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Topic

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Ribs

The ribs are 24 curved flat bones (12 pairs) forming the thoracic cage, which protects the lungs, heart, and major vessels while supporting respiration. Each rib articulates posteriorly with the thoracic vertebrae at the costovertebral and costotransverse joints, and most articulate anteriorly with the sternum (via costal cartilages).

Classification of Ribs:

  • True ribs (1–7): Directly attached to the sternum via costal cartilages

  • False ribs (8–10): Indirectly attached to sternum via cartilage of rib 7

  • Floating ribs (11–12): No anterior attachment, end in abdominal wall musculature

Typical ribs (3–9) have a head (with two articular facets for vertebral bodies), a neck, a tubercle (for articulation with transverse process), an angle, and a shaft with a costal groove for neurovascular structures. Atypical ribs (1, 2, 10, 11, 12) show modified anatomy.

The ribs serve as structural supports for the thoracic wall, provide protection to internal organs, and facilitate respiration by their movements during breathing. Clinically, ribs are important in trauma (fractures), congenital anomalies, thoracic outlet syndrome, metastases, and infections.

Synonyms

  • Costae

  • Thoracic ribs

  • Costal bones

Function

  • Protect thoracic and upper abdominal viscera (lungs, heart, liver, spleen, kidneys)

  • Support respiratory mechanics by expanding/reducing thoracic volume

  • Provide muscle attachment for thoracic, abdominal, and back muscles

  • Form part of the thoracic cage with sternum and vertebrae

MRI Appearance

T1-weighted images:

  • Cortical bone appears dark (low signal)

  • Bone marrow shows intermediate signal intensity

  • Useful for detecting marrow-replacing lesions

T2-weighted images:

  • Cortex remains hypointense, while marrow has variable signal

  • Pathological lesions (tumors, edema, infection) may appear hyperintense

STIR:

  • Suppresses fat to highlight marrow edema, fractures, or infiltrative disease as hyperintense areas

  • Highly sensitive for detecting stress fractures and metastases

T1 Post-Gadolinium (Gd-enhanced MRI):

  • Enhances areas of infection, tumor, or inflammation within ribs and surrounding soft tissues

  • Useful for detecting osteomyelitis, neoplastic invasion, or post-traumatic changes

MRI Non-Contrast 3D Imaging:

  • Provides multiplanar reconstructions of rib cage and articulations

  • Useful for congenital anomalies, surgical planning, and trauma evaluation

CT Appearance

Non-contrast CT:

  • Best for bone detail: fractures, cortical disruption, callus formation, or congenital anomalies

  • Detects subtle injuries not visible on X-ray

CT Post-Contrast:

  • Highlights adjacent soft tissue, pleura, and vascular structures

  • Useful in detecting tumor invasion, infection, or vascular abnormalities

  • 3D reconstructions clearly display rib fractures, deformities, or resection planning

CT images

Ribs anatomy CT axial image -img-00000-00000

CT images

Ribs anatomy CT coronal image -img-00000-00000

MRI images

Ribs MRI axial image -img-00000-00000

MRI images

Ribs MRI coronal image -img-00000-00000

CT 3D VRT image

Ribs