Unit Ii Anatomy Lecture 10

Front 1

Describe the relationships of the lines of pleural reflection

Back 1

Sharp lines of reflection occur where costal pleura becomes continuous with mediastinal or diaphragmatic pleura and are important because they limit the pleural cavities
These lines can be mapped on the surface of the anterior aspect of thoracic wall in relation to bony landmarks

Front 2

Describe the surface of the lungs during expiration and quiet breathing

Back 2

Recesses exist in pleural cavity
During deep respiration, all of the parietal pleura is in contact with visceral pleura
Inferior edge of lungs remain about two ribs higher posterolaterally than that of pleura
Surface projection of inferior pulmonary edge occurs at 8th rib in midaxillary line and at 10th thoracic vertebrae in back
Biopsy of liver could be obtained through the 8th intercostal space in axilla without injury to lung

Front 3

Describe the borders of the lungs

Back 3

1) Cervical pleura and apices of lungs pass through superior thoracic aperture into supraclavicular fossae. Each fossa is located superior and posterior to clavicle and lateral to tendons of sternocleidomastoid muscles
2) Anterior borders of each lung occur adjacent to anterior line of reflection of parietal pleura below 4th intercostal space
3) At 4th intercostal space, margin of left pleural reflection continues laterally and then at cardiac notch turn inferiorly to reach 6th intercostal cartilage. Anterior border of left lung has a deeper indented notch (cardiac notch)
4) Medial aspect of left lung has a pleural reflection that continues inferiorly from 4th to 6th costal cartilage and is paralleled by anterior border of right lung. Both pleural reflections and anterior lung borders pass laterally at 6th costal cartilage

Front 4

Describe the thoracic cavity

Back 4

Composed of three compartments: two pulmonary cavities- each lies lateral to mediastinum and houses and lung and pleurae- and medistinum- containing heart and great vessels
Bounded by thoracic wall, diaphragm, and suprapleural membrane (layer of fascia that arches over each lung)

Front 5

Describe the pleura of the thoracic cavity

Back 5

Serous membrane that forms pleural cavities, invests each lung, and consists of two membranes:
1) parietal pleura- lines pulmonary cavities
2) Visceral pleura- covers each lung, adheres to all surfaces, and provides a slippery surface allowing free movement between lungs and parietal pleura and allows each pleural cavity to remain empty
Pleural cavity is not a true space, rather a potentional space that occurs between layers of serous pleura and contains serous pleural fluid
Surface tension provides cohesion keeping each lung in contact with thoracic wall, thus lung expands as chest expands

Front 6

Describe the parietal pleura

Back 6

Lines pulmonary cavities and adheres to thoracic wall, mediastinum, and diaphragm
Has four parts:
1) Costal pleura covering internal surfaces of thoracic wall
2) Mediastinal pleura covering lateral aspects of mediastinum at hilum (where it encloses structures comprising the root of the lung) and becomes continuous at hilum with the visceral layer (inferior to root it forms a double layer that continues with visceral layer to form pulmonary ligament)
3) Diaphragmatic pleura covering thoracic surface of diaphragm on each side of mediastinum except along its costal attachments (phrenicopleural fascia connects pleura with diaphragm)
4) Cervical pleura (or dome or cupula of pleura) extending through thoracic inlet to root of neck forming a cup-shaped pleural dome over apex of lung, continuation of costal and mediastinal layers of pleura and is strenghtened by an extension of endothoracic fascia (Sibson's)

Front 7

Describe the phrenicopleural fascia

Back 7

Connects the diaphragmatic pleura with muscles of diaphragm

Front 8

Describe Sibon's fascia

Back 8

If a defect is present, the intrathoracic pressure is increased, and cervical lung herniation may occur
Cupola of lung protrudes into or through fascia at superior thoracic aperture
Unknown if inherent weakness in fascia predisposes individuals to this type of hernia
Formed by several membranes- deep cervial fascia, suprapleural membrane, and suprapleuralis membrane- and acts like a diaphragm across thoracic inlet
Originates from transverse process of 7th cervical vertebrae and inserts along inner border of first rib and costal cartilage
At periphery, thickened portion of endothoracic fascia blends with Sibson's fascia
Fascia also blends into parietal pleura and is often reinforced by scalenus minimus muscle

Front 9

Describe the lungs

Back 9

Elastic and recoil to about 1/3 of inflated size when chest wall is opened
Healthy, lungs appear pinkish, light, soft, elastic and spongy

Front 10

What are five superficial features of the lungs?

Back 10

1) Hilum- occurs where both layers of pleura are continuous and structures of root enter and exit
2) Root- contains bronchus and pulmonary vessels which enter and exit lungs
3) Pleural sleeve or mesopneumonium- encloses each root of each lung within an area of continuity between the parietal and visceral layers of pleura
4) Pulmonary ligament- hangs inferiorly from pleural sleeve
5) Apex of each lung- occurs at superior end, is blunt, covered by cervical pleura, ascends above 1st rib

Front 11

Describe the three surfaces of the lung

Back 11

1) Costal- smooth and convex and related to costal pleura that separates it from the ribs, costal cartilages, and innermost costal muscles
2) Mediastinal- concave and related to middle part of mediastinum (contains pericardium and heart)
3) Diaphragmatic- concave and forms base of lung that rests on diaphragm

Front 12

Describe the borders of the lungs

Back 12

1) Anterior- costal and mediastinal surfaces meet anteriorly and overlap heart (cardiac notch indents on left lung). Cardiac notch occurs along anteroinferior aspect of superior lobe of left lung and often creates a thin process of superior lobe (i.e., lingula)
2) Inferior- surround diaphragmatic surface of lung and separates it from costal and mediastinal surfaces
3) Posterior- where costal and mediastinal surfaces meet posteriorly and lies adjacent to thoracic vertebrae

Front 13

Describe the lobes of the lung

Back 13

Demarcated by horizontal and/or oblique fissure
Right lung has two fissures- oblique and horizontal- and three lobes- superior, middle, and inferior
Left lung has single fissure- oblique- and two lobes- superior and inferior

Front 14

Describe the impressions and grooves of the lungs

Back 14

Lie on mediastinal aspect and hilum of lung
Occurs as sulci and reveal associations with SVC, esophagus, and cardiac impression of heart
On left lung, groove for arch and descending parts of aorta

Front 15

Describe the recessions of each lung

Back 15

Include a costodiaphragmatic and costomediastinal
Costodiaphragmatic recess is potential space surrounded by upward convexity of diaphragm within thoracic cavity

Front 16

Describe the trachea

Back 16

Usually bifurcates posterior to heart and divides at lungs
Held open by hyaline cartilage and lined with respiratory epithelium (cilia: in conjuction with mucous and goblet cells) which helps to remove particulate matter from lungs

Front 17

Describe the bronchial tree

Back 17

Formed, in part, by constant branching of primary bronchi as they enter hila of each lung and continue to divide distally
There are several divisions of bronchi that occur within each lung
Each has a specific name, innervation, arterial supply, and venous drainage

Front 18

Describe the main, or primary, bronchi

Back 18

Arise from trachea and branch to each lung
C-shaped hyaline cartilage are housed within walls of trachea and bronchi
Right bronchi is wider, shorter, and runs more vertically than does left bronchi which passes directly to hilum

Front 19

Describe the lobar or secondary bronchi

Back 19

Branch from each main bronchus
Two for left lung and three for right lung
Each supplies a lobe of lung

Front 20

Describe the segmental, or tertiary, bronchi

Back 20

Branch from each lobar bronchi and supply bronchopulmonary segments of each lung

Front 21

Describe the bronchopulmonary segments

Back 21

Largest subdivision of lobe, separated by adjacent segments by CT septa
Supplied independently by segmental bronchus artery and tertiary branch of pulmonary artery and drained by intersegmental part of pulmonary veins (occurs in CT between and drains adjacent segments)
Surgically resectable part of lung (aka structural unit of lung)
Number per lobe:
Right lung: superior- 3, middle- 2, inferior- 5 and left lung: superior- 5, inferior- 5

Front 22

Describe the terminal bronchioles

Back 22

Branch beyond lobar and segmental bronchi and include 20 to 25 branches

Front 23

Describe the respiratory bronchioles

Back 23

Branch off terminal bronchioles

Front 24

Describe alveolar ducts

Back 24

Branch of respiratory bronchioles

Front 25

Describe the alveolar sacs

Back 25

Arise from alveolar ducts
Lined by alveoli (5-6 sacs) the basic structural unit of gas exchange

Front 26

What is the air-pathway of bronchi within the middle lobe of right lung?

Back 26

Right main bronchus--> right lobar bronchi (branches to all lobes of lung)--> right middle lobar bronchus--> lateral and medial segmental bronchi (specific tertiary branches supplying bronchopulmonary segments of lung)

Front 27

Describe the vessels of the lungs

Back 27

Include pulmonary trunk (at right ventricle) which divides intor left and right pulmonary arteries that transports poorly oxygenated blood to the lungs
Exception for arteries in regard to function
Pulmonary arteries subdivide into lobar and segmental arteries within lungs
Pulmonary capillaries are where gas exchange occurs within each lung
Pulmonary veins drain into and return well oxygenated blood to left atrium of heart

Front 28

Describe the bronchial arteries

Back 28

Transport nutrition to several structures including the root of each lung, supporting tissues of each lung, visceral pleura, NOT parietal pleura
Two left bronchial arteries occur and usually arise from thoracic aorta
Single right bronchial artery is present and it may originate at one of three locations- superior posterior intercostal artery, 3rd posterior intercostal (1st aortic intercostal), and left superior bronchial artery
Bronchial arteries provide branches to trachea, lung tissue, and lymph nodes, posterior aspects of main bronchi supplying their branches as far distally as respiratory bronchioles, and distal most branches form anastomoses with pulmonary arteries (in walls of bronchioles and visceral pleura)

Front 29

Describe the superior intercostal artery

Back 29

Not the same as the superior or highest thoracic artery (1st branch of axillary artery)
Arterial branches to esophagus include upper esophageal branches (from inferior thyroid artery), middle esophageal braches (from left inferior phrenic artery), and lower esophageal branches (left gastric artery)

Front 30

Describe pulmonary circulation

Back 30

Transports oxygenated and poorly oxygenated blood to and from lungs, whereas bronchial circulation supplies nutrients for lungs and associated tissues
Bronchial arteries will anastomose with pulmonary arteries deep within the lungs (as far as respiratory bronchioles)

Front 31

Describe the bronchial veins

Back 31

Drain only part of blood supplied to lungs by bronchial arteries
Some blood is drained by pulmonary veins and some by esophageal veins
Right bronchial vein drains into azygous vein, whereas left drains into accessory hemiazygous vein or left superior intercostal vein

Front 32

Describe the nerves of the visceral pleura

Back 32

Derived from pulmonary plexuses anterior and (mainly) posterior to roots of lungs
Nerve network consists of parasympathetic and sympathetic fibers

Front 33

Describe parasympathetic contributions to lungs

Back 33

From vagus nerve (bronchoconstrictor, vasodilator, secretomotor)
Parasympathetic ganglion occurs in pulmonary plexuses along the branches of bronchial tree

Front 34

Describe sympathetic contributions to the lungs

Back 34

Includes cervical sympathetic ganglia which occur in paravertebral sympathetic ganglia of cervical sympathetic trunk

Front 35

Describe the innervation of parietal pleura

Back 35

Receives innervation from both phrenic and intercostal nerves
Phrenic nerve innervates central part of diaphragmatic pleura and mediastinal pleura (sensory for pain), whereas intercostal nerves supply costal pleura and peripheral part of diaphragmatic pleura (mediate sensations of touch and pain

Front 36

Describe the vagus nerve in relation to the lungs

Back 36

Serves as motor to smooth muscles of bronchioal tree (bronchoconstrictor), an inhibitor to pulmonary vessels (vasodilator), a secretor to glands of bronchial tree (secretomotor contributes to cough reflexes), bronchial muscles, Hering-Breuer reflexes (mechanism limits respiratory excursions), pulmonary arteries as pressor receptors, pulmonary veins as chemoreceptors

Front 37

Describe the superficial (subpleural) lymphatic plexus of the lungs

Back 37

Lies deep to visceral pleura and drains lung parenchyma (tissue) and visceral pleura
Lymphoid tissues from superficial plexus drains into bronchopulmonary lymph nodes (hilar lymph nodes) located in hilum of lung

Front 38

Describe the deep lymphatic plexus

Back 38

Located in submucosa of bronchi and in peribronchial CT
Mainly drains structures that form the root of lung
Lymphoid vessels from this deep plexus drain first into pulmonary lymph nodes (located along lobar bronchi)
Lymphoid vessels from pulmonary lymph nodes follow bronchi and pulmonary vessels to hilum of lung and drain into bronchopulmonary (hilar) lymph nodes

Front 39

Describe drainage of the superficial and deep lymph nodes

Back 39

Drain into superior and inferior tracheobronchial lymph nodes, superior and inferior to bifurcation of trachea and main bronchi, respectively
Right lung drains primarily through respective sets of nodes on right side
Left lung has superior lobe that drains primarily through respective nodes to left side
Many lyphatics from lower lobe of left lung drain to right superior tracheobronchial nodes, lymph then continues to follow right side pathway

Front 40

Describe the tracheobronchial lymph nodes

Back 40

Pass to right and left bronchomediastinal lymph trunks
Trunks usually terminate on each side at venous angles (junctions of subclavian and internal jugular veins)
Right bronchomediastinal trunk may first merge with other lymphatic trunks, convergin here to to form short right lymphatic duct
Left trunk may terminate in thoracic duct
Lymph from parietal pleura drains into lymph nodes of thoracic wall (intercostals, parasternal, mediastinal, and phrenic)
A few lymph vessels from cervical parietal pleura drain into axillary lymph nodes

Front 41

Describe the diaphragm

Back 41

Muscular structure with two main parts
1) Central tendon
2) Muscular part
Aorta and thoracic duct course through aortic hiatus
Inferior vena cava courses through caval foramen
Esophagus courses through esophageal hiatus (hiatal hernia- where stomach protrudes through esophageal hiatus)

Front 42

Describe auscultation of lungs

Back 42

Listening to lung sounds with stethoscope
Accompanied with percussion (tapping the chest over the lungs with fingers to detect sounds in apices of lungs)
Should always include root of neck
To auscultate inferior-posterior portion of lung, clinician applies a stethoscope to posterior thoracic wall at level of T10

Front 43

Describe particulate matter and its effect on the lungs

Back 43

Agents that promote emphysema including asbestos (asbestosis, mesothelioma), cotton (brown lung), silicon or sand, coal dust (black lung), and saw dust
Particulate matter can cause major damage
Lungs become blocked and form lesions which form tumors and may involve pleura
Lungs can handle a considerable amount of carbon without being adversely affected
Phagocytes can remove carbon from gas exchange surfaces and deposit it on non-active CT supporting each lung
Carbon may be deposited in lymph nodes that receive lymph from lungs
Particulate matter that reaches the lungs can cause lungs to look black

Front 44

Describe variations of lobes of lungs

Back 44

May include extra fissures which divide a lung or a fissure may be absent
Azygous lobe is most common accessory lobe of right lung and occurs in 1% of population
Azygous vein arches over apex of right lung rather than right hilum, isolating medial part of apex as azygous lobe

Front 45

Describe pneumonia

Back 45

Inflammation of the lungs caused by bacteria, viruses, and chemical irritants
Pathological change that proceeds death
Names of pneumonia describe what part of lung is involved

Front 46

Describe adhesions of the lungs

Back 46

Might result from pneumonia, which might leak fluid into space outside of lung
Lobes become sticky and adhere to each other forming scar tissue outside of the lung
Pleural adhesions involve visceral pleura which may stick to space outside the lung (parietal pleura)

Front 47

Describe emphysema

Back 47

Formation of scar tissue within lung tissue where alveoli die and form dead air spaces which join to form larger dead air spaces which results in breathlessness during exertion because of loss of surface area for gas exchange
Stages of development proceed as follows: develops in apex, inferior lobe, and middle part of lung
Progressive disease that may involve normal scarring of a lung with little lung tissue affected, moderate progression that involves part of the lung, and severe progression that involves the entire lung

Front 48

Describe the mucous membrane covering the carina

Back 48

Most sensitive area of bronchial tree and is associated with cough reflex

Front 49

What is dyspnea?

Back 49

Difficult breathing

Front 50

Describe asthmatics

Back 50

There is no hyaline cartilage below bronchial tree to keep passages open
Asthmatic attackes are caused by varying degrees by contraction of smooth muscles, edema of mucosa, and mucus in lumen of bronchi and bronchioles
Changes are caused by local release of spasmogens (substance causing smooth muscle contractions) and vasoactive substances influencing the tone and caliber of blood vessels (e.g., histamine or prostoglandin)
Smooth muscles along this part of the airway may constrict air flow especially for exhaling due to elastic nature of lung
As an asthmatic tries to exhale, the lungs recoil, air ways are consticted and makes a wheezing sound
Bronchioles are drawn open during inhalation

Front 51

Describe obstruction of a pulmonary aorta by a thrombus (blood clot)

Back 51

Common cause of morbidity (sickness) and mortality (death)
Plug in pulmonary artery forms when a thromus, fat globule, or air bubble travels in blood to lungs from a deep or superficial vein of leg
When a large embolus occludes a pulmonary artery, patient suffers acute respiratory distress because of a major decrease in oxygenation of blood and may die within minutes
In active people, collateral circulation often exists and develops further when there is a PTE so an infarction is ot as likely to occur

Front 52

Describe a diaphragmatic hernia

Back 52

Congenital defect resulting in connection usually between left pleural cavity and peritoneal cavity (viscera from abdomen enters thorax)
Diaphragmatic hernia may occur because of events that occur during embyogenesis

Front 53

Describe injuries to the cervical pleura and apex of the lung

Back 53

May result due to association between inferior sloping of 1st pair of ribs and superior thoracic aperature
If injured, cervical pleura and apex of lung can project via a hole into neck
Can occur posterior to inferior attachments of SCM
Consequently, lungs and pleural sacs may be injured in wounds to neck

Front 54

Describe a pneumothorax

Back 54

Entry of air into pleural cavity
May result from penetrating wound of parietal pleura or rupture of lung from a bullet or broken ribs

Front 55

Describe a hydrothorax

Back 55

Accumulation of a signigicant amount of fluid in pleural cavity is called hydrothorax and may result form pleural effusion (escape of fluid into pleural cavity)

Front 56

Describe a hemothorax

Back 56

Blood enters the pleural cavity and may result from a number of events like knife or bullet wounds

Front 57

Describe the apex beat of the heart

Back 57

Impulse that results from the apex of the heart being forced against the anterior thoracic wall when the left ventricle contracts
The location of the apex beat varies in position but may be located in intercostal spaces 4-5

Front 58

Describe heart sounds at the valves

Back 58

Interest in surface anatomy of the heart and cardiac valves results from their need to listen to valve sounds
Areas are wide apart as possible so that the sounds produced at any given valve may be clearly distinguished from those produced at other valves
Blood tends to carry sound in the direction of its flow
Each area is situated superficial to chamber or vessel into which the blood has passed and in a direct line with valve oriface

Front 59

What are four valves located posterior to the sternum?

Back 59

Pulmonary, aortic, mitral, and tricuspid valves

Front 60

Describe the auscultatory areas of the heart

Back 60

1) Mitral area- 5th left intercostal space
2) Tricuspid area- 4th left intercostal space
3) Secondary pulmonic area- 3rd left intercostal space
4) Pulmonic area- left upper sternal border
5) Aortic area- right upper sternal border

Front 61

Describe the anatomical features of the heart

Back 61

The heart wall is composed of three layers: epicardium, myocardium, and endocardium

Front 62

Describe the epicardium

Back 62

Has superficial layer that is thin and mesothelium and formed by visceral layer of serous pericardium

Front 63

Describe the myocardium

Back 63

Has a middle layer that is thick and composed of cardiac muscle
Cardiac muscle is striated with intercalated discs

Front 64

Describe the endocardium

Back 64

Internal layer that is thin, lines the inner surface of the heart, covers the valves, and is continuous with the endothelium and underlying CT of vessels entering and leaving the chambers

Front 65

What are the two pericardial sinuses of the heart?

Back 65

Transverse pericardial and oblique pericardial

Front 66

Describe the transverse pericardial sinus

Back 66

Especially important to cardiac surgeons
After the pericardial sac is opened anteriorly, a digit can be passed through the transverse sinus and a surgical clamp or ligature may by placed around these vessels, inserting tubes of a coronary bypass machine
By tightening a ligature, surgeons can stop or divert the circulation of blood of these large arteries during cardiac surgery

Front 67

Describe the oblique pericardial sinus

Back 67

Occurs between pulmonary veins and is a blind-ended pouch or recess

Front 68

Describe the anatomical sides of the heart

Back 68

All relate to shape and orientation of heart in thorax
Include sternocostal margin (heart and roots of great vessels), apex (bottom of heart, formed by inferolateral part of left ventricle), base (opposite apex, formed mainly by left atrium)

Front 69

Describe the surfaces of the heart

Back 69

Include the diaphragmatic surface (left ventricle, partly by right ventricle, rests on central tendon of diaphragm), sternocostal surface or anterior surface (mainly right ventricle), pulmonary surface (formed mainly by left ventricle)

Front 70

What are the borders of the sternocostal surface of the heart?

Back 70

Left, right, superior, and inferior

Front 71

Describe the sulci of the heart

Back 71

Depressions on the surface of the heart where the left and right coronary arteries and cardiac veins travel
Coronary arteries supply the heart with well oxygenated blood (prime subjects for arteriosclerosis)
Heart attacks can occur when these arteries become clogged

Front 72

Describe the atrioventricular sulcus

Back 72

Houses the coronary arteries and its branches

Front 73

Describe the coronary sulcus

Back 73

Encircles the base of the heart and separates the atria and ventricles

Front 74

Describe the interventricular sulci

Back 74

Divide the right and left ventricles

Front 75

Describe the sternocostal surface

Back 75

Houses the anterior interventricular groove

Front 76

Describe the anterior interventricular sulcus

Back 76

Anterior interventricular artery=anterior descending artery
Forms an arch over the apex

Front 77

Describe the diaphragmatic surface

Back 77

Houses the inferior interventricular groove or posterior interventricular groove
Sulcus houses the posterior interventricular artery

Front 78

Describe the vessels of the heart

Back 78

Include the pulmonary trunk which continues from the right ventricle and divides into right and left pulmonary arteries
The SVC and IVC drain into the right atrium
Aorta arises from left ventricle of heart

Front 79

Describe the circuits of the heart

Back 79

1) Pulmonary circuit- right ventricle of heart, blood associated with lungs
2) Systemic circuit- left ventricle of heart, blood associated with body and aorta
3) Coronary circuit- provides atrial and venous blood to the heart

Front 80

What are the four chambers of the heart?

Back 80

1) Right atrium
2) Right ventricle
3) Left atrium
4) Left ventricle

Front 81

Describe the right atrium

Back 81

Receives venous blood flow from systemic system via SVC and IVC
Except in fetus, no valves restrict flow

Front 82

Describe the right ventricle

Back 82

Receives poorly oxygenated blood via the right atrium and sends it to the lungs via the pulmonary trunk

Front 83

Describe the left atrium

Back 83

Receives well oxygenated blood from lungs via the pulmonary veins

Front 84

Describe the left ventricle

Back 84

Receives newly oxygenated blood via the left atrium and sends it to the body (systemic via the aorta) and to the lungs (bronchials)

Front 85

What are the seven internal structures of the heart?

Back 85

1) Trabeculae carneae
2) Papillary muscle
3) Pectinate muscle
4) Crista terminalis
5) Chordae tendinae
6) Septomarginal trabecula
7) Conus arteriosus

Front 86

Describe the trabeculae carneae

Back 86

Occurs on surface of myocardium of ventricles

Front 87

Describe the papillary muscle

Back 87

Cone-shaped and projects into lumen
Forms walls of ventricles

Front 88

Describe the pectinate muscles

Back 88

Forms walls of atria

Front 89

Describe the crista terminalis

Back 89

Junction between smooth and ridged muscles of atria and occurs on both the posterior and anterior walls of the atria

Front 90

Describe the chordae tendinae

Back 90

Strong fibrous bands that run from the papillary muscle to the cusps of an AV valve

Front 91

Describe the septomarginal trabeculae

Back 91

Moderator band
Occurs in right ventricle and is composed of trabeculae carnae that lie partly free
Carries right branch of AV bundle

Front 92

Describe the conus arteriosus

Back 92

Occurs in right ventricle along the anterior part and terminates in the pulmonary artery

Front 93

Describe the valves of the heart

Back 93

Include two sets- atrioventricular and semilunar- and their subdivisions- classifications
Valve terms include nodule (where thickening of a valve is greatest) and lunule (region adjacent to a nodule and is thin)

Front 94

Describe the atrioventricular valves

Back 94

Occur between atria and ventricles
Anchored to papillary muscles by chordae tendeneae and are classified as:
Tricuspid valve- right AV with three flaps or cusps
Bicuspid valve (mitral)- left AV with two flaps or cusps

Front 95

Describe the semilunar valves

Back 95

Prevent blood from returning to ventricles and include:
Pulomary semilunar valve- proximal end of pulmonary trunk
Aortic semilunar valve- proximal end of aorta

Front 96

Describe innervation of the heart

Back 96

Initiation of cardiac cycle is myogenic, originating in SA node
Harmonized in rate, force, and output by autonomic nerves operating on the nodal tissues and their prolongations, on coronary vessels, and on the working atrial and ventricular musculature
Both efferent (sympathetic and parasympathetic) and afferent components supply the heart
All cardiac branches of the vagus and sympathetic contain both afferent and efferent fibers except the cardiac branch of the superior cervical sympathetic ganglion (purely efferent)

Front 97

Describe the efferent preganglionic cardiac sympathetic fibers

Back 97

Arise from neurons in the intermediolateral column of the upper 4-5 thoracic spinal segments
They pass by white rami communicantes to synapse in upper thoracic sympathetic ganglia, but many ascend to synapse in cervical ganglia
Postganglionic fibers from these ganglia form sympathetic cardiac nerves, which accelerate the heart and dilate the coronary arteries

Front 98

Describe the efferent cardiac parasympathetic axons

Back 98

Arise from dorsal vagal nucleus and neurons near the nucleus ambiguous and run in vagal cardiac branches to synapse in the cardiac plexuses and atrial walls
Vagal fibers slow the heart and cause constriction of the coronary arteries
Intrinsic cardiac neurons are limited to the atria and interatrial septum, and are most numerous in the subepicardial CT near the SA and AV nodes
These intrinsic ganglia are not simple nicotinic relays, but may act as sites for integration of extrinsic nervous inputs and form complex circuits for the local neuronal control of the heart, and possibly local reflexes

Front 99

Describe the cardiac plexuses

Back 99

Occur near the heart
Autonomic nerves form a mixed cardiac plexus that are described in terms of a superficial component inferior to aortic arch lying between it and the pulmonary trunk and a deep part between the aortic arch and tracheal bifurcation
May also be described in regional names for its coronary, pulmonary, atrial and aortic extensions
Contain ganglion cells (found in the heart along the distribution of branches of the plexus)
Confined to atrial tissue with a preponderance adjacent to SA node
Their axons are considered to be (mostly) postganglionic parasympathetic
Adrenergic fibers supply the coronary arteries and cardiac veins
Rich plexuses of nerves containing cholinesterase, adrenergic transmitters and other peptides (e.g., neuropeptide Y) are found in the subendocardial regions of all chambers and in the cusps of the valves

Front 100

Describe the superficial (ventral) part of the cardian plexus

Back 100

Lies inferior to aortic arch and anterior to right pulmonary artery, and is formed by the cardiac branch of the left superior cervical sympathetic ganglion and the lower of teh two cervical cardiac branches of the left vagus
A small cardiac ganglion is below the aortic arch and right of the ligamentum arteriosum and connects with the deep plexus, right coronary plexus, and left anterior pulmonary plexus

Front 101

Describe the deep (dorsal) part of the cardiac plexus

Back 101

Anterior to tracheal bifurcation, above division of pulmonary trunk and posterior to aortic arch
Formed by cardiac branches of cervical and upper thoracic sympathetic ganglia and of the vagus and recurrent laryngeal nerves
Only the cardiac branches that join the superficial part of the plexus do not contribute to the deep plexus
This plexus supplies the right anterior pulmonary plexus, right coronary plexus, right atrium, left coronary plexus (right half of plexus), and left half of plexus contributes to left atrium, left anterior pulmonary plexus, and left coronary plexus

Front 102

Describe the left coronary plexus

Back 102

Larger than the right plexus and formed primarily by the deep plexus
Accompanies left coronary artery to supply the left atrium and ventricle

Front 103

Describe the right coronary plexus

Back 103

Formed from both superficial and deep plexuses and accompanies the right coronary artery to supply the right atrium and ventricles

Front 104

Describe the atrial plexuses

Back 104

Derivatives of the right and left continuations of the cardiac plexus along the coronary arteries
Their fibers are distributed to the corresponding atria and overlapping those from the coronary plexus

Front 105

Describe cardiac pain

Back 105

Phenomenon whereby noxious stimuli originating in the heart are perceived by a person as pain arising form a superficial part of the body (e.g., skin on left upper limb)

Front 106

Describe anginal pain

Back 106

Commonly felt as radiating from the substernal and left pectoral region to the left shoulder and the medial aspect of the left upper limb (supplied by medial cutaneous nerve of arm)
Often the lateral cutaneous branches of 2-3 intercostal nerves (intercostobrachial) join or overlap in their distribution with the medial cutaneous nerve of the arm
Cardiac pain is felt in upper limb because the spinal cord segments of cutaneous nerves (T1-T3) are also common to visceral afferent terminations of coronary arteries
Synaptic contact may also be made with commissural neurons (connector) which conduct impulses to neurons on right side of comparable areas of spinal cord
This is why cardiac pain may be felt on right side, both sides, or back

Front 107

Describe the sinoatrial node of teh heart

Back 107

Pacemaker of the heart
Embedded in anterolaterally and deep to epicardium of right atrium near entrance of the SVC
It initiates cardiac muscle contractions and determines heart rate
Contractions spread through atrial wall until reaching AV node, which sits within the floor of the atrium near opening of coronary sinus

Front 108

Describe conduction of electrical signal through the heart

Back 108

AV bundle passes from AV node to part of the interventricular septum and divides into right and left bundle branches
Right bundle takes a pathway from the anterior wall of ventricle to anterior papillary muscle where excitation spreads throughout right ventricular wall via Purkinje fibers
Left bundle takes a pathway where the branches enter the wall of the left ventricle and give rise to branches, then to Purkinje fibers

Front 109

How does damage to the conducting system affect it?

Back 109

Causes disturbances in cardiac muscle contraction
Septomarginal trabecula was once called moderator band because it was believed its contraction during systole part of cardiac cycle caused the moderated outward bulging of the ventricle's anterior wall- not proven

Front 110

What is the cardiac cycle?

Back 110

Period between heart beats or alternate periods of contractions and relaxations of heart chambers
For any single chamber, divided into two phases: contracton or systole where chamber ejects blood into another heart chamber or into an arterial trunk and relaxtion or dystole where a chamber fills with blood and prepares for teh start of the next cycle

Front 111

What are the steps of the cardiac cycle?

Back 111

1) Ventricular diastole (late) is a phase where all chambers relax and blood enters ventricles
2) Atrial systole where atria contract to force additional blood into ventricles
3) Atrial diastole where atria reflex and ventricular contractions begin
4) Ventricular systole where ventricular contractions close AV valves and semilunar valves open (only after pressure build and exceed that of arterial trunks)
5) Ventricular diastole (early) where ventricles relax, pressure drops, semilunar valves close, and blood enters relaxed atria

Front 112

Describe the coronary arteries

Back 112

Proximal most two branches of the ascending aorta
Right coronary artery arises from right aortic sinus and follows coronary groove and continues until reaching the posterior interventricular sulcus
Forms an anastomosis with circumflex branch of left coronary artery
Left coronary artery arises from the left aortic sinus and follows the coronary sulcus
If bifurcates distally to form two arteries (anterior interventricular and circumflex arteries)

Front 113

Describe the additional branches of the heart

Back 113

1) Left SA nodal- supplies left atrium and SA node
2) Right SA nodal- supplies pulmonary trunk and SA node
3) Left marginal branches- supply anterior wall of left ventricle
4) Right marginal branches- supply right ventricle and apex of heart
5) AV nodal- supplies AV node
6) Left circumflex- supples left atrium and left ventricle
7) Posterior descending branch- anastomose with anterior descending branch of left coronary

Front 114

Describe venous drainage of the heart

Back 114

Coronary sinus courses along the coronary sulcus (between left atrium and ventricle). It is major drainage vessel of heart and empties into right atrium
Several major veins drain into coronary sinus including the great cardiac, middle cardiac, small cardiac, left oblique of left atrium, and left posterior ventricular

Front 115

What is the blood flow within the heart

Back 115

Coronary sinus--> Right atrium--> Right AV valve (tricuspid)--> Right ventricle--> Pulmonary semilunar valve--> Pulmonary trunk--> Right and left pulmonary arteries--> Capillaries of lungs--> Right and left pulmonary veins--> Left atrium--> Left AV valve (mitral, bicuspid)--> Left ventricle--> Aortic semilunar valve--> Ascending aorta--> Aortic arch

Front 116

Describe the fetal blood flow

Back 116

Umbilical cords have two umbilical arteries that carry blood away from fetus, carrying waste to placenta (becomes medial umbilical ligament in adults)
One umbilical vein runs toward fetus and carries oxygen rich blood and is the life-line of a developing fetus (becomes round ligament of liver in adult)
Ductus venosus allows blood to go directly to fetal heart and bypasses fetal liver (becomes ligamentrum venosum in adult)
Foramen ovale allows blood to shunt between two atria and allows blood to bypass lungs and go directly to heart; open in fetus and closes in 90% of population to become fossa ovalis in adult
Ductus arteriosus is small vessel connecting pulmonary trunk with aorta and enables most blood to bypass fetal lungs (becomes ligamentum arteriosum in adult)

Front 117

Describe arteriosclerosis

Back 117

Hardening of coronary arteries
Occurs in any vessel that is elastic and contains smooth muscles, in discrete zones
Episodic event, may be little to no symptoms until 95% of vessel is blocked
Likely scar endothelial lining
Blocked coronary circulation or heart block may occur because blood flow to capillary beds is blocked
Coronary arteries do not anastomose well but can be increased by exercise

Front 118

Describe coronary bypass grafting

Back 118

Common surgical technique used to deal with blocked vessels
Can be double-quintuple
Not usually repeated because vessels become weak and brittle

Front 119

Describe angioplasty

Back 119

Common surgical technique to deal with blocked vessels
Involves a small catheter-like device with a balloon on the tip that is inserted into a clogged artery to clean it out
Loose plaque could cause heart attack by stopping blood flow

Front 120

What are the two basic types of aneurysm?

Back 120

1) Straight
2) Dissecting

Front 121

Describe a straight aneurysm

Back 121

Creates a weak wall because of the turbulence within vessel and ballooning occurs for affected vessel
Can occur within any vessel and is named for region of occurrence

Front 122

Describe a dissecting aneurysm

Back 122

Vessel wall splits, may be along entire length of vessel