Longissimus thoracis

Longissimus
Deep muscles of the back - longissimus capitis visible at top right, longisimus cervicis visible at center upper right, and longissimus dorsi visible at center right
Details
Origin	transverse process
Insertion	transverse process
Artery	lateral sacral artery
Nerve	posterior branch of spinal nerve
Actions	Laterally: Flex the head and neck to the same side. Bilaterally: Extend the vertebral column.
Antagonist	Rectus abdominis muscle
Identifiers
Latin	musculus longissimus
TA	A04.3.02.010
FMA	77178
Anatomical terms of muscle []

The longissimus (Latin for 'the longest one') is the muscle lateral to the semispinalis. It is the longest subdivision of the erector spinae that extends forward into the transverse processes of the posterior cervical vertebrae.

The longissimus thoracis is the intermediate and largest of the continuations of the erector spinae.

In the lumbar region, where it is as yet blended with the iliocostalis lumborum, some of its fibers are attached to the whole length of the posterior surfaces of the transverse processes and the accessory processes of the lumbar vertebræ, and to the anterior layer of the lumbodorsal fascia.

In the thoracic region, it is inserted, by rounded tendons, into the tips of the transverse processes of all the thoracic vertebræ, and by fleshy processes into the lower nine or ten ribs between their tubercles and angles.

The longissimus cervicis (transversalis cervicis), situated medial to the longissimus thoracis, arises by long, thin tendons from the summits of the transverse processes of thoracic vertebræ 1-5, and is inserted by similar tendons into the posterior tubercles of the transverse processes of cervical vertebrae 2-6.

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 sternocleidomastoid.