abdomen anatomy

what is the abdomen's primary characteristic as a container?

it is a flexible container for most of the organs of the alimentary (gi) and urogenital system.

what forms the superior boundary of the abdomen?

the diaphragm forms the superior boundary.

what forms the inferior boundary of the abdomen?

the pelvic muscles form the inferior boundary.

what type of membrane lines the abdomen?

it is lined by a serous membrane.

what does the genital branch of the genitofemoral nerve supply in the spermatic cord?

the cremaster muscle.

what are the two layers of the scrotum?

pigmented skin and dartos fascia.

what muscle is contained within the dartos fascia, and what is its effect?

the dartos smooth muscle, which gives the external skin a wrinkled appearance.

how is the scrotum internally divided?

into right and left halves by the septum of the scrotum.

what is the scrotal raphe?

a ridge marking the line of fusion of embryonic labioscrotal swellings.

what are the two primary products of the testes?

sperm and testosterone.

what suspends the testes within the scrotum?

the spermatic cord.

what covers the surface of each testis?

the visceral layer of the tunica vaginalis.

describe the tunica albuginea.

it is a tougher, fibrous layer that lies directly upon the testis.

what extends inward from the tunica albuginea, and what do these contain?

septa extend inward, dividing the testis internally, and containing the seminiferous tubules.

what structures produce sperm within the testes?

the seminiferous tubules.

what is the pathway for sperm drainage from the seminiferous tubules to the epididymis?

seminiferous tubules drain into straight tubules, then the rete testis, and efferent ductules before joining the epididymis.

what is the epididymis's primary function?

it is an elongated, convoluted tubular structure that stores sperm as they mature and await ejaculation.

how are sperm moved within the epididymis?

by fluid currents.

what are the three main parts of the epididymis?

the head, body, and tail.

what is the head of the epididymis composed of?

lobules formed by the coiled ends of 12-14 efferent ductules.

what is the tail of the epididymis's function regarding sperm?

it is the site of storage for the majority of sperm until peristaltic movements transport them into the ductus deferens during ejaculation.

what percentage of abdominal hernias do inguinal hernias account for?

75%.

what percentage of inguinal hernias occur in males?

86%.

what characterizes a direct inguinal hernia?

a bulge from the posterior wall of the inguinal canal.

how does the risk of direct inguinal hernias change with age?

the risk of incidence increases with increased age.

what characterizes an indirect inguinal hernia?

a bulge that passes through the inguinal canal or the groin.

why is an indirect inguinal hernia difficult to feel?

due to the external oblique muscle.

can indirect inguinal hernias extend into the scrotum?

yes, they can distend into the scrotum.

in what age group are indirect inguinal hernias normally found?

in young patients.

what is the most common type of hernia in neonates?

umbilical hernias.

what other patient population commonly experiences umbilical hernias?

obese female patients.

what is an epigastric hernia?

a hernia found between the umbilicus and xyphoid process, most commonly at the linea alba.

what is another name for cryptorchidism?

undescended testes.

how is cryptorchidism typically treated?

surgically.

is cryptorchidism usually unilateral or bilateral?

usually unilateral.

what are the significant risks associated with undescended testes?

increased risk of testicular cancer (and more difficulty to find until later stages) and poor fertility of the affected testicle.

what is a hydrocele of the testis and/or cord?

the presence of excess fluid from the visceral layer of the tunica vaginalis.

what is a varicocele?

swelling in the veins of the spermatic cord.

how is a varicocele often visualized and described?

usually visualized when standing, referred to as a 'bag of worms.'

why is testicular torsion a surgical emergency?

it is twisting of the spermatic cord, obstructing venous drainage, leading to edema and decreased arterial supply, with a high risk of necrosis.

what is the peritoneum?

a continuous serous membrane that lines the abdominopelvic cavity, investing the viscera.

what is the difference between the visceral and parietal layers of peritoneum?

the visceral layer lies upon the organs, and the parietal layer lines the abdominopelvic wall.

what does 'intraperitoneal' mean for viscera?

it means the viscera are largely or completely covered by peritoneum and suspended within the peritoneal cavity.

what does 'extraperitoneal' mean for viscera?

it means the viscera are located outside the peritoneal cavity (e.g., retroperitoneal or subperitoneal).

what does 'retroperitoneal' mean?

behind the peritoneum.

name five retroperitoneal organs using the 'sad pucker' mnemonic.

suprarenal (adrenal) glands, aorta/ivc, duodenum (most), pancreas, ureters.

name the remaining retroperitoneal organs from the 'sad pucker' mnemonic.

colon (ascending and descending only), kidneys, esophagus (abdominal part), and rectum.

what is a mesentery?

a double layer of peritoneum that occurs as a result of an invagination of peritoneum by an organ.

what are the functions of a mesentery?

it anchors an organ to the body wall and provides a neurovascular route to the organ.

what is an omentum?

a double-layered extension (fold) of peritoneum that passes from the stomach to other abdominal organs.

name the two primary omenta.

the greater omentum and the lesser omentum.

what does the abdominal esophagus descend from and to?

it descends from the diaphragm to the cardiac orifice of the stomach.

how long is the abdominal esophagus?

it is only 1.25 cm long.

what is the function of the stomach?

it accumulates food and begins to chemically and mechanically digest it.

how much can the stomach hold when full?

it can hold up to 2-3 liters.

what are the four parts of the stomach?

cardia, fundus, body, and pyloric part.

what is the cardia of the stomach?

it surrounds the cardiac orifice, located at the 6th left costal cartilage and t11 vertebra.

what is the fundus of the stomach?

it is the dilated superior part related to the left dome of the diaphragm.

what are the two main parts of the pyloric region of the stomach?

pyloric antrum (narrows to pyloric canal) and pylorus.

what is the function of the pylorus?

it is the most distal segment and contains smooth muscle that regulates the exit of chyme into the duodenum.

what is a hiatal hernia?

it is a protrusion of part of the stomach into the mediastinum through the esophageal hiatus.

what is the more common type of hiatal hernia?

what happens in a sliding hiatal hernia?

the cardia and fundus of the stomach slide into the thorax.

what happens in a paraesophageal hiatal hernia?

the cardia remains in its normal position, but part of the fundus pushes through.

what is pyloric stenosis?

it is hypertrophy of the pyloric sphincter in children.

in which demographic is pyloric stenosis more common?

it is about 6 times more likely in male infants.

what is the primary symptom of pyloric stenosis?

chyme is unable to leave the stomach, leading to "hungry vomitters" and projectile vomiting after feeds.

how is pyloric stenosis treated?

surgically, with a pyloromyotomy where the hypertrophic muscle is cut.

what is the primary site for nutrient absorption?

the small intestine.

what are the three regions of the small intestine?

duodenum, jejunum, and ileum.

describe the duodenum.

it is the shortest and widest region, forming a c-shape around the head of the pancreas.

what is specialized about the duodenum?

it is a highly specialized area with multiple accessory organs connecting to it.

where do the bile and main pancreatic ducts empty into the duodenum?

they form the hepatopancreatic ampulla, which empties via the major duodenal papilla.

is most of the duodenum fixed or mobile?

most of the duodenum is fixed to the posterior abdominal wall (retroperitoneal).

where does the jejunum begin?

at the duodenojejunal flexure, where the gi tract resumes an intraperitoneal course.

where does the ileum end?

at the cecum of the large intestine.

what anchors the jejunum and ileum to the posterior abdominal wall?

the mesentery.

what is the primary function of the large intestine?

water absorption from indigestible residues.

what are the three main characteristics of the large intestine?

omental appendices (or epiploic appendages), teniae coli, and haustra.

what are omental appendices?

small fatty projections.

what are teniae coli?

longitudinal smooth muscle bands that provide longitudinal tension, shortening the large intestine.

what are haustra?

sacculations (pouches) that bunch in response to the tension of the teniae coli.

what is the cecum?

the enlarged, first region of the large intestine, continuous with the ascending colon.

what is the appendix?

a blind intestinal diverticulum made of lymphoid tissue.

where is the appendix typically positioned?

it has a variable position, but is typically retrocecal.

what is appendicitis?

acute inflammation of the appendix resulting in acute abdominal pain.

what typically causes appendicitis in younger patients?

hyperplasia of lymphatic tissue.

what typically causes appendicitis in older patients?

a fecalith (calcified fecal mass).

what are the potential consequences if an inflamed appendix ruptures?

infection can enter the peritoneum, leading to severe abdominal pain, nausea, vomiting, fever, and abdominal rigidity.

what are the four parts of the colon?

ascending, transverse, descending, and sigmoid.

what are the two flexures of the colon?

the right colic (hepatic) flexure and the left colic (splenic) flexure.

which segment of the colon is the longest and most mobile?

the transverse colon.

which part of the colon is retroperitoneal?

the descending colon.

what happens to the teniae coli at the rectosigmoidal junction?

they terminate at this junction, about 15 cm from the anus.

what is the rectum?

the fixed terminal region of the large intestine.

how is the rectum positioned regarding the peritoneum?

it is retro and subperitoneal.

what is the rectum continuous with?

the anal canal.

describe the spleen's appearance and size.

it is an ovoid, purplish organ about the size of a fist.

how delicate is the spleen?

it is a very delicate, vulnerable organ.

what type of organ is the spleen?

it is the largest lymphatic organ.