Vertebra Prominens or Seventh Cervical Vertebra [C7]

Vertebra prominens is the common name for 7th cervical vertebra or C7, the largest and most inferior vertebra of the cervical region of the spine.

It is named because it has a large spinous process that protrudes posteriorly and can be felt prominently on palpation.

Vertebra prominens is easily recognized on palpation of the back of the neck from above downwards because of its palpation.

Cervical spine is formed by seven vertebras named as C1 to C7.  First vertebra is known as atlas and second as axis. Third to sixth cervical vertebra are typical in anatomical structure. But as the cervical spine approaches its end, its last vertebra or seventh cervical vertebra, C7 changes in shape.

[read more on cervical spine anatomy]

This vertebra prominens is used as a landmark in the clinical examination for numbering the vertebra during spine examination

Structural Features

The transverse processes are comparatively large in size, the posterior root is larger than the anterior. The anterior tubercle is absent. The foramen transversarium is relatively small, sometimes double, or may be entirely absent.

The anterior root of the transverse process may sometimes be separate and form cervical rib.

The upper surface of transverse processes usually bears a shallow sulcus for the eighth spinal nerve.

The spinous process is thick, long and nearly horizontal going straight back. Unlike other cervical vertebrae, It is not bifid but ends in a tubercle.

C7 vertebra forms joints with C6 vertebra above and T1 vertebra below.

Attachments

•  Tip of spinous process-
  • Ligamentum nuchae
  • Trapezius
  • Rhomboideus minor
  • Serratus posterior superior
  • Splenius capitis
  • Semispinalis thoracis
  • Spinalis cervicis
  • Interspinales
  • Multifidus.
• Transverse process
  • Transmits only an accessory vertebral vein
• Posterior tubercle
  • Suprapleural membrane
• Lower border
  • Levator costarum.

Clinical significance

Anatomical Landmark

In most of the people, C7 is most prominent vertebra and is considered as a landmark in clinical examination of spine. This gives a landmark to count vertebrae above and downward.

But it must be borne in the mind that only 70% of people have C7 as most prominent. In the rest, either C6 or T1 can make the most prominent vertebra. Therefore, it introduces a chance of error in such cases.

Cervical Rib

Anterior root of the C7 vertebra can form the cervical rib. It could be asymptomatic in most of the people but can give rise to Thoracic outlet syndrome.