Cardiac Anatomy

Question 1

Mediastinum

Answer 1

Slightly shifted to the left and sits on top of the diaphragm
Divided into: anterior, superior, middle and posterior

Question 2

Anterior mediastinum

Answer 2

Borders:
Anterior= sternum
Posterior= middle mediastinum
Contents:
Thymus, lymph nodes, internal thoracic vessels, thyroid tissue

Question 3

Middle mediastinum

Answer 3

Contents:
Pericardium, heart, ascending aorta, SVC/IVC, brachiocephalic vessels, pulmonary vessels, trachea and main bronchi, phrenic nerve, vagus nerve, left recurrent laryngeal nerves

Question 4

Superior mediastinum borders

Answer 4

Manubriosternal joint
Inferior edge of T4 body

Question 5

Posterior mediastinum borders

Answer 5

Anterior: middle mediastinum
Posterior: anterior thoracic vertebral column

Question 6

Posterior mediastinum contains

Answer 6

Oesophagus
Azygos and hemiazygos
Descending aorta

Question 7

Endocardium

Answer 7

Innermost layer
Made of epithelial cell layer
Thin layer of fibrous connective tissue lined on its inner surface by a single flat layer of simple squamous endothelial cells

Lines the heart chambers and valves

Question 8

Myocardium

Answer 8

Muscular middle layer
Cardiac myocytes:
Striated branching cells
Many mitochondria
Central nucleus
Intercalated discs- allow for contraction in syncytium
cells remain separate and do not form a syncytium
• Shorter refractory period than skeletal muscle
• Do not fatigue
• Secrete hormones

Question 9

Intercalated discs

Answer 9

(pale areas between adjacent myocytes when stained with H&E)- specialised connections between myocytes which join them together to form long, branching chains.
-Connect actin filaments of adjacent myocytes
-contain: gap junctions (allows flow of ions to connect cells electrochemically), adhering junctions and desmosomes (connect cells by linking intermediate cytoskeleton filaments)

Question 10

Lipofuscin

Answer 10

Yellow/brown pigment that accumulates in cardiac myocytes with increasing age

Question 11

Endomysium

Answer 11

between myocytes loose fibrous connective tissue (endomysium)- may contain small number of lymphocytes

Question 12

Atrial vs ventricular myocytes

Answer 12

• Large myocytes found in wall of left ventricle
• Atrial myocytes contain perinuclear neuroendocrine granules (atrial natriuretic peptide) located near the nuclei- hormone that is released when the cells are stretched excessively. This hormone increases the excretion of water and sodium and potassium ions by the kidney. It also inhibits renin secretion causing a lowering of blood pressure.

Question 13

Epicardium

Answer 13

layer of fatty connective tissue- underlying adipose connective tissue, vessels and nerves
• between pericardium and myocardium
• Layer contains the coronary arteries

Question 14

Pericardium

Answer 14

heart lies in a fibrous sack lined by a layer of mesothelial cells
• outermost layer of the heart
• Layer of squamous mesothelioma cells resting on thin layer of connective tissue
• Visceral pericardium - layer on outer surface of the heart. layer is reflected at the roots of the great vessels to become the parietal pericardium, the inner of the two layers of tissue that form the pericardial sack
• parietal pericardium- layer of cells on inner surface of fibrous sack containing the heart

Question 15

Fibrous pericardium

Answer 15

Outer layer
Tough connective tissue which anchors the heart to the mediastinum

Question 16

Serous pericardium

Answer 16

Simple squamous epithelial layer
Parietal pericardium- lines the fibrous pericardium and secretes fluid
Visceral pericardium- covers outer surface of the heart

Question 17

How is blood pressure information transferred from Baroreceptors to the central nervous system

Answer 17

The carotid sinus conveys information about blood pressure via the IX cranial nerve (glossopharyngeal nerve) across a finite pressure range

Question 18

Which nerve does the aortic arch Baroreceptors convert information about blood pressure across

Answer 18

Cranial nerve X (vagus nerve)

Question 19

3 types of capillary

Answer 19

Continuous
Fenestrated
Sinusoidal

Question 20

Blood vessels myogenic tone

Answer 20

Vascular smooth muscle is never fully relaxed

Question 21

How much thinner is right ventricle than left ventricle walls

Answer 21

1/3

Question 22

Cardiac muscle compared to skeletal muscle

Answer 22

Striated
Branched
Intercalated discs

Question 23

Where are the greatest proportion of musculi pectinati found?

Answer 23

Right atrium

internal muscular ridges on the anterolateral surface of the chambers and they are only present in the area derived from the embryological true atrium.