ANATOMY BLOCK 2: Clinical Applications

Surface Anatomy: What can be found in the four quadrants?

• Left Upper Quadrant: Stomach, spleen

• Left Lower Quadrant: End of descending colon, sigmoid colon

• Right Upper Quadrant: Liver, gallbladder

• Right Lower Quadrant: Cecum, appendix (McBurney’s Point)

Surface Anatomy: Which of the nine regions have referred pain patterns?

• Epigastric region for referred pain in foregut

• Umbilical reigon for referred pain in midgut

• Pubic/Hypogastric region for referred pain in hindgut

What are the subdivisions of extraperitoneal fascia (fascia deep to transversalis fascia, separates transversalis fascia from the peritoneum)?

• Preperitoneal: Found towards the anterior part of the body

• Retroperitoneal: Found towards the posterior part of the body

What incision was once used to provide wide access to whole abdominal contents, and allow for laparotomy?

Central Craniocaudad Incision: surgical incision from xiphoid process to pubic symphysis

• Now with development of tiny cameras, smaller incisions can be made

  • PROCESS: Peritoneal cavity inflated with CO₂, instruments inserted via portholes

    • Applicable to cholescystectomy (removal of gallbladder), and appendectomy (removal of appendix)

What reflex arc is supplied by the genital branch of the genitofemoral nerve (L1/L2), and has a sole purpose of elevating the testes?

Cremaster Reflex: involves the cremaster muscle + fascia (middle and seconding covering of spermatic cord)

• REFLEX ARC: Gentle touch at/around skin of medial aspect of superior part of thigh → stimulate sensory fibers of ilioinguinal nerve → enter spinal cord at L1 → stimulate motor fibers of genitofemoral nerve → elevate testis

What common mass in the groin involves of a protrusion of viscus (partial or whole) through a normal or abnormal opening, and can be examined through groin or scrotum examination?

Hernias - can either be inguinal (through superficial inguinal ring, above pubic tubercle), or femoral (through femoral canal, below pubic tubercle)

• Exam via

  • Groin → want to determine position of inguinal ligament, as hernias are ABOVE it

  • Scrotum → examine for a lump by trying to see if there’s an inability to feel upper edge

• Reduce swelling by applying gentle, firm pressure

• Important things to look out for: Position in relation to pubic tubercle, increases in temperature and pain = strangulation or infection

What type of hernias fit this criteria:

• Protrusion or passage of peritoneal sac (w/ or w/o abdominal contents) through a weakened part of abdominal wall in groin

• Enters via

  • Indirect: deep inguinal ring

  • Direct: Posterior wall of abdominal wall

• More likely to happen in men than women

Inguinal Hernias

• Indirect: Congenital, occurs through deep inguinal ring → inguinal canal → superficial inguinal ring (follows descent of testes pathway, will be lateral to inferior epigastric a.)

• Direct: Older adults, occurs through or around weakened conjoint tendon → superficial inguinal ring (will NOT follow descent of testes pathway, will be medial to inferior epigastric a.)

What is the main problems with hernias?

• Bowel and fat stuck in hernia sac can cause appreciable pain and bowel obstruction

• Strangulation can occur → blood supply cuts off at neck of hernial sac

  • Bowel becomes ischemic, susceptible to perforation

What can the peritoneum be used for, due to its large surface area?

• Facilitate the spread of disease through the peritoneal cavity and over the bowel and visceral surfaces

• Administer certain types of treatment a number of procedures

What is the innervation of the peritoneum?

• Parietal → innervated by associated spinal nerves, making it sensitive to well-localized pain

• Visceral → innervated by visceral afferents that accompany S-ANS/P-ANS back to CNS, making it more likely to have referred pain patterns (poorly localized sensations of discomfort; reflex visceral motor activity)

Because of its contribution of its large surface area, what can possibly happen if there is infection in the peritoneal cavity?

Infection and malignant disease can spread easily

• Can enter via direct invasion → RAPID SPREAD

• Existing malignant tumor starts releasing malignant cells into cavity → WORSEN PROGNOSIS

What mesentery is known as the policeman of abdominal cavity, as it can migrate to inflamed areas and wrap around to wall off inflammation?

Greater omentum → double-layered vascular membrane that attaches to the greater curvature of the stomach, drapes over the transverse colon, and is suspended within the cavity

• CONS: Can also be the reason for metastatic spread, usually in the carcinoma of ovaries

What is a mixture of cholesterol and bile pigment that undergoes calcification, and could possibly be lodged in the neck of the gallbladder?

Gallstones → if lodged in the neck of the gallbladder, the gallbladder would not be able to empty, and contractions to make it empty will cause pain

• If this occurs, a cholecystectomy is needed

• If lodged in the sphincter of ampulla → no bile can go into the duodenum, will produce jaundice

What condition involves the inflammation of the gallbladder, and has pain that is felt in the right upper quadrant and shoulder?

Cholecystitis

• Pain in shoulder due to innervation of phrenic nerve (C3-C5)

What is the condition that involves a yellow discoloration of the skin and scleras of the eyes?

Jaundice → caused by excess bilirubin in the plasma

• Any obstruction to the biliary tree can produce jaundice, but the two most common are:

  • Gallstones within the bile duct

  • Obstructing tumor at the head of the pancreas

What complex disorder of the liver involves a histological confirmation, as it is characterized by widespread fibrosis with areas of nodular regeneration and abnormal reconstruction of existing lobular architecture?

Hepatic Cirrhosis → presence implies previous or continuing liver cell damage

• Poorly functioning hepatocytes cannot break down blood and blood products → increase in serum bilirubin, manifesting as jaundice

• As cirrhosis progresses, can cause portal hypertension (increase pressure in splenic vasculature = spleen enlargement)

  • At sites of portosystemic anastomosis, there will be large, dilated varicose veins that are susceptible to bleeding and may produce marked blood loss (fatal)

At the z-line of the gastroesopheal junction, what transition of epithelia occur and its clinical relevance?

Transition from stratified squamous non-keratinized epithelia → simple columnar

• Sometimes, the histological junction doesn’t occur with the anatomical junction, occuring in the lower 1/3 of the esophagus

  • This disposes people to esophageal ulceration, and increased risk of adenocarcinoma

What type of duodenal ulceration erodes directly on the gastroduodenal artery or posterior superior pancreaticoduodenal artery?

Posterior Duodenal Ulcers → can lead to torrential hemorrhage, which is fatal

• TREATMENT: Extensive upper abdominal surgery involving ligation of vessels and catheter retrograde from the femoral artery to the celiac artery

  • Implenting a catheter retrograde here means the common hepatic and gastroduodenal artery are cannulated → bleeding is blocked via small coils, which stem flow of blood

What type of duodenal ulceration erodes into the peritoneal cavity, causing peritonitis?

Anterior Duodenal Ulcers → inflammation and local ileus promote adhesion of the greater omentum, which attempts to seal off the perforation

• Stomach and duodenum → holds a lot of gas → gas can enter peritoneal cavity and show up as subdiaphragmatic gas in a chest radiograph

What abdominal emergency occurs when the appendix is obstructured by fecalith or enlargement of lymp nodes, causing inflammation due to bacteria proliferation and invasion of the appendix wall?

Acute Appendicitis → may resolve spontaneously OR lead to localized or generalized peritonitis

• PAIN PATTERN:

  • Initial Inflammation of Appendix Only → central/periumbilical pain

    • Innervation by visceral sensory fibers (T10) - will go REVERSE of the sympathetic fibers, causing referred pain

    • Everytime peristalsis occurs in ileocecal region → cause wave of colic pain

  • As disease progresses, inflammation comes in contact with parietal peritoneum in R. Iliac Fossa → Constant Focal Pain → inflammation of parietal peritoneum

    • Innervation by somatic sensory nerves (L1/L2)

    • Will predominate over colic pain

What type of bowel obstruction involves a(n) intraluminal, mural, or extrinsic mass that is secondary to foreign body, obstructing tumor in the wall, extrinsic compression from an adhesion, or an embryological band?

Mechanical bowel obstruction

What type of bowel obstruction involves the inability of the bowel to peristalse, and is typically the postsurgical state of those who undergo excessive intraoperative bowel handling?

Functional bowel obstruction

• Small bowel obstructions → caused by: adhesions following previous surgery, inguinal hernias, volvulus (bowel twisting in own mesentery)

• Large bowel obstructions → caused by: tumors, hernias, inflammatory diverticular disease of sigmoid colon

What disease involves the development of multiple colonic diverticula (predominantly in the sigmoid colon due to its small diameter, and thus increased intraluminal pressure)?

Diverticular Disease → patient will develop signs and symptoms when neck of diverticulum becomes obstructed by feces and becomes infected

• Inflammation can spread to abdominal wall causing abdominal pain

• The anatomical position of the sigmoid colon can cause complications

  • If it were to perforate → can cause abcess in pelvis

  • If it were to be an inflammatory mass → obstruct L. ureter

  • If inflammation were to spread to bladder → fistula between sigmoid colon and bladder can occur

What disease involves occlusions that can occur throughout the abdominal aorta and at openings of the celiac trunk and superior and inferior mesenteric arteries?

Atherosclerosis

• Will not suffer many complications due to anastomoses of the right, middle, and left colic arteries

  • Enlarhement of these = continuous marginal artery that is able to supply the distal large bowel, replacing inferior mesenteric blood supply

What are the portocaval anastomoses and their associated pathologies for someone with portal hypertension?

• SUPERIORLY → Gastroesophageal junction around the cardia of the stomach: L. gastric v → esophageal v. → azygos system

  • Esophageal varices

• ANTERIORLY → Anterior abdominal wall around the umbilicus: Veins near ligamentum teres hepatis → paraumbilical v. → superior, inferior, and superficial epigastric v. → superior vena cava and inferior vena cava

  • Caput medusae

• INFERIORLY → The anus: Superior rectal v. → inferior rectal v. → internal iliac v. → inferior vena cava

  • Hemorrhoids

What type of stones occur more frequently in men than women, those aged 20-60, and those who live a sedentary lifestyle?

Urinary Tract Stones

• Stones made of polycrystalline aggregates of Ca²⁺, PO₄^3-, oxalate, urate and other soluble salts within an organic matrix

  • Urine becomes saturated with salts → small variations in pH = cause salts to precipitate

• Pain will radiate from infrascapular region (loin) → groin → scrotum or labia majora

• Hematuria may be noticed

What kind of transplant is common for patients with end-stage renal failure?

Kidney Transplant → placed in the L or R iliac fossa, allowing a new space to be created without compromise to other structures

• Utilize a curvilinear incision → parallel to iliac crest and pubic symphysis

  • External oblique, internal oblique, and transversus abdominis and transversalis fascia → divided

  • Parietal peritoneum medially retracted → reveal external iliac a.+ v. and bladder

  • Internal iliac a. → ligated to renal a. of donor kidney, v. →ligated to donor vein, and ureter → tunneled obliquely from bladder wall

What condition involves the dilation of the aorta, typically in the infrarenal region?

Abdominal Aorta Aneurysm → as the aortic dilation expands, the risk of rupture increases (if dilation is >5.6cm, NEED SURGERY)

• TREATMENT: Inserting endovascular graft

  • Surgically dissecting femoral a. below inguinal ligament

  • Incision in femoral a. → preloaded compression graft with metal support struts is passed on a large catheter into abdominal aorta thru femoral a. (use x-ray for guide)

  • Attachments to graft extend to common iliac vessels

    • Excludes abdominal aortic aneurysm

What potentially fatal condition occurs when a clot/thrombus is formed in the deep venous system of the legs and pelvis?

Deep Vein Thrombosis → PREDISPOSING FACTORS: Hospitalization, surgery, oral contraceptives, smoking, air travel, and clotting abnormalities (protein S and protein C deficiency

• Diagnosis may be difficult as symptoms include: leg swelling + pain, discomfort in calf

• Can be dangerous when clot dislodges → passes thru venous system → into right side of heart → into main pulmonary arteries

  • If the clot is big enough, this can obstruct blood flow to the lung, causing death

• Other complications include: destruction of normal valvular system in legs → venous incompetncy, chronic leg swelling with edema

• Cannot optimize with prophylatic treatment → treat by putting filter in IVC to trap large clots then remove past risk period

What kind of hernia occurs due to a lax diaphragm at the esophageal hiatus?

Hiatal Hernia → when there’s a lax diaphragm at the esophageal hiatus, the fundus of the stomach herniates into posterior mediastinum

• Can cause acid reflux, ulceration → bleeding and anemia

What are the four embryonic structures in which the diaphragm is made from?

• Septum transversum → will make the central tendon of the diaphragm

• Posterior esophageal mesentery

• Pleuroperitoneal membrane

• Peripheral rim

All will fuse together and separate abdominal cavity from thoracic cavity

What are the common failed points of fusion that can occur in the fusion of the embryonic structures that make the diaphragm?

• Morgagni’s Hernia: between the xiphoid process and costal margins on the right

• Bochdalek’s Hernia: thru an opening on left when pleuroperitoneal membrane fails to close the pericardioperitoneal canal

• Can also occur in the central tendon, causing a congenitally large esophageal hiatus

These appear around or at birth → allows abdominal bowel into throacic cavity → which can compress lungs and decrease respiratory function

Requires surgical closure

What can occur to the psoas muscle if an intervertebral disc is infected?

Psoas muscle abcess

• Psoas muscle and sheath → arise from lumbar vertebrae and intervertebral discs

  • In infection, disc is affected → can spread anterolaterally and pass onto psoas muscle sheath

    • Will appear as a mass below inguinal ligament

Why is it likely for a pelvic fracture to occur on two sides?

The pelvis is made up of a series of anatomical rings: three bony rings (sacrum, ilium, and pubis, as well as the obturator foraminae), and four fibro-osseous rings (greater and lesser sciatic foraminae)

• If a fracture is demonstrated on one side, because it’s made up of rings, it’ll be the same on the other side as a second fracture.

What occurs during the process of defecation?

• BEGINNING OF DEFECATION: Closure of larynx to stabilize diaphragm, increased intra-abdominal pressure by contraction of abdominal wall muscles

• DEFECATION PROCEEDS:

  • Puborectalis m. RELAXES around anorectal junctions → straightening out anorectal angle (increase by 130°-140°)

  • Both external and internal anal sphincters RELAX → allow passage of feces thru anal canal

  • Fatty tissue in ischioanal fossa → allows for changes in position and size of anal canal and anus

• DURING DEFECATION:

  • Anorectal junction moves down and back, pelvic floor descends slightly

  • Circular m. of Rectal wall → WAVE OF CONTRACTION pushes feces towards anus

  • As feces emerges, Longitudinal m. of Rectum and Levator Ani M. bring canal back up

  • Feces expelled, and anus and retum return to normal positions

When the perineal body is expected to be stretched and torn during childbirth, what procedure can be done that involves an incision in the perineal body to allow the head of the fetus to pass through the vagina?

Episiotomy

• Two Types:

  • Median: Cuts THRU the perinal body

  • Mediolateral: 45° from the midline

• Maternal benefits: less trauma to perineum, decreased pelvic floor dysfunction

  • HOWEVER: New research says DO NOT do this routinely, as there is no true decrease of pelvic floor dysfunction

What cancer is the most common tumor of the urinary tract, disease of sixth/seventh decades, and have a increasing trend of younger patients having it?

Urinary Bladder Cancer → can spread thru bladder wall and invade rectum, uterus, and lateral walls of pelvic cavity (no prostatic involvement)

• Can cause complications: invasion and obstruction of ureters → obstruct kidneys and cause kidney failure

What are the three scenarios that increase the risk of a urinary tract infection?

• Short urethra length in women

• Vaginoplasty in trans women (surgically made shorter urethra)

• Metoidioplasty or phalloplasty in trans men (neourethra lacks muscular and elastic tissues, making it harder to clear urine)

• SYMPTOMS Cystitis (inflammation of bladder) → if spread to ureters and kidneys = renal damage → renal failure

• Requires early diagnosis and treatment

What is performed to drain a patient’s urine when the patient is unable to micturate?

Urethral cathertization

• FOR MEN: Spongy urethra → angles superiorly to pass thru the perineal membrane and into pelvis

  • Inferior to perineal membrane → wall of urethral bulb is thin, and prone to damage when inserting catheters or doing cytoscopy

• FOR WOMEN: Urethra is short and straight → simple procedure

What could potentially occur in the seventh month of gestation in regards to the descent of testes?

Undescended Testes

• Normally: testes begin descent from posterior abdominal wall → inguinal canal → scrotum

  • During descent → may arrest (undescended) or end up in ectopic position, causing infertility and increased risk of tumors

What is known as an accumulation of fluid within the cavity of the tunica vaginalis?

Hydrocele of the Testis → typically unilateral, unknown cause (could possible be secondary to physical trauma, infection or tumor)

What cancer is one of the most commonly diagnosed malignancies in men, and are often advanced at diagnosis?

Prostate cancer → occurs in the peripheral regions of prostate, and are usually asymptomatic

• Diagnosed by:

  • CIS MEN: Digital recetal exam

  • TRANS WOMEN: Transvaginal exam

  • Blood tests → serum acid phosphatase and serum prostate-specific antigen (PSA)

  • Diagnosis will also be made by several biopsies of prostate

What conditions occurs with increasing age, and involves the enlargement of the central region of the prostate?

Benign Prostatic Hypertrohy → enlargement of the central region of the prostate can cause compression of urethra → cause urinary flow obstruction

• This can further cause hypertrophy of bladder → urine cannot pass, need transurethral/suprapubic catherization

What cancer is challenging to diagnose and treat due to numerous cell types in this specific structure needing different imaging, testing, treatment, and thus different prognosis?

Ovarian cancer → can occur at any age, usually older with strong family history

• Can spread via blood and lymph → metastasize in the peritoneal cavity: allow passage in paracolic gutters and over liver = disseminate easy

  • At time of diagnosis, it’s likely to have already metastasized

• One or both ovaries can be removed (or retained for gender-affirming procedures [Oophorectomy])

• Screen via

  • CIS WOMEN: Transvaginal ultrasound

  • TRANS MEN: Transrectal or transabdominal ultrasound

What procedure involves the surgical removal of the uterus, with complete excision of its body, fundus, cervix (may be left), and sometimes even the ovarian tubes and ovaries?

Hysterectomy → performed in patients with reproductive malignancy (uterine, cervical, and ovarian cancers), or in those with strong family history of reproductive disorders, endometriosis, and excessive bleeding; excessive postpartum bleeding, or for gender-affirming care for trans men

• Performed with Pfannenstiel’s incision: transverse suprapubic incision

  • **BE CAREFUL FOR URETERS! “Water under the bridge” The ureters are close to the uterine a. (which needs to be ligated during a hysterectomy)

What pouch found in those with female anatomy is known as the lowest portion of the abdominopelvic cavity when supine?

Rectouterine Pouch [of Douglas] → can be palpitated via transvaginal or transrectal digital palpitation

• If an abcess were to occur here → drain with needle placed thru posterior vaginal fornix or anterior wall of rectum

What kind of anesthetic can be used to relieve pain associated with childbirth, especially in the perineum?

Pudendal Block Anesthesia → can relieve pain associated with childbirth in the perineum, and relieve chronic pelvic pain and used in some rectal or urological procedures

• Inject where pudendal n. crosses lateral aspect of sacrospinous ligament, near its attachment to the ischial spine

• FOR CHILDBIRTH: Palpitate the ischial spine with finger (or with imaging guidance), then pass needle transcutaneously to medial aspect of ischial spine and around sacrospinous ligament = perineum anesthetized

• Not as common as epidural anesthesia

What can be done to cure prostate cancer?

Removing en masse: prostate and its attachments, and seminal vesicles

• PROBLEM: The inferior hypogastric plexus has some nerves that innervate erectile tissue of the penis

  • If these nerves are not preserved this can cause impotence in men, as well as sexual dysfunction in women

What condition involves an engorgement of veins related to the anal sphincter?

Hemorrhoids → slight genetic disposition, but straining during bowel movements, obesity, and sedentary lifestyle = produce hemorrhoids and portal hypertension

• SYMPTOMS: Irritation, pain, swelling

• Types:

  • Internal → originate from internal rectal plexus inside rectum, has a tendency to bleed

  • Prolapsed → Internal hemorrhoids that pass outside anal canal → lumps = thrombosis = painful

  • External → originate from exteranl rectal plexus, can occur at distal boundary of anal canal

What are the well-defined anatomical points of urethral rupture?

• MOST COMMON: Rupture of proximal spongy urethra, below perineal membrane

  • Tear when caught between object and inferior pubic arch

  • Urine escapes rupture and into superficial perineal pouch, descends into scrotum, and onto anterior abdominal wall, deep to the superficial fascia

• WITH SEVERE PELVIC FRACTURES: Rupture at prostatomembranes junction above deep perineal pouch

  • Urine → true pelvis

• WORST: Complete disruption of puboprostatic ligaments

  • Prostate is dislocated superiorly by ligamentous disruption and hematoma in true pelvis

  • Diagnosis made by palpitating elevated prostate during digital rectal exam