270 



The Abdominal Muscles. 



Foramen 

 venae cavae 



Centrum teudineum 

 N. vagus sinister 



Oesophagus 



N. vagus dexter 



Aorta 



, Ductus 

 thoracicus 



Cms 

 laterale 



ntum 



)stalc 



terale 



'gos and 



lanchnici 



msversus 



i lumb. I 



us sympa- 



hicus 



srraedium ^ 1 



us medialo ! 



leaf of the fascia lumbodorsalis 



Crus 

 intermedium 



Crus 

 mediale 



- Costa XII 



M. transversus 

 abdominis 



" ^ M. psoas major 



M. psoas minor 

 Corpus vertebrae lumbalis III 



M. quadratus 

 lumborum 



315. Diaphragm, pars lumbal is, vieAved from below and in front. 



(The dia2)lira<4in has been separated from the tipper ribs and from the sternum and drawn 

 somewhat upward; on the right the mm. psoas and quadratus lumborum have been removed.) 



Diaphrag'uia (continued). The pars hmibalis arises from the lig. longitudinale anterius 

 and is divided on each side by perforating vessels and nerves (somewhat variably) into three 

 crwa: crus mediale from the anterior surface of the S^d and 4tii, crus intermedium, narrow, 

 Irom the anterior surface of the 2"d and 3rd ctiis laterale, from the lateral surfaci> of the 

 2nd (oj. 1st) lumbar vertebral body and from a strip of fiiscia which extends thence in front of 

 the m. psoas to the transverse process of the 1^^ lumbar vertebra (arcus lumbocostulis mcdialis 

 [Halleri]). "A second strip of fascia, between the point last mentioned and the r2tii rib (arcus 

 lumhocostalis lateralis [Halleri]), forms a bridge over the m. quadratus lumborum and serves 

 chiefly to give origin also to muscle fibers ; it is not rare to find a triangular space in the muscle 

 over it. Tlie crura medialia of the two sides diverge somewhat above and in front and leave 

 between them and the spine an oblong space, the hiatus aorticus (for the aorta and ductus 

 thoracicus), which is closed above by a small tendinous arch. Over this, the right crus mt^liale 

 diyides into two bundles which enclose a slit which reaches almost to the centrum teudiutnun, the 

 hiatus oesopharieus (for the oesophagus and the nn. vagi); the left crus mediale sends only a few 

 corresponding fibers to the right. Between the crus mediale and the crus intermedium run usually 

 the V. azygds (or hemiazygos) and the nn. splanchnici : b(>tw(>en the crus intermedium and the crus 

 laterale runs tlie truncus sympathicus. Insertion : on all sides radially td tlie centrum tendiaeum 

 (O. T. central tendon), which has the shape of a clover-leaf and consists of interwoven tendon bundles. 

 In its right half lies the foramen venae cavae, quadrangulary rounded (for the v. cava inferior 

 and the raun' jiluvnicoabduniinales n. plirenici dextri). Action: it enlarges the thoracic cavity ; the 

 cupolae de.scen( 1 markedly, the centrum teudineum descends less. I n n e r v a t i o n : nn. phrenici and 

 the rami anteriores [nn. intercostalesj of the nu. thoracales VII XII (especially VII, VIU and XI) 



