ANATOMY IN A NUTSHELL. 465 



anterior surface of this muscle beneath this fascia are the last dorsal, ilio-hypo- 

 gastric, and ilio-inguinal nerves. The middle layer of the lumbar fascia sep- 

 arates this muscle from the Erector spinae. This muscle as its name implies 

 is quadrilateral, broader below than above. 



Origin. — From the ilio-lumbar ligament and the crest of the ilium for 

 about two inches. Occasionally a second portion of this muscle is found situ- 

 ated in front of the muscle, and when so found it has its origin from the upper 

 borders of the transverse processes of three or four lower lumbar vertebrae and 

 is inserted into the lower margin of the last rib. 



Insertion. — Into the apices of the transverse processes of the four upper 

 lumbar vertebrae and into the lower border of the last rib for about half its 

 length. 



Action. — To draw down the last rib and acts as a muscle of inspiration. 



Nerve Supply. — Last dorsal, first and occasionally the second lumbar. 



Blood Supply. — Intercostal and lumbar arteries. 



LESSON CXLIX 



The word membrane is used to name any thin expansion of tissue, and has 

 the following classes: (1) Serous membrane, which is the simplest of all 

 forms. These serous membranes derive their name from the fact that they 

 are moist with a fluid like blood-serum. The serous membranes are closed sacs, 

 such as the pericardium, pleura, and peritoneum. However, the peritoneum 

 in the female is an open sac. (2) Synovial membrane which lines the joints. 

 This membrane secrets synovia, which resembles the white of egg. Under 

 synovial membrane we have three classes, (a) articular, which occurs hi joints, 

 (b) vaginal, which is found where the tendons of muscles run over bones, (c) 

 bursal. A synovial bursa is a bag which is lined with synovial membrane and 

 placed between the tendon of a muscle and a bone, or two muscles, or two 

 tendons. (3) Mucous membrane. The mucous membrane lines open cavi- 

 ties. (4) Cutaneous membrane, which is commonly called skin. 



The peritoneum is a serous membrane with a smooth shining surface. This 

 membrane is transparent, uncolored, strong, and moist. The peritoneum is 

 reflected from the abdominal walls and from pelvic walls over the viscera 

 to invest and at the same time hold them in position. The part which lines the 

 abdominal and pelvic wall is called parietal or external peritoneum, and 

 that which invests the viscera, to agreater or lessextent, is called the visceral 

 or internal peritoneum. If it were possible to separate the entire peritoneum 

 from the body, it would be in the form of a large closed sac with a constric- 

 tion a little above its center, thus forming the greater and lesser sacs of the 

 peritoneum. The passage way between these two sacs is called the foramen 

 OF Winslow. The foramen of Winslowhas above it the caudate lobe of the 

 liver, in front of it the lesser omentum, below it the duodenum, and hepatic 

 vessels, behind it the inferior vena cava. The lesser sac of the peritoneum 

 lies back of and below the stomach and liver, while the greater sac lies in front 

 and below these viscera. 



