MUSCLES OF THE TRUNK. 191 



4. The Great Complexus. (Fig. 106, 6, 7.) 



Synonyms. Dorso-occipitalis Girard. {Complexus major Percivall.) 



Situation Direction Form. A powerful muscle, included between the 

 internal surface of the splenius and the cervical ligament, whose oblique 

 direction forwards and upwards it follows ; it is triangular, flattened on both 

 sides, elongated from before to behind, and divided longitudinally into two 

 unequal portions a posterior and anterior. 



Structure. The posterior portion (Fig. 106, 6), the most considerable, 

 is aponeurotic at its origin, intersected by linear fibrous bands which obliquely 

 cross its direction, and is formed of fleshy fibres directed forwards. Those 

 which compose the anterior portion (Fig. 106, 7), intermixed with some 

 tendinous flsciculi, are directed upwards, and appear to be inserted into the 

 preceding. It is this difference in the direction of the fibres of the two 

 portions of the great complexus which allows them to be distinguished from 

 one another ; the two being only really separated by an interstice near their 

 inferior extremity. Superiorly, the muscle is constricted to form the 

 summit of the elongated triangle it represents, and terminates by a strong 

 tendon. 



Fixed insertions. The posterior portion derives its origin : 1, From the 

 summit of the spinous processes of the first dorsal vertebras, by a strong 

 aponeurosis which is confounded with that of the splenius and the anterior 

 small serratus ; 2, From the transverse processes of the four or five dorsal 

 vertebraB which follow the second, by as many aponeurotic digitations united 

 by their margins. The anterior portion is fixed : 1, To the transverse 

 processes of the two first dorsal vertebras, by two tendinous digitations 

 analogous to those of the posterior portion ; 2, To the articular tubercles of 

 the cervical vertebrae, by the inferior extremity of its fleshy fasciculi. 



Movable insertion. The movable insertion of the great complexus is 

 effected through its superior tendon, which is fixed to the posterior face of 

 the occipital protuberance, beside the cervical tuberosity. 



^Relations. It is covered by the splenius and the small complexus. It 

 covers the cervical ligament, the upper branch of the ilio-spinalis, the trans- 

 verse spinous of the neck, and the oblique and posterior straight muscles of 

 the head. The aponeurotic digitations which attach it to the dorsal trans- 

 verse processes are comprised between the two branches of the ilio-spinalis. 

 The interstice which separates, inferiorly, the two portions of the muscle 

 affords a passage to the superior cervical artery. 



Action. It is a powerful extensor of the head. 



5. Small Complexus. (Figs. 105, 6, 7 ; 106, 8, 9.) 

 Synonyms. Dorsomastoideus Girard. (Trachelo-mastoideus PercivalL) 



Situation Direction. Situated at the internal face of the splenius, in an 

 oblique direction upwards and forwards, this muscle lies along the anterior 

 border of the great complexus, and follows the inferior branch of the ilio- 

 spinalis, which it appears to continue to the head. 



Form Structure. The small complexus is a long muscle, divided into 

 two fleshy, fusiform, and parallel portions anterior and posterior which we 

 might strictly consider as two distinct muscles. Both are composed of 

 successive fasciculi, which become longer as they are superficial, and 

 terminate by a tendon at their superior extremity. The tendon of the 

 posterior muscle is flattened, and joins the mastoid aponeurosis of the 



