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STUDY OF HUMAN ANATOMY
ANATOMY OF THE ABDOMEN
DEFINITION OF ABDOMEN
• A region of the body bounded by
the following regions:–
–
–
–
Superiorly – thorax
Inferiorly – pelvis/perineum
Posteroinferiorly – back
Inferolaterally – lower limbs
BONY LANDMARKS OF THE ABDOMEN
• Xiphoid process
• Costal margin – 7th – 11th costal
cartilages
• Pelvic bones
• L1 – L5 Lumbar vertebrae
ABDOMINAL CAVITY
• extends btw thoracic
diaphragm & pelvic
diaphragm –
abdominopelvic cavity
• upper part is under cover of
the osteocartilagenous
thoracic cage
• occupied by organs of the
digestive, urogenital,
endocrine & vascular
structures.
CONTENTS OF THE ABDOMINAL CAVITY
CONTENTS OF THE ABDOMINAL CAVITY
ABDOMINAL WALL
PLANES OF THE ABDOMEN
• 4 planes divide the abdominal cavity into 9 regions
– 2 vertical (midclavicular), midclavicular to midinguinal
– 2 transverse – ( subcostal & transtubercular)
• Subcostal – pass through 10th costal cartilage
• Transtubercular – pass through iliac tubercle
REGIONS OF THE ABDOMEN
REGIONS OF THE ABDOMEN
QUADRANTS OF THE ABDOMEN
• 2 planes delineate the abdominal cavity into 4 quadrants
• 1 vertical – median
• 1 transverse – transumbilical
POSITIONS OF THE ABDOMINAL ORGANS
ANTEROLATERAL ABDOMINAL WALL
• Anterior & lateral walls
extending from the thorax to
pelvis
• Consists of the
– (1) Skin
– (2) Fascia Subcutaneous & deep
– (3) Muscles
– (4) Transversalis fascia
– (5) Extraperitoenal fat
– (6) Peritoneum
ANTEROLATERAL ABDOMINAL WALL
• Anterior & lateral walls
extending from the thorax to
pelvis
• Consists of the
– (1) Skin
– (2) Fascia Subcutaneous & deep
– (3) Muscles
– (4) Transversalis fascia
– (5) Extraperitoenal fat
– (6) Peritoneum
SKIN
• Loosely attaches to the
superficial fascia, except at the
umbilicus.
• Varies in texture - wrinkle,
rough, smooth, scars.
• Thin in front and thick at the
back
• Distribution of hair varies with
sex, age and race.
• Natural tension lines run
horizontally around the body
wall.
FASCIA
• (L. panniculi – apron)
• Composed of fatty tissues and
fibrous connective tissue
• Divided into two layers
– (1) Superficial
– (2) Deep – covers abdominal
muscles
• (1) Same as elsewhere and
varies in amount of fat.
• (1) Major site of fat storage.
• (1) Excessive fat deposition in
the lower anterior abdominal
wall – morbid obesity
SUPERFICILA FASCIA/TISSUE
•
Superior to umbilicus
– Consistent with other regions
•
Inferior to umbilicus
– Reinforced by collagen and
elastic fibers
– Thus 2 layers –
• (1) Superficial fatty layer
(Camper’s fascia)
• Same elsewhere
• (2) Deep membranous layer
(Scarpa’s fascia)
•
Membranous continues to the
perineum – Colles’s fascia, not to
the thigh.
SUPERFICIAL FASCIA
SUPERFICIAL FASCIA
MUSCLES OF THE ANTEROLATERAL ABDOMINAL WALL
• 5 pairs of muscles bilaterally – 3
flat, 2 vertical
•
•
•
•
•
(1) External oblique
(2) Internal oblique
(3) Transversus abdominis
(4) Rectus abdominis
(5) Pyramidalis
EXTERNAL OBLIQUE MUSCLE
•
•
•
•
O: external surfaces of 5th – 12th ribs
I: linea alba, pubic tubercle, ant ½ of iliac crest
N: thoracoabdominal nerves (T7-T11 spinal nerves), subcostal nerve.
A: compresses the abdomen to provide support for abdominal organs.
INTERNAL OBLIQUE MUSCLE
•
•
•
•
O: thoracolumbar fascia, ant 2/3 of iliac crest, lat 1/3 of inguinal ligament.
I: inferior borders of 10th – 12th ribs, linea alba, pecten pubis, conjoint tendon.
N: thoracoabdominal nerves (T6-T12 spinal nerves), L1 nerve
A: compresses and supports abdominal viscera
TRANSVERSUS ABDOMINIS MUSCLE
•
•
•
•
O: thoracolumbar fascia, internal surfaces of 7th-12th costal cartilages, iliac crest,
lat 1/3 of inguinal ligament.
I: linea alba, pubic crest, pecten pubis, conjoint tendon.
N: thoracoabdominal nerves (T6-T12 anterior rami of spinal nerves), L1 nerve
A: compresses and supports abdominal viscera
RECTUS ABDOMINIS MUSCLE
•
•
•
•
O: pubic symphysis & pubic crest
I: xiphoid process & 5th-7th costal cartilages
N: thoracoabdominal nerves (T6-T12 spinal nerves)
A: flexes trunk, compresses and supports abdominal organs, prevents pelvic
tilting
ABDOMINAL MUSCLES
ABDOMINAL MUSCLES
DEEP FASCIA
• Dense connective tissue layer , devoid of fat, that covers the muscles
and their aponeurosis.
• 3 layers – superficial, intermediate & deep.
DEEP FASCIA
PYRAMIDALIS MUSCLE
• Small, insignificant muscle.
• Absent in 20% of people
•
•
•
•
O: pubic crest, pubic symphysis
I: linea alba
N: subcostal nerve (T12)
A: tenses the abdomen
RECTUS SHEATH
•
A strong incomplete fibrous
compartment
• Formed by decussation and
interweaving of the flat
abdominal muscles.
• Internal oblique
aponeurosis splits into two
layers: anterior & posterior
and invest the rectus
abdominis muscle.
RECTUS SHEATH
• Anterior wall – external oblique,
anterior layer of internal oblique
• Posterior wall – transversus
abdominis and posterior layer of
internal oblique.
• All aponeuroses fuse in the
midline – linea alba.
• In the midline, it contains the
umbilical ring. A defect where
fetal umbilical vessels pass to
the placenta.
• Splitting of internal oblique,
lateral to rectus abdominis –
semilunar line.
RECTUS SHEATH
• Posterior wall ends slightly below the umbilicus – arcuate line of
Douglas.
• The rectus abdominis is covered by the transversalis fascia posteriorly.
CONTENTS OF THE RECTUS SHEATH
• Contents of the Rectus
Sheath.
– Rectus abdominis
muscle
– Pyramidalis
– Superior & inferior
epigastric vessels
– Intercostal nerves
(T7-T11)
RECTUS SHEATH
ENDOABDOMINAL FASCIA
•
A membranous and areolar sheets.
•
Named according to muscle or
aponeurosis it lines.
•
Transversalis fascia as it lines the
transversus abdominis muscle.
•
A variable amount of fat separates the
fascia above from the peritoneum –
extraperitoneal fat.
•
Peritoneum – a single layer of
epithelial cells and connective tissue.
NERVES OF THE ANTEROLATERAL ABDOMINAL WALL
• (1) thoracoabdominal
nerves (T7 – T11)
• (2) Subcostal nerve
(anterior ramus of T12)
• (3) Iliohypogastric
• (4) Ilioinguinal
VESSELS OF THE ANTEROLATERAL ABDOMINAL WALL
• (1) superior epigastric artery
• (2) musculophrenic artery
• (3) 10th & 11th post intercostal
arteries
• (4) subcostal artery
• (5) inferior epigastric
• (6) deep circumflex iliac
• (7) superficial circumflex iliac
• (8) superficial epigastric
VEINS & LYMPHATICS OF THE ANTEROLATERAL ABDOMINAL WALL
• (1) Subcutaneous venous plexus
• (2) Paraumbilical veins
• (3) Lateral thoracic vein
• (4) Superficial epigastric veins
• (5) superficial circumflex iliac
• (6) superior & inferior epigastric
• (7) deep circumflex iliac
• (8) posterior interocstal (11th) &
subcostal veins
FUNCTIONS OF THE ABDOMINAL MUSCLES
• Form a strong expandible
support for the wall
• Support organs from injuries
• Compress to increase
intraabdominal pressure to
facilitate expulsion
• Move trunk to maintain posture
• Assists in breathing
FINIS