Mediastinum Clinical Anatomy PA 544 Tony Serino, Ph.D. Biology Department Misericordia Univ.

Mediastinum Anterior Superior Middle Posterior Superior and anterior are continuous with each other; both may be referred to as the superior mediastinum

Superior Mediastinum Great Vessels of the Heart Aortic arch Transverse thoracic plane

Remnant of Ductus arteriosus Ligamentum arteriosum

Usual Aortic Arch Pattern 65% of all people RS BT LS LC RC

Aortic Arch Variations 27% one BT with both CC exiting 5% 1.2% two BT left vert. a.

SVC BC SVC Vagus Phrenic

Pulmonary Arteries and Veins

Trachea and Primary bronchi

Structure Order BC Aorta PA Trachea

Esophagus Function: Deglutition Two sphincters: upper and lower esophageal sphincters (lower is physiological only) Retropleural position (therefore, covered by adventitia) Mucosa: stratified squamous with many mucus glands (esophageal glands) Muscularis: changes from skeletal to smooth muscle

Thymus Gland Bilobed organ that is largest in children, but begins to regress sharply at the onset of puberty (around age 11) It is the site of T-cell lymphocyte production and produces hormones (such as, thymosin) that modifies their physiology

General Circulatory System 1.Cardiovascular –Consists of a closed system of vessels which transport blood –Two circuits: Systemic and Pulmonary –Arteries move blood away from the heart –Veins move blood toward the heart

Heart Development

Fetal Circulation

Selected Heart Defects

Heart as a Dual Pump Cardiac muscle arranged as whorls that squeeze the blood Twin pumps: systemic and pulmonary Four chambers: 2 atria and 2 ventricles

Cardiac Muscle Cells

Cardiac Muscle Depolarization

Heart: Location

Heart in Relation to other Organs

Layers of the Heart and Pericardium

Heart: Anterior View Transverse Pericardial sinus

Heart: Posterior View Oblique Pericardial sinus

Heart: Internal Anatomy

Differences in Ventricular Wall

Coronary Artery Schematic (LAD)

Most Common Coronary Arterial Pattern Fig Ant. Desc. a. (LAD) Post. Desc. a. R. Marginal a. L. Marginal a. Circumflex a.

Coronary Variation 15% LCA dominant Single CA Most people right dominant. Circumflex from right aortic sinus (4% have an accessory coronary artery) (note: which branch gives rise to posterior descending a.determines dominance)

Fig b

Fig c

Fig d

Coronary Vein Schematic

Coronary Veins Fig Coronary sinus Great Cardiac v. Small Cardiac v.Middle Cardiac v. Ant. Cardiac veins

Major Cardiac Valves

aortic valve (SL) AV (tricuspid) Heart Valves sinus Nodule (corpara aranti) cusps

Diastole: Period of Ventricular Filling

Systole: Isovolumetric Contraction

Systole: Ventricular Ejection

Diastole: Isovolumetric Relaxation

Conduction System of Heart

ECG and electrical changes

Normal ECG

ECG Normal Sinus Rhythm Junctional Rhythm (AV node rhythm)

Second Degree Heart Block Ventricular Fibrillation (V-fib)

Heart Sounds “Lub-dub” Sound associated with valve closing producing turbulent blood flow

Heart Rate Control Sinus Rhythm = normal SA node control Autonomic Activity –Sympathetic (thoracic trunk) = accelerator (induces tachycardia) –Parasympathetic (vagus n.)= brake (induces bradycardia) Hormones –epinephrine Drugs -caffeine, nicotine, atropine, etc.

Posterior Mediastinum Thoracic aorta Sympathetic trunk Vagus n. Azygous v. Trachea Esophagus Phrenic n. Intercostal a., v., & n. Hemiazygous v. Lung root Thoracic duct

Small Aortic Branches Bronchial a. Intercostals Coronary Esophageal

Azygous vein Hemiazygous v.

Nerves of Post. Mediastinum

Thoracic Duct