Removal of the Ribcage
Costal parietal pleura: Thin serous membrane immediately under endothracic fascia and rib
Loosely adhered to the inner surface of the ribcage
Transverse thoracis muscles: adjacent to the lower end of the sternum
Innermost layer of the intercostal m.
Can see on reflected ribcage
Internal mammary (thoracic) a.: On the innerside of the removed ribcage
Course vertically adjacent to sternum
Branch off subclavian a
Branches into superior epigastric a. and musculophrenic a. near xiphisternal junction
Superior epigastric a. anastamoses with inferior epigastric a.
Within each intercostal space is an anterior intercostal a
Arises from the internal thoracic a.
In each space, an anterior intercostal a. and posterior intercostal a. anastomoses at level of costocervical junctions
Provides collateral pathway
Dissection of Pleural Sacs
Layer 1: Pleural sac
Layer 2: Parietal pleyra
Layer 3: Percardium sac
Layer 4: Mediastrinal pleura
Phrenic n. descends vertically through mediastinum between layer 3 and 4
Course just anterior to root of the lung
Diaphragm: Located just below each lung
Dissection of Superior Mediastinum
Contains roots of great vessels (aortic arch, R brachiocephalic trunk and a., LCCA, L subclavian)
L and R brachiocephalic v. + Azygous v. → SVC
Azygous v. on posteriolateral side of SVC (arches over root of the lungs)
Joins outside pericardial sac
Internal jugular + subclavian veins → L brachiocephalic v.
Runs obliquely
R braciocephalic is vertical
Aortic arch → Brachiocephalic trunk, L CCA and L subclavian a.
External of pericardial sac
Ascending aorta is posterior to the sac
Brachiocephalic a. → R CCA and R subclavian a.
Trachea: immediately posterior to brachiocephalic trunk and L CCA
Esophagus lies deep to trachea
Phrenic n. ascends behind the subclavian v. then crosses 1st rib and anterior scalene m.
Vagus n.: enters thorax
R side: Crosses right subclavian b/w brachiocephalic trunk and R braciocephalic v.
R Recurrent laryngeal n.: Arises around lower border of R subclavian a. and then turns superiorly (ascend between trachea and esophagus)
L side: Between L CCA and L subclavian a.
Crosses aortic arch
L Recurrent laryngeal n.: Turns medially under ligamentum arteriosum (around aortic arch)
Heart
Within pericardial sac
Note that the L atrium is located posteriorly
Apex points inferolaterally
Pulmonary veins (4 of them) are located on the posterior aspect of the pericardial sac
Enter L atrium
1st intercostal space
Space between the 1st and 2nd ribs
Anterior intercostal artery
Small artery that arises from the internal thoracic artery
Located in each intercostal space
Anastomoses with posterior intercostal artery at the level of the costochondral junctions
Anterior scalene muscle
Deep to phrenic nerve (after they ascend behind the subclavian v. and cross the 1st rib)
Aortic arch
Transition between ascending and descending aorta
Branches off of the aortic arch: Brachicocephalic trunk, L CCA, L Subclavian)
Apex of the heart
Tip of the left ventricle pointing inferolaterally
Ascending aorta
Arises from the left ventricle
Azygous vein
Arches over the root of the lung to join with the SVC outside the pericardial sac
Brachiocephalic trunk
The right-most branch of the aortic arch
R subclavian and R CCA arises from the brachiocephalic trunk
Brachiocephalic veins
Formed by the convergence of the R/L internal jugular and subclavian veins
R brachiocephalic v. is nearly vertical
L brachiocephalic v. passes obliquely from L to R
Join to form the SVC
Common Carotid artery
L CCA is a branch off the aorta
R CCA is a branch off the brachiocephalic trunk
Each split into an internal and external carotid artery
Diaphragm
Dome-shaped muscle inferior to the lungs
Contraction flattens and expands lung volume
Esophagus
Located immediately posterior to the trachea
Inferior vena cava
Join with the right atrium (along with the superior vena cava)
Innermost intercostal muscle
Transverse thoracis muscles adjacent to the lower end of the sternum
Intercostal nerve
Located near the upper border of an intercostal space (within the costal groove)
Internal jugular vein
Joins with subclavian v. to form the brachiocephalic veins
Drains blood from the brain, face, and neck
Internal mammary/thoracic artery
Vessels that course vertically adjacent to the sternum between the internal intercostal muscles and transversus thoracis muscle
Divides into 2 terminal branches near the xiphisternal junction (superior epigastric a. and musculophrenic a.)
Left atrium
Receives oxygenated blood from pulmonary veins (2 L and 2 R)
Left ventricle
Pumps blood into ascending aorta
Located posteriorly
Ligamentum arteriosum
Adult remnant of ductus arteriosus (shunt during fetal circulation)
Musculophrenic artery
One of the terminal branches of the mammary artery
Parietal pleura
External layer covering lungs
Space between parietal and visceral pleura = pleural cavity
Phrenic nerve
Arises in the neck from the ventral rami of C3, 4, 5
Descend vertically through mediastinum between mediastinal parietal pleura and pericardium
Course just anterior to root of the lung
Have sensory and motor components
Pleural sac
Consist of outer parietal pleura and inner visceral pleura that encloses the lungs
Pulmonary veins
Veins that travel to the left atrium from the lungs
Carry oxygenated blood
Recurrent laryngeal nerve
Arises from the vagus nerve
R recurrent laryngeal n. at the lower border of the right subclavian artery and turns superiorly to ascend in the neck between the trachea and esophagus
Right atrium
Receives deoxygenated blood from coronary sinus, SVC, and IVC
Right ventricle
Receives deoxygenated blood from the right atrium
Pumps to R and L lungs through pulmonary arteries (1 R and 1 L)
Subclavian artery
L subclavian branches directly off aortic arch
R subclavian branches off brachiocephalic trunk
Subclavian vein
Converge with internal jugular v. to form brachiocephalic veins
Superior epigastric artery
Terminal branch of mammary artery that anastamoses with the inferior epigastric artery
Superior vena cava
Drains into right atrium
Trachea
Located immediately posterior to the brachiocephalic trunk and L CCA
Can palpate the cartilaginous rings
Transverse thoracis
Innermost intercostal muscles (just adjacent to the sternum)
Vagus nerve (CN X)
R vagus crosses R subclavian artery between the brachiocephalic trunk and R brachiocephalic vein
L vagus is located between the L CCA and L subclavian a.
Descends on the L side of the aortic arch angling downward to pass behind the root of the lung
Giving rise to the L recurrent laryngeal n. (turns medially under ligamentum arteriosum)