lec 5

Jejunum versus ileum

The small intestine measures about 6 to 7 meters and is divided into jejunum, the first two-fifths, and ileum, the last three-fifths. There is no clear macroscopic border between them, so you identify them by regional and wall features rather than a single visible line. The trap is to look for a sharp anatomical cutoff like at the duodenojejunal flexure. If the examiner asks for the limit, say there is no macroscopic boundary

External aspect of the small intestine

The small intestine is round and covered by visceral peritoneum except along the thin mesenteric attachment line. It forms about 15 to 16 loops occupying the inframesocolic compartment. The trap is to describe it as fixed like the duodenum. Jejunum and ileum are mobile because they are suspended by mesentery

Meckel diverticulum

Meckel diverticulum may be found about 50 to 70 cm before the ileocecal junction and represents the embryologic remnant of the omphaloenteric duct. It arises from the ileum, not the jejunum. The trap is to place it near the duodenum because that is also proximal small bowel. If the outpouching is near the terminal ileum, think Meckel diverticulum

Mesentery of jejunum and ileum

The mesentery is the root of the jejunum and ileum and contains vessels, nerves, lymphatics, lymph nodes, and fat between two peritoneal folds. It attaches the small intestine to the posterior abdominal wall while allowing mobility of the loops. The trap is to think it is only a vessel fold. It is the full suspensory and neurovascular pedicle of the jejunoileum

Radix mesenterii

The root of the mesentery is an oblique insertion line on the posterior abdominal wall. From left to right it crosses the left ureter, inferior mesenteric vein, duodenum, abdominal aorta, inferior vena cava, right ureter, and right genital vessels. The trap is to describe it as horizontal. Its oblique course is high yield and explains many relations

Mesentericocolic triangles

Together with the colic frame, the root of the mesentery divides the inframesocolic space into a right and a left mesentericocolic triangle. These are spaces created by peritoneal arrangement, not bowel wall structures. The trap is to confuse them with the duodenal recesses near Treitz. If the spaces are split by radix mesenterii and the colic frame, they are mesentericocolic triangles

Plicae circulares of Kerkring in the small intestine

These circular mucosal folds are produced by the intestinal wall and are especially developed in the jejunum and much less so toward the terminal ileum. They increase absorptive surface area by about 400 percent. The trap is to say the folds are equally strong throughout jejunum and ileum. If the internal relief is tall and numerous, think proximal small intestine

Villi intestinales

Intestinal villi are long rounded mucosal projections about 0.5 to 1.5 mm high. Each villus contains capillaries, nerve fibers, and a central lacteal, and they further increase the absorptive surface by about 600 percent. The trap is to confuse villi with plicae circulares. Plicae are large folds of the wall, villi are smaller mucosal projections on top of them

Tunica mucosa of the small intestine

The mucosa is lined by simple columnar epithelium made of absorptive cylindrical cells. Between villi are the intestinal glands of Lieberkühn, which secrete mucus. The trap is to say villi exist in the large intestine too. Villi are a key small-intestine feature, not a colonic one

Glandulae intestinales Lieberkühn in the small intestine

These intestinal glands lie between the villi and secrete mucus. They are part of the mucosa, not the submucosa. The trap is to move them into the submucosa just because the duodenum has submucosal glands. Lieberkühn glands are mucosal glands

Peyer plaques versus solitary lymphoid nodules

Solitary lymphoid nodules can occur in the small intestine generally, while aggregated lymphoid nodules, the Peyer plaques, are characteristic of the terminal ileum. This makes the terminal ileum immunologically distinctive. The trap is to place Peyer plaques in the jejunum. If the lymphoid aggregates are large and numerous near the end of the ileum, they are Peyer plaques

Tunica submucosa of the small intestine

The submucosa is areolar tissue containing blood vessels, lymphatics, and the submucosal plexus of Meissner. It supports the mucosa and participates in glandular regulation. The trap is to place Auerbach's plexus here. Meissner is submucosal, Auerbach is myenteric

Tunica muscularis of the small intestine

The small intestine has an inner circular and outer longitudinal muscle layer. Between them lies the myenteric plexus of Auerbach, which coordinates motility. The trap is to reverse the order of the layers. Circular is inner, longitudinal is outer

Tunica serosa of the small intestine

The external surface of the jejunum and ileum is covered by peritoneal serosa except along the mesenteric attachment. This reflects their intraperitoneal mobile nature. The trap is to call the external coat adventitia. Jejunum and ileum are intraperitoneal and therefore have serosa

Arteriae jejunales et ileales

These arteries arise from the superior mesenteric artery and are arranged in anastomotic arterial arches, usually in about three levels. From the last arches, straight vessels perforate the intestinal wall. The trap is to think there is one direct artery for each loop without arcades. The mesenteric arcade pattern is the defining arrangement

Veins of the small intestine

The veins mirror the arterial arrangement and drain into the superior mesenteric vein. They are not systemic caval veins. The trap is to think lymphatic-rich villi imply direct caval drainage. Venous return is portal through the SMV

Lymph drainage of the small intestine

Lymph drains through solitary nodules and Peyer plaques into intestinal trunks, then into cisterna chyli at the L2 level. This reflects the major role of lacteals and lymphatic absorption in the small intestine. The trap is to say lymph goes first to the portal vein because nutrients do. Fats especially enter the lymphatic system first

Innervation of the small intestine

Sympathetic fibers come from the celiac plexus and parasympathetic fibers from the anterior and posterior vagal trunks. These fibers enter Meissner and Auerbach plexuses in the wall. The trap is to say pelvic splanchnics innervate jejunum and ileum. Proximal gut parasympathetic supply here is vagal

Large intestine, general extent

The large intestine begins at the ileocecal junction and continues to the anus. It measures about 1.5 meters and includes cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anal canal. The trap is to stop the large intestine at the rectum. In this lecture, the anal canal is included in the sequence

External distinguishing features of the colon

The colon is recognized externally by taeniae coli, haustra, and appendices epiploicae. These features result from the arrangement of the muscular wall. The trap is to describe the colon as a smooth-walled tube like small intestine. If you see sacculations and fatty tags, think colon

Taenia libera

Taenia libera is the taenia visible along the anterior surface of the colon. It is one of the three longitudinal muscle bands and helps identify colonic orientation. The trap is to confuse it with taenia mesocolica. If it is the free anterior band, it is taenia libera

Taenia mesocolica

This taenia marks the insertion of the mesocolon. It is important because it identifies the mesenteric attachment of the colon. The trap is to say the omentum inserts here. Mesocolica is for mesocolon, not the greater omentum

Taenia omentalis

Taenia omentalis corresponds to the insertion of the greater omentum on the transverse colon. It is absent on the sigmoid colon. The trap is to assume all three taeniae persist identically along the whole large intestine. Omentalis is specifically missing on the sigmoid colon

Proximal and distal fate of taeniae coli

Proximally, the three taeniae unite at the base of the appendix on the cecum. Distally, they spread out and disappear into the continuous outer longitudinal layer of the sigmoid colon end and rectum. The trap is to expect taeniae on the rectum. Rectum does not preserve the taeniae pattern

Appendices epiploicae

These are peritoneum-covered fat appendages attached along the surfaces of the taeniae. They are a distinguishing feature of the colon and are absent from the small intestine. The trap is to confuse them with mesenteric fat. If the fat hangs as little peritoneal tags from the colonic surface, they are appendices epiploicae

Haustra coli

Haustra are the sacculated dilated segments of the colon produced by contraction of the circular muscle layer between them. They give the colon its segmented external appearance. The trap is to think they are caused by the taeniae alone. Taeniae shorten the colon overall, but the circular layer creates the haustral segmentation described here

Tunica mucosa of the colon

The colonic mucosa is flat and lacks circular folds and villi. Its simple columnar cells form Lieberkühn glands that secrete abundant mucus. The trap is to say the colon has villi like the small intestine. Flat mucosa with many glands is the colonic pattern

Tunica muscularis of the colon

The circular muscle separates the haustra, while the longitudinal muscle is condensed into the taeniae. This muscular organization explains the characteristic external shape of the colon. The trap is to describe the longitudinal layer as uniform all around. In the colon it is banded into taeniae

Serosa versus adventitia in the colon

Much of the colon is covered by serosa, but where mesocolic insertions occur and on the posterior surfaces of the ascending and descending colon, the outer layer is adventitia. This reflects the retroperitoneal fixation of those segments. The trap is to call the whole colon intraperitoneal. Ascending and descending colon have posterior adventitia

Caecum, general position

The cecum is a blind pouch in the right iliac fossa, about 5 to 7 cm long. It lies on the iliopsoas muscle and femoral nerve. The trap is to place it high under the liver routinely. Its standard location is in the right iliac fossa, though the appendix may vary

Relations of the cecum

Anteriorly the cecum contacts the abdominal wall, medially it borders intestinal loops and the ileocecal junction, laterally it relates to iliac muscle and iliac crest, and inferiorly it may relate to bladder or in women uterus and right ovary. The trap is to give only bowel relations and ignore musculoskeletal or pelvic relations. The cecum is strongly tied to the right iliac fossa anatomy

Fixed versus mobile cecum

Usually the cecum is fixed to the posterior abdominal wall and its posterior surface is not covered by peritoneum. Sometimes a true mesocecum exists, making the cecum very mobile. The trap is to state that the cecum is always freely mobile because it is bowel. Its mobility varies depending on mesocecum

Recessus ileocaecalis superior et inferior and recessus retrocaecalis

These are peritoneal blind recesses around the cecal region. The superior and inferior ileocecal recesses and the retrocecal recess are separated by plica caecalis vascularis and plica ileocaecalis. The trap is to confuse these with colonic haustra or appendiceal positions. They are peritoneal spaces around the cecum

Plica caecalis vascularis versus plica ileocaecalis

Plica caecalis vascularis is formed by a branch of the ileocecal artery, while plica ileocaecalis is another peritoneal fold in the same region. Together they separate the cecal recesses. The trap is to think both are simple mucosal folds. These are peritoneal folds, not intraluminal mucosal folds

Appendix vermiformis, insertion

The appendix is inserted into the cecum about 2 to 3 cm from the ileocecal junction, exactly where the three taeniae unite. This convergence is the best way to locate the base of the appendix. The trap is to search for the appendix using the ileocecal valve alone. Follow the taeniae to their meeting point

Appendix positions

The appendix may be pelvic, retrocecal, mesoceliac, or subhepatic, among other variants. The normal position emphasized here is descending toward the pelvis, seen in about 30 to 40 percent of cases. The trap is to call retrocecal the only normal position. The lecture stresses pelvic descent as the common normal pattern here

Appendix retrocaecalis

In this position the appendix lies behind the cecum. It is important clinically because inflammation may present less clearly on the anterior abdominal wall. The trap is to confuse retrocecal position with retroperitoneal fixation of the cecum itself. One describes appendix direction, the other cecal attachment

Appendix mesoceliacus

In this position the appendix points medially toward the umbilical region between intestinal loops. It is a variable directional form. The trap is to call it "mesenteric appendix" in the sense of normal mesoappendix only. Mesoceliac here refers to the medial direction toward the umbilicus

Appendix pelvinus

In the pelvic appendix, the tip descends into the lesser pelvis. This position helps explain pelvic symptoms in appendicitis. The trap is to confuse it with the cecum itself descending into the pelvis. The cecum stays in the right iliac fossa

the appendiceal tip descends

Appendix subhepaticus

In this variant the appendix lies anterior or lateral to the cecum, but its tip reaches near the gallbladder. The trap is to diagnose all right upper quadrant pain as hepatobiliary. A subhepatic appendix can mimic gallbladder-related pain

McBurney point

McBurney point lies at the junction of the lateral third and medial two-thirds of the right spinoumbilical line. It is a classic surface landmark for appendiceal pain. The trap is to measure it from the opposite direction. Start from the right ASIS toward the umbilicus and mark the junction described

Lanz point

Lanz point lies on the bispinosus line between the right lateral third and the middle plus left two-thirds. It is another appendiceal surface landmark. The trap is to place it on the spinoumbilical line like McBurney point. Lanz is on the line between the two anterior superior iliac spines

Iacobovici triangle

This triangle is bordered by the right spinoumbilical, bispinosus, and pararectalis lines. It is used as another topographic guide in appendiceal pathology. The trap is to think it is an intraperitoneal triangle like Calot. It is a surface projection triangle on the abdominal wall

Colon ascendens

The ascending colon occupies the right lateral abdomen and extends from the cecum to the right colic flexure. It is secondarily retroperitoneal, with peritoneum covering only its anterior and lateral surfaces. The trap is to describe it as fully mobile like the transverse colon. Ascending colon is relatively fixed

Relations of the ascending colon

Anteriorly it relates to the anterior abdominal wall and the inferior surface of the liver, posteriorly to iliacus, quadratus lumborum, and the inferior part of the right kidney, medially to the second part of the duodenum, small intestine loops, right ureter, and right genital vessels, and laterally to the abdominal wall and diaphragm. The trap is to forget the kidney and ureteral relations. These retroperitoneal relations are high yield

Toldt I fascia

Toldt I fascia lies between the ascending colon and the posterior retroperitoneal structures behind it. It is an important plane of surgical mobilization. The trap is to call all fusion fasciae simply "Toldt fascia" without side distinction. Here the lecture specifically names Toldt I for the ascending colon plane

Sulcus paracolicus dexter

This is the space between the ascending colon and the right lateral abdominal wall. Through it, the supramesocolic region communicates with the pelvis. The trap is to think this communication is blocked by the liver. The right paracolic gutter is a free pathway

Colon transversum

The transverse colon is the most mobile part of the colon because of its broad mesocolon. It stretches between the right and left colic flexures and hangs across the abdomen. The trap is to call the sigmoid colon the most mobile part just because it has a mesocolon. The lecture emphasizes transverse colon as most mobile due to the broad root

Flexura coli sinistra

The left colic flexure is related anteriorly to the greater curvature and diaphragm through the phrenicocolic ligament, laterally and superiorly to the spleen, and posteriorly to the left kidney. The trap is to think both colic flexures have the same relations. The left flexure is especially tied to spleen and phrenicocolic ligament

Ligamentum phrenicocolicum or sustentaculum lienis

This ligament connects the diaphragm region with the left colic flexure and helps support the spleen. It is a left-sided relation of the transverse colon and splenic flexure. The trap is to confuse it with the splenorenal ligament. If the structure supports the splenic flexure and spleen from below, it is phrenicocolic ligament

Mesocolon transversum

The transverse mesocolon inserts on taenia mesocolica of the transverse colon and divides the abdominal cavity into supra- and inframesocolic compartments. Its root crosses several posterior abdominal structures. The trap is to reduce it to just a small vascular fold. It is a major partition of the abdominal cavity

Root of the transverse mesocolon

The root of the transverse mesocolon crosses from left to right the left renal pelvis, anterior margin of the pancreatic body, duodenojejunal angle, head of the pancreas, descending duodenum, inferior vena cava, and right kidney. The trap is to confuse this with radix mesenterii of the small intestine. Both are oblique posterior insertions, but they cross different key structures

Colon descendens

The descending colon lies in the left lateral abdomen. It is related posteriorly to posterior muscles, the left kidney, and the iliohypogastric and ilioinguinal nerves, with Toldt II fascia between them. The trap is to describe it as suspended like the sigmoid. Descending colon is relatively fixed and retroperitoneal

Toldt II fascia

Toldt II fascia lies between the descending colon and the posterior structures behind it. It is the fusion fascia corresponding to the descending colon side. The trap is to use Toldt I here. In this lecture, ascending side is Toldt I, descending side is Toldt II

Sulcus paracolicus sinister

This left paracolic gutter lies between the descending colon and the left abdominal wall. It is the left counterpart of the right paracolic gutter. The trap is to assume it communicates exactly like the right without restriction. The right side is classically freer toward the supramesocolic region, while the left is more limited by the phrenicocolic arrangement

Colon sigmoideum

The sigmoid colon has two parts, an iliac segment and a pelvic segment. The iliac segment is fixed, while the pelvic segment is mobile and has mesocolon sigmoidei. The trap is to think the whole sigmoid is equally mobile. Its iliac part is fixed in this lecture description

Iliac segment of the sigmoid colon

The iliac segment lies on iliopsoas, left external iliac artery and vein, left genital vessels, and genitofemoral nerve. These posterior relations are high yield for pelvic and lower abdominal anatomy. The trap is to think the sigmoid is entirely pelvic. Its proximal iliac segment lies above the lesser pelvis

Pelvic segment of the sigmoid colon

The pelvic segment is mobile and possesses the sigmoid mesocolon. This makes it the looped pelvic continuation before the rectum. The trap is to describe the whole sigmoid as retroperitoneal. The pelvic part is clearly mesocolic and mobile

Rectum, general description

The rectum is the last part of the digestive tract before the anal canal, about 12 cm long, and lies in the lesser pelvis. The rectosigmoid junction is at S3, where the sigmoid mesocolon ends. The trap is to place the transition at the pelvic floor or anal verge. S3 is the important upper landmark

Ampulla recti versus canalis analis

The rectum presents ampulla recti, about 8 to 9 cm, and canalis analis, about 3 to 4 cm. These correspond to different curves and internal features. The trap is to call the whole rectum "ampulla." The anal canal is the distal specialized part

Flexura sacralis versus flexura perinealis

Flexura sacralis has anterior concavity and corresponds to the ampulla recti. Flexura perinealis has posterior concavity and corresponds to canalis analis. The trap is to switch the direction of the curves. Sacral follows the sacrum anteriorly

perineal bends backward

Peritoneal covering of the rectum

Only a small superior part of the ampulla recti is covered by peritoneum. The rest of the rectum lies in the subperitoneal pelvic space. The trap is to call the rectum intraperitoneal because it is intestine. Most of it is subperitoneal, not free in the peritoneal cavity

Plicae transversae recti of Houston

These are three transverse folds in the superior rectal mucosa formed by contraction of the circular muscle layer. They are internal rectal folds, not external curvatures. The trap is to confuse them with haustra or anal columns. If the folds are transverse and in the upper rectum, they are Houston folds

Plica Kohlrausch

The middle rectal fold is usually the most developed and is called plica Kohlrausch. It is one of the plicae transversae recti. The trap is to think it is a separate sphincter-like structure. It is simply the most prominent transverse rectal fold

Columnae anales Morgagni

These are 8 to 10 longitudinal folds in the inferior part at the junction of ampulla recti and canalis analis. They define the upper anal canal region. The trap is to call them rectal folds of Houston. Houston folds are transverse in the rectum

Morgagni columns are vertical in the anal canal

Sinus anales and valvulae anales

The anal columns delimit 8 to 10 grooves called anal sinuses, whose inferior parts are the anal valves. These structures outline the pectinate line region. The trap is to confuse the sinuses with pathological fistulas. In normal anatomy they are mucosal recesses between the columns

Linea pectinata

The pectinate line is traced by the inferior ends of the anal columns. It is the boundary between territories of different vascular supply, portal versus caval venous systems, and autonomic versus somatic innervation. The trap is to treat it as only a mucosal color change. It is a major embryologic and clinical boundary

White line of Hilton

The white line of Hilton lies between the internal and external anal sphincters. It is distinct from the pectinate line and marks another important zone in the anal canal. The trap is to use it as a synonym of the pectinate line. Hilton is lower, between sphincters

Linea anocutanea

This is the line marking the transition between anal mucosa and perineal skin. It is more external and inferior than the pectinate line. The trap is to place it at the same level as the anal valves. It is the mucocutaneous transition line

Pecten analis

Pecten analis is the narrow segment of the anal canal between the pectinate line and the white line of Hilton. At this level the wall includes both sphincter muscles, especially internal and deep part of external sphincter. The trap is to call the whole anal canal pecten. Pecten is only the short intermediate zone

Arterial supply of the colon and rectum

The large intestine is supplied by branches of the superior mesenteric artery, inferior mesenteric artery, and internal iliac artery. At the colic margin these form a continuous marginal artery called the Drummond arcade. The trap is to assign rectum entirely to mesenteric supply. The middle and inferior rectal arteries come from internal iliac territory

Arteria ileocolica

The ileocolic artery supplies the cecum through anterior and posterior cecal branches and also supplies the appendix through the appendicular artery. It belongs to superior mesenteric territory. The trap is to assign appendix supply to the right colic artery. Appendix supply follows the ileocolic system

Arteria colica dextra

The right colic artery supplies the ascending colon and right colic flexure. It belongs to the superior mesenteric arterial field. The trap is to confuse it with the middle colic because both reach the right upper colon. Right colic is for ascending colon and right flexure

Arteria colica media

The middle colic artery ascends and divides into right and left branches. The right branch anastomoses with the ascending branch of the right colic artery, and the left branch with the ascending branch of the left colic artery, contributing to the Riolan-Haller anastomosis. The trap is to think it supplies only the exact middle of the transverse colon. Its branches extend toward both flexures

Riolan-Haller anastomosis

This is the anastomotic connection between the left branch of the middle colic artery and the ascending branch of the left colic artery. It links the superior and inferior mesenteric arterial territories. The trap is to confuse it with the marginal artery of Drummond. Riolan-Haller is a key intermesenteric connection, not the entire colic marginal arcade

Arteria colica sinistra

The left colic artery has an ascending branch contributing to the Riolan-Haller arch and a descending branch supplying the descending colon. It belongs to inferior mesenteric territory. The trap is to think it supplies only the sigmoid. Left colic is mainly descending-colon territory

Arteriae sigmoideae

These are 2 to 5 arteries supplying the sigmoid colon. The last sigmoid artery anastomoses with the superior rectal artery at the Sudeck point. The trap is to identify only one sigmoid artery. Multiple sigmoid branches are the rule here

Sudeck point

Sudeck point is the anastomosis between the last sigmoid artery and the superior rectal artery. It is an important vascular point in colorectal surgery. The trap is to confuse it with McBurney point. Sudeck is vascular in the sigmoid-rectal transition, not appendiceal on the abdominal wall

Arteria rectalis superior

The superior rectal artery is the terminal branch of the inferior mesenteric artery and supplies the ampulla recti. It represents the mesenteric continuation into the upper rectum. The trap is to think all rectal supply is internal iliac. Upper rectum is IMA territory

Arteria rectalis media

The middle rectal artery arises directly from the internal iliac artery. It supplies the rectal region below the superior rectal territory. The trap is to derive it from the inferior mesenteric artery. Middle rectal is internal iliac territory

Arteria rectalis inferior

The inferior rectal artery arises from the internal pudendal artery, itself a branch of internal iliac. It supplies the lower anal canal region. The trap is to say it branches directly from the external iliac because of its perineal territory. It is from internal pudendal

Venous drainage of colon and rectum

The veins generally mirror the arteries. Colonic veins drain into the superior and inferior mesenteric veins, while middle and inferior rectal veins drain into the internal iliac system. The trap is to assume all rectal veins are portal. Only the superior rectal vein is portal through the IMA/IMV system

Portocaval anastomosis in the rectum

The anastomosis between superior rectal vein and middle rectal vein creates a portocaval connection. This is a major clinical venous crossroads. The trap is to place the portocaval rectal site at the pectinate line only as a surface landmark. The real basis is the venous communication between portal and systemic rectal veins

Lymph drainage of the large intestine

Lymph drains through multiple nodal groups including ileocolic, right and middle colic, superior mesenteric, left colic, sigmoid, inferior mesenteric, sacral, pararectal, internal iliac, and common iliac nodes. The trap is to give only mesenteric nodes for the whole large intestine. Rectum adds pelvic nodal drainage

Sympathetic innervation of colon versus rectum

Sympathetic fibers to the colon come from the superior and inferior mesenteric plexuses, while for the rectum they come from the aortic plexus and inferior hypogastric plexus. The trap is to say the whole large intestine uses one identical sympathetic plexus. Rectal sympathetic pathways are more pelvic

Parasympathetic innervation of the large intestine

Vagus supplies the cecum, ascending colon, and right two-thirds of the transverse colon. Pelvic splanchnic nerves S2 to S4 supply the left third of the transverse colon, descending colon, sigmoid colon, and rectum. The trap is to extend vagal supply all the way to the anus. Hindgut parasympathetic supply is pelvic splanchnic

Cannon-Bohm point

This is the boundary on the transverse colon between vagal and pelvic splanchnic parasympathetic supply. It also marks the vascular boundary between superior and inferior mesenteric arteries and the embryologic limit between midgut and hindgut. The trap is to think it is only a nerve point. It is simultaneously neural, vascular, and embryologic

Kidney position

The kidneys are retroperitoneal and lie roughly between Th11 and L3. The right kidney is lower than the left because of the liver. The trap is to place them symmetrically. If one is lower due to a large suprarenal abdominal organ, it is the right kidney because of the liver

Capsula fibrosa of the kidney

This is the fibrous capsule directly covering the surface of the kidney. It is the innermost of the covering layers. The trap is to confuse it with fascia renalis. Fibrous capsule is directly on the kidney surface

Capsula adiposa or corpus adiposum perirenalis

This is the fat surrounding the fibrous capsule of the kidney. It lies inside the renal fascia. The trap is to confuse it with pararenal fat. Perirenal fat is around the capsule, not behind the posterior renal fascia

Fascia renalis

The renal fascia surrounds the perirenal fat and has anterior and posterior lamellae. The anterior lamella is thin and continuous across the midline, whereas the posterior lamella is thicker and interrupted. The trap is to think both lamellae behave the same. Anterior crosses, posterior is interrupted

Fascia retrorenalis of Zuckerkandl

This is the posterior lamella of the renal fascia. It lies behind the perirenal fat and in front of the pararenal fat. The trap is to call Gerota fat the same thing. Zuckerkandl is posterior fascial lamella, not the fat layer

Corpus adiposum pararenalis Gerota

This is the fat posterior to the posterior lamella of the renal fascia and anterior to quadratus lumborum. It is a different fat compartment from perirenal fat. The trap is to mix up perirenal and pararenal adipose tissues. Pararenal fat lies outside the renal fascia posteriorly

External configuration of the kidney

Each kidney has a rounded superior extremity, a sharper inferior extremity, anterior and posterior surfaces, a concave medial margin with the hilum, and a convex lateral margin. The trap is to describe the kidney as symmetrical top to bottom. The superior pole is rounder and closer to the midline

Extremitas superior renis

The superior pole is larger, rounder, lies under the diaphragm, and is closer to the midsagittal plane than the inferior pole. The trap is to think the inferior poles are closer to the midline because they point downward. Superior poles converge more medially

Extremitas inferior renis

The inferior pole is thinner and sharper and lies on quadratus lumborum and iliopsoas. It is farther from the midsagittal plane than the superior pole. The trap is to assume the inferior pole is just a continuation of the long axis with no distinct topography. Its posterior muscular relations are important

Facies anterior of the kidney

The anterior surface is crossed on the right by the insertion line of the transverse mesocolon. It faces abdominal viscera rather than the posterior abdominal wall. The trap is to treat anterior and posterior renal surfaces as equivalent because the kidney is retroperitoneal. Anterior still has visceral relations