Vasculature of thoracic walls and sympathetic trunk PDF

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Vasculature of thoracic walls (anterior and posterior) and sympathetic trunk...

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Vasculature of thoracic walls and sympathetic trunk POSTERIOR THORACIC WALL Arterial supply: Paired posterior intercostal + subcostal arteries => supply the posterior ICS 

First 2 pairs (1st & 2nd intercostal spaces) = superior/supreme intercostal arteries from the costocervical trunk branch off the 2nd part of subclavian artery

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Pairs 3-11= posterior intercostal arteries from the thoracic descending aorta

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Pair 12= subcostal arteries from the thoracic descending aorta

Venous drainage: Azygos venous system in the PMS draining the posterior intercostal veins, which drain the posterior ICS Azygos vein: 

drains the right posterior intercostal veins and subcostal vein from the T5T12.

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Azygos vein begins as a continuation of the right ascending lumbar vein (which also drains into IVC) when it joins with the right subcostal vein at level T12.

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It ascends along the RHS of vertebral column and drains into the SVC at azygos arch =level of sternal angle (T4/T5), where the azygos vein arches over the root of the left lung

LHS equivalent to azygos vein/tributaries of the azygos vein: 

Accessory hemiazygos drains left posterior intercostal veins T5-T8

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Hemiazygos vein drains left posterior intercostal veins and subcostal veinT9T12 => HA vein connects to left ascending lumbar vein (which also drains into IVC)

**N.B. left and right superior intercostal veins (which are posterior) 

within the SMS

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drain the 2nd 3rd & 4th intercostal spaces (T2 T3 T4).

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The left T2-T4 intercostal spaces are not drained by azygous, but the Left superior intercostal vein drains into the left brachiocephalic vein at level of venous arch.

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The right superior intercostal vein drains blood from the right T2-T4 intercostal spaces and does drain into the Azygos vein.

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(NB. Left bronchial vein drains into the left superior intercostal vein, BUT the right bronchial vein drains into the azygous vein at arch of azygos).

=> The hemiazygos and accessory hemiazygos veins drain into the azygos which drains all the blood into the SVC Therefore=> the azygous vein receives blood from: 1. Posterior intercostal and subcostal veins on the RHS 2. The hemiazygos vein 3. The accessory hemiazygos vein 4. Also some bronchial, oesophageal, pericardial veins- right bronchial vein drains to azygos The azygous vein ascends into the thoracic cavity through the aortic hiatus level T12 with the descending aorta(descending) and thoracic duct(ascending) The azygous system is an indirect connection between the SVC & IVC, because the azygos vein, which drains into the SVC, and the hemiazygos are inferiorly connected to/are superior continuations of the right and left ascending lumbar veins, which drain into the IVC.

Nerve supply: 1. Paired Intercostal nerves T1-T11 and subcostal nerve T12= Anterior rami of thoracic spinal nerves: 

Same on both sides

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Mixed motor and sensory nerves

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Give off branches as they travel through the IC space

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Same nerves for the anterior thoracic wall- extend the whole way forward

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Muscular branch => motor innervation innermost, internal and external IC muscles.

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Parietal branch => innervate parietal pleura of lung

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Lateral and anterior cutaneous branches => innervate skin & superficial fascia of thorax

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T1=> contributes to brachial plexus

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T2=> motor innervation to IC muscles of 2nd IC space, sensory innervation to axilla and medial surface of arm

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T3-T6=> motor innervation to IC muscles of 3rd to 6th IC spaces, sensory innervation to anterior thoracic chest wall

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T7-T12 =>innervate the IC Muscles of remaining IC spaces, some abdominal muscles, overlying skin

2. Sympathetic thoracolumbar trunk – system of sympathetic ganglion giving off sympathetic nerve (in the PSM):

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=A pair of chains of ganglia, one extending along each side of the vertebral column from the base of the skull to the coccyx. Each trunk is part of the sympathetic nervous system and consists of a series of ganglia connected by various types of fibres.

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Same on both sides It allows nerve fibres to travel to spinal nerves splanchnic nerves, arise directly from the trunks. Gray and white communicantes connect the sympathetic trunk ganglia to the spinal nerve (intercostal nerve) in the intercostal space.

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nerves to T1-T5 => to thoracic viscera

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sympathetic nerve from T5-T9 or T5-T10 => greater splanchnic nerve

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sympathetic nerve from T9-T10 or T10-T11=> lesser splanchnic nerve

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sympathetic nerve from T12 = least splanchnic nerve

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the greater, lesser and least are all preganglionic fibres, pass into the abdominal cavity through the diaphragm, synapse in ganglia and become post-ganglionic fibres

No “posterior” or “anterior” ICN’s Each posterior intercostal space contains one posterior intercostal artery, one posterior intercostal vein, and one intercostal nerve The V, A, N travels together as a bundle known at the intercostal neurovascular bundle in the intercostal/costal groove on the inner inferior border of the superior rib of the intercostal space – the V, A, N each give off small collateral branched which travel in a small bundle along the superior border of the inferior rib.

ANTERIOR THORACIC WALL

Arterial supply: Paired anterior intercostal + subcostal arteries=> supply the anterior ICS, same on both sides: 

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Pairs 1-6 (in 1st to 6th IC spaces) => from internal thoracic (mammary) artery, a branch off the 1st part of subclavian artery (ITA is a common artery used for heart bypass). Pairs 7-9 (7th – 9th anterior ICS) => from musculophrenic artery, lateral branch of internal thoracic artery at the 6th CC/ICS (medial branch = superior epigastric artery) **NO ANTERIOR INTERCOSTAL ARTERIES BELOW 9TH IC SPACE => no anterior intercostal arteries in 10th & 11th IC spaces or an anterior subcostal artery – related to fact that the 11th and 12th ribs are floating from the posterior. N.B. the branches off the internal thoracic (mammary) artery: 1. Pericardiacophrenic artery = the most superior lateral branch 2. Pericardial branches = Perforating branches medially 3. Mediastinal branches= Perforating branches medially 4. Sternal branches = Perforating branches medially 5. 1st-6th pairs on anterior intercostal arteries, in upper 6 ICS 6. Bifurcates at the level of 6thCC/ICS… 7. Medial terminal branch = superior epigastric artery 8. Lateral terminal branch = musculophrenic artery => provides the lower 3 pairs of anterior intercostal arteries for the 7th to 9th ICS.

Venous drainage: internal thoracic (mammary) vein, draining the anterior intercostal veins, which drain the anterior ICS     

Same on both sides ITV formed by union of the 2 venae comitantes of the internal thoracic artery, behind the 3rd CC Similar to structure of ITA, superior epigastric and musculophrenic veins join to form ITV The ITV ascends close to and medial to the ITA ITV drains into the brachiocephalic (innominate) vein

Nerve supply: Same as posterior thoracic chest wall: Paired Intercostal nerves T1-T11 and subcostal nerve T12= Anterior rami of thoracic spinal nerves: 

same on both sides



Mixed motor and sensory nerves



Give off branches as they travel through the IC space



Same nerves for the anterior thoracic wall- extend the whole way forward



Muscular branch => motor innervation innermost, internal and external IC muscles.



Parietal branch => innervate parietal pleura of lung



Lateral and anterior cutaneous branches => innervate skin & superficial fascia of thorax



T1=> contributes to brachial plexus



T2=> motor innervation to IC muscles of 2nd IC space, sensory innervation to axilla and medial surface of arm

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T3-T6=> motor innervation to IC muscles of 3rd to 6th IC spaces, sensory innervation to anterior thoracic chest wall

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T7-T12 =>innervate the IC Muscles of remaining IC spaces, some abdominal muscles, overlying skin

No “posterior” or “anterior” ICN’s=> the same intercostal (or subcostal) nerve travels from spinal cord within the vertebral column, from the posterior to anterior thoracic chest wall in the costal groove. Same as posterior thoracic wall => Each anterior intercostal space contains one anterior intercostal artery, one anterior intercostal vein, and one intercostal nerve Same as posterior thoracic chest wall => The V, A, N travels together as a bundle known at the intercostal neurovascular bundle in the intercostal/costal groove on the inner inferior border of the superior rib of the intercostal space...