ANATOMYOFTHEDI
APHRAGM
Thehumandi aphragm isadouble-domedmuscul otendinouspart
iti
ont hatseparatesthe
t
horaci
cf rom t
heabdomi nalcavi
ty.I
tsconcaveinferi
orsurfacefacestheabdomi nalcav i
ty,
whi
leitsconvexsuperi
orsur f
acefacesthethoraciccavit
y.Iti
stheprimarymuscl eof
r
espir
ation.Onlyt
hecentralpartdescendsduri
ngi nspi
rati
on.Thecentraltendonispar t
ial
ly
f
usedwi ththeinf
eri
orsurfaceofthefibr
ouspericardi
um.
SHAPEOFTHEDI
APHRAGM
Itcurvesi
ntotherightandtheleftdomes.Theri
ghtdomei shi
ghert
hanthelef
tdome
becauseoft heri
ghtlobeoft hel
iver.Theri
ghtdomereachesthe5t
hrib,
whil
etheleftdome
reachest he5t
hinter
coastalspace.Thel ev
elsoft
hedomesv ari
eswit
h;post
ure,
phaseof
respirat
ion,si
zeanddegr eeofdistenti
onofabdominalvi
scera.
PARTSOFTHEDI
APHRAGM
Thecentr
altendonhasnobonyattachment.Itli
esinthecent
erofthedi
aphragm,
buti
t'
s
closert
otheant er
iorsur
faceoft
hethorax.Thef i
ber
softhemuscularpar
tdiv
erger
adi
all
yin
thecentr
altendon.Basedonitsper
ipher
alattachments,i
t'
sdiv
idedi
nto3part
s.
I
.Ster
nalpar
t:I
tconsi
stsof2muscul
arsl
i
ps(
ri
ghtandl
eft
)thatat
tacht
othepost
eri
oraspect
ofxi
phoi
dprocess.
II
.Costalpart:I
tconsi
stsofwi
demuscularsl
i
pst
hatat
tacht
othedeepsur
facesoft
hel
ower6
coast
al car
ti
lagesandthei
radj
oini
ngr
ibs.
I
II.Lumbarpart:Itari
sesfr
om 2aponeuroti
carches,t
hemedialandlater
al ar
cuateli
gaments
andt he3superiorlumbarver
tebr
ae.I
tformstherightandl
eftmuscularcrurathatascendst
o
thecentr
altendon.
THECRURAOFTHEDI
APHRAGM
Thesear
emuscul
otendi
nousbandst
hatar
isef
rom t
he;
I
.Ant
eri
orsur
faceoft
hebodi
esoft
hesuper
ior3l
umbarv
ert
ebr
ae.
I
I.Ant
eri
orl
ongi
tudi
nal
li
gament
.
Theri
ghtcr
usisl
argerandlongert
hant
hel
eftcr
usandar
isesfrom t
hef
ir
st3-
4lumbar
v
ertebr
ae,
whil
ethel
eftcrusari
sesfr
om t
hef
ir
st2-3l
umbarvert
ebrae.
Amedi anarcuateli
gamentwhichcrossestheanter
iorsur
faceoftheaort
a,connectst
he
fi
brousmedi alborder
softhetwocrura.Musclesfi
bersoftheri
ghtpassestotheleft
surroundi
ngt heesophageal
ori
fi
ceinast i
ng-l
ikel
oop.Thesefiber
sactsasphincterandpr
event
regurgi
tat
ionofthestomachcontentintothethor
acic.
APHRAGM
Thehumandi aphragm isadouble-domedmuscul otendinouspart
iti
ont hatseparatesthe
t
horaci
cf rom t
heabdomi nalcavi
ty.I
tsconcaveinferi
orsurfacefacestheabdomi nalcav i
ty,
whi
leitsconvexsuperi
orsur f
acefacesthethoraciccavit
y.Iti
stheprimarymuscl eof
r
espir
ation.Onlyt
hecentralpartdescendsduri
ngi nspi
rati
on.Thecentraltendonispar t
ial
ly
f
usedwi ththeinf
eri
orsurfaceofthefibr
ouspericardi
um.
SHAPEOFTHEDI
APHRAGM
Itcurvesi
ntotherightandtheleftdomes.Theri
ghtdomei shi
ghert
hanthelef
tdome
becauseoft heri
ghtlobeoft hel
iver.Theri
ghtdomereachesthe5t
hrib,
whil
etheleftdome
reachest he5t
hinter
coastalspace.Thel ev
elsoft
hedomesv ari
eswit
h;post
ure,
phaseof
respirat
ion,si
zeanddegr eeofdistenti
onofabdominalvi
scera.
PARTSOFTHEDI
APHRAGM
Thecentr
altendonhasnobonyattachment.Itli
esinthecent
erofthedi
aphragm,
buti
t'
s
closert
otheant er
iorsur
faceoft
hethorax.Thef i
ber
softhemuscularpar
tdiv
erger
adi
all
yin
thecentr
altendon.Basedonitsper
ipher
alattachments,i
t'
sdiv
idedi
nto3part
s.
I
.Ster
nalpar
t:I
tconsi
stsof2muscul
arsl
i
ps(
ri
ghtandl
eft
)thatat
tacht
othepost
eri
oraspect
ofxi
phoi
dprocess.
II
.Costalpart:I
tconsi
stsofwi
demuscularsl
i
pst
hatat
tacht
othedeepsur
facesoft
hel
ower6
coast
al car
ti
lagesandthei
radj
oini
ngr
ibs.
I
II.Lumbarpart:Itari
sesfr
om 2aponeuroti
carches,t
hemedialandlater
al ar
cuateli
gaments
andt he3superiorlumbarver
tebr
ae.I
tformstherightandl
eftmuscularcrurathatascendst
o
thecentr
altendon.
THECRURAOFTHEDI
APHRAGM
Thesear
emuscul
otendi
nousbandst
hatar
isef
rom t
he;
I
.Ant
eri
orsur
faceoft
hebodi
esoft
hesuper
ior3l
umbarv
ert
ebr
ae.
I
I.Ant
eri
orl
ongi
tudi
nal
li
gament
.
Theri
ghtcr
usisl
argerandlongert
hant
hel
eftcr
usandar
isesfrom t
hef
ir
st3-
4lumbar
v
ertebr
ae,
whil
ethel
eftcrusari
sesfr
om t
hef
ir
st2-3l
umbarvert
ebrae.
Amedi anarcuateli
gamentwhichcrossestheanter
iorsur
faceoftheaort
a,connectst
he
fi
brousmedi alborder
softhetwocrura.Musclesfi
bersoftheri
ghtpassestotheleft
surroundi
ngt heesophageal
ori
fi
ceinast i
ng-l
ikel
oop.Thesefiber
sactsasphincterandpr
event
regurgi
tat
ionofthestomachcontentintothethor
acic.
