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Define surface landmarks, 4 Quadrants, 9 Regions

Layers of Abdominal Wall, attention to superficial fascia and muscles

Function and neurovasculature of abdominal wall

Rectus sheath, arcuate line, conjoint tendon Clinical stuff– Sites of surgical incisions,

McBurney’s point, appendicitis, Hematoma of Rectus Sheath, Liposuction & Hernias

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Largest cavity in body

Location- between diaphragm and pelvic inlet (superior pelvic aperture)

Continuous with pelvic cavity

Lined with parietal peritoneum (serous membrane)

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Pelvic inlet

Superior Diaphragm

• Concave dome • Spleen, liver, part of

stomach & kidneys lies under dome• Protected by lower ribs and

costal cartilages Inferior

Lies in greater pelvis • Between ala or wings of

ilia • Ileum, cecum and sigmoid

colon partly protected Anterior & lateral

wallsMuscles

Posterior wallVertebral column, lower

ribs & associated muscles4

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Xiphoid process Lower six costal

cartilages Lumbar vertebrae

(L1 to L5) Pelvis

◦ Iliac crest ◦ Anterior superior

iliac spine (ASIS) ◦ Pubic symphysis ◦ Pubic crest and

pubic tubercle

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Costal margin

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Xiphoid process

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Linea alba

Linea alba •A fibrous raphe where aponeuroses of external oblique, internal oblique and transversus abdominis on either side unite•Slight indentation from xiphoid process to pubic symphysis

Linea alba •A fibrous raphe where aponeuroses of external oblique, internal oblique and transversus abdominis on either side unite•Slight indentation from xiphoid process to pubic symphysis

Inguinal ligament

Pubic tubercle

Ant. Sup. Iliac spine

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Four quadrants ◦ Right upper ◦ Left upper ◦ Right lower ◦ Left lower

Planes-◦ Median plane

From xiphoid process to pubic symphysis

◦ Transumbilical plane Horizontal line at level of

umbilicus

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Passes through lower border of 10th cc

Transpyloric plane- Sometimes used instead of subcostal

Interspinous plane-Passes through easily palpated ASIS on each side

Transpyloric plane- Sometimes used instead of subcostal

Interspinous plane-Passes through easily palpated ASIS on each side

Transtubercular or Intertubercular plane- passes through tubercles of iliac crests and body of L5

Midpoint of clavicle to midinguinal point

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Nine regions ◦ For more accurate,

descriptive & diagnostic purposes

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4 quadrants & 9 regions are essential in clinical practice ◦ Each area represents

certain visceral structures

◦ Allow correlation of pain & referred pain from these areas to specific organs

◦ Palpated, percussed & auscultated during clinical examination

Midway between superior borders of manubrium & pubic symphysis (typically L1 vertebral level)

Transects pylorus when patient is recumbent (supine or prone)

Passes through tip of 9th cc

Structures located at this plane◦ Gall-Bladder (fundus)◦ Origin of SMA◦ Pylorus of Stomach◦ Duodenojejunal junction◦ Pancreas (neck)◦ Kidneys (hilum)

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Subcostal incision

Muscle-splitting incision

Transverse incision

Median or midline incision

Left paramedian incision

Suprapubic incision

McBurney's point

A surface landmark that roughly indicates location of appendix

Location- ~1/3rd of the way along a line from ASIS to umbilicus

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AppendicitisInflammation of appendixPain- may presents in umbilical region and then

localizes in right lower quadrantRupture of appendix leads to peritonitis

(inflammation of peritoneum) Presents with severe pain, fever & abdominal rigidity

Muscle-splitting incision (of McBurney)

Used to access appendixEach muscle layer is split in direction of fiber

orientation

Flexible, dynamic container, housing most of the organs of alimentary system & part of urogenital system

Subdivided into ◦ Anterior, right

and left lateral & posterior wall

Protect viscera Help maintain posture Can raise internal pressure

(voluntary or reflexive contraction) to aid◦ Expulsion of fluid (urine or

vomitus), flatus, feces or fetuses from abdominopelvic cavity

◦ Expulsion of air from thoracic cavity Accommodate expansions

caused by ingestion, pregnancy, fat deposition or pathology

7 layers1. Skin2. Superficial fascia

[fatty & membranous layers]

3. Deep fascia4. Muscular layer5. Fascia transversalis6. Extra peritoneal fat7. Peritoneum

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Superficial fatty layer◦ Camper's fascia◦ Major site of fat

storage◦ Fatty layer continuous

with superficial fascia of thorax & thigh

Deep membranous layer ◦ Scarpa's fascia

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Scarpa's fascia◦ Membranous layer

continuous with Dartos layer of

scrotum (dartos fascia)

Superficial perineal fascia (Colles' fascia)

Superficial penile fascia

◦ Fuses with Fascia lata of thigh

Note the Arrangement of fatty layer & membranous layer of superficial fascia in lower part of anterior abdominal wall 22

•Note the line of fusion between membranous layer & deep fascia of thigh (fascia lata)•~2.5 cm inferior & parallel to inguinal ligament

Arrows indicate paths taken by urine in cases of ruptured urethra

Note the attachment of membranous layer to posterior margin of perineal membrane

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Arrows indicate paths taken by urine in cases of ruptured urethra

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Three flat muscles & two vertical muscles

External Oblique Internal Oblique Transversus

abdominis Rectus abdominis Pyramidalis

Fiber bundles of each layer run in different directions

Largest & superficial Fibers run

downward, forward & medially

Fibers end in aponeurosis that contributes to rectus sheath

Innervation- T7-T11 spinal nerves and subcostal nerve

Derivatives of external oblique aponeurosis◦ Inguinal ligament

Thickens and folds back on itself

◦Lacunar ligament Forms medial boundary of

femoral ring◦Superficial inguinal

ring Triangular-shaped Defect in aponeurosis of

external oblique above pubic tubercle

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Thin muscular layer Fibers run

upwards, forwards and medially

Fibers end in an aponeurosis that contributes to rectus sheath

Innervation- ◦ Ventral rami of T6-T12

spinal nerves◦ First lumbar nerves

Inferior aponeurotic fibers of internal oblique join with those of transversus abdominis to form Conjoint tendon◦ Insert onto pubic tubercle ◦ Strengthens the posterior wall of medial half of inguinal

canal

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Intramuscular & intermuscular fiber exchanges within the bilaminar aponeuroses of external and internal oblique muscles

Fibers run transversely & medially

Fibers end in an aponeurosis that contributes to rectus sheath

Innervation- ◦ Ventral rami of

T6–T12 spinal nerves

◦ First lumbar nerves

Separated by linea alba in midline

Wider superiorly than inferiorly

Composed of four segments connected by tendinous intersections that attach anteriorly to the sheath of this muscle

Innervation- ◦ Ventral rami of T6–T12 spinal nerves ◦ First lumbar nerves

Superior epigastric & inferior epigastric arteries running on their deep surfaces

Semilunar line (linea semilunaris) ◦ Vertical indentation seen as a curved line from tip

of 9th rib cartilage to pubic tubercle on each side ◦ Represents lateral edge of rectus abdominus

muscle

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When you see a six pack, this is the muscle you're seeing

Semilunar line

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Small, insignificant, triangular muscles

Lies anterior to rectus abdominis

Located in rectus sheath

Function◦ Tenses the linea alba◦ Surgeons use

attachment of pyramidalis to linea alba as a landmark for median abdominal incision

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Pubic crest linea alba

Absent in ~20% people

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Tough, incomplete fibrous sheath

Semilunar line marks lateral border

Composed of aponeuroses of three flat muscles

Contents- ◦ Rectus abdominis

& pyramidalis◦ Superior &

inferior epigastric vessels, lymphatics, & ventral primary rami of T7–T12

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Arcuate line (linea semicircularis)◦ Crescent-

shaped line◦ Demarcates

lower limit of posterior layer of rectus sheath

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Above arcuate lineAnt layer

Formed by fusion of aponeurosis of external oblique and anterior leaf of aponeurosis of internal oblique

Post layer Formed by fusion of

posterior leaf of aponeurosis of internal oblique and aponeurosis of transverses abdominis

Below arcuate lineAnt layer

Formed by aponeuroses of all three muscles

Post layer Absent below arcuate line

(~4-5cm below umbilicus) Rectus abdominis is in

contact with transversalis fascia

Linea alba ◦ Tendinous raphe ◦ Running vertically in

midline ◦ Formed by union of

aponeuroses of flat muscles on either side

◦ Largely avascular

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Umbilicus◦ Found in midline◦ All layers of

anterolateral abdominal wall fuse at this point

Neurovascular plane ◦ Found between

internal oblique & transversus abdominis

◦ Contains vessels & nerves supplying skin and muscles of anterior and lateral abdominal wall

◦ Nerves and vessels are transversely oriented and segmental

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Arteries ◦ Branches of Internal

thoracic Superior epigastric Musculophrenic

◦ Branches of External iliac Inferior epigastric Deep circumflex iliac

◦ Branches of Femoral Superficial epigastric Superficial circumflex iliac

◦ Branches of Posterior intercostal (10th & 11th) & Subcostal

Veins ◦ Veins corresponding to

arteries◦ Drains away from umbilicus

to caval system 45

Superficial lymphatics ◦ Above

umbilicus→ drains to axillary nodes

◦ Below umbilicus→ drain to superficial inguinal nodes

Deep lymphatics ◦ Accompany deep

veins ◦ Drain to external

iliac, common iliac and lumbar nodes

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LiposuctionSurgical method for removing

unwanted subcutaneous fat Method-

By putting a percutaneously suction tube and high vacuum pressure

Tubes are inserted subdermally through small skin incisions

Excess fat accumulation owing to overnourishment most commonly involves subcutaneous fatty layer

Lined by parietal peritoneum Has five peritoneal folds (below the umbilicus)

◦ Median umbilical fold Represents remnant of urachus

◦ Medial umbilical folds (two) Represent remnants of umbilical arteries

◦ Lateral umbilical folds (two) Over the inferior epigastric vessels

Falciform ligament ◦ Extends between abdominal wall & liver (above the

umbilicus) ◦ Contains round ligament of liver

Abdominal HerniasHernia

When part of an internal organ bulges through a weak area of muscle

Most hernias occur in abdomen

Types- InguinalUmbilicalEpigastric Spigelian

Umbilical herniasCongenital

Common in newborns especially LBW infants

Anterior abdominal wall is relatively weak in umbilical ring

Usually result from increased intra-abdominal pressure in presence of incomplete closure of anterior abdominal wall after ligation of umbilical cord at birth

Acquired umbilical hernias Occur most

commonly in women and obese people

Extraperitoneal fat and/or peritoneum protrude into the hernial sac

Epigastric herniaIn epigastric region

through linea alba (in upper abdomen)

Spigelian hernias Along the semilunar

lines

Tend to occur in obese and >40 years old

Ascites‐related hernia

Thank You!Thank You!

References Keith L. Moore, Anne M. R. Agur; Essential Clinical

Anatomy- 3rd Edition, Lippincott Williams & Wilkins, 2007.

Keith L. Moore, Arthur F Dalley, Anne M. R. Agur; Clinically Oriented Anatomy- 6th Edition, Lippincott Williams & Wilkins, 2010.

Susan Standring; Gray's Anatomy: The Anatomical Basis of Clinical Practice 39th edition, Churchill Livingstone 2004.

Richard S. Snell; Clinical Anatomy By Regions- 8th Edition, Lippincott Williams & Wilkins, 2008.

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