Mediastinum
Clinical Anatomy
PA 544
Tony Serino, Ph.D.
Biology Department
Misericordia Univ.
Mediastinum
Superior
Anterior
Middle
Posterior
Superior and anterior are continuous with each other; both may be
referred to as the superior mediastinum
Superior Mediastinum
Transverse thoracic plane
Aortic arch
Great Vessels of the Heart
Remnant of Ductus arteriosus
Ligamentum
arteriosum
Usual Aortic Arch Pattern
LC
RC
RS
BT
65% of all people
LS
Aortic Arch Variations
left vert. a.
27% one BT with
both CC exiting
5%
1.2% two BT
SVC
Vagus
Phrenic
BC
SVC
BC
Pulmonary Arteries and Veins
Trachea and Primary bronchi
Structure Order
Trachea
BC
Aorta
PA
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
• 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
Thymus Gland
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
Circumflex a.
L. Marginal a.
Ant. Desc. a. (LAD)
Post. Desc. a.
R. Marginal a.
Fig. 1.51
Coronary Variation
Most people right dominant. 15% LCA dominant
(note: which branch gives rise to posterior descending a.determines dominance)
Single CA
Circumflex from right aortic sinus
(4% have an accessory coronary artery)
Fig. 12.66b
Fig. 12.66c
Fig. 12.66d
Coronary Vein Schematic
Coronary Veins
Ant. Cardiac veins
Great Cardiac v.
Coronary sinus
Small Cardiac v.
Middle Cardiac v.
Fig. 1.52
Major Cardiac Valves
Heart
Valves
cusps
AV (tricuspid)
sinus
aortic valve (SL)
Nodule (corpara aranti)
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 duct
Intercostal a., v., & n.
Sympathetic trunk
Trachea
Vagus n.
Thoracic aorta
Lung root
Phrenic n.
Esophagus
Hemiazygous v.
Azygous v.
Small Aortic Branches
Coronary
Bronchial a.
Esophageal
Intercostals
Azygous vein
Hemiazygous v.
Nerves of Post. Mediastinum
Thoracic Duct