m, thorax, lectures i

8/10/2019 M, Thorax, Lectures I

1/30

Lecture ILecture I

IntroductionIntroduction totoThorax.Thorax.

Thoracic CAGE (SkeletonThoracic CAGE (Skeleton ofofThorax).Thorax).

InletInlet ofof THORAX.THORAX.

OutletOutlet ofofTHORAX.THORAX.

Bony and!ark"Bony and!ark" ofofThorax.Thorax.

Interco"tal S#ace".Interco"tal S#ace".

Interco"tal $u"cle".Interco"tal $u"cle".Interco"tal %er&e".Interco"tal %er&e".


2/30

IntroductionIntroduction toto ThoraxThorax

''Trunk of body is divided by diaphragmTrunk of body is divided by diaphragmintointoanan upperu

pperpartpartThoraxThorax andand

lowerlowerpartpartAdo!enAdo!en..

'' ThoraxThoraxis supported by a skeletalis supported by a skeletal

frameworkframework (Thoracic Ca*e)(Thoracic Ca*e)and containsand containsprincipalprincipal(main)(main)organs of respirationorgans of respiration(lungs) and circulation (heart).(lungs) and circulation (heart).

'' Thoracic cageThoracic cageis an osseocartilagenous,is an osseocartilagenous,elasticelastic cage which is primarily designedcage which is primarily designedfor increasing and decreasing intra-for increasing and decreasing intra-thoracic pressure, so that air is alternatelythoracic pressure, so that air is alternately

sucked into lungs during inspiration andsucked into lungs during inspiration andexpelled out during expirationexpelled out during expiration


3/30


4/30

THORACIC CAGETHORACIC CAGE(Skeleton of Thorax)(Skeleton of Thorax)

+or!ation+or!ation ,,nteriorlynteriorly Sternum.Sternum.

,,!osteriorly!osteriorly "# Thoracic vertebrae and intervening intervertebral discs."# Thoracic vertebrae and intervening intervertebral discs.

,,$n each side$n each side "# %ibs with their cartilages."# %ibs with their cartilages.

Sha#eSha#e''Thorax resembles aThorax resembles a truncated conetruncated cone& which is narrow above and broad below.& which is narrow above and broad below.

'''arrow upper end is continuous with root of neck& from which it is partly'arrow upper end is continuous with root of neck& from which it is partlyseparated byseparated by suprapleural membranesuprapleural membrane..

''road lower end is almost completely separated from abdomen byroad lower end is almost completely separated from abdomen by dia#hra*!dia#hra*!..

''Thoracic cavity is actually muchThoracic cavity is actually much smallersmallerthan what it appears&than what it appears& becausebecause -- pper narrow part appears broad due to shoulders.pper narrow part appears broad due to shoulders.

--*ower part is greatly encroached by abdominal cavity.*ower part is greatly encroached by abdominal cavity.

''+n transverse section, thorax is+n transverse section, thorax is reniformreniform(idney- shaped)& with a greater(idney- shaped)& with a greatertransverse diameter than anteroposterior.transverse diameter than anteroposterior.


5/30


6/30

SUPERIOR APERTURESUPERIOR APERTURE((o#enin* holeo#enin* hole))((InletInlet) of T$%) of T$%

'' +t is narrow upper end of thorax& which is continuous with neck.+t is narrow upper end of thorax& which is continuous with neck.

Boundarie"Boundarie"

, Anterior, Anterior pper border of manubrium sterni.pper border of manubrium sterni. , /o"terior, /o"terior Superior surface of body of /rst thoracic vertebra.Superior surface of body of /rst thoracic vertebra.

, On each "ide, On each "ide 0irst rib with its cartilage.0irst rib with its cartilage.

Sha#eSha#e%eni-forrm.%eni-forrm.(kidnet shape)(kidnet shape)

0i!ention"0i!ention"--Transverse diameter ( 1 - 2 inches).Transverse diameter ( 1 - 2 inches).

--nteroposterior diameter ( # - #3 inches).nteroposterior diameter ( # - #3 inches).


7/30


8/30


9/30

Suprapleural e!"raneSuprapleural e!"rane((#iaphrag!#iaphrag! ofof inletinlet of thoraxof thorax))

''+t partly separates thorax from neck.+t partly separates thorax from neck.

'' +t is+t is trian*ulartrian*ular in shapein shape

-- A#exA#exis attached to tip of transverseis attached to tip of transverseprocess ofprocess of C1C1 vertebra.vertebra.

-- Ba"eBa"eis attached to inner border ofis attached to inner border of/rst rib and its cartilage./rst rib and its cartilage.

-- +unction+unctionit provides rigidity toit provides rigidity tothoracic inlet so that root of neck isthoracic inlet so that root of neck isnot pu4ed up and down duringnot pu4ed up and down duringrespiration.respiration.

''+ts inferior surface is fused to cervical+ts inferior surface is fused to cervicalpleura, and its superior surface ispleura, and its superior surface isrelated to subclavian vessels andrelated to subclavian vessels andother structures at root of neck.other structures at root of neck.

I$%ERIOR APERTUREI$%ERIOR APERTURE(( i h li h l ))


10/30

I$%ERIOR APERTUREI$%ERIOR APERTURE((o#enin* holeo#enin* hole))((OutletOutlet) of T$%) of T$%

''+t is broad lower end of thorax, which surrounds upper part of abdominal cavity,+t is broad lower end of thorax, which surrounds upper part of abdominal cavity,

but it is separated from it by diaphragm.but it is separated from it by diaphragm.

Boundarie"Boundarie"

, Anterior, Anterior

infrasternal angle between two costal margins.infrasternal angle between two costal margins.

, /o"terior, /o"terior inferior surface of body of "#th thoracic vertebra.inferior surface of body of "#th thoracic vertebra.

, On each "ide, On each "ide") 5ostal margin, formed by cartilages of 6th, 7th, 8th and "9th ribs.") 5ostal margin, formed by cartilages of 6th, 7th, 8th and "9th ribs.

#) ""th and "#th ribs.#) ""th and "#th ribs.

Sha#eSha#e

it is wider transversely than from before backwards, and slopes obli:uelyit is wider transversely than from before backwards, and slopes obli:uely

downwards and backwards.downwards and backwards.

0ia#hra*!0ia#hra*!((diaphragmdiaphragm ofof outl tutl t ofof thoraxthorax))'' musculotendinous partition which, separates thorax from abdomen and forms musculotendinous partition which, separates thorax from abdomen and forms

;oor of thorax.;oor of thorax.


11/30


12/30

Bony and!ark"Bony and!ark" ofofThoraxThorax'' Su#ra"ternalSu#ra"ternal ((jugularjugular))notchnotch+t lies at level of lower border of body of second+t lies at level of lower border of body of second

thoracic vertebra.thoracic vertebra.

'' Sternal an*leSternal an*le ((angleangle ofof LouisLouis))+t is felt as a transverse ridge below suprasternal+t is felt as a transverse ridge below suprasternalnotch. +t marks manubrio-sternal


13/30


14/30

I tI!#ortance fof t l l"ternal an*le


15/30

I!#ortanceI!#ortance ofof "ternal an*le"ternal an*le

'' Ri"Ri"are counted from this level down.are counted from this level down.

''>arks>arks #lane#lanewhichwhich separatesseparatessuperior from inferior mediastinum.superior from inferior mediastinum.

'' A"cendin* aortaA"cendin* aortaends at this level.ends at this level.

'' ArchArch ofof aortaaortabegins and also ends at this level.begins and also ends at this level.'' 0e"cendin* aorta0e"cendin* aortabegins at this level.begins at this level.

'' TracheaTrachea divides into two principaldivides into two principal(main)(main)bronchi.bronchi.

'' A3y*o" &einA3y*o" &einarches over root of right lung and opens into superior vena cava.arches over root of right lung and opens into superior vena cava.

'' /ul!onary trunk/ul!onary trunkdivides into two pulmonary arteries arks upper limit of a"ea"e ofof heartheart..

'' Cardiac #lexu"e"Cardiac #lexu"e"are situated at same level.are situated at same level.


16/30


17/30


18/30

Interco"tal S#ace"Interco"tal S#ace"

'' %ibs are separated%ibs are separated bybyintercostal spacesintercostal spaces, which are, which are 4444on each side.on each side.

''Typically, each intercostal spaceTypically, each intercostal space containscontains

- 5 Interco"tal !u"cle"- 5 Interco"tal !u"cle"

ExternalExternal intercostal,intercostal, InternalInternalintercostal @intercostal @ Tran"&er"u"Tran"&er"u" thoracis.thoracis.

- 5- 5 $ther$therinterco"tal "turcture"interco"tal "turcture"nn arteryartery, a, a &ein&ein@ a@ a ner&ener&e..


19/30


20/30

Interco"talInterco"tal

u&cle&u&cle&

''rranged inrranged in 5 layer"5 layer", like = layers of, like = layers ofmuscles of anterior abdominal wall.muscles of anterior abdominal wall.

''+n both thorax and anterior abdominal+n both thorax and anterior abdominalwall, nerves and vessels liewall, nerves and vessels lie betweenbetweeninternal and innermost layers.internal and innermost layers.

External interco"talExternal interco"tal Ori*inOri*infrom lower border of upper rib.from lower border of upper rib.

In"ertionIn"ertioninto outer lip of upper border ofinto outer lip of upper border oflower rib.lower rib.

+ier"+ier" directed downwards and medially.directed downwards and medially.

ExtentExtent

,,from costochondral


21/30

InternalInternal

interco"talinterco"tal

Ori*inOri*infrom ;oor of costal groove offrom ;oor of costal groove ofupper rib.upper rib.

In"ertionIn"ertioninto inner lip of upperinto inner lip of upperborder of lower rib.border of lower rib.

+ier"+ier" directed upwards and medially.directed upwards and medially.

ExtentExtent,,from lateral border of sternum tofrom lateral border of sternum to

angle of rib.angle of rib.

,, PosteriorlyPosteriorly, it continuous as, it continuous asinternal (posterior) intercostalinternal (posterior) intercostalmembranemembrane..


22/30

Tran"&er"u" thoraci"Tran"&er"u" thoraci"

Tran"&er"u" thoraci"Tran"&er"u" thoraci"'' 0ormed of0ormed of 5 #art"5 #art"

4) Suco"tali"4) Suco"tali"con/nedcon/ned (enclosed)(enclosed) toto#o"terior#o"teriorparts of lower spacesparts of lower spaces onlyonly..

Ori*inOri*infrom inner surfaces of rib nearfrom inner surfaces of rib nearangle.angle.

In"ertionIn"ertioninto inner surface of #nd or =rdinto inner surface of #nd or =rdrib below.rib below.

6) Interco"tali" inti!i6) Interco"tali" inti!i(inner!o"t)(inner!o"t)

'' inin !iddle!iddle678678of space.of space.Ori*inOri*infrom inner surface of upper rib.from inner surface of upper rib.

In"ertionIn"ertioninto inner surface of lower rib.into inner surface of lower rib.

5) Sternoco"tali"5) Sternoco"tali"'' +n+n anterioranteriorpart of upper spaces, exceptpart of upper spaces, except

/rst space./rst space.

Ori*inOri*infromfrom,,*ower*ower 99 of posterior surface of body ofof posterior surface of body of

sternum.sternum.

,,!osterior surface of xiphoid process.!osterior surface of xiphoid process.

,,!osterior surfaces of costal cartilages of!osterior surfaces of costal cartilages oflower = or 1 true ribs.lower = or 1 true ribs.

In"ertionIn"ertioninto costal cartilages of #nd tointo costal cartilages of #nd to

Ath ribs.Ath ribs.


23/30


24/30

%er&e Su##ly%er&e Su##ly

+ntercostal nerve or nerves.+ntercostal nerve or nerves.

Action"Action"4)4)Blevators of ribs.Blevators of ribs.

6)6)>ain action of intercostal muscles is to prevent retraction during>ain action of intercostal muscles is to prevent retraction duringinspiration and bulging during expiration of intercostal spaces.inspiration and bulging during expiration of intercostal spaces.

''Such movements are indicative ofSuch movements are indicative ofparalysis of intercostalparalysis of intercostalmusclesmuscles..


25/30

Interco"tal %er&e"Interco"tal %er&e"

''nterior (ventral) primary rami ofnterior (ventral) primary rami ofT4 : T44T4 : T44 nerves are callednerves are called

intercostalintercostalnervesnerves..

' T46' T46isis subcostal nervesubcostal nerve, because it runs below last rib., because it runs below last rib.'' pper intercostal nerves (pper intercostal nerves (T4 : T5T4 : T5) supply upper limb.) supply upper limb.

'' *ower intercostal nerves (*ower intercostal nerves (T1 : T44T1 : T44) are) are thoracoabdominalthoracoabdominalnerves, supplynerves, supplyabdominal wall& in addition to thoracic wall.abdominal wall& in addition to thoracic wall.

''%est (%est (T8 : T;T8 : T;) nerves are called) nerves are called ty#icalty#ical intercostal nerves.intercostal nerves.

'' Subcostal nerve (Subcostal nerve (T46T46) is distributed to abdominal wall and skin of buttock.) is distributed to abdominal wall and skin of buttock.


26/30


27/30

T'picalT'pical+ntercostal 'erveC+ntercostal 'erveC

''Bach nerve passes below neck ofBach nerve passes below neck ofrib ofrib of samesamenumber, and entersnumber, and enters

costal groove.costal groove.'' +n costal groove, it lies below+n costal groove, it lies below

intercostal vessels, relation beingintercostal vessels, relation beingDD


28/30

B hB h


29/30

Branche"Branche"

$u"cular$u"cular,, NumerousNumerous branches, supply intercostal muscles and transversus thoracis.branches, supply intercostal muscles and transversus thoracis.

, Collateral, Collateral branch arises near angle of rib, runs in lower part of space, to supplybranch arises near angle of rib, runs in lower part of space, to supplymuscles of space, parietal pleura and periosteum of ribs.muscles of space, parietal pleura and periosteum of ribs.

Cutaneou"Cutaneou",, ateralateral cutaneouscutaneous branchbranch!ierces intercostal muscles and body wall along!ierces intercostal muscles and body wall along

midaxillary line, distributed to skin after dividing into anterior @ posterior branches.midaxillary line, distributed to skin after dividing into anterior @ posterior branches.

, Anterior, Anterior cutaneouscutaneous branchbranchBmerges on side of sternum to supply overlying skinBmerges on side of sternum to supply overlying skinafter dividing into medial and lateral branches.after dividing into medial and lateral branches.

Co!!unicatin*Co!!unicatin*

- Each ner&e- Each ner&eis connected tois connected to thoracic "y!#athetic *an*lionthoracic "y!#athetic *an*lionbyby

,, =hite=hitepreganglionic ramus to corresponding ganglion.preganglionic ramus to corresponding ganglion. ,, *rey*reypostganglionic ramus from corresponding ganglion.postganglionic ramus from corresponding ganglion.

--'erve is also connected to ad


30/30

m, thorax, lectures i

Documents