The Abdomen and Pelvis

Surface anatomy and

surface markings

• The midline linea alba is evident• linea semilunaris• The tendinous intersections

• The xiphoid. The costal margin extends from the 7th costal cartilage at the xiphoid to the tip of the 12th rib (although the latter is often difficult to feel); this margin bears a distinct step, which is the tip of the 9th costal cartilage.

• The iliac crest ends in front at the anterior superior iliac spine from which the inguinal ligament (Poupart’s ligament) passes downwards and medially to the pubic tubercle. Identify this tubercle by direct palpation and also by running the fingers along the adductor longus tendon (tensed by flexing, abducting and externally rotating the thigh) to its origin just inferior to the tubercle.

• In the male feel the firm vas deferens between the finger and thumb as it lies within the spermatic cord at the scrotal neck. Trace the vas upwards and note that it passes medially to the pubic tubercle and thence through the external inguinal ring, which can be felt by invaginating the scrotal skin with the fingertip.

Vertebral levels

• T9 – the xiphoid.•L1 – the transpyloric plane of Addison,•This plane passes through the pylorus, the pancreatic neck, the duodenojejunal flexure, the fundus of the gall bladder, the tip of the 9th costal cartilage (felt as a distinct ‘step’) and the hila of the kidneys. It also corresponds to the level of termination of the spinal cord.

Vertebral levels• L3 – the subcostal plan• Lowest part of the costal margin,• inferior margin of the 10th rib. It passes through the origin of

the inferior mesenteric artery.• L4 – the supracristal plane (supracristal line) at the level of the

summits of the iliac crests. This corresponds to the level of the bifurcation of the aorta. It is also a useful landmark in performing a lumbar puncture, since it is well below the level of the termination of the spinal cord, which is approximately at L1

• The umbilicus is an inconstant landmark. In the healthy adult it lies at the

junction of the L3 and L4 vertebrae. It is lower in the infant and, naturally,

when the abdomen is pendulous. It is higher in late pregnancy

Surface markings of individual viscera

Liver

•Mark the position of the right 10th rib in the midaxillary line (the costal border); mark the 5th right intercostal space in the midaxillary line; mark the left 5th intercostal space in the midclavicular line. Join these three points and you have outlined the position of the normal liver.This is not palpable in the normal subject – what is often mistaken for the liver edge, especially in a muscular subject, is the rolled up anterior abdominal muscles gathered up by the examining fingers. Confirm this by percussion – the ‘liver’ will be resonant to percussion

•SpleenThis underlies the 9th, 10th and 11th ribs posteriorly on the left side commencing 2 in (5cm) from the midline. It is approximately the size of thesubject’s cupped hand. The spleen must be enlarged to at least three timesits normal size to be clinically palpable – so an easily felt spleen isenormous!

•Gall bladderThe fundus of the gall bladder corresponds to the point where the lateral border of the right rectus abdominis cuts the costal margin; this is at the tip of the 9th right costal cartilage, easily detected as a distinct ‘step’ when the fingers are run along the costal margin.

•PancreasThe transpyloric plane defines the level of the neck of the pancreas, which overlies the vertebral column. From this landmark, the head can be imagined passing downwards and to the right, the body and tail passing upwards and to the left.

•AortaThe pulsations of the aorta can be felt by firm downward palpation of the abdomen in the midline. Because of the lumbar lordosis, the lower part of the aorta is pushed forwards and is therefore more readily felt than its. upper part. These pulsations terminate at the level of the aortic bifurcationat L4, which is demarcated by a line joining the summits of the right and left iliac crests – the supracristal line. •A pulsatile swelling detected below this level may be an iliac, but cannot be an aortic, aneurysm. (Consider also transmitted pulsations through a pelvic mass.

•KidneysThe lower pole of the normal right kidney may sometimes be felt in the thin subject on deep inspiration. Anteriorly, the hilum of the kidney lies in the transpyloric plane four finger-breadths from the midline. Posteriorly, the upper pole of the kidney lies deep to the 12th rib. The right kidney normally extends approximately 1 in (2.5 cm) lower than the left. Using these landmarks, the kidney outlines can be projected onto either the anterior or posterior aspects of the abdomen.