Transcript THORACIC CAVITY - University of Kansas Medical Center

THORACIC CAVITY
HEART
Pericardial Cavity

Heart is located in the middle inferior
mediastinum within the pericardial cavity.
Visceral Pericardium
Serous membrane
 Fig 1.37, p 139)
 Referred to as epicardium.
 Arterial mesocardium.
 Venous mesocardium.

Visceral Pericardium

Transverse sinus:
Space between arterial and venous
mesocardium.

Oblique sinus:
Space between right and left pulmonary
veins.
Pericardium
Pericardial cavity.
 Parietal (serous):

Fused to fibrous pericardium.

Fibrous:
Fused with central tendon of diaphragm:
Pericardiacophrenic ligament.
Fused with sternum:
Superior and inferior sternopericardial
ligaments.
Pericardium

Blood supply (Fig. 1.38, p 139):
Pericardial arteries.
Pericardiacophrenic arteries.
Musculophrenic arteries.

Nerve supply:
CN X.
Phrenic nerve.
Sympathetic trunk.
Cardiac Projections
Apex is down and to left.
 Base of heart is superior to apex:

Upside down triangle.

Base projection:
Horizontal plane across sternum.
Level of costal cartilage 3.
Ends 2 cm to left of left parasternal line.
Cardiac Projections

Apex projection:
5th intercostal space.
8 cm (interclavicular line) to left of median
line of sternum.

Pericardium extends up to sternal angle.
Layers of the Heart

External:
Epicardium
Visceral layer of serous pericardium +
subserous layer of connective tissue.

Middle:
Myocardium:
Thickest
Cardiac muscle tissue.
Layers of the Heart

Inner:
Endocardium:
Endothelial layer
Cardiac Skeleton

4 interlocking fibrous rings:
Annuli fibrosi.
Interconnected with membranous portion of
interventricular septum.

Fig. 1.40B, p 143)
Cardiac Skeleton
 Functions
of annuli fibrosi:
Rigid attachment for cardiac muscle
fibers.
Support for valves.
External Heart

Base:
Posterior aspect of heart.
Mostly left atrium + small part of right atrium.

Apex:
Located at intercostal space 5 medial to
nipple.
Formed from left ventricle

Fig. 1.42A, p 146.
External Heart

Diaphragmatic surface:
Rests on diaphragm.
Mostly left ventricle and a small part of right.

Sternocostal surface:
Faces anteriorly.
Mostly right ventricle.
External Heart
 Left
margin (border):
Left side of heart formed mostly of left ventricle and
left auricle.
 Inferior
margin (border):
Intersection of diaphragmatic and sternocostal
surfaces.
Formed mostly from right ventricle.
 Superior
border:
Left and right atria and auricles.
Anterior Surface of Heart
CC: common carotid A.
AA: aortic arch
SC: subclavian V.
SVC: sup. VC
RPA: right pulmonary
artery.
RPV: right pulmonary
veins.
RCA: right coronary A.
IVC: inferior vena cava.
LA: ligamentum
arteriosum
Anterior Surface of Heart
LPA: left pulmonary A.
LPV: left pulmonary V.
CB: circumflex branch
of left coronary A.
LM: left marginal A.
LAD: left anterior
descending A.
Blood Supply to Heart
 Blood
supply to heart is via two
coronary arteries (Fig. 1.49A&B, 157):
Coronary arteries are the direct and only
branches off the ascending aorta.
Right Coronary Artery
Passes between pulmonary trunk and right
auricle.
 To coronary sulcus.
 Follows coronary sulcus to diaphragmatic
surface.
 Anastomoses with left coronary artery.

Right Coronary Artery Supplies:
Right atrium.
 Right ventricle.
 Posterior half of interventricular septum.

Right Coronary Artery Branches
Artery to SA node.
 Artery to AV node.
 Right marginal artery.
 Posterior interventricular artery

= posterior descending artery (PDA)
Left Coronary Artery
 Passes
between pulmonary trunk and
left atrium.
 Supplies:
Left atrium.
Left ventricle.
Anterior half of interventricular septum.
Left Coronary Artery
 Major
branches:
Anterior interventricular artery (= left anterior
descending LAD).
Circumflex artery.
Left marginal artery.
Venous Drainage from Heart

Fig. 1.51, page 159

Coronary sinus:
Located in posterior coronary sulcus.
Opens into right atrium.
Direct continuation of great cardiac vein.
Tributaries:
Great cardiac vein.
Middle cardiac vein.
Small cardiac vein.
Right Atrium
Fig. 1.43, p 148:
 Receives blood from:

Superior vena cava.
Inferior vena cava.
Coronary sinus.
Anterior cardiac veins.

Large, thin-walled chamber.
Right Atrium

Sub-chambers:
Main posterior cavity:
Sinus venarum.
Anterior cavity:
Auricle.
Lined with pectinate muscles.
Right Ventricle
Fig. 1.44, p 149
 Receives blood from right atrium.
 Thicker walled than right atrium.
 Trabeculae carnae.
 Moderator band:

(septomarginal trabecula)
Conveys right branch of atrioventricular
bundle.
Right Atrioventricular Valve
Also called the tricuspid valve.
 Chordae tendinae.
 Papillary muscles.
 Fig. 1.45 B&C, p 150

Right Ventricle

Pulmonary valve:
Formed from three semilunar cusps.

Pulmonary trunk:
Divides into left and right pulmonary arteries.
Left Atrium

Left atrium (Fig. 1.46, p 152):
Receives blood from four pulmonary veins.
Smaller and thicker-walled than right atrium.
Posterior smooth portion receives pulmonary
veins.
Anterior portion = auricle:
with pectinate muscles.
Left Ventricle
Fig. 1.47, p 153
 Wall = 2-3 x as thick as wall of right
ventricle.
 Trabeculae carnae are less coarse than
those of right ventricle.
 No moderator band.
 Two large papillary muscles:

Anterior and posterior.
Left Atrioventricular/Aortic Valves

Left atrioventricular valve:
= bicuspid or mitral valve.

Aortic valve:
Composed of three semilunar cusps.
Conduction System of the Heart
Composed of modified specialized cardiac
muscle cells.
 No nervous tissue in heart.
 Fig. 1.52, p 163)

Sinoatrial Node
Referred to as pacemaker of heart.
 Located in right atrium near opening of
SVC:

Superior end of sulcus terminalis.

Receives direct stimulation from:
Sympathetic cardiac nerves.
Parasympathetic vagus nerves.
Conduction System of the Heart

Atrioventricular node:
Located in interatrial septum near tricuspid
valve.

Interventricular bundle:
Descends through channel in fibrous
skeleton.
Reaches membranous interventricular
septum.
Only connection between myocardium of
atria and that of ventricles.
Conduction System of the Heart

Interventricular bundle:
Divides into two bundles in membranous
portion:
Right crus (bundle branches) passes through
moderator band.
Left crus (bundle branches)
Conduction System of the Heart
 Purkinje
fibers:
Terminal endings of bundle fibers.
Embedded in myocardium of ventricle.
Great Vessels

Ascending aorta:
Runs behind sternum to sternal angle.
Only branches are the two coronary arteries.

Fig. 1.58, p 172
Arch of the Aorta

Lies within superior mediastinum.
Arches to the left over the left pulmonary
artery.
Apex of the arch reaches the middle of the
manubrium.
 Three main branches:

Brachiocephalic.
Left common carotid.
Left subclavian.
Arch of the Aorta

Anterior relationships:
Left phrenic nerve.
Left vagus nerve.
Superficial cardiac plexus.
Arch of the Aorta

Inferior relationships:
Left recurrent laryngeal nerve.
Ligamentum arteriosum.
Pulmonary trunk.
Left primary bronchus.
Arch of the Aorta

Posterior relationships:
Trachea
Left recurrent laryngeal nerve.
Descending Aorta
Lies within posterior mediastinum.
 Begins at level of sternal angle.
 Ends in front of thoracic vertebra 12.
 Continuous with abdominal aorta.

Descending Aorta Branches
Paired intercostal arteries.
 Paired subcostal arteries.
 Two or more bronchial arteries.
 Two to five esophageal arteries.

Other Thoracic Vessels

Supreme intercostal:
From costocervical trunk of subclavian
artery.
Supplies IC spaces one and two.

Internal thoracics:
Arise within root of neck.
Descend lateral to sternum.
Internal Thoracic Arteries

Branches:
Musculophrenic (terminal):
To diaphragm
To intercostal spaces 7-9
Superior epigastric (terminal)
Internal Thoracic Arteries

Branches:
Pericardioacophrenic arteries:
Accompanies phrenic nerve.
Supplies pericardium, mediastinal
pleura, diaphragm.
Perforating branches:
Accompany anterior cutaneous
branches of intercostal nerves.
Largest in intercostal spaces 2-4 in
females.
Right Brachiocephalic Vein

From:
Right internal jugular.
Right subclavian.

Tributary:

Right internal intercostal vein.
Fig. 1.64, p 182
Left Brachiocephalic Vein

Formed from:
Left internal jugular vein.
Left subclavian vein.

Tributaries:
Left internal thoracic vein.
Left superior intercostal.
Inferior thyroid veins.
Superior Vena Cava

Formed from:
Right brachiocephalic vein.
Left brachiocephalic vein.

Receives:
Azygos vein.
Azygos System
Drains most of blood from thoracic wall.
 Consists of longitudinal veins lying on
either side of thoracic vertebral bodies.
 Variable.

Azygos Vein
Forms in abdomen:
 From right subcostal and ascending
lumbar veins.
 Drains all right posterior intercostal veins
except first.
 Also receives blood from the bronchial and
esophageal veins.

Hemiazygos Vein

Forms in abdomen:
 From
left subcostal and left ascending
lumbar veins.
Receives four posterior intercostal veins.
 Crosses over thoracic vertebrae at T8
level.
 Empties into azygos vein.

Other Thoracic Vessels
 Accessory
hemiazygos vein:
Drains intercostal spaces 4-7(8) on left side.
Crosses over thoracic vertebrae at level T7.
Empties into azygos vein.

Note: Intercostal space 1 is drained by the
supreme intercostal vein emptying into the
brachiocephalic vein.