Cervical rib

Also known as Eve's rib
Usually from 7th cervical vertebra

Radiograph:
Rib arising from a horizontal transverse process (thoracic vertebrae show upward sloping transverse process)
0.5% of population
In 90% asymptomatic

Cervical rib syndrome
Cervical rib with pain and weakness of arm, swelling of the hand, variation in pulse intensity Angiograom may be useful

References:
Jeung MY et al. Imaging of Chest Wall Disorders. Radiographics. 1999;19:617-637