292 A MANUAL OF ANATOMY 



The outer insertions are fleshy, and are attached to the backs of the 

 transverse processes of the lumbar vertebrae, and the outer surfaces 

 of the lower ten ribs external to the tubercles. 



Transversalis Cervicis (longissimus cervicis). — ^This continues the 

 longissimus dor si to the neck. It arises from the transverse pro- 

 cesses of the upper five or six thoracic vertebrae, and is inserted 

 into the posterior tubercles of the transverse processes of cervical 

 vertebrae from the second to the sixth inclusive, where it is internal 

 to the splenius colli and cervicalis ascendens. 



Trachelo-mastoid (longissimus capitis). — ^This muscle has been so 

 named because it extends from the neck to the mastoid process, 

 and it continues the longissimus dorsi to the head. It arises 

 from the transverse processes of the upper five or six thoracic 

 vertebrae in close connection with the longissimus cervicis, and 

 from the articular processes and capsular ligaments of the lower 

 three cervical vertebrae. Its insertion is into the lower part of the 

 outer surface of the mastoid process under cover of the splenius 

 capitis. Towards its insertion this muscle is very narrow and 

 ribbon-like, and it is marked by a tendinous intersection. 



Action. — The muscles of the middle column act as extensors and 

 lateral flexors of the vertebral column. They also extend the head 

 and flex the neck to one side, the face being turned to the same side. 



Inner Column. — ^This consists of the spinalis dorsi, which is 

 intimately associated with the inner part of the longissimus dorsi. 

 It arises from the lower two thoracic and upper two lumbar spines, 

 and it is inserted by tendinous slips into the upper thoracic spines 

 — sometimes the upper four, sometimes as many as the upper eight. 



Action. — ^This muscle is an extensor of the thoracic portion of 

 the vertebral column. 



Nerve-supply. — ^The erector spinas and its component muscles 

 are supplied by the posterior primary divisions of the spinal nerves. 



Between the iliac crest and the last rib the erector spinae is enclosed 

 in a sheath, the posterior wall of which is formed by the posterior 

 lamina of the lumbar aponeurosis, affording origin to the latissimus 

 dorsi and serratus posticus inferior, whilst the anterior wall is 

 formed by the middle lamina of that aponeurosis. On the back 

 of the sacrum its tendon gives origin deeply to fibres of the multifidus 

 spinae, whil t superficially, between the sacrum and the iliac crest, 

 a few fibres of the gluteus maximus arise from it. 



Complexus — Origin. — (i) The extremities of the transverse pro- 

 cesses of the upper six thoracic and last cervical vertebrae ; and 

 (2) the backs of the articular processes and capsular ligaments of 

 three or four cervical vertebrae above the seventh. The muscle 

 may receive a fleshy slip from the spine of the seventh cervical. 



Insertion. — The occipital bone between the superior and inferior 

 curved lines, commencing at the crest and extending outwards for 

 about 2 inches. The inner fibres of the muscle are interrupted about 

 the level of the sixth cervical vertebra by an elongated tendinous 

 intersection, having the appearance of a tendon, with a fleshy belly 



