Cervical vertebra C4

Function

Mid-cervical vertebra transmitting the C4 nerve root, which contributes to the diaphragm via the phrenic nerve (C3, 4, 5 keeps the diaphragm alive) and to shoulder-top sensation.

Landmarks

• Body
• Transverse foramen
• Bifid spinous process
• Intervertebral foramen for C4 nerve

Articulations (joints)

• C3 above
• C5 below

Clinical relevance

Spinal cord injury at C4 risks phrenic nerve dysfunction and respiratory failure — injuries at this level and above often require ventilatory support.