splenius cervicis muscle splenius cervicis muscle the splenius cervicis (/ˈspliːniəs sərˈvaɪsɪs/) (also known as the splenius colli, /- ˈkɒlaɪ/) is a muscle in the back of the neck. it arises by a narrow tendinous band from the spinous processes of the third to the sixth thoracic vertebrae; it is inserted, by tendinous fasciculi, into the posterior tubercles of the transverse processes of the upper two or three cervical vertebrae. splenius cervicis musclemuscles connecting the upper extremity to the vertebral column. (splenius capitis et cervicis labeled at upper right, at neck.)detailsoriginspinous processes of t3-t6insertiontransverse processes of c1-c3arterytransverse cervical artery and occipital arterynerveposterior rami of the lower cervical spinal nervesactionsbilaterally: extend the head & neck, unilaterally: lateral flexion to the same side, rotation to the same side.identifierslatinmusculus splenius cervicista98a04.3.02.104ta22274fma22681anatomical terms of muscle its name is based on the greek word σπληνίον, splenion (meaning a bandage) and the latin word cervix (meaning a neck). the word collum also refers to the neck in latin. the function of the splenius cervicis muscle is extension of the cervical spine, rotation to the ipsilateral side and lateral flexion to the ipsilateral side. additional images position of splenius cervicis muscle (shown in red). lateral view. posterior view. muscles of the neck. lateral view. section of the neck at the level of the sixth cervical vertebra.