🫁 Thorax & Lungs – Complete Study Guide

🔹 Anatomy & Landmarks

• Thoracic cage → cone-shaped, protects heart & lungs.
• Sternum, 12 ribs, 12 thoracic vertebrae.
• (True Ribs) 1–7: attach to sternum.
• (False Ribs) 8–10: attach to cartilage above.
• (Floating Ribs) 11–12: floating.
• Costochondral junctions are points at which ribs join their cartilages; they are not palpable.

🔹 Chest Configuration

• Normal: Transverse Diameter : Anterior Posterior Diameter = 2:1.
• Barrel chest: 1:1 (common in COPD).

• Trachea should be midline.
• Thoracic expansion: equal both sides.

🫁 Lungs & Thoracic Cavity

📍 Lungs

• Located in right and left pleural cavities.
• Borders to note:
• Apex – top of lungs (extends above clavicle).
• Base – rests on diaphragm.
• Lateral – side surfaces.
• Posterior – back surfaces.

🔹 Lungs

• Lungs are paired but not symmetric.
• Right lung → 3 lobes, shorter (liver).
• Left lung → 2 lobes, narrower (heart).

• Mediastinum: middle section of thoracic cavity containing esophagus, trachea, heart, and great vessel
• Anterior chest → mostly upper/middle lobes.
• Posterior chest → mostly lower lobes.
• Lateral chest → apex of axilla to ~7th/8th rib.

🫀 Thoracic Cavity

• Encloses lungs, heart, great vessels, and mediastinum.
• Each lung is cushioned and protected by its pleural cavity.

🫁 Pleurae

• Slippery pleurae form a protective envelope between lungs and chest wall.

🔹 Types of Pleura

• Visceral Pleura 🩻 – Lines the outside of the lungs, dipping into fissures.
• Parietal Pleura 🛡️ – Lines the chest wall (not in your note, but important to pair with visceral).

⚖️ Pleural Cavity

• Vacuum / Negative Pressure – Holds lungs tightly against chest wall → prevents collapse.
• Potential Space – Normally only contains a few mL of lubricating fluid.
• Function: allows smooth gliding during breathing movements.

🫁 Trachea & Bronchial Tree

📍 Trachea

• Lies anterior to the esophagus.
• Length: 10–11 cm in adults.
• Connects environment → lungs for gas exchange.

🔹 Main Bronchi

• Right main bronchus: shorter, wider, more vertical.
• Clinical note: higher risk for aspirated objects.
• Left main bronchus: longer, narrower, more horizontal.

⚖️ Functions

• Transport gases between environment and lung parenchyma.
• Create dead space:
• Air that does not participate in gas exchange.
• About 150 mL in adults.
• Bronchial tree protects alveoli from small particulate matter.

🧪 Structure

• Lined with goblet cells → secrete mucus to trap debris.
• Cilia help sweep mucus upward toward pharynx.

🫀 Acinus (Functional Unit)

• Includes:
• Bronchioles
• Alveolar ducts
• Alveolar sacs
• Alveoli → site of gas exchange (O₂ ↔ CO₂).

🔹 Respiratory Physiology

• Functions: O₂ in, CO₂ out, regulates acid–base balance, minor heat exchange.
• Control (factors that trigger breathing):
• Main drive = ↑ CO₂ (hypercapnia).
• ↓ O₂ (hypoxemia) also stimulates breathing.
• Breathing mechanics:
• Inspiration = chest expands, air in.
• Expiration = chest recoils, air out.
• Observe rhythm: inspiration → pause → expiration.
• Tachypnea = rapid, shallow breathing. Hyperventilation = rapid, deep breathing.

Assessment

🔹 Subjective Data (ask patient)

Ask at least 3 questions:

• Do you have a cough? Do you suffer from any respiratory condition or illness?
• Do you feel short of breath?
• Do you have chest pain with breathing?
• History of respiratory infections?
• Smoking history?
• Environmental exposures (dust, smoke)?

🔹 Objective Assessment

1. Inspection 👀

• Chest movement: symmetric rise/fall.
• Skin: color, lesions, abrasions.
• Shape/configuration: 2:1 ratio.
• Face: nasal flaring, accessory muscles, diaphoresis, JVD, anxiety.
• Trachea: should be midline.

2. Nail & Skin Assessment 💅🧴

• Nails: check for clubbing (chronic hypoxia), cyanosis, capillary refill (< 3 sec).
• Skin:
• Color changes (pallor, cyanosis, jaundice).
• Moisture (dry, clammy, sweaty).
• Temperature (warm, cool).
• Mobility (pinch test).
• Turgor (return after pinch → tenting = dehydration).

👉 This step is crucial because nail/skin changes often reveal chronic respiratory or cardiac problems.

3. Palpation ✋

• Check for: lesions, masses, moisture, tenderness/pain.
• Thoracic expansion: thumbs at lower lungs (front & back), watch for symmetry.
• Tactile fremitus: patient says “99”, feel equal vibrations with both hands.

• Check spine alignment (scoliosis).
• Assess skin mobility (pinch) & turgor (return).

4. Percussion 🔨

• Compare side to side.
• Posterior chest: percuss top to bottom.
• Note dullness (fluid/mass) vs resonance (normal air).

5. Auscultation 🎧

• Use diaphragm of stethoscope.
• Listen to full inspiration/expiration.
• Compare both sides, same level.

• Normal breath sounds:
• Bronchial sound (over trachea).
• Bronchovesicular (major bronchi).
• Vesicular (peripheral lung fields).

• Adventitious sounds:
• Wheeze → asthma.
• Crackles → fluid, pneumonia, atelectasis.
• Absent sounds → obstruction or collapse.
• Voice sounds (if abnormal suspected):
• Bronchophony → “99” heard clearly = abnormal.
• Egophony → “eee” sounds like “aaa.”
• Whispered pectoriloquy → whispers heard loudly.

🔹 Oxygen Saturation

• Normal: 95–100%.
• COPD: acceptable at 88 - 92%.

🔹 Clinical Tips (Important for Testing)

• Don’t let hyperventilating patients stand → risk of fainting.
• Leaning forward can help in respiratory distress.
• Barrel chest often linked to chronic lung disease.
• Respiratory distress can also indicate cardiac problems.
• During CPR, pressing too low may break the xiphoid process.

🔹 Developmental Considerations

• Pregnant women: uterus pushes diaphragm → physiologic dyspnea.
• Older adults: ↓ vital capacity, ↑ residual volume, ↓ elasticity/gas exchange.
• Residual volume: the volume of air left in the lungs after a maximum forced exhalation.
• Infants/children:
• Immediate lung function needed at birth.
• Environmental smoke → ↑ SIDS, behavior issues, adolescent smoking.

🌍 Culture & Genetics

• Lung cancer → 2nd most common cancer; smoking major risk.
• Tuberculosis (TB) → affects ⅓ of world; linked to migration/social factors.
• Asthma → most common chronic disease in kids; higher rates in poverty; influenced by environment & ethnicity.

🔹 Extra Clinical Frameworks

• Pain → PQRST (Provocation, Quality, Region, Severity, Timing).
• Skin breakdown (stages):

• Spirometer → measure lung capacity (clinical tool).

📍 Reference Lines of the Chest

Reference lines are used to pinpoint vertical findings on the chest during assessment.

🫀 Anterior Chest

• Midsternal line → runs vertically down the center of the sternum.
• Midclavicular line → runs vertically through the midpoint of each clavicle.

🦴 Posterior Chest

• Vertebral (midspinal) line → straight down the spine.
• Scapular line → runs vertically through the inferior angle of the scapula.

➡️ Lateral Chest

(Arm lifted 90° for accuracy)

• Anterior axillary line → vertical line from the anterior axillary fold (front of armpit).
• Posterior axillary line → vertical line from the posterior axillary fold (back of armpit).
• Midaxillary line → vertical line through the middle of the armpit.

Abnormalities. Just in case… Pectus carinatum.

Pectus escavatum