(2) Abdomen in General

8/8/2019 (2) Abdomen in General

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ABDOMEN IN GENERAL

Dr. Reynaldo V. LopezSenior LecturerDepartment of Anatomy


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Learning Objectives:

At the end of the lecture, the student should beAt the end of the lecture, the student should beable to:able to:

1. Define the region of the abdomen.

2. Enumerate its boundaries.

3. Delineate the abdominal quadrants & regions.

4. Describe the abdominal cavities & peritoneum.

5. Describe the structure of the abdominal walls,both anterior & posterior.

6. Describe the surface landmarks of the abdominalwalls.


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Definition


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Abdomen

defined as the region ofthe trunk that lies

between the diaphragm

above & the inlet of the

pelvis below


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Boundaries of the Abdomen

Superior Boundary:

- diaphragmdiaphragm which separates the abdominal

cavity from the thoracic cavity .

Inferior Boundary:

- continous with the pelvic cavity thru the pelvic

inlet or thepelvic brimpelvic brim


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Diaphragm

Vena Caval Foramen:Hole for the Inferior VenaCava, where it passes to the liver. Around T8

It is located in the central tendon (superior mostpart) of the diaphragm.

Eosphageal Hiatus: Opening that admits theesophagus, guarded by two muscles left crus

and right crus. Left Gastric Artery and Left GastricVein also pass

through the eosphageal hiatus.

Passes through at T10.


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Diaphragm

Aortic Hiatus: Is actually posterior to thediaphragm -- not really a hole in the diaphragm.

T

horacic Duct goes posterior through this openingas well as aorta.

About Level 12, at lower most part of diaphragm.

Lumbocostal Arches: Transversalis Fascia on

the posterior wall of the diaphragm.Sympathetic Ganglia come through along these

arches.


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Muscles of the ThoraxDiaphragm Openings

CavalCaval

EsophagealEsophageal

AorticAortic


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Pelvic Brim

It consists of the Right andLeft Coxal Bones. Each coxal bone is made up of

an ilium, ischium, and pubicbone.

Iliac Crest: The superiorportion of the iliac bone.TheIliacTubercles are bonyprominences on the iliac

crest. Anterior Superior Iliac Spine

(ASIS):The anterior mostfeature on the iliac crest.

PubicTubercle: Lateral edgeof pubic bone.


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Pelvic Brim

Inguinal Ligament: Found between the ASIS and thepubic tubercle, running in the same direction as theASIS. Formed from aponeurosis part of the external abdominal

oblique. The femoral vessels and the inguinal canal are both related

to the inguinal ligament.


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Boundaries of the Abdomen

Anterolateral Boundary:- above by the lower part of the thoracic cage

- below by the muscles of abdominal wall:

rectus abdominis, transversus abdominis, andinternal & external abdominal oblique.

Posterior Boundary:

- lumbar vertebrae & discs,1

2th

rib & upper part ofbony pelvis

- psoas, quadratus lumborum and transversusabdominis & iliacus muscles.


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Quadrants & Regions


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Abdominal Quadrants

Abdomen is dividedinto quadrants byusing a vertical &horizontal line thatintersect at theumbilicus

Epigastrium: areabetween the xiphoid

process & above theumbilicus

Periumbilical: areaaround the umbilicus


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Abdominal Quadrants


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Abdominal Regions

Vertical lines of division:(L) and (R) mid-clavicularlines

Horizontal lines ofdivision: Transpyloric Plane:

Sometimes used. It ishalfway between thejugular notch and the pubicbone.

Subcostal Plane:Upperplane, passing through theinferior-most margin of theribs.

Transtubercular Plane: Theline transversing the pubictubercle.


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Abdominal Regions

Figure 22.4b


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Abdominal Cavity


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Abdominal Cavity

Abdominal CavityAbdominal Cavity::- Everything but the

lateral, posterior,

and anterior body

walls of theabdomen, including

both the peritoneal

cavity and theretroperitonealspace.


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Abdominal Cavity

Peritoneal Cavity:Peritoneal Cavity:

-That part of the abdomen invaginated by

peritoneum

Retroperitoneal Space:Retroperitoneal Space: The area behind(posterior to) the peritoneum.


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Peritoneum

Peritoneal layers

Visceral Peritoneum:Surrounds the

digestive organs. Parietal Peritoneum:Lines the abdominalwall.


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Peritoneum

Mesentery a double layer of peritoneum

Holds organsin place

Sites of fatstorage

Provides aroute forcirculatoryvessels andnerves


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Abdominal Contents

Intra-PeritonealOrgans:Organscompletely or almost completelyenclosed by peritoneum.

Stomach Liver

Gall Bladder

Transverse Colon: completely

Jejunum Ileum

Cecum (very start of ascendingcolon)


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Abdominal Contents

Retro-PeritonealOrgans:Organs located mostlyor completely behind the posterior parietalperitoneum.

Duodenum Ascending Colon (only 25-50% covered) Descending Colon (only 25-50% covered) Sigmoid Colon Pancreas Kidneys Great Vessels and their primary branches: Abdominal

Aorta and Inferior Vena Cava, CeliacTrunk, andSuperior and Inferior Mesenteric arteries and veins.


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Abdominal Walls


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Anterior Abdominal Wall

Layers:Layers:

1. Skin

2. Superficial Fascia -- Connective tissue that is not

aponeurosis, tendon, or ligament.This is thesame thing as the hypodermis.

1. Camper's Fascia: Fatty layer, first of the two layers. Itis found throughout.

2. Scarpa's Fascia: Lower layer, found in the lower 1/3 ofthe anterior abdominal wall.


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Limits of superficial fascia :

The area is restricted to the anterior abdominal wall.

Lateral Limit: Basically the inguinal ligament, where it

intersects with fascia lata, so that fluid does not passinto the thigh.

Inferior Limit = the base of the scrotum.

Posterior Limit = it goes back to the anus, and fills the

pelvis in between.


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The outlined region is called the superficial perinealspace.

It is called different fascia at different places:D

artos Fasciain scrotum / labia majora, and Colles Fascia around

perineum.

3. Fundiform Ligament: The false suspensory ligamentof the penis or clitoris. It is an extension of superficialfascia.


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3. Deep Fascia

A true suspensory ligament occurs in the deep fascia

layer, which extends into the penis / clitoris. So, we haveboth a true suspensory ligament (deep fascia) and afalse one (fundiform ligament / superficial fascia).

Deep fascia encompasses all muscles of the entire body.


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4. Muscles1. External Abdominal Oblique

- muscle fiber direction isantero-inferior

Originate at border ofThoracicribsT5 -T12

Extends to midline andattaches on linea alba & iliaccrest.

Aponeurosis portion form theinguinal ligaments &superficial inguinal ring, whichallows passage of thespermatic cord (male) or round

ligament (female).


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4. Muscles2. Internal Abdominal Oblique

Fibers attach along the inguinalligament to the pubic crest.

Direction of fibers tends to gooutward, from medial to lateraland a little bit inferiorly(inferolaterally).

Borders on ribs 7 - 12.

The aponeurosis splits and goesboth anteriorly (to merge withexternal aponeurosis) andposteriorly (to merge withtransversus aponeurosis)


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4. Muscles3. Transversus Abdominis -

deep most layer of flatmuscles.

Borders on ribs 7 - 12. Extends

down to the pubic crest andmedially to the linea alba.

Creates a diagonal pathway for

the spermatic cord or roundligament to pass through.

Fibers run transversely! --horizontally from lateral to

medial.


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4. Muscles4. Rectus Abdominis: -

Straight muscle.

Passes from xiphoid process

inferiorly to pubic symphysis(inferior center of pubic bone).

Rectus Sheath holds this rectusmuscle in place. It is directlyshallow to it, formed by the

aponeuroses of the three flatmuscles. It has a posterior andanterior layer, formed from theaponeuroses of the three flatmuscles.


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4. Muscles Upper 3/4 of Abdominal Wall: All three muscle layers converge

on rectus sheath, and pass both anteriorly (external

aponeurosis) and posteriorly (transversus aponeurosis).

Lower 1/4 of abdominal wall is transversalis fascia.Here, allthree muscle layers pass anteriorly. Here it is calledtransversalis fascia.


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NERVOUS SUPPLY : Ventral rami ofT7 -T12, & L1.

ARTERIAL SUPPLY :

Superior Epigastric Artery -- Runs directly over rectusabdominis muscle.

Inferior Epigastric Artery

Superficial Epigastric Artery

VENOUS SUPPLY :The same as the arteries above.


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Posterior Abdominal Wall

Layers:Layers:

1. Thoracolumbar Fascia: an extension of theaponeuroses of the transversus abdominis and

external abdominal oblique muscles. Divides into an anterior plane and posterior plane that

compartmentalize the muscles, which lies in betweenthe two planes.

Anterior plane attaches to the transverse process of thelumbar vertebrae.

Posterior plane attaches to join with the other muscles in

the back.


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2. Muscles1. Psoas MajorMuscle: Chief

flexor of the thigh and trunk

Passes all along vertebralcolumn starting atT12.

Passes deep to the inguinalligament and attaches to thelesser trochanter of the femur.

Innervated by L2-L4.

Contraction: Pulls the bodytoward the leg, or the thigh

toward the body.


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2. Muscles2. Iliacus Muscle: Aids the psoas

major in flexing the thigh andtrunk

Attaches to the iliac fossa

(anterior surface of the iliacbone).

Inserts into psoas tendon, and

hence the two musclestogether are often called theiliopsoas muscle.


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2. Muscles3. Quadratus Lumborum:

Stabilizes the 12th(floating) rib duringinspiration. Inserts on the12th rib.


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Vessels1. Abdominal aorta

The abdominal aortapasses through thediaphragm at the levelofT12 vertebra.

It passes inferiorly onthe bodies of the

lumbar vertebrae. Infront of the body ofL4, it divides into thecommon iliac arteries.


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Vessels2. Inferior vena cava

This vessel is formed onthe right side of theaortic bifurcation, atthe level of the L5vertebra, by the unionof the two commoniliac veins.

It ascends to the rightof the aorta and passesbehind the liver topierce the diaphragm atthe level ofT8 vertebra& almost immediately

enters the heart.


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Nerves

The nerves of the posterior abdominal wall arebranches of the lumbosacral plexus.

The roots of the plexus are: L1

L2

L3 L4

L5


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L1 gives rise to theiliohypogastric andilioinguinal nerves.

L1 + L2 gives riseto thegenitofemoralnerve

L2 + L3 gives riseto the lateralfemoral cutaneousnerve


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L2 + L3 + L4 giverise to the femoral

and obturator

nerves L4 + L5 give rise to

the lumbosacral

trunk which joinssacral nerves to

form the sacral

plexus.


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Surface Landmarks


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Surface Landmarks

The linea alba is a midline depression runningfrom the xiphisternum to the pubis.

The linea semilunaris is a smooth, curved line,

representing the lateral margin of the rectusabdominis.


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Surface Landmarks

The inguinal ligament runs from the anterior

superior iliac spine to the pubic tubercle.

The deep inguinal ring lies at the midinguinal

point (halfway between the anterior superioriliac spine and the pubic tubercle).


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Surface Landmarks

The arcuate line is the line that divides the

upper 3/4 of abdomen from lower 1/4, by the

differences in the aponeurotic layers.


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Surface Landmarks

McBurney's Point:

The point of surgical

incision for anappendectomy.

Is located on a linealong the ASIS.


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Surface Landmarks


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Surface Landmarks

LiverLiver The inferior border

extends from the (R) 10th

costal cartilage in the

midclavicular line to the(L) 5th rib in themidclavicular line.

The upper border runsbetween the (L) & (R) 5thribs; both points are in themidclavicular line.

The right border runs fromthe 5th (R) rib to the 10th


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Surface Landmarks

FundusFundus of the gall bladderof the gall bladder This lies deep to the

intersection of the linea

semilunaris with thecostal margin in thetranspyloric plane.

At this point the fundus

of the gall bladder liesbehind the 9th costalcartilage


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Surface Landmarks

Spleen Lies deep to the 9th,10th, and 11th ribs on theleft behind themidaxillary line.

It is not palpable unless itis enlarged, at which

point the spleen extendsinferiorly and anteriorlyalong the 10th rib tobelow the costal margin.


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Surface Landmarks

PancreasPancreas The head of the pancreas

lies in the C shapedconcavity of the duodenum

at the level of the L2vertebra.

The neck of the pancreaslies anterior to the L1vertebra in the transpyloric

plane. The pancreas continues to

the left, curving upwardstowards the hilum of the

spleen.


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(2) Abdomen in General

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