Lecture 1 Flashcards
What is the mediastinum divided into?
Into superior and inferior regions. With the inferior mediastinum being divided into - anterior, middle and posterior.
What divides the mediastinum?
Critical line at the sternal angle, in line with rib 2. Coming between T4-5.
Describe the surface anatomy of the heart?
The heart is situated between rib 2 (at the sternal angle) and rib 5. The right hand border will be parasternal. The apex point will be halfway on the clavicle in the mid-clavicular line (in the fifth intercostal space).
Describe the layers of the heart/pericaridum?
Created by the heart developing and pushing into the potential space. There are two layers to the pericardium:
1) Fibrous pericardium (adherent to the diaphragm inferiorly and holds the heart in place). The pericardium on the outermost surface.
2) Serous pericardium:
i) parietal pericardium
- pericardial cavity -
ii) visceral pericardium (epicardium). This is the outermost layer of the heart (so actually part of the heart).
3) Myocardium (heart muscle).
4) Endocardium (internal lining of the heart itself).
How is the pericardium innervated?
Innervated very similarly to the pleural cavity. The visceral pericardium has no sensory fibres, where as the parietal pericardium is innervated by the phrenic nerve.
Describe pericarditis?
This is inflammation of the pericardium. This is referred pain in the shoulder, due to the phrenic nerve having C3-5 nerves.
Describe cardiac tamponade?
When the pericardial space fills up with blood. This comprises the heart, and the hear cannot beat properly as pressure builds up. The heart needs to be drained.
Describe pericardial sinuses?
This is where the pericardium is reflected and folded.
Describe the oblique pericardial sinus?
Reflection onto the pulmonary veins of the heart.
Describe the transverse pericardial sinus?
Reflection that separates the arterial system from the venous system. Separates the aorta and the pulmonary trunk. Can slide your finger and clamp off the artery and the veins during open heart surgery.
Describe the orientation of the pericardium?
The base of the pericardium is inferior and the apex of the pericardium is superior.
Describe the orientation of the heart?
The base of the heart points directly posteriorly and the apex points to the left lower intercostal side.
Describe the grooves of the heart?
1) Atrio-ventricular groove: running between the two atria and the two ventricles.
2) Inter-ventricular groove: running between the two ventricles.
Each of the grooves are lined with fat which protects the vessel.
Describe the components of the heart?
ANTERIOR VIEW:
The right atrium makes up the right hand border of the heart. The right auricle stretches across the heart anteriorly. The right coronary artery runs in the atrioventricular groove. Coming around the anterior surface of the heart is the right ventricle (makes up the inferior margin). The anterior inter-ventricular groove runs between the left and right ventricles. Running in the IV groove is the anterior inter ventricular branch of the left coronary artery (left anterior descending artery). The apex is made up of the left ventricle. Part of the left border is the left auricle (ear like projection from the left atrium). Majority of the left atrium sits posteriorly.
POSTERIOR VIEW:
Majority of the left border is made up of the left ventricle, yet most of the posterior surface is the left atrium.
Describe the coronary circulation of the heart?
The coronary arteries come off the aorta and are situated in the aortic valve. The right coronary artery runs down in the right atrioventricular groove - gives a small branch to the SA node. Runs down between the RA and RV and supplies both. It gives off a branch at the inferior border - right marginal branch. The right coronary artery tucks under the heart where it heads off posteriorly and gives off a branch which supplies the AV node (important for regulation of the heart). The right coronary artery continues down in the posterior inter-ventricular groove as the posterior inter-ventricular artery (runs between LV and RV). The left coronary artery comes off the aorta and runs behind the pulmonary trunk, where it gives off a branch which heads directly laterally between the LV and LA - this is the left circumflex artery. When the LAD gets to the bottom it meets the posterior ventricular artery.
