⭐ Spleen — 20% That Gives 80% Marks (High-Yield Summary)

1️⃣ Location & Relations (Ultra-High Yield)

• Left upper quadrant, under the diaphragm.
• Lies deep to ribs 9–11 (MCQ favourite).
• Long axis = along the 10th rib.
• Does NOT cross anterior to mid-axillary line → if palpable = splenomegaly.

Key Relations

• Hilum → lies between stomach & left kidney

→ both give gastric & renal impressions.

• Colic area → touches splenic flexure + phrenicocolic ligament (spleen rests on this).

2️⃣ Development (Most students forget this!)

• Spleen develops in the dorsal mesogastrium → explains:
• Intraperitoneal position
• Ligaments: gastrosplenic & splenorenal
• Notched anterior border = due to fusion of multiple embryonic “splenules”.

3️⃣ Peritoneal Relationships

• Spleen lies in greater sac, but sits at the margin of the lesser sac.
• Covered by peritoneum except at hilum.

Important Ligaments

• Gastrosplenic → contains short gastric + left gastroepiploic vessels.
• Splenorenal → contains splenic vessels + tail of pancreas (very important surgically).

4️⃣ Clinical Exam Clues

• Not normally palpable.
• If enlarged, moves towards right iliac fossa (diagonal).
• Dull percussion (vs. stomach → tympanic).

5️⃣ Splenic Statistics — the “1–3–5–7–9–11 rule” (Memory GOLD)

• 1 × 3 × 5 inches
• 7 ounces
• Lies between ribs 9–11

Exam HOT SPOT — they love this rule.

💡 Why These Are the Most Important Points

Most exam questions ask about:

• Relations (stomach, kidney, diaphragm, ribs)
• Peritoneal ligaments → especially splenorenal (tail of pancreas!)
• Development (dorsal mesogastrium)
• Palpation & enlargement direction
• 1-3-5-7-9-11 rule

These will cover 80% of anatomy questions.

⭐ Spleen — High-Yield 20% (From This Passage)

1️⃣ Peritoneal Covering & Ligaments (VERY HIGH YIELD)

• The spleen is intraperitoneal → completely covered by visceral peritoneum (serous coat)

→ except at the hilum.

Two key ligaments (direct continuation of peritoneum):

1. Gastrosplenic ligament
• Runs from spleen → greater curvature of stomach.
• Contains short gastric + left gastroepiploic vessels (exam favourite).
2. Splenorenal ligament
• Runs from spleen → anterior surface of left kidney.
• Tail of pancreas lies inside it ⟶ extremely important surgically (risk of pancreatic injury in splenectomy).

👉 These ligament relationships ALONE give many MCQs.

2️⃣ Contact (Impressions) — How to Identify Surfaces

Hold spleen in left hand:

• Notched anterior border → front (towards thumb)
• Concavity near notches → gastric impression
• Behind hilum → renal impression
• Lower pole → small colic impression

💡 Exam logic: They love asking “which structure forms which impression.”

So remember:

• Gastric → anterior concavity
• Renal → behind hilum
• Colic → at lower pole

3️⃣ Splenic Enlargement (How It Grows — Very Important Clinically)

Direction of enlargement

• Downwards + forwards → towards umbilicus

(NOT straight downward like a kidney)

Key exam points:

• Must be > 2× normal size before the anterior border passes below the costal margin.
• Notched border makes the spleen unmistakable when palpable.
• Mass moves with respiration because it is in contact with the diaphragm.

Percussion Sign (Super High Yield)

• Spleen covers the splenic flexure, which is anchored by the phrenicocolic ligament →

NO colonic resonance over spleen.

To differentiate from kidney mass:

• Kidney = retroperitoneal → colon stays in front → band of colonic resonance over mass.
• Spleen = intraperitoneal → no resonance.

This is asked VERY often.

4️⃣ Massive Splenomegaly

• May cross midline → right iliac fossa.
• Still moves with respiration.
• Still remains dull on percussion.

(Blood Supply, Lymph, Nerve, Development)

1️⃣ Blood Supply — MOST IMPORTANT FACTS

Splenic artery

• One of the largest branches of the coeliac trunk.
• Runs inside the splenorenal ligament.

(Exam hotspot: NOT in the gastrosplenic ligament).

At the hilum

• Divides into 2–3 main branches → each gives 5+ segmental branches.

Clinical pearl

• Possible vascular segments, but segmentation is not definitively proven.
• Surgeons still consider segmental splenectomy in selected cases.

Veins

• Veins follow arteries → unite to form splenic vein.
• Joins superior mesenteric vein → portal vein.

2️⃣ Lymph Drainage (Very High Yield)

• Lymph → hilar nodes

→ pancreaticosplenic nodes (along splenic artery)

→ coeliac lymph nodes.

💡 Remember: Spleen → pancreas pathway → coeliac.

3️⃣ Nerve Supply

• Sympathetic only → from coeliac plexus.
• No parasympathetic supply.

👉 This is frequently asked because most abdominal organs have both sympathetic & parasympathetic — spleen is an exception.

4️⃣ Development — SUPER HIGH YIELD

Origin

• Appears in week 6.
• From mesodermal condensations (NOT endoderm → NOT from gut tube!).

Location logic

• Develops inside dorsal mesogastrium →

dorsal mesogastrium gets stretched → becomes splenorenal & gastrosplenic ligaments.

👉 This development explains all peritoneal relations.

5️⃣ Accessory Spleens (Exam Favourite)

• Failure of fusion of the embryonic splenic buds → accessory spleens (“splenunculi”).
• Found in up to 20% of people.
• Common locations:
• Near splenic hilum
• Along splenic vessels
• Inside gastrosplenic or splenorenal ligament

Clinical significance

• In diseases needing splenectomy (e.g., ITP), an accessory spleen can maintain splenic function → platelet count may not rise unless accessory spleen is removed.

Surgical Approach (20% that gives 80% marks)

1️⃣ What splenectomy really means (core concept)

Splenectomy = cutting the spleen’s two pedicles:

1. Splenorenal ligament (contains splenic vessels + tail of pancreas)
2. Gastrosplenic ligament (contains short gastric vessels)

👉 Everything in splenectomy revolves around safely controlling these TWO pedicles.

🔥 2️⃣ Emergency Splenectomy — FAST and LIFE-SAVING

In rupture + haemorrhage:

Step 1 — Open the splenorenal ligament (posterior layer)

• Cut posterior layer →
• Turn spleen medially to expose splenic vessels.

Step 2 — Control splenic vessels

• Carefully separate them from the tail of pancreas

(danger! tail lies within splenorenal ligament).

• Ligate artery FIRST, then vein.

(Prevents massive venous congestion → safer.)

Step 3 — Divide gastrosplenic ligament + short gastric vessels

• After vessels are controlled, cut short gastric vessels and finish removal.

👉 Main danger here: injuring the tail of the pancreas → postoperative pancreatic fistula.

⭐ 3️⃣ Elective Splenectomy — Safe, Controlled Method

Sequence is reverse of emergency:

Step 1 — Enter the lesser sac

• Done by dividing gastrosplenic ligament + its vessels.

Step 2 — Deal with the pedicle

• Expose splenic vessels → ligate arteries + veins.
• Then divide the splenorenal ligament.

👉 This approach avoids rushing and allows careful dissection.

⚠️ 4️⃣ Critical Structures to Protect (Exam GOLD)

Must NOT injure:

• Tail of pancreas

(lies in the splenorenal ligament → most important surgical danger)

• Stomach

(short gastric vessels are right against it)

• Splenic flexure of colon

(spleen sits above it → traction injury possible)

👉 These are the three organs examiners always test.