HEART 2
Right Coronary Artery
The right coronary artery (RCA) originates above the right cusp of the aortic valve. It travels down the right atrioventricular groove, towards the crux of the heart. It branches into the posterior descending artery and the right marginal artery. At the origin of the RCA is the conus artery.
In addition to supplying blood to the right ventricle (RV), the RCA supplies 25% to 35% of the left ventricle (LV).
In 85% of patients (Right Dominant), the RCA gives off the posterior descending artery (PDA).
Aortic Valve
The aortic valve is one of the two semilunar valves of the heart, the other being the pulmonary valve. The aortic valve normally has three cusps, although in 1-2% of the population it is found to congenitally have two cusps. It lies between the left ventricle and the aorta.
Ascending Aorta
Commences at the upper part of the base of the left ventricle, on a level with the lower border of the third costal cartilage behind the left half of the sternum. It’s total length is about 5 centimetres (2.0 in).
The only branches of the ascending aorta are the two coronary arteries which supply the heart; they arise near the commencement of the aorta from the aortic sinuses which are opposite the aortic valve.
Mitral Valve
The mitral valve lies between the left atrium (LA) and the left ventricle (LV). The mitral valve is typically 4–6 cm² in area and has two cusps.
Tricuspid Valve
The tricuspid valve lies between the right atrium and the right ventricle. The function of the valve is to prevent back flow of blood into the right atrium. The normal tricuspid valve usually has three cusps.
Pulmonary Valve
The pulmonary valve is a semilunar valve that lies between the right ventricle and the pulmonary artery and has three cusps. Similar to the aortic valve, the pulmonary valve opens during ventricular systole.
Left Coronary Artery
The left coronary artery is an artery that arises from the aorta above the left cusp of the aortic valve and supplies blood to the left side of the heart.
It typically runs for 10 to 25 mm and then bifurcates into the left anterior descending (LAD) and the left circumflex artery.
Anterior Interventricular Branch of the Left Coronary Artery (Left Anterior Descending Artery)
The artery supplies the anterolateral myocardium, apex, and interventricular septum. The left anterior descending (LAD) typically supplies 45-55% of the left ventricle (LV) and is therefore considered the most critical vessel in terms of myocardial blood supply.
Circumflex Artery
The circumflex artery is a branch of the left coronary artery. The circumflex artery curves to the left around the heart within the coronary sulcus, giving rise to one or more left marginal arteries as it travels towards the posterior surface of the heart.
Left Coronary Sinus
The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). It delivers deoxygenated blood to the right atrium.
Right Coronary Sinus
The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). It delivers deoxygenated blood to the right atrium.
Cardiac Fibrous Skeleton
The cardiac skeleton, also known as the fibrous skeleton of the heart, is a high density single structure of connective tissue that forms and anchors the valves and influences the forces exerted through them. The cardiac skeleton separates and partitions the atria from the ventricles.
SA Nodal Artery
The sinoatrial nodal artery is an artery of the heart which supplies the sinoatrial node and arises from the right coronary artery in around 60% of people. In about 40% of cases, the sinoatrial artery is a branch of the left coronary artery or one of its branches.
Question 2
2. Zygomatic bone
Question 3
4. Sphenoid lesser wing
Question 4
6. Frontal process of maxilla
7. Orbital part of frontal bone
Question 8
14. Supra-orbital foramen
Question 9
16. Naison
17. Nasal septum
Question 10
19. Frontozygomatic suture
20. Pterion
Question 15
12. Nasolacrimal canal
Question 16
14. Frontozygomatic suture
Question 17
Question 18
Question 19
- Medial, lateral, superior, inferior recti
- Superior and inferior oblique
- Levator palpebrae superioris
Nerve supply can be remembered by the mnemonic LR6 SO4 AO3:
Lateral rectus: Abducens nerve (CNVI)
Superior oblique: Trochlear nerve (CNIV)
All others: Ophthalmic nerve (CNIII)
The Orbit Summary
- Identify
- Labelled
The Orbit
The orbits are conical or four-sided pyramidal cavities, which open into the midline of the face and point back into the head. Each consists of a base, an apex and four walls.
The apex lies near the medial end of superior orbital fissure and contains the optic canal (containing the optic nerve and ophthalmic artery), which communicates with middle cranial fossa.
The roof (superior wall) is formed primarily by the orbital plate frontal bone, and also the lesser wing of sphenoid near the apex of the orbit. The orbital surface presents medially by trochlear fovea and laterally by lacrimal fossa.
The floor (inferior wall) is formed by the orbital surface of maxilla, the orbital surface of zygomatic bone and the minute orbital process of palatine bone. Medially, near the orbital margin, is located the groove for nasolacrimal duct. Near the middle of the floor, located infraorbital groove, which leads to the infraorbital foramen. The floor is separated from the lateral wall by inferior orbital fissure, which connects the orbit to pterygopalatine and infratemporal fossa.
The medial wall is formed primarily by the orbital plate of ethmoid, as well as contributions from the frontal process of maxilla, the lacrimal bone, and a small part of the body of the sphenoid. It is the thinnest wall of the orbit, evidenced by pneumatized ethmoidal cells.
The lateral wall is formed by the frontal process of zygomatic and more posteriorly by the orbital plate of the greater wing of sphenoid. The bones meet at the zygomaticosphenoid suture. The lateral wall is the thickest wall of the orbit, important because it is the most exposed surface, highly vulnerable to blunt force trauma.
Boundaries
The base, which opens in the face, has four borders. The following bones take part in their formation:
Superior margin: frontal bone and sphenoid
Inferior margin: maxilla, palatine and zygomatic
Medial margin: ethmoid, lacrimal bone, and frontal
Lateral margin: zygomatic and sphenoid