Quadrants of the Mammary Gland

Upper Outer Quadrant - Why It Matters

Clinical Significance of Quadrants

Frequency of Breast Carcinoma by Quadrant

Lymphatic Drainage by Quadrant

• Outer quadrants and subareolar plexus → drain primarily to axillary lymph nodes (~75%); first to the pectoral (anterior/external mammary) Level I nodes
• Inner quadrants → may drain to parasternal (internal mammary) nodes alongside the internal thoracic vessels; also to contralateral breast and abdominal nodes
• All quadrants communicate via the subareolar plexus of Sappey

• Level I - inferior axilla (lateral to pec minor)
• Level II - midaxilla (behind pec minor)
• Level III - superior axilla (medial to pec minor)

Other Conditions by Quadrant

• Fibroadenosis (fibrocystic change) - most common in the UOQ and axillary tail
• Fibroadenoma - more commonly found in the lower half of the breast, though may occur anywhere
• Carcinoma - can occur in any quadrant including the axillary tail, but predominates in UOQ
• Retraction/dimpling of the nipple toward the UOQ is a classic sign of carcinoma in that region (tethering by Cooper's ligaments and tumor fibrosis)

Internal Organization (Lobar Architecture)

• Are separated by the suspensory ligaments of Cooper (fibro-collagenous septa anchoring skin to deep fascia)
• Cooper's ligaments are more pronounced superiorly than inferiorly
• Glandular tissue is concentrated centrally; adipose tissue lies more peripherally
• The breast lies within the superficial fascia, which provides the surgical dissection plane; its posterior surface overlies the fasciae of pectoralis major, serratus anterior, external oblique, and rectus sheath

1. Lesser Sac (Omental Bursa)

Boundaries of the Lesser Sac

Recesses of the Lesser Sac

• Superior recess - extends upward behind the caudate lobe of the liver to the diaphragm
• Inferior recess - extends downward between the layers of the greater omentum
• Splenic recess - extends to the left toward the hilum of the spleen between the gastrosplenic and splenorenal ligaments

Clinical Significance of the Lesser Sac

• Posterior gastric ulcer perforation - gastric contents leak into the lesser sac, causing perigastric abscess formation contained within the bursa (rather than spreading to the greater peritoneal cavity)
• Acute pancreatitis - pancreatic enzymes/pseudocysts collect in the lesser sac (posterior relation to pancreas)
• Lesser sac abscess - presents insidiously because the sac is walled off; diagnosed by CT; drained surgically or radiologically

2. Epiploic Foramen (Foramen of Winslow / Omental Foramen)

Boundaries of the Epiploic Foramen

Contents of the Hepatoduodenal Ligament (Anterior Wall of Foramen)

• B - Bile duct (CBD) - rightmost, anterior
• H - Hepatic artery proper - left anterior
• A - portal vein (behind both, posterior)

Clinical Applications of the Epiploic Foramen

1. Pringle Maneuver - a finger is placed through the epiploic foramen to compress the hepatoduodenal ligament between thumb and index finger, occluding the portal vein and hepatic artery. This controls hepatic inflow hemorrhage during liver surgery or trauma. The common bile duct is also within the ligament so it is compressed simultaneously. - Fischer's Mastery of Surgery, p. 4493
2. Herniation through the epiploic foramen - a rare internal hernia where bowel loops (typically small intestine) prolapse through the foramen into the lesser sac, causing intestinal obstruction. It is a surgical emergency requiring manual reduction.
3. Gallstone ileus - a large gallstone can erode from the gallbladder into the duodenum (Mirizzi's area) and impact distally; the epiploic foramen region is a landmark in hepatobiliary surgery.
4. Access to lesser sac - surgeons enter the lesser sac via the epiploic foramen or by dividing the gastrocolic ligament to access the pancreatic body/tail, posterior gastric wall, or to drain collections.

3. Morrison's Pouch (Hepatorenal Recess / Hepatorenal Fossa)

Why it matters - Most Dependent Point

• It lies posterior to the liver and anterior to the right kidney
• Gravity directs fluid here when the patient lies flat
• It is separated from the liver by peritoneum and from the kidney by the hepatorenal ligament

Clinical Applications of Morrison's Pouch

Relation of Morrison's Pouch to Other Peritoneal Recesses

SUPRAHEPATIC SPACE
     ↓ (right subphrenic space)
MORRISON'S POUCH (right subhepatic/hepatorenal)
     ↓
RIGHT PARACOLIC GUTTER
     ↓
PELVIS (rectouterine / rectovesical pouch = pouch of Douglas)

Summary Table