Notes on Thorax Anatomy

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• Internal thoracic (internal mammary) artery; lateral thoracic artery; thoracoacromial branches of axillary artery, and intercostal arteries.


• Axillary vein.


• Axillary and parasternal lymph nodes.


• Intercostal nerves 2-6.


• 1-7 = true.

• 8-10 = false.

• 11-12 = floating.

Respiratory Distress Syndrome:

• Newborns of diabetic moms, premature infants, prolonged intrauterine asphyxia.

• Deficiency of surfactant; treat with thyroxine and cortisol.

Hyaline Membrane disease:

• Complication of RDS.

• Damaged alveolar lining.

• Atelectasis and eosinophilic (pink) membrane covering the alveoli.

Outermost to innermost:

• Parietal pleura, pleural cavity, visceral pleura.

Innervation of parietal pleura:

• Intercostal nerves: costal + peripheral diaphragmatic pleura.

• Phrenic nerve: central diaphragmatic and mediastinal pleura.



• Left and right pulmonary arteries from pulmonary trunk (deoxygenated blood from r. ventricle); bronchial arteries from thoracic aorta.


• Superior right and left, and inferior right and left pulmonary veins (carry oxygenated blood to l. atrium).


• Bronchopulmonary (superficial); pulmonary (deep).


• Anterior and posterior plexuses; sympathetic = bronchodilator; parasympathetic = bronchoconstrictor

Parasympathetic NS:

+ Bronchoconstrictor.

Sympathetic NS:

+ Bronchodilator.

Atrial Septal Defect:

• Opening between atria.

• If small, delayed symptoms till age 30.

Ventricular Septal Defect:

• Opening between ventricles.

• Left-to-right shunting; pulmonary hypertension.

• Right-to-left shunting; Eisenmenger complex - cyanosis.

Transposition of great vessels:

• Right-to-left shunt; cyanosis.

Tetralogy of fallot:

• Pulmonary stenosis; overriding aorta; right ventricular hypertrophy; interventricular septal defect.

Persistent truncus arteriosus:

• Right-to-left shunt; cyanosis.

• Combined aorta and pulmonary vein; one vessel leaves the ventricles.

What is Patent Ductus Arteriosus?

• Unclosed ductus arteriosus creates link between aorta and pulmonary vein.

• Caused by prostaglandin E and intrauterine or neonatal asphyxia.

• Treat with prostaglandin inhibitors (eg., ACh).


• Motor supply: phrenic nerve.



• Right (r. atrium).

• Left (l. ventricle and auricle of l. atrium).

• Superior (r. and l. auricles, and conus arteriosus of r. ventricle).

• Apex (l. ventricle).


• Anterior/sternocostal (r. ventricle).

• Posterior (l. atrium).

• Diaphragmatic (l. ventricle).


• Right (3rd r. costal cartilage to 6th r.costal cartilage).

• Inferior (6th r. costal cartilage to 5th l. intercostal space).

• Left (5th l. intercostal space to 2nd l costal cartilage).

• Superior (2nd left costal cartilage to 3rd r. costal cartilage).

Arterial supply:

• R. coronary artery; branches include: SA nodal artery, r. marginal artery, posterior interventricular artery

• L. coronary artery; branches: anterior interventricular artery, and circumflex artery

Venous drainage:

• Coronary sinus, great cardiac vein, middle cardiac vein, venae cordis minimae (thebesian veins), and anterior cardiac veins.

Conduction system:


• Pacemaker.


• Receives impulses from SA; slows impulses so they reach atria before ventricles.

Bundle of His:

• Conducts impulses to ventricles.


Parasympathetic NS:

+ Slows HR.

Sympathetic NS:

+ Increases HR.

Additional Notes:

• Peau d'orange sign in breast cancer caused by blocked lymphatic breast channels.

• Skin dimpling or retraction in breast cancer caused by Cooper ligaments.

• Internal intercostal muscles used during forced expiration in dyspnea.

• Tension pneumothorax more damaging than open or closed pneumothorax.

• Oxygen and nutrients supplied to lungs by bronchial arteries.

• Tumors from the kidneys first spread to the lungs through the inferior vena cava.

• Musculi pectinati: look like teeth of a comb; found in appendix.

• Heart begins to beat on day ~ 21 to 22 of embryo development.

• Breast nipple innervated by 4th branch of intercostal nerves.

• An injection close to the upper border of the rib induces minimum damage.

• Damaged serratus anterior: winged scapula.

• Cyanotic child assumes squatting position for relief: aorticopulmonary septum is displaced anteriorly and superiorly.

• Anterior interventricular branch (LAD) of the left coronary artery: most commonly occluded in fatal MI; affects bundle of His.

Additional Reading:

Histology and Cytology

1. Cell Components
2. Nervous Tissue
3. Muscle Tissue
4. Lymphoid Tissue
5. Integument
6. Respiratory System
7. Gastrointestinal System
8. Renal/Urinary System
9. Male Reproductive System
10. Female Reproductive System

Gross Anatomy

1. Back and Nervous System
2. Thorax
3. Abdomen, Pelvis, and Perineum
4. Upper Limb
5. Lower Limb
6. Head and Neck
7. Chest Wall
8. Shoulder

Anatomy Videos

1. Video of Musculoskeletal Examination in a Clinical Setting
1. Video of HEENT Examination in a Clinical Setting

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1. Jugular Venous Distention Workup

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