The Abdominal WallThe Abdominal Wall

Muscles of the Trunk Muscles of the Trunk

Raymond G Buick FRCS

Muscles of the Trunk• large cavity• bounded by– posterior abdominal wall– diaphragm– anterior abdominal wall– pelvic floor

Layers of Abdominal Wall• antero-lateral wall of abdomen• several layers– skin – s/c tissue – a superficial fat and fascial layer– muscles– transversalis fascia– extraperitoneal fat– parietal peritoneum

Layers of Abdominal Wall– s/c tissue – a superficial fat and fascial layer

• 2 layersCamper’s fascia – thick, fatty layer Scarpa’s Fascia - deeper fascial layer

Layers of Abdominal Wall– s/c tissue – a superficial fat and fascial layer

thickfatty layer

continuous with superficial. fascia of thigh

Camper’s FasciaCamper’s Fascia

dartos muscle no fatty tissueinvoluntary muscle fibrespale reddish in colour

Layers of Abdominal Wall– s/c tissue – a superficial fat and fascial layer

deeperthinner layermembranous

large amount of yellow elastic fibres

blends with fascia lata of thigh

Scarpa’s FasciaScarpa’s Fascia

helps form dartos muscle

Muscles of the Trunk– muscles

• 4 paired muscles

Muscles of the Trunk

• 3 paired flat muscles + strap muscles– external oblique– internal oblique– transversus abdominis

Muscles of the Trunk

• 3 paired flat muscles + strap muscles– external oblique - rectus abdominis– internal oblique– transversus abdominis

Muscles of the Trunk

3 paired muscles rectus abdominis

Layers of Abdominal Wall• antero-lateral wall of abdomen• several layers– skin – s/c tissue – a superficial fat and fascial layer– muscles– transversalis fascia– extraperitoneal fat– parietal peritoneum

Layers of Abdominal Walltransversalis fascia (or transverse fascia) • is a thin aponeurotic membrane• thick and dense in structure inferiorly and

thins out as it ascends to the diaphram• deep to transversus abdominis muscle• superficial to extraperitoneal fat and parietal

peritoneum

Layers of Abdominal Wallextraperitoneal fat

variable with age and location • most apparent in the falciform ligament

below the upper part of the linea alba

Muscles of the Trunk

3 paired muscles – external oblique– internal oblique– transversus abdominis

Muscles of the Trunk3 paired muscles– laterally

lower ribs

lumbodorsal fascia

iliac crest

inguinal ligament

Muscles of the Trunk3 paired muscles– medially

aponeurosis

Muscles of the Trunk3 paired muscles– medially

linea alba

Aponeurosis• A sheetlike fibrous membrane resembling a flattened tendon

that serves as a fascia to bind muscles together (or to connect muscle to bone).

• shiny, whitish-silvery colour, • histologically similar to tendons• few blood vessels and nerves• pleural: aponeuroses

external obliqueexternal obliqueexternal oblique

external obliqueexternal obliqueexternal oblique

external obliqueexternal obliqueexternal oblique

external obliqueexternal obliqueexternal oblique

external obliqueexternal obliqueexternal oblique

aponeurosisaponeurosis

external oblique

• inguinal ligament– ant. sup. iliac spine– pubic tubercle

internal obliqueinternal obliqueinternal oblique

transversus abdoministransversus transversus abdominisabdominis

transversus abdoministransversus transversus abdominisabdominis

external obliqueexternal oblique

3 flat muscles

external obliqueexternal oblique

internal obliqueinternal oblique

3 flat muscles

external obliqueexternal oblique

internal obliqueinternal oblique

transverse abdoministransverse abdominis

3 flat muscles

rectus abdominis

rectus rectus abdominisabdominis

rectus abdominis

tendinous intersectionstendinous intersections

an additional muscle

PyramidalisPyramidalis

Muscles of the Trunk

PyramidalisPyramidalis

Rectus Sheath

Rectus Sheath

level of arcuate line

linea semicircularis

Rectus Sheath – upper 3/4

transversus transversus abdominisabdominis

internal obliqueinternal oblique

external obliqueexternal oblique

transversalis fasciatransversalis fascia

peritoneuperitoneumm

linea albalinea alba

extraperitoneal extraperitoneal fatfat

skinskin

s/c s/c tissuetissue

Muscles of the Trunk

transversus transversus abdominisabdominis

internal obliqueinternal oblique

external external obliqueoblique

transversalis fasciatransversalis fascia

peritoneumperitoneum

upper three quarters lower quarter

arcuate line linea semicircularis

or Douglas' line

SpigelianSpigelianHerniaHernia

The EndThe End

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