The
semispinalis capitis (
complexus) is situated at the upper and back part of the
neck, deep to the
splenius muscles, and medial to the
longissimus cervicis and
longissimus capitis. It arises by a series of tendons from the tips of the
transverse processes of the upper six
thoracic vertebrae, and from the articular and transverse processes of the lower four
cervical vertebrae. The tendons, uniting, form a broad muscle, which passes upward, and is inserted between the superior and inferior
nuchal lines of the
occipital bone. It lies deep to the
trapezius muscle and can be palpated as a firm round muscle mass just lateral to the cervical spinous processes. An intermediate tendinous intersection divides the muscle into an upper and a lower part, and is more marked in the medial bundles than in the lateral ones . The
semispinalis cervicis (or
semispinalis colli), arises by a series of tendinous and fleshy fibers from the transverse processes of the upper six
thoracic vertebrae, and is inserted into the cervical
spinous processes, from the axis to the fifth
cervical vertebrae inclusive. The semispinalis cervicis is thicker than the semispinalis thoracis. The fasciculus connected with the
axis is the largest, and is chiefly muscular in structure. The
semispinalis thoracis (or
semispinalis dorsi) muscle consists of thin, narrow, fleshy
fasciculi, interposed between
tendons of considerable length. It arises by a series of small tendons from the
transverse processes of the sixth to the tenth
thoracic vertebrae, and is inserted, by tendons, into the
spinous processes of the upper four thoracic and lower two
cervical vertebrae. The semispinalis muscles are innervated by the dorsal rami of the
cervical spinal nerves. ==See also==