Anatomy, Lecture 7, The Heart 2 (Slides)

8/8/2019 Anatomy, Lecture 7, The Heart 2 (Slides)

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Heart (2)Heart (2)

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Superior & InferiorSuperior & Inferior MediastinaMediastina

Pages 111Pages 111--130 Snell 8130 Snell 8thth editionedition


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Innervation to The HeartInnervation to The Heart

Conducting System (initiator)

Autonomic System


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Conducting SystemConducting System

1. Initiates cardiac contraction2. Conducts impulse to ventricles

Sino-Atrial node (SA node)

Atrio-Ventricular node (AV node)

Atrio-Ventricular Bundle (bundle of His)

Rt & Lt bundle branches

Purkinje fibers

(subendocardial plexus)


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SS--A Node (A Node (The PacemakerThe Pacemaker))

Site of contraction initiation

stellate cells (P-cells)

Modified cardiomyocytes

Rt. Atrium:

upper part, anterolateral to SVC

Impulse spreads from SA node

through atrial walls toAV node


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AA--V NodeV Node

The pulse conductor

Lower part ofatrial septum

(above septal cusp)

Conduct pulse to ventricles

through AV bundle


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AV bundle (septum)

Right (moderator) & Left

bundle branches

Purkinje fibers


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Autonomic InnervationAutonomic Innervation

1. Modifies cardiac contraction

To SA & AV nodes

Sympathetic (sympathetic trunk):increase heart rate

increase force of contraction

dilatation of coronary artery

Parasympathetic (vagus nerve):decrease heart rate

reduce force of contraction

constriction of coronary artery


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Arterial SupplyArterial Supply

Coronary arteries:

From ascending aorta & just above the valve

Left (larger):most of Lt ventricle and atrium

anterior 2/3 of ventricular septum , RBB, LBB

Right: rest of the heart


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Left Coronary ArteryLeft Coronary Artery

Larger but shorter

Arises between pulmonary trunk

& Lf. Auricle

Divides to:

1. ant. interventricular a.

2. circumflex a

3. SA nodal (35 - 40%)


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Ant. Interventricular ArteryAnt. Interventricular Artery

LAD: Left AnteriorDescending

Pass in ant. intervent. Groove

turns around the apex

anastomose with post. intervent.

artery

Gives rise to diagonal artery (lateral)


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Circumflex ArteryCircumflex Artery

Pass in left AV groove

winding around the heart in a circle

anastomoses with Rt. coronary posteriorly

Gives rise to left marginal artery


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Angina PectorisAngina Pectoris

Severe chest pain due to O2 shortage to the heart wall

(ischemic heart disease)

Cause:

Partial obstruction or spasm of a coronary artery(arteriosclerosis)

Symptoms:

chest discomfort (pressure, heaviness or tightness)

substernal pain specially after ?

referred pain over the left arm, neck & lower jaw

Complication:

Infarction (death of a part of myocardium)

Angina = G, strangling, Pectoris= L, chest


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Myocardial InfarctionMyocardial Infarction

Interruption of bld. Supply to a part of the heart leading todeath ofheart muscle on that region.

Known as:

Heart Attack

Cause:

complete block of a coronary artery (thrombosis)

Symptoms:

chest pain (as in angina)

dyspnea

Rx.:

Coronary bypass surgery


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Heart ValvesHeart Valves

4 valves:

- 2 semilunar:

Aortic

Pulmonary

- 2 A-V:

Rt A-V:Tricuspid

Lt A-V: Mitral


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Semilunar ValvesSemilunar Valves

Pulmonary:

3 semilunar cusps (2 ant. & 1 post.)

Cusp: folding of endocardium with C.T. inside

Sinus: space behind each cusp

Aortic : similar to pulmonary

2 post. & 1 ant. cusps


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Tricuspid ValveTricuspid Valve

Rt. A-V orifice

3 cusps:

1. ant. 2. post. 3. septal

Attached to papillary m. through

Chordae tendineae

Chordae of each P.M. are connected to adjacent parts of 2 cusps


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Mitral ValveMitral Valve

Left A-V orifice

2 cusps (bicuspid):

Ant. & Post.

Similar attachments &

fxn. as tricuspid valve


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Auscultation of Heart ValvesAuscultation of Heart Valves

((Read Next Slide for Complete DetailsRead Next Slide for Complete Details))

Mitral (M)

Tricuspid (T)

Aortic (A)

Pulmonary (P)


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Auscultation of Heart ValvesAuscultation of Heart Valves

Mitral (M): Lt of sternum, 4th CC

Over the apex

Tricuspid (T): Rt of sternum, 4th intercostal space

Rt of lower end of body of sternum

Aortic (A): Lt of sternum, 3rd intercostal space

Medial end of of 2ndRt intercostal space

Pulmonary (P): medial end of 3rdLtCC

Medial end of of 2ndLt intercostal space


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Posterior MediastinumPosterior Mediastinum


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BoundariesBoundaries

Anterior:

Pericardium & diaphragm

Posterior:

T5 T12

Superior:

??

Inferior:

diaphragm


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ContentsContents

1. Descending thoracic aorta

2. Azygos & hemiazygos veins

3. Thoracic duct

4. Sympathetic trunk

5. Esophagus


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Thoracic AortaThoracic Aorta

Starts left to lower border of T4 body

As it descends shifts to midline

Terminates:

ant. to T12 body (opening ??)

Pass posterior to Lf. Lung root


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BranchesBranches

1. Bronchial a.:trachea, bronchi & lungs

2. Esopahgeal a.

3. Pericardial a.

4. Posterior intercostal a.:

9 pairs (3rd-11th)

5. Subcostal arteries: along the

inferior border of the 12th rib

and goes to the abdomen


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Azygos System of VeinsAzygos System of Veins

(G, unpaired)

Drains Post. thoracoabdominal walls

Exhibits Many variations

3 veins:

Azygos (Rt.)

Inf. hemiazygos (Lf.)

Sup. (accessory) hemiazygos (Lf.)


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Inferior Hemiazygos VeinInferior Hemiazygos Vein

On Left side

From T12J T8

Drains:Lower Lf. Post. intercostal vein

(9th-11th, & subcostal)

At T8:

Turns to Rt. azygos vein


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Accessory HemiazygosAccessory Hemiazygos

On left side (superiorly)

Receives:

4

th

-8

th

Lf. Post. intercostal v.

At T 7:

Turns to Rt. azygos vein

Azygos system provides alternativeAzygos system provides alternative

pathway betweenpathway between

SVC& IVCSVC& IVC


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LymphaticLymphatic

Thoracic DuctThoracic Duct


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Thoracic DuctThoracic Duct

The largest lymph duct in the body

Begins in abdomen as a dilated sac

(cisterna chyli)

Aortic Hiatus

(between aorta & azygos)

Lf. Brachiocephalic Vein

(Jxn: Int. jugular & Subclavian)

Drains lymph from all body except:

Rt. Thorax, Rt. Upper limb, Rt. Head & Neck


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Right Lymphatic DuctRight Lymphatic Duct

Drains:

Rt. Thorax

Rt. Upper Limb

Rt. Head & Neck

Opens:

Junx of Rt. Internal jugular

& Rt. Subclavian

Communicates with thoracic duct


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Thoracic Part of Sympathetic ChainThoracic Part of Sympathetic Chain

Most lat. Structure in mediastinum

Runs on the heads of the ribs

Leaves behind medial arcuate lig.


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EsophagusEsophagus

A tubular structure Begins opposite to C6 as a continuation of thepharynx & ends in the stomach

3 parts:

cervical

thoracic (relations)

abdominal

Pass through sup. & post.

mediastinum

Then through esophageal opening

(T10)


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Thoracic Part RelationsThoracic Part Relations

Anterior:

Trachea & Lf. Recurrent laryngeal n.

(Superior Mediastinum)

Posterior:

Bodies of thoracic vrtebrae

Then

Descending aorta

Thoracic ductAzygos vein


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The Superior MediastinumThe Superior Mediastinum


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BoundariesBoundaries

Sup.: Anatomical thoracic inlet

Inf.: Imaginary line

Ant.: manubrium

Post.: T1-T4


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ContentsContents

1. Brachiocephalic veins & SVC

2. Aortic arch & branches:

brachiocephalic

Lf. C.C.a.

Lf. Subclavian a.

3. Vagus & Phrenic n.

4. Trachea

5. Esophagus


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Brachiocephalic VeinsBrachiocephalic Veins

Formed by union : Int. Jug. v. & Subclavian v.

(at sternoclavicular joints)

Lf.: longer (6 cm)

pass post. to manubrium

ant. to aortic branches

Rt.: 2-3 cm

vertical to right 1

st

cc

Unite behind Rt. 1st cc to form SVC


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Superior Vena Cava (SVC)Superior Vena Cava (SVC)

Starts behind Rt. 1st cc

Ends behind Rt. 3rd cc

Rt. Atrium

Relations:Ant.: Rt. Lung & covering pleura

Post.: root of Rt. Lung

Medial: Ascending aorta

Lateral: Rt. Phrenic & Rt. lung

Tributaries:

Azygos Vein


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AortaAorta

4 Parts4 Parts::

1. Ascending Aorta:

lies within fibrous pericardium sup. to Rt. Until Rt. 2nd cc

branches:

Rt & Lt coronary arteries


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Arch ofArch of AortaAorta (sup. mediast)

curved continuation of Ascending aorta

at Rt. 2nd cc

arches upward-backward & to Lf. Side

infero-posterior

Lf. Side of T4 body (sternal angle)

Relations:

Arches over:

Rt. Pulmonary a. & Lf. Main bronchus

Crossed ant.:

Lf. Vagus & phrenic n.

Rt.:Trachea & Esophagus


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Branches of The ArchBranches of The Arch

1. Brachiocephalic a.: (Rt.)

largest branch

S-C jointJ Rt. CC a. & Rt. Subclavian a.

2. Lf. Common Carotid a.:

enters the neck at S-C joint

3. Lf. Subclavian a.:

most post. branchloops over 1st rib J upper limb


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3. Descending Thoracic Aorta:

Discussed previously

4. Abdominal Aorta:

starts at T12- L1

ends by dividing into:

Rt. & Lf. common iliac a.

at L4


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Nerves in Mediastinum:Nerves in Mediastinum:

Vagus & PhrenicVagus & Phrenic


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Vagus NerveVagus Nerve

CN X (parasympathetic)

Rt. Vagus:

- Lat. to the trachea

- Medial to azygos

- Post. to root of the Rt. lung

- Join esophagus:esophageal opening (Post.)

Gives Rt. Recurrent laryngeal n. that loops around subclavian a.


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Left VagusLeft Vagus

- Descends between Lf. Cc & Lf.

Subc. arteries

- ant. & Lf. to aortic arch

Lf. Recureent laryngeal n.

- Post. to lung root

- Join esophagus:

esophageal opening (ant.)


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Phrenic NervePhrenic Nerve

C3, 4, 5

Motor:

Sole motor to diaphragm

Sensory: Sensory to central part of

diaphragm

Pericardium

Parietal pleura (mediastinal &

diaphragmatic)

Peritoneum (diaphragmatic)


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Rt. PhrenicRt. Phrenic

Descends lat. to

brachiocephalic & SVC

Ant. to root of Rt. Lung

Rt. Side of pericardium

Rt. to IVC:

caval opening


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Left PhrenicLeft Phrenic

Enters Lf. To subclavian a.

Lat. To vagus n (X)

Ant. to root of Lf. Lung


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TracheaTracheaFibrocartilaginous tube

(C6-sternal angle)

In deep inspiration it reaches thelevel of?

U-shaped bars ofhyaline catilage

& smooth muscle (trachialis)

Rt. bronchus:

Wider, shorter & more vertical

Lf. Bronchus:Narrower, longer & more horizontal

Relations of Lf. bronchus?Inf. To aortic arch, ant. To esophagus


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Tracheal RelationsTracheal Relations

Anterior:Lf. Brachiocephalic v. & manubrium

Posterior:

esophagus & recurrent laryngeal n.

Right:Rt. Vagus n. & Azygos v. (just inf.)

Left:Aortic arch, Lf. CC & Subclav. A & Lf. Vagus n.


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Anatomy, Lecture 7, The Heart 2 (Slides)

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