Horizontal Fingernail Trenches and Spinal Problems

Horizontal trenches across the fingernails are usually interpreted as revealing injuries or problems with the spine. The thumbnail shows the top 2 vertebrae, the index fingernail is C3-C7, middle fingernail is T1-12, ring fingernail is L1-4, and baby fingernail is the sacrum and coccyx.

Horizontal trenches are not always due to whiplash or other spinal injuries, however. They can also be caused by simply digging away at the cuticle with a metal object (such as nail clippers). This changes the meaning completely, and is then interpreted very much like bitten nails and cuticles (but more obsessive/compulsive).

You can still apply the related area of the spine to the interpretation. If the thumb shows the deep horizontal trench, for example, expect to also find pain caused by excessive muscle tension located near the base of the skull.