Thoracic Wall 2 Flashcards
Function of pectoralis major
Abducts and medially rotates humerus (flexion)
Function of pectoralis minor
stabilises scapula
Function of serratus anterior
holds scapula against thoracic wall
How many pairs of intercostal spaces are there?
11
Where are the external intercostal muscles located?
Extend from inferior edge of the rib above to the superior edge of the rib below
Function of the external intercostal muscles
Raise ribs in inspiration
Where are the external intercostal muscles replaced by membrane
Anteriorly (upper edge is closer to vertebral column
Where are the internal intercostal muscles located?
Extend from lateral edge of rib above to superior edge of rib below
Function of the internal intercostal muscles
Prevent indrawing; aid elastic recoil in expiration
Where are internal intercostal muscles replaced by membrane?
Posteriorly (lower attachment is closer to vertebrae)
Name 3 other muscles of the thoracic wall
Innermost intercostal muscle, transverus thoracis, subcostalis
What passes through the intervertebral foramen?
spinal nerve
What nerves don’t form a plexus?
Anterior rami of thoracic spinal nerve – maintain their segmental orientation
Where do the intercostal nerve, artery and vein lie?
Costal groove at the inferior edge of the rib between the internal and innermost intercostal muscles
What other nerves supply the anterior thoracic wall?
Supraclavicular (C3-4); descend over clavicle as far as the 2nd CC
What thoracic nerve is at risk during breast surgery?
T2, intercostobrachial supplies thorax wall in the axilla and upper, medial part of upper limb
What does the ventral ramus of T1 supply?
Small muscles of the hand, skin if the medial aspect of the arm and forearm and muscles of the 1st intercostal space
What does the ventral ramus of T2-T11 supply?
Motor fibres of intercostal muscles and abdominal muscles and sensory supply to the skin and parietal pleura
What does the subclavian artery split into?
Vertebral artery (supplies CNS), thyrocervical trunk, costo-cervical trunk, internal thoracic artery
What level is the thoracic aorta at?
T4-T12 (T4/5 = sternal angle)
What does the thoracic aorta split into?
Posterior intercostal arteries (3rd-11th), subcostal artery and superior phrenic artery
What does the internal thoracic artery split into?
Superior epigastric and musculophrenic arteries (anterior)
Where do the 1st and 2nd intercostal arteries arise from?
Supreme intercostal branch of costo-cervical trunk
Where do the anterior intercostal arteries arise from?
- Internal thoracic artery (1-6)
- 7-10 = branch from musculophrenic
Where do the anterior intercostal veins drain to?
Internal thoracic vein –> brachiocephalic vein
Where do the posterior intercostal veins drain to?
Brachiocephalic or superior vena cava via azygos system
Where does the azygos system pass?
Behind diaphragm with the aorta and thoracic duct
What does the azygos vein connect to
Superior and inferior vena cava
Where does the hemiazygos vein cross to the right?
T9 to join azygos
Where does the hemiazygos vein pass?
Through or behind left crus of diaphragm
What does the accessory hemiazygos vein drain?
5-8 of left side
Name the anterior lymph nodes of the thoracic wall
Parasternal node and broncho-mediastinal trunks
Name the posterior lymph nodes if the thoracic wall
Intercostal nodes, thoracic duct (inferior) and broncho-mediastinal trunks (superior)
What does the hemiazygos vein drain?
Left posterior intercostal veins of ribs 9-12
