408 THE MUSCLES 



and testicle, with their convexities directed downwards and closely connected with 

 the fascia propria of the testicle; finally, they collect into a narrow tendinous band, 

 which is attached to the spine and crest of the pubes. (2) A <,m)up of diverirent 

 lleshy fibres, which pass from the origin downwards and inwards to l)e lost ui)on 

 the fascia propria. (3) A smaller group, which descend from the tendinous inser- 

 tion to be lost in a similar manner upon the front of the fascia propria. 



Between these fleshy fibres, Avhich are often thin and difiicult to recognise, 

 there is a layer of connective tissue, called the cremasteric fascia, Avhich unites 

 them and forms one of the coverings of the testicle and cord. 



Nerve-supply. — The genital branch of the genito-ci-ural, from the first and 

 second lumbar nerves, gives ofif numerous filaments which enter the muscle upon 

 its deep and posterior aspect. 



Action. — To raise the testicle, and draw it upwards towards the external 

 abdominal ring. This action is involuntary, and is usually of a reflex character, 

 being readily excited by any irritation of the adjacent skin either of the scrotum 

 or thigh. 



Relations. — Superficially, the external oblique aponeurosis above, the inter- 

 colunmar fascia, dartos, and integuments below; deeply, the spermatic cord and 

 testicle with its fascia propria. 



3. TRANSVERSALIS ABDOMINIS 



The transversalis abdominis — named from the general direction of its fibres — 

 is an irregularly quadrilateral curved sheet, partly muscular, partly aponeurotic. 



Origin. — (1) The inner surface of the cartilages of the last six ribs, close to their 

 junction Avith the ribs, by teeth which interdigitate with the attachments of the 

 diajthragm; (2) the strong aponeurosis called the lumbar fascia, which arises (a) 

 Ijv its anterior layer from the front of the transverse processes of the five lumljar 

 vertebrte, (b) by its middle layer from the tips of the transverse processes of the five 

 lumbar vertebne, (c) by its posterior layer from the general vertebral aponeurosis 

 which is attached to the spines of the thoracic, lumbar, and sacral vertebras (3) the 

 anterior two-thirds of the inner lip of the crest of the ilium; (4) the outer third 

 of Poupart's ligament. 



Insertion. — (1) The whole length of the linea alba; (2) the anterior border of 

 the crest of the pubes; (3) the inner end of the ilio-pectineal line for about one 

 inch and a half (4 cm.). 



Structure. — Arising by short tendinous intermixed with fleshy fil)res, the muscle 

 passes transversely forwards, diverging slightly to its insertion. The change from 

 fleshy to aponeurotic fibres is in a curved line, the upper and lower extremities of 

 which approach the linea alba more closely than in the central part of the muscle. 

 In the upper part the fleshy fibres are overlapped in front ])v tlie rectus muscle; 

 and at the lower ])order of the muscle Avhere it terminates in a small arch, passing 

 over the spermatic cord or round ligament, the fleshy fibres cease just above the 

 middle of Poupart's ligament. The muscles of the two sides, joined as they are by 

 the central aponeurosis, may be looked upon as a single muscle with a central 

 aponeurosis, like the dia]>hragm. 



Inits upi)erthree-fourtlis the anterior aponeurosis is closely l)lended with the 

 posterior division of the a])oneurosis of the internal ol^lique muscle, and forms the 

 hinder part of the sheath of the rectus in tliis region. In the lower fourth, tlie 

 anterior aponeurosis is blended with the undivided aponeurosis of the internal 

 oblique, and passes in front of the rectus muscle and the pyramidalis. 



The posterior aponeurosis, or lumbar fascia, consists of strong transverse 

 fibres. The middle layer is the strongest, and has in its substance fibrous bands 

 passing outwards from the tips of the transverse processes of the lumbar vertebrae, 

 and continuing the series of the ribs connected with the dorsal transverse ])rocesses. 

 Between this middle layer and the anterior layer Avhich sjirings from the front of 

 the tips of the transverse processes is placed the (]uadratus luml)orum; and a 

 thickening of this anterior layer passing from the tips of the transverse processes 

 of tlie first and second luml)ar vertehne to the lowt'st rib, called the li(f(niu'ii(um 



