Thoracic Wall Layers
Six layers from skin to pleura. Understanding each layer guides chest drain insertion, thoracotomy incision planning, and CT interpretation.
✦ The Mnemonic
"Skilled Surgeons Cut, Mobilise Ribs, Enter Pleural spaces"
Skin · Subcutaneous · Muscles · Ribs+intercostals · Endothoracic fascia · Parietal pleura
Clinical Breakdown
The parietal pleura is the final layer — penetrating it enters the pleural cavity. It has somatic innervation (intercostal + phrenic nerves) — sensitive to pain. The visceral pleura has no somatic innervation — pleural pain only arises from parietal pleural irritation.
Breast tissue occupies the subcutaneous layer of the anterior chest wall — 2nd to 6th rib, lateral sternal edge to mid-axillary line. The axillary tail of Spence extends into the axilla. Lymph drains predominantly (75%) to axillary nodes; medial quadrants to parasternal (internal mammary) nodes.
In a standard posterolateral thoracotomy: skin → subcutaneous fat → latissimus dorsi → serratus anterior → 4th or 5th intercostal space → intercostal muscles and endothoracic fascia → pleural cavity.
⭐ Clinical Pearl
Winged scapula: long thoracic nerve (C5–7) damage paralyses serratus anterior. Without it, the medial scapular border wings posteriorly when the arm is pushed forward. Causes: axillary node dissection, radical mastectomy, overhead athletic activities, neuralgic amyotrophy.