404 THE MUSCULAR SYSTEM. 
of the pubis. The front wall of the canal is formed by the aponeurosis of the 
obliquus externus, and in its outer part by the muscular fibres of the obliquus 
internus; the back wall of the canal is formed by the fascia transversalis, and in 
its inner part by the conjoint tendon; while the floor of the canal is formed by 
Poupart’s ligament, and in its inner part by Gimbernat’s ligament. The spermatic 
cord enters the canal, after piercing the transversalis fascia, at the internal 
Vena caval opening C£sophageal opening Central tendon (middle part) 
A : 
Aortic opening 
Central tendon 
(left part) 
DIAPHRAGM, LEFT 
CRUS 
Central tendon (right part) 
DIAPHRAGM, COSTAL FIBRES 
Internal arcuate ligament 
External arcuate ligament 
Last thoracic nerve 
End of last rib } 
Lumbar nerve I. 
Ilio-hypogastric 
Lumbar nerve II. 
End of last rib 
Last thoracic nerve 
Ant. layer of lumbar fascia 
Lumbar fascia 
Tlio-hypogastrie — 
Lumbar vessels and syimpa- 
thetic communicating nerves 
[lio-inguinal —¢ 
Tlio-inguinal 
QUADRATUS 
LUMBORUM 
Lumbar nerve III. 
QUADRATUS LUMBORUM 
Genito-crural 
External cutaneous nerve Lumbar nerve IV. 
PsoaS MAGNUS 
ILIACUS | 
Lumbo-saeral cord Luimbo-sacral cord 
Genito-crural nerve 
Anterior crural nerve — 
Obturator nerve 
External cutaneous nerve 
Anterior crural nerve 
Obturator nerve 
Great sciatic nerve 
Great sciatic nerve 
| Obturator nerve 
ADDUCTOR LONGUS (origin) 
| ADDUCTOR BREVIS (origin) 
GRACILIS (origin) 
| ADDUCTOR MAGNUs (origin) 
PECTINEUS (cut) 
| | Superficial branch of obturator nerve 
Deep branch of obturator nerve 
OBTURATOR EXTERNUS 
Fria. 299.—Vinw or THE PosTERIOR “ABDOMINAL WALL, TO SHOW THE MUSCLES AND THE NERVES OF 
THE LUMBO-SACRAL PLEXUS. 
abdominal rine, and is there invested by its first envelope, the infundibuliform fascia, 
derived from the margin of the ring (fascia transversalis). It then passes obliquely 
inwards, downwards, and forwards, below the lower border of the obliquus internus 
muscle, from which it carries off a second investment, partly fascial, partly muscula 
the cremasteric fascia. Continuing its course in front of the conjoint tendon, 
it emerges through the external abdominal ring, from the edges of which the 
intercolumnar fascia is derived, the third or external investment for the cord. 
