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Tubercle of rib

The tubercle of the rib is a small bony prominence located on the posterior surface of a rib at the junction of the neck and shaft. It presents two parts:

  • A medial articular facet that articulates with the transverse process of the corresponding thoracic vertebra, forming the costotransverse joint.

  • A lateral non-articular part that serves as an attachment point for the lateral costotransverse ligament.

The tubercle is most prominent in the upper ribs (1st–10th) where costotransverse joints exist, and absent or rudimentary in the floating ribs (11th and 12th). Its articulation, along with the rib head–vertebral body articulation, provides stability and flexibility to the thoracic cage during respiration.

Clinically, the tubercle of the rib is important in thoracic trauma, costovertebral joint disorders, arthritis, and rib fractures. It is a common landmark in radiology and spinal surgery.

Synonyms

  • Costal tubercle

  • Rib tubercle

Function

  • Provides articulation with the transverse process of thoracic vertebra (T1–T10)

  • Serves as an attachment point for the lateral costotransverse ligament

  • Contributes to the mechanics of respiration by stabilizing rib movement during inspiration and expiration

  • Acts as a landmark in thoracic radiology and surgery

MRI Appearance

T1-weighted images:

  • Cortical bone appears low signal intensity (dark)

  • Marrow shows intermediate signal, if present in the rib tubercle region

  • Costotransverse joint capsule may be visualized as a thin low-signal rim

T2-weighted images:

  • Cortical bone: persistently low signal

  • Joint fluid or inflammation in the costotransverse articulation appears hyperintense

  • Useful in detecting arthritis, effusion, or edema

PD-FS (Proton Density Fat-Suppressed):

  • Suppresses fat, improving visualization of marrow edema or micro-fractures at the tubercle

  • Highlights ligamentous injury or inflammatory changes

  • Sensitive for occult trauma at costotransverse joint

STIR:

  • Enhances detection of marrow edema, inflammatory disease, or fractures

  • Particularly useful in acute trauma and spondyloarthropathy assessment

T1 Post-Gadolinium:

  • Enhances in areas of synovitis, infection, or neoplastic infiltration of the rib or costotransverse joint

  • Helps differentiate between infectious vs. degenerative changes

MRI 3D Non-Contrast (Bone-focused):

  • Provides volumetric depiction of rib alignment, articulation with vertebra, and surrounding structures

  • Useful in congenital anomalies or pre-surgical planning

CT Appearance

Non-contrast CT:

  • Best modality for visualizing cortical bone

  • Tubercle seen as a bony prominence at the junction of rib neck and shaft

  • Detects fractures, sclerosis, or degenerative changes at costotransverse joints

CT Post-Contrast:

  • Not routinely required for bony anatomy

  • Enhances evaluation of adjacent soft tissue pathology, infections, or tumor involvement

CT image

tubercle of rib CT axial image -img-00000-00000

MRI image

tubercle of rib MRI axial image -img-00000-00000