jugular vein

**Anatomy** - **Internal jugular vein (IJ):** Begins at the jugular foramen as the continuation of the sigmoid sinus (exits with CN IX, X, XI). Descends in the carotid sheath lateral to the internal then common carotid artery, with the vagus nerve (CN X) posterior between them. Joins the subclavian vein behind the sternoclavicular joint to form the brachiocephalic vein. Tributaries: inferior petrosal sinus, facial, lingual, pharyngeal, superior and middle thyroid veins. - **External jugular vein (EJ):** Formed by the posterior auricular vein and the retromandibular vein (posterior division) near the angle of the mandible. Runs superficially over the sternocleidomastoid (SCM), deep to platysma, and drains into the subclavian vein. - **Anterior jugular vein:** Small, drains the anterior neck into the EJ or subclavian vein. - Jugular foramen contents: CN IX, X, XI and the IJ. Jugular foramen syndrome (Vernet) affects CN IX, X, XI.

**Jugular venous pressure (JVP)** - The IJ connects almost directly to the right atrium, so its pulsations reflect right atrial pressure. Normal JVP is under 8 cm H2O above the sternal angle (about 3-4 cm above the angle, or about 8 cm above the right atrium). - Waveforms: - **a wave:** atrial contraction (absent in atrial fibrillation; giant/cannon in AV dissociation, complete heart block, or pulmonic stenosis/pulmonary hypertension). - **c wave:** tricuspid bulging into the RA during isovolumetric ventricular contraction. - **x descent:** atrial relaxation and downward displacement of the tricuspid valve during ventricular systole (absent or blunted in tricuspid regurgitation). - **v wave:** passive venous filling of the RA against a closed tricuspid valve (giant v waves in tricuspid regurgitation). - **y descent:** tricuspid opening and RA emptying into the RV (steep/rapid in constrictive pericarditis; blunted in tamponade).

**Clinical correlations** - **Elevated JVP:** right heart failure, left heart failure with biventricular failure, volume overload, tricuspid stenosis or regurgitation, constrictive pericarditis, cardiac tamponade, restrictive cardiomyopathy, pulmonary hypertension or PE, and SVC obstruction (in SVC syndrome the JVP is elevated but nonpulsatile). - **Low JVP:** hypovolemia, hemorrhage, or distributive shock. - **Kussmaul sign:** paradoxical rise in JVP on inspiration (normally it falls). Seen in constrictive pericarditis, restrictive cardiomyopathy, and right ventricular infarction or severe RV failure. It is usually absent in tamponade. - **Hepatojugular reflux:** sustained JVP rise (over 3 cm for at least 15 s) with abdominal pressure, suggesting RV failure. - **Cannon a waves:** the RA contracts against a closed tricuspid valve. - **Pulsus paradoxus with elevated JVP and muffled heart sounds (Beck triad):** cardiac tamponade. - **Central venous access:** the right IJ is preferred (straight path to the SVC, lower pleural dome). Complications include carotid artery puncture, pneumothorax, air embolism, and thoracic duct injury (left side). Ultrasound guidance is standard. The IJ lies lateral to the carotid artery at the apex of the triangle formed by the two heads of the SCM. - **Air embolism:** neck veins are under negative pressure and do not collapse when injured. Patients can aspirate air during neck trauma or line removal, which causes a "mill-wheel" murmur. Treatment is left lateral decubitus with head down (Durant maneuver). - **IJ thrombosis:** associated with central lines, IV drug use, and malignancy. Lemierre syndrome is septic thrombophlebitis of the IJ, usually after oropharyngeal infection with *Fusobacterium necrophorum*, with septic pulmonary emboli. - **EJ distension:** visible in the supine position in normal people, but it can be a marker of elevated CVP when seen at 45° or upright. - **Dural venous sinuses:** the sigmoid sinus drains to the IJ, so mastoiditis can cause sigmoid sinus thrombosis and raised intracranial pressure.

**Mnemonics and pearls** - The IJ is the better JVP indicator because it is in direct line with the RA. The EJ is less reliable because of valves and kinking. - Right IJ JVP is assessed with the patient at 45° and the head turned slightly left. - Palpable pulsation versus visible JVP: the JVP is biphasic, not palpable, falls with inspiration, and rises with abdominal pressure. The carotid pulse is the opposite.