Supernumerary ribs

Supernumerary ribs occur most commonly as a cervical rib arising from C7 or a lumbar rib arising from L1. In extremely rare situations, there can be sacral, coccygeal, intrathoracic, or aberrant lumbar ribs . Rarely supernumerary ribs (cervical and lumbar ribs aside) have been found as 'normal' anatomic variants, without evidence of any clinical sequelae.

Associations

• Turner syndrome
• cleidocranial dysplasia
• Aarskog syndrome
• trisomy 8 syndrome
• incontinentia pigmenti
• fifteen thoracic vertebrae each with a pairs of ribs: isolated case report

Supernumerary ribs have been used as a marker for developmental toxicity bioassays in test animals .