THE PELVISIn common usage, thepelvisis the part of the trunk
that isinferoposterior to the abdomen, and is the area of
transition between thetrunk and the lower limbs. Thispelvic
cavityis a continuation of theabdominal cavity. Anatomically, the
pelvis is the part of the bodysurrounded by the pelvic girdle (bony
pelvis), part of the appendicularskeleton of the lower limb (Fig.
!").The superior boundary of the pelvic cavity is the pelvic inlet,
the superiorpelvic aperture. The pelvis is limited inferiorly by
the pelvic outlet, whichis bounded anteriorly by the pubic
symphysis (L. symphysis pubis) andposteriorly by the coccy#. The
pelvic inlet (superior pelvic aperture) isbounded by the linea
terminalis of the pelvis, which is formed by the$Fig. N1 Pelvic
girdle.Features of the pelvic girdle demonstratedanatomically (A).
The pelvic girdle is formed by the two hip bones (ofthe inferior
a#ial skeleton) anteriorly and laterally and the sacrum (ofthe
a#ial skeleton) posteriorly.1.PELVIC GIRDLE
Thepelvicgirdleisabasin%shapedringof bonesthatconnectsthevertebral
column to the two femurs. The primary functions of the pelvicgirdle
are to$ &ear the weight of the upper body when sitting and
standing. Transfer that weight fromthea#ial tothelower
appendicularskeleton for standing and walking.
'rovideattachmentforthepowerful musclesof locomotionandposture and
those of the abdominal wall, withstanding the forcesgenerated by
their actions.(onse)uently, the pelvic girdle is strong and rigid,
especially comparedto the pectoral (shoulder) girdle. *ther
functions of the pelvic girdle areto$ (ontain and protect the
pelvic viscera (inferior parts of the urinarytracts and the
internal reproductive organs) and the inferiorabdominal
viscera(intestines), whilepermittingpassageoftheirterminal parts
(and, in females, a full%term fetus) via the perineum. 'rovide
support for the abdominopelvic viscera and gravid(pregnant) uterus.
'rovide attachment for the erectile bodies of the e#ternal
genitalia.
'rovideattachmentforthemusclesandmembranesthatassistthefunctionslistedabovebyformingthepelvic+oorand,llinggaps
that e#ist in or around it.COP!RISON OF !LE !ND FE!LE "ON#
PELVESFig. N$T%&racic a'd a(d&)i'&pelvic cavity. ! a'd
".Thepelvisisthespacewithinthepelvicgirdle,
overlappede#ternallybytheabdominal andgluteal
(lowerlimb)regionsandtheperineum. Thus,
thepelvishasnouni)uee#ternalsurface area.$. THE *IDNE#$.1. POSITION
!ND SH!PEThe kidneys are paired retroperitoneal organs that lie
lateral to theupper lumbar vertebrae. In the rela#ed, supine
position, theirsuperior polesarelevel
withthetwelfththoracicvertebra, whiletheir inferior polesarelevel
withthethirdlumbar vertebraandabout -.. cm superior to the iliac
crest. *n deep inspiration in theerectposition, however,
bothkidneysmaydescendnearorevenpast the iliac crest. /sually the
right kidney lies " to - cm inferior tothe left kidney because its
developmental ascent is blocked by theliver.&othkidneys
lieinclosepro#imitytotheabdominal aortaandinferiorvenacava.
Thesema0orvesselse#tendbranchestoeachkidney that enter at a
notched, medially located area of theparenchyma knownas the
hilum.At the levelof the kidneys,theabdominal aorta lies directly
anterior to the vertebral column,passing about -.. cm anteromedial
to the left kidney.Note:The inferior vena cava lies to the right of
the aorta, nearly touchingthe medial aspect of the right kidney.
&oth kidneys are rotated sothat their medial surfaces
areslightlyanterior, facilitatingtheirconnection to these ma0or
vessels. And ,nally, The suprarenalglandsarebilateral
glandstypicallyrelatedtothesuperomedialaspects of the kidneys but
not attached to them.$.$. F+NCTIONS OF THE *IDNE#Fig. N,
P&-iti&' a'd relati&'- &. /id'ey0 Anteriorviews
Theovoidkidneysremovee#cesswater, salts, andwastesofprotein
metabolism from the blood while returning nutrients andchemicals to
the blood.$.,. !NTERIOR REL!TIONS1idneydevelopment
occursintheretroperitoneal spaceoneachsideof adorsal mesentery,
whichisinitiallyattachedalongthemidline of the posterior body wall.
2uring growth of the liver androtation of the gut, certain portions
of the gut fuse to the posteriorbody wall and become secondarily
retroperitoneal. Throughout thisprocess, peritoneal re+ections
areshiftedfromthemidlineanddistorted in an irregular but
predictable pattern. After developmentiscomplete, certainpartsof
thekidneyscontact intraperitonealorgans through an intervening
layer of peritoneum, whereas otherparts contact primarily or
secondarily retroperitoneal organs withoutaninterveninglayer of
peritoneum. Thepresenceor absenceofintervening peritoneummay a3ect
the spread of infection ormetastatic disease.$.,.1. Le.t *id'eyThe
superolateral aspect of the left kidney contacts the
spleen.4eparating these organs is the peritoneumthat forms
theposterior surface of the perisplenic region of the
greaterperitoneal sac. A triangular area on the superomedial aspect
ofthe left kidney contacts the stomach. 4eparating these organsis
the peritoneum of the lesser sac (omental bursa). The splenicand
gastric areas of the anterior renal surface are separated bythe
splenorenal ligament, a derivative of the dorsal mesenterythat
forms the left boundary ofThe lesser sac. The two layers of the
peritoneum that form thesplenorenal ligament enclose the splenic
vessels.The perihilarregion of the left kidney contacts the tailof
thepancreas, a secondary retroperitoneal organ, withoutintervening
peritoneum. This point of contact occurs posteriorto the left
e#tremity of the transverse mesocolon.$.,.$.Rig%t*id'ey.The upper
two thirds of the right kidney contact the right lobeof theliver.
Thesuperior polee#tends abovethecoronaryligament to directly
contact the bare area of the liver withoutintervening peritoneum.
Inferior to the pole, the kidney
iscoveredwithperitoneumthatformstheposteriorwall ofthehepatorenal
recess (also known as the 5orison pouch), part ofthe subhepatic
space of the greater peritoneal sac.Theperihilarregionof theright
kidneydirectlycontactsthesecond (descending) part of the duodenum,
which issecondarily retroperitoneal. 5ost of the lower third of the
rightkidney is in direct contact with the right colic +e#ure6
however,asmall sectionof theinferior polemay contact
thesmallintestine through a layer of inframesocolic peritoneum.Fig
N1 Anterior relations of kidneys.$.1. POSTERIOR REL!TIONS The
appro#imate upper third of both kidneys contacts thediaphragm. The
diaphragm normally separates the kidneysfromthe diaphragmatic part
of the parietal pleura. *noccasion, however, a de,ciency in the
region of the lateralarcuate ligament or the lumbocostal trigone
allows one ofthe kidneys to directly contact the overlying
diaphragmaticpleura. Theupperthirdof theleftkidneyliesanteriorto,
andisthus protectedby, theeleventhandtwelfthleft ribs. Asmaller
portion of the right kidney receives similarprotection in its
relationship to right twelfth rib. 7ithregardtothelowertwothirdsof
bothkidneys, thelateral aspects rest on the aponeuroses of the
transversusabdominis muscles6 the central aspects rest on theFig N2
8evel of 8"9- intervertebral disc)uadratus lumborum muscles6 and
the medial aspects reston the psoas muscles.$.2. GROSS STR+CT+RE
The renal artery and vein, as well as the urine collecting
system,enter and e#it the medialaspect of each kidney at the
hilum.This indentedregionleads toaspacious cavitywithineachkidney
known as the renal sinus. 7ithin the renal sinus, a matri#of
perinephricfatsurroundsbranchesof therenal arteryandvein, aswell
asthelargebranchesof theurinarycollectingsystem. The veins are
generally the most anterior and thebranches of the collecting
systemmost posterior, with thearteries coursing in between.
Theentireouter rimof therenal parenchymaconsists of
abrownishpinkregionknownastherenal corte#. 2eeptothecorte#,
numerous darker%colored renal pyramids, with
basesdirectedperipherallyandapices
directedcentrally,collectivelyformtherenal medulla.
Theapicesoftherenal pyramidsareknown as the renal papillae. Two or
more pyramids may fuse attheir papillae6
thustherearemorepyramidsthanpapillaeineach kidney. The areas of
corte# overlying the bases of the pyramids,separating them from the
outer surface of the kidney, are knownas cortical arches. The areas
of corte# pro0ecting betweenpyramids are known as renal (cortical)
columns (of &ertin).
Theterm:column;referstotheirappearanceonsection6 infact,they are
more like walls, which surround and separate thepyramids.,. +RIN!R#
"L!DDER The urinary bladder, a hollow viscus with strong muscular
walls,is characteri