332 



MUSCLES OF THE TEIlIXiEUM. 



bule ; again approaching each other in front, they become narrow, and 



Fi;r. 231. 



Fig. 231. — Muscles of the PERiNiEUM in 

 THE Female. (A. T.) \ 



a, clitoris ; h, crus clitoridis ; c, is placed 

 in the vestibule above the orifice of the 

 iiretlira ; d, vagina ; x , anus ; e, coccyx ; 

 1, external sphincter ani muscle ; 2, 

 sjihincter vaginte ; 2', a few of its fibres 

 i:)rolongeil to the clitoris ; 3, levator <ani ; 

 4, on the left ischial tuberosity, points to 

 the transversus periuM (the inner fibres of 

 this muscle are represented too far forwards 

 in the figure) ; 5, G, ischio-cavernosus ; 7, 

 gracilis ; 8, adductor magnus and semi- 

 tendinosus, &c. ; 9, gluteus maximus. 



are niscrted upon the corpora caver- 

 nosa of the clitoris, a fasciculus 

 crossing over these and including 

 the vena dorsalis. The two halves 

 of this elliptical muscle appear to 



corrcs]wnd strictly to those of the bulbo-cavernosus muscle in the male. 

 A deep transverse muscle, corresponding to part of the constrictor 



nrethrte of the male, has been described as resting on the pubic surface 



of the female urethra. 



THE MOBPHOLOGY OF THE FASCIA AND MUSCLES OF THE 

 TRUNK AND HEAD. 



Fasciae. — There is a general correspondence in the relation of the deep fascia 

 to the skeleton and masses of the trunk muscles throughout vertebrate animals. 

 In its simplest and lowest form the general investing fascia is prolonged from 

 the surface towards the skeleton in four places, viz., two median, which have 

 been called respectively the ncuml and lucmal septa, and two lateral, one on 

 each side, running towards the transverse processes of the vertebra. The layers 

 of the haemal septum are in close contact in the caudal region, but they are 

 separated and somewhat complicated in the rest of the trunk by the interpo- 

 sition of the visceral cavity between them. 



In man and the higher animals the dorsal part of the general investing fascia 

 is represented by the tendinous attachments of the trapezius, latissimus dorsi, 

 and serrati postici muscles, and by the vertebral aponeurosis and deep temporal 

 fascia, while the deep fascia of the side and front of the trunk, neck, and 

 head and the aponeurotic sheath of the limbs correspond with its ventral portion. 

 The neural septum remains as the median fascial interval of the dorsal spinal 

 muscles, ligamentum nuchas, &o. The hasmal septum partlj- constitutes the linea 

 alba, and is elsewhere separated into two as an investment of the visceral cavity, 

 forming the transversalis, Hiac, and pelvic fasciae. The lateral septum, which is 

 strongly developed in fishes and amphibia, is only seen at all clearly in the 

 middle layer of the lumbar aponeurosis of man and the higher animals, being 

 in them situated much nearer the dorsal than the ventral aspect of the body. 

 This difference of position is coincident with the greater development of the 

 ventro-lateral muscles and the limbs in the higher than iii the lower vertebrntes. 



Muscles. — The dor.so-lati-ral muscle consists of fibres which more than any 

 others retain their original segmented character and longitudinal direction. It 

 is represented in man by the mass of muscles, the chief of which is the erector 

 spiaa3, which lies in the vertebral groove of the back, and which, arising from the 

 lower vertebra), splits up as it passes forwards to be inserted iuto other vertebrJB, 

 the ribs and the skull. It may be divided into three sets of muscles, characterized 

 by the ditterent direction of their fibres. The lirat set consist of those which riux 



