The Fourth Cervical Vertebra (C4)

The C4 vertebra is a typical cervical vertebra, structurally similar to C3 and C5. It serves as a central support for head and neck movement, playing a role in flexion, extension, and rotation. C4 lies at the level of the thyroid cartilage (Adam’s apple). The C4 spinal nerve plays a major role in neck muscle control and contributes significantly to the phrenic nerve, which powers the diaphragm — essential for breathing.

Key Points

Type: Typical cervical vertebra
Location landmark: Behind the thyroid cartilage
Transverse foramen: Contains vertebral artery
Spinal nerve C4: Contributes to the phrenic nerve → controls diaphragm
Common symptoms: Tightness in neck, shoulder pain, breathing difficulty
Joints: Facet joints allow motion & protect spinal cord

Important Questions & Answers

Q: What kind of vertebra is C4?

Ans: A typical cervical vertebra, similar to C3 and C5.

Q: What landmark is at the level of C4?
Ans: The thyroid cartilage (Adam’s apple).

Q: What nerve exits at the level of C4?
A: The C4 spinal nerve.

Q: What important nerve does C4 help form?
Ans: The phrenic nerve, which controls the diaphragm.

Q: What symptoms may indicate C4 dysfunction?
Ans: Neck pain, shoulder pain, shallow breathing, and reduced neck rotation.

Q: What artery passes through the transverse foramen of C4?
Ans: The vertebral artery.

Clinical Insight

1. C4 lesions may affect the phrenic nerve, leading to diaphragm dysfunction (shallow breathing or hiccups).
2. Can also cause referred shoulder pain and scalene tightness.
3. Gentle cervical mobilization can restore nerve communication and improve breathing or posture.