Longissimus capitis muscle

Origin: Transverse processes from T3-T1 and C7-C3

Insertion: Mastoid process

Nerve: Posterior rami of the spinal nerves C2 to T3

Description: 
The Longissimus capitis (Trachelomastoid muscle) lies medial to the Longissimus cervicis, between it and the Semispinalis capitis. It arises by tendons from the transverse processes of the upper four or five thoracic vertebrae, and the articular processes of the lower three or four cervical vertebrae, and is inserted into the posterior margin of the mastoid process, beneath the Splenius capitis and Sternocleidomastoideus. It is almost always crossed by a tendinous intersection near its insertion.