Thoracic duct Its course relations origin and termination and tributaries

THORACIC DUCT

1. THORACIC DUCT DR MAYURA SETIYA ASSOCIATE PROFESSOR

2. THORACIC DUCT Largest lymphatic vessel in body Measurements: Length: 45 cm Width: 5 mm Extent: Extends from upper part of abdomen to lower part of neck Appearance: Has beaded appearance due to presence of numerous valves Human Anatomy/Yogesh Sontakke 2

3. THORACIC DUCT Beginning Begins as continuation of upper end of cisterna chyli at lower border of T12 Cisterna chyli is a lymphatic sac that collects lymph from lower body and drains into thoracic duct. It is located at the level of L1-L2 Human Anatomy/Yogesh Sontakke 3

4. THORACIC DUCT Course Enters in thoracic cavity through aortic opening of diaphragm at level of T12 Ascends upward in posterior mediastinum Crosses from right to left , opposite to T 5 Ascends upward in superior mediastinum along left edge of esophagus In Neck – arches laterally opposite transverse process of C7 vertebra (3–4 cm above left clavicle) Human Anatomy/Yogesh Sontakke 4

5. THORACIC DUCT Termination In Neck – opens at the junction of left internal jugular vein and left subclavian vein Human Anatomy/Yogesh Sontakke 5

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7. THORACIC DUCT Relations At aortic opening Anterior: Diaphragm (median arcuate ligament of diaphragm) Posterior: T12 vertebra To right: Azygos vein To left: Descending thoracic Aorta Human Anatomy/Yogesh Sontakke 7

8. Relations In posterior mediastinum Anterior: Diaphragm Oesophagus Posterior : Vertebral column (T5-T12) Right posterior intercostals arteries Terminal parts of hemiazygos and accessory hemiazygos veins To right: Azygos vein To left: Descending thoracic aorta Human Anatomy/Yogesh Sontakke 8

9. Relations In superior mediastinum Anterior: Arch of aorta Commencement of left subclavian artery Posterior : Vertebral column To right: Edge of oesophagus To left: Left lung and pleura Human Anatomy/Yogesh Sontakke 9

10. Relations In root of neck Anterior: Carotid sheath ( left common carotid, left internal jugular vein, left Vagus nerve) Posterior : Vertebral artery and vein Sympathetic trunk Scalenus anterior Phrenic nerve Human Anatomy/Yogesh Sontakke 10

11. Tributaries Formed by the upward continuation of cisterna chyli Pair of descending thoracic lymph trunks Pair of ascending lumbar lymph trunks Lymph vessels from posterior mediastinal lymph nodes Human Anatomy/Yogesh Sontakke 11

12. In neck Left jugular lymph trunk – drains left half of head and neck Left subclavian lymph trunk – drains lymph from left upper limb Left Broncho mediastinal lymph trunk – drains left lung and left side of heart Tributaries 12

13. THORACIC DUCT Area of Drainage Drains lymph from all parts of body except Right side of head and neck Right upper limb Right of chest wall Right lung and right side of heart Right surface of liver Human Anatomy/Yogesh Sontakke 13

14. CLINICAL APPLIED Thoracic duct is thin walled and appears to be colorless during surgery therefore it may be injured inadvertently during surgical procedures in the posterior mediastinum . Leakage of chyle into the pleural cavities produces a clinical condition called Chylothorax May occur due to rupture of thoracic duct (may be caused by trauma, tuberculosis, or malignancy) Human Anatomy/Yogesh Sontakke 14

15. CLINICAL APPLIED Cervical part of thoracic duct may be damaged during block dissection of the neck .It should be ligated immediately. If not detected and ligated it may cause thoracic duct fistula - Chylous fistula Human Anatomy/Yogesh Sontakke 15

16. CLINICAL APPLIED Obstruction of thoracic duct Thoracic duct gets obliterated may be due to infection by microfilarial Wuchereria bancrofti parasite or by obstruction from external structures such as malignancies leading to effects like Chylothorax, chyloperitoneum, chyluria Human Anatomy/Yogesh Sontakke 16

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