MEDIASTINUM — Drawable Diagram

Draw this in exam: Lateral view showing 4 compartments + contents + masses + syndromes
MEDIASTINUM — Lateral View (Draw This Cross-Section) Patient facing LEFT. Sternum = front. Spine = back. STERNUM (front) SPINE (back) T4 plane (Sternal angle = Angle of Louis) SUPERIOR • Aortic arch + 3 branches (brachiocephalic, L carotid, L subclavian) • SVC · Trachea (bifurcates T4) · Esophagus (behind trachea) • Thymus · Thoracic duct · Vagus · Phrenic • L Recurrent Laryngeal N. — hooks UNDER aortic arch MASS: Retrosternal goiter → Pemberton's sign SYNDROME: SVC obstruction, Horner's (sympath chain) ← PERICARDIUM → ANTERIOR Behind sternum In front of pericardium • Thymus (remnant) • Fat, lymph nodes • Int. thoracic vessels MASSES — 4 T's: Thymoma Teratoma Terrible lymphoma Thyroid (retrosternal) Thymoma → MG (30-50%) Lymphoma = commonest anterior mass overall 🇮🇳 Hodgkin's in young Indians MIDDLE = Pericardium + contents • Heart + pericardium • Ascending aorta • Pulmonary trunk • SVC • Main bronchi (carina) • Phrenic N. (on pericardium) MASS: Lymphadenopathy 🇮🇳 TB = #1 cause in India Also: sarcoid (bilat hilar) Phrenic palsy → elevated hemidiaphragm + sniff test POSTERIOR Behind pericardium In front of T5-T12 • Desc. aorta • Esophagus • Thoracic duct • Azygos vein • Vagus → plexus • Sympathetic chain MASS: Neurogenic Schwannoma / Neuroblastoma 🇮🇳 Esoph compressed by large LA (RHD→MS) ↑ Sternum side Spine side ↑ COMPRESSION SYNDROMES — What Masses DO Each structure compressed → a named syndrome. Draw as table. STRUCTURE SYNDROME FEATURES CAUSE SVC SVC Syndrome (obstruction) Face/arm edema, plethora Neck veins, Pemberton's Worse bending forward Lung Ca (small cell) L Recurrent Laryngeal N. Ortner's Syndrome (when from LA/RHD) Hoarseness (L > R) Bovine cough (weak) Lung Ca, 🇮🇳 RHD→MS Phrenic N. (C3-C5) Phrenic Palsy Elevated hemidiaphragm Paradox on sniff test Tumor, cardiac surgery Sympathetic Chain Horner's Syndrome Miosis, ptosis, anhydrosis (ipsilateral) + enophthalmos Pancoast tumor (apex) Esophagus Dysphagia Dysphagia lusoria (aberr R subcl) 🇮🇳 LA enlarge (RHD→MS) Vascular, RHD, Ca RULE: Anterior = 4 T's | Middle = Heart + nodes (TB in India) | Posterior = Nerves L RLN hooks under AORTIC ARCH → left hoarseness > right. "Left takes scenic route, pays the price."
🧠 5 RETENTION ANCHORS:
1. T4 (sternal angle) divides superior from inferior. Everything above T4 = superior.
2. Anterior = 4 T's (Thymoma→MG 30-50%, Teratoma, Terrible lymphoma, Thyroid retrosternal)
3. Middle = pericardium + contents. TB lymphadenitis = #1 cause of middle mediastinal mass in India
4. Posterior = neurogenic tumors (schwannoma adult, neuroblastoma child). "Nerves hide in the back"
5. RHD→MS→large LA compresses: esophagus (dysphagia), L RLN (Ortner's hoarseness), L main bronchus (collapse). One disease, three compressions.