Intervertebral disk of fourth cervical vertebra

Looks like

The pad between C4 and C5: a small disc, thicker at the front, giving the neck its forward curve. A tough fibre ring surrounds a soft gel core.

What it does

Joins the two vertebrae, absorbs shock and lets this level bend and twist a little.

Keeping it well

A bulge at C4–C5 can pinch the C5 nerve, giving pain or tingling in the shoulder and outer upper arm, with weak arm lifting. Weak or clumsy hands and legs mean cord pressure and need prompt review.

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