chest wall,lung anatomy and physiology

8/12/2019 Chest Wall,Lung Anatomy and Physiology

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Chest Wall and LungAnatomy and

Physiology

Zeyad S Alharbi, M.D.


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Anatomy and Physiology of the Thorax

Thoracic Skeleton 12 Pair of C-shaped Ribs

Ribs 1-7: Join at sternum with cartilage end-points Ribs 8-10: Join sternum with combined cartilage at 7thrib

Ribs 11-12: No anterior attachment Sternum Manubrium

Joins to clavicle and 1strib

Jugular Notch

Body Sternal angle (Angle of Louis)

Junction of the manubrium with the sternal body

Attachment of 2ndrib

Xiphoid Process Distal portion of sternum


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Thoracic Skeleton Topographical Thoracic Reference Lines

Midclavicular line Anterior axillary line

Mid-axillary line Posterior axillary line Intercostal Space

Artery, Vein and Nerve on inferior margin of each rib Thoracic Inlet

Superior opening of the thorax

Curvature of 1st

rib with associated structures Thoracic Outlet

Inferior opening of the thorax 12thrib and associated structures & Xiphisternal joint


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Blood Supply and Innervation


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Anterior Chest Wall Deformities

1. Pectus excavatum 2. Pectus carinatum

3. Polands syndrome 4. Sternal defects 5. Miscellaneous


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Etiology and Incidence of Pectus Excavatum

It is reported 1/700 of lives birth M:F=3.4:1

37% occur in Families with Chest walldeformities It is a posterior depression of the sternum and

costal cartilage due to over grow of costal

cartilage The 1stand 2ndribs, manubrium are in normalposition


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M-S Abnormalities with Pectus Excavatum

Scoliosis Kyphosis

Myopathy Marfans syndrome Cerebral palsy Prune-belly syndrome Tuberous sclerosis


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Symptoms of Pectus Excavatum

Decreased exercise tolerance Fatigability

Dyspnea on exertion, and sternal pain Palpitations and multiple respiratory tract

infections are reported

MOST complaint : cosmetic deformityrather than symptomatology


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Pectus Carinatum

( Pigeon Chest )

It refers to anterior protrusion of the sternum

It is less common than pectus excavatum


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Categories of Pectus Carinatum

1. Chondrogladiolar

(I) It is the most common pectus carinatum

(II) It consists of anterior protrusion of

the body of sternum and lower costalcartilages


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(2) Lateral Pectus Carinatum :a unilateral protrusion of the costal cartilages and

is usually accompanied by sternal rotation to the

opposite side

(3) Chondromanubrial:(I) Uncommon

(II) Protrusion of Manubrium,2ndand 3rdcostal cartilages withrelative depression of the body andsternum


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Polands Syndrome1841

It refers to a congenital absence of thepectoralis major and minor muscles, ribs,

breast abnormality, chest wall depressionand syndactyly, brachydactyly or absenceof phalanges

It is present in 1/30000 The etiology is unknown


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Thoracic Outlet Syndrome TOS

Cervical Rib:

0.5-1% population (not allare symptomatic)

Neurogenic symptoms95%

Ulnar nerve C8-T1 is usuallyaffected

Vascular Symptoms 5% Subclavian artery

Subclavian vein

{cervical rib between the transverse

process of C7 & the 1strib. You can

see the cervical rib in the other side

elevating the brachial plexus.}

{Definition of cervical rib: an accessory rib

which is not normally present. If present itmay cause compression of important

structures in the thoracic outlet.}


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Vascular Symptoms of TOSSubclavian Artery:

Prolonged compression & trauma

Intimal injury

Stenosis, Thrombosis

Post-stenotic Dilatation or Aneurysm

Distal Micro-embolisation

BandCervical

Rib

{In Unilateral Raynauds alwayssuspect TOS, because usuallyRaynauds phenomenon issystemic & will cause bilateralsymptoms}


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Depending on the surgeons preference, there are 2 approachesfor the surgery:

Supraclavicular Approach: Scalenectomy

Excision of 1strib & fibrous bands

Repair of subclavian artery if its injured and patient has vascular

problems: Thrombectomy, patch angioplasty Excision of aneurysm & bypass graft

{scalenectomy & 1strib excision are enough in those with

neurological symptoms}

Transaxillary Approach: Excision of 1strib. This causes the brachial to go down a little relieving

the compression

Surgical Treatment of TOS


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The Respiratory Muscles


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Pleura:appears between the 4th and 7th gestational weeks

Visceral Pleura Cover lungs

Parietal Pleura Lines inside of thoracic cavity.

Pleural Space


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The relationships of the pleural reflections andthe lobes of the lung to the ribs that at the

midclavicular line, the recess is between ribspaces 6 and 8, at the midaxillary line between8 and 10 and at the paravertebral line between10 and 12.


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LungsGross Anatomy Paired, cone-shaped organs in thoracic

cavity Separated by heart and other

mediastinal structures

Covered by pleura Extend from diaphragm inferiorly tojust above clavicles superiorly

Lies against thoracic cage (pleura,muscles, ribs) anteriorly, laterally andposteriorly


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LungsGross Anatomy

Hilum Medial root of the lung

Point at which vessels, airways and lymphaticsenter and exit

Cardiac Notch

Lies in medial part of left lung toaccommodate the heart


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Lobes and Fissures


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LungBlood Supply

Dual Supply Bronchial Supply: arises from superior

thoracic aorta or the aortic arch. Supply bronchi, airway airway walls and pleura

Pulmonary Supply

Pulmonary arteries enter at hila and branchwith airways


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Lymphatics

Lymphatic drainage follows vessels Parabronchial (peribronchial) lymphatics

and nodes hilar nodes mediastinalnodes pre- and para-tracheal nodes supraclavicular nodes


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Mediastinum Central space within thoracic cavity

Boundaries Lateral: Lungs Inferior: Diaphragm Superior: Thoracic inlet

Structures Heart Great Vessels Esophagus Trachea

Nerves Vagus

Phrenic

Thoracic Duct


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Respiratory Center in ReticularFormation of the Brain Stem Medullary Rhythmicity Center

Controls basic rhythm of respiration

Inspiratory (predominantly active) andexpiratory (usually inactive in quietrespiration) neurones

Drives muscles of respiration

Pneumotaxic Area Inhibits inspiratory area

Apneustic Area Stimulates inspiratory area, prolonging

inspiration


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Regulation of Respiratory Center

Chemical Regulation Most important

Central and peripheral chemoreceptors

Most important factor is CO2 (and pH)

in arterial CO2 causes in acidity of

cerebrospinal fluid (CSF)in CSF acidity is detected by pH sensors

in medulla

Medulla rate and depth of breathing


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Regulation of Respiratory Center

Cerebral CortexVoluntary regulation of breathing

Inflation Reflex Stretch receptors in walls of bronchi/bronchioles

Respiratory Centers and Reflex Controls


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Figure 23.27

Respiratory Centers and Reflex Controls


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Pulmonary function is affected by lungresection, extent varies:

pneumonectomy:

FEV1: 34~36% FVC: 36~40%VO2max: 20~28%

lobectomy:

FEV1: 9~17% FVC: 7~11%VO2max: 0~13%

Am J o f Med (2005) 118, 578583


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chest wall,lung anatomy and physiology

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