Pelvis

An axial section of the pelvis includes a CT scan, anatomical diagram, and orientation guide. Text notes anatomical features and variations at the L4 level. https://www.w3.org/1999/xlink" content-type="colour" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003679868/1695039f-b7ac-4492-8001-b65743b8361c/content/fig107_191_1_C.jpg "/> ➜ Notes This section passes through the body of the fourth lumbar vertebra ( 14 ), the cranial portion of the iliac crests ( 7 ) and the umbilicus ( 1 ). There are wide individual variations in these landmarks, but the umbilicus is usually around the level of L4. The inferior mesenteric artery ( 20 ) has just arisen from the aorta at the level of the third lumbar vertebra. More caudally, it will give rise to the superior rectal artery (see Axial section 2, 24 ). The accompanying inferior mesenteric vein ( 20 ) has a long ascending retroperitoneal course to enter the splenic vein. The aorta ( 19 ) is commencing to bifurcate on both the section and the CT image ( 31 ). This level of bifurcation, anterior to the fourth lumbar vertebra, is surprisingly constant, even in subjects with gross arteriosclerosis or with aneurysmal dilation of the aorta. ➜ Section level This image displays an illustration of the human vertebral column, or spine, with an emphasis on the lumbar region. The text highlights a specific section level for viewing. https://www.w3.org/1999/xlink" content-type="colour" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003679868/1695039f-b7ac-4492-8001-b65743b8361c/content/fig107_191_2_C.jpg "/> ➜ Orientation Diagram with a circle and arrows pointing to Anterior, Posterior, Right, and Left, indicating orientation. https://www.w3.org/1999/xlink" content-type="colour" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003679868/1695039f-b7ac-4492-8001-b65743b8361c/content/fig107_191_3_C.jpg "/>