Morphology of the semispinalis capitis muscle of the neck

Trevidi, Soham, Negar Mehrabi, and Mary Tracy-Bee

The semispinalis capitis muscle is found in the posterior neck of humans.  This muscle allows us to extend our head and neck.  The semispinalis capitis muscle is also known as the biventer cervicis muscle.  The majority of anatomy textbooks and atlases depict this muscle as containing two bellies of muscle with a linear intervening white tendonous band that neatly separates the muscle into upper and lower parts.  We dissected the posterior neck and upper back of eight cadavers to isolate this muscle and gain better clarification of this muscle’s appearance.  We found that this muscle does not appear as commonly depicted in most anatomy books.  Instead we found that its intervening tendon is not linear. Its tendon consists of multiple different parts that are commonly disconnected and lie either superior or inferior to each other.  Our discovery will change the way in which this muscle is drawn in textbooks.  Future studies planned involve increasing our sample size and quantifying the tendon and its relationship to the muscle belly and nearby anatomical structures.