MUSCLES OF THE TRUNK. 297 



oblique portion arises, by a narrow tendinous process, from the anterior 

 tubercle of the body of the atlas, and is inserted into the fore part of 

 the transverse processes of the third, fourth, and fifth cervical vertebras. 

 b. The inferior oblique, the smallest part of the muscle, extends ob- 

 liquely downwards and inwards from the transverse processes of the 

 fifth and sixth cervical to the bodies of the first two or three 

 dorsal vertebras, c. The vertical part, connected by its extremities 

 with the other divisions, is attached superiorly to the bodies of 

 the second, thii'd, and fourth cervical vertebrse, and inferiorly to the 

 bodies of the three lower cervical and two or three upper dorsal 

 vertebrse. 



IM(iii(in.\\ — By its anterior surface this muscle is in contact with the pharjnix 

 and oesophagus, the great vessels of the neck contained in their sheath, the sym- 

 pathetic and recurrent laryngeal nerves, and the inferior thyroid artery. 

 Behind, it rests upon the vertebraj. 



Nerves. — The rectus capitis anticus major and minor are supplied by branches 

 from the upper cervical nerves ; the longus colli and scaleni by branches of the 

 lower cervical nerves. 



Actions. — The scalene muscles, when the vei-tebral column is fixed, act as 

 elevators of the ribs, and by many are considered as constant aids m the move- 

 ment of inspiration. They may also act as lateral flexors of the neck when the 

 ribs are fixed. The longus colli muscle is chiefly a flexor of the vertebral 

 column. The recti muscles are capable of producing some degree of flexion of 

 the head, and from the obliquity of their fibres may probably, when acting on 

 one side, also give rise to slight rotation. 



IV.— MUSCLES Al^TD FASCIA OP THS TRUITK, 



The muscles passing between the trunk and the upper limb having 

 been already described, those which belong exclusively to the trunk 

 itself will now be treated of under the three divisions of, 1. Dorsal 

 muscles, extending throughout the whole length ; 2. Thoracic muscles, 

 including the diaphragm ; and 3. Abdominal and Perineal muscles. 



I.— DORSAL MUSCLES AND FASCI.E. 



The muscles to be described under the above head, taken as a whole, 

 occupy the vertebral groove or hollow between the line of vertebral 

 spines and the prominences formed by the mastoid processes, the trans- 

 verse cervical processes, the most projecting parts of the ribs, and the 

 crest of the ilium, and they extend from the superior curved line of the 

 occi]»ital bone to the lower part of the sacrum. Some of them are 

 small and are limited to certain parts of the extensive region now 

 referred to ; others extend either continuously or by the serial repetition 

 of similar short fasciculi, throughout the greater part of it. These 

 muscles, together with those in the same region which belong more 

 properly to the upper limb, have been frequently described as con- 

 stituting six successive layers ; but the limits of several of these layers 

 are ill-defined, and it will be sufficient for the purpose of description 

 to arrange the muscles falling properly within the present section, 

 according to the main characteristics of their form and position, in 

 the following groups : viz., a, the posterior serrati muscles ; b, the 

 splenius and long erectors of the spine ; c, the complexus and trans- 

 verso-spinales ; d, the interspinales and intertransversales ; c, the 



