  • Upper arm bone

  • Os humeri

Function

  • Provides the structural framework of the upper arm

  • Serves as a lever for muscle attachment and movement

  • Transmits forces from the upper limb to the shoulder and forearm

  • Participates in shoulder and elbow joint motion

MRI Appearance

T1-weighted images:

  • Cortical bone: low signal intensity (black)

  • Bone marrow: intermediate signal, distinguishing red and yellow marrow

  • Soft tissue attachments visible around tubercles and epicondyles

T2-weighted images:

  • Cortical bone: low signal

  • Marrow fat: relatively hyperintense

  • Bone marrow edema, tumors, or cysts: bright hyperintensity

STIR:

  • Fat suppression highlights bone marrow edema, stress fractures, tumors, or infection

  • Sensitive for early detection of trauma and pathology

T1 Post-Gadolinium (with contrast):

  • Normal cortical bone does not enhance

  • Enhancing areas indicate tumors, infection, or inflammatory lesions

  • Helps characterize bone and soft tissue tumors

MRI Non-Contrast 3D Imaging:

  • Provides 3D reconstruction of humeral anatomy

  • Useful for preoperative planning in fractures, arthroplasty, or deformity correction

CT Appearance

Non-contrast CT:

  • Excellent for cortical bone evaluation, fractures, and alignment

  • Provides detailed morphology of fracture fragments and articular surfaces

CT Post-Contrast:

  • Highlights vascularity of tumors, infection, or soft tissue involvement

  • Helps differentiate between benign and malignant bone lesions

  • 3D reconstructions aid in surgical planning and orthopedic fixation

MRI images

Humerus MRI axial anatomy image

MRI images

Humerus MRI sagittal anatomy image

CT image

Humerus anatomy CT axial image -img-00000-00000

CT image

humerus bone CT CORONAL IMAGE

CT 3D VRT image

humerus bone 3D VRT IMAGE

X ray image

x ray humerus ap