Atlas of Human Anatomy by Netter

d. Innervated segmentally by the ventral rami of T6-T12 spinal nerves
The transversus abdominis
a. Innermost of the three flat muscles
b. Fibers run transversely and medially and end in an aponeurosis that contributes to the rectus sheath.
c. Innervated segmentally by the ventral rami of T6-T12 spinal nerves
Linea alba
a. Tendinous raphe running vertically in the midline
b. Formed by the union of the aponeuroses of the flat muscles on either side
c. Largely avascular
d. Umbilicus found in midline
Vertical muscle = rectus abdominis
Paired
Separated by the linea alba in the midline
Wider superiorly than inferiorly
Typically composed of four segments connected by tendinous intersections that attach anteriorly to the sheath of this muscle
Innervated segmentally by the ventral rami of T6-T12 spinal nerves
Have the superior epigastric and the inferior epigastric arteries running inferiorly and superiorly, respectively, on their deep
surfaces.
Pyramidalis muscle
Small, insignificant, triangular muscles arising from the body of the pubis inferiorly
Inserts into the linea alba medially
Absent in 20% of people
Rectus sheath
A tough, fibrous sheath composed of the aponeuroses of the three flat muscles
Extends from the xiphoid process and fifth through seventh costal cartilages to pubic symphysis and crests
Contains the superior and inferior epigastric vessels, lymphatics and branches of the ventral primary rami of T7-T12
Encloses the rectus abdominis and the pyramidalis muscle
Semilunar line marks lateral border
Has a crescent-shaped line-the arcuate line-on its posterior wall approximately three fourths of the way down the wall
Above the arcuate line:
Anterior wall composed of the aponeurosis of the external abdominal oblique and the anterior layer of the aponeurosis of the
internal abdominal oblique
Posterior wall composed of the posterior layer of the aponeurosis of the internal abdominal oblique, the aponeurosis of the
transversus abdominis, the transversalis fascia of the abdomen, and parietal peritoneum
Below arcuate line
Aponeuroses of all three flat muscles pass anterior to the rectus muscle, reinforcing the anterior wall
Posterior wall composed of just transversalis fascia and parietal peritoneum
Has vessels and nerves entering the sheath at its lateral edge, the semilunar line, to supply the rectus muscle.

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Muscle Proximal Attachment (Origin) Distal Attachment

(Insertion)

Innervation Blood Supply Main Actions

External

oblique

External surfaces of 5th to 12th

ribs

Linea alba, pubic tubercle,

and anterior half of iliac

crest

Inferior seven

thoracic nerves

Superior and

inferior epigastric

arteries

Compresses and

supports

abdominal viscera;

flexes and rotates

trunk

Internal

oblique

Thoracolumbar fascia, anterior

two thirds of iliac crest, and

lateral half of inguinal ligament

Inferior borders of 10th to

12th ribs, linea alba, and

pubis via conjoint tendon

Ventral rami of

inferior six

thoracic and

1st lumbar

nerves

Superior and

inferior epigastric

and deep

circumflex iliac

arteries

Compresses and

supports

abdominal viscera;

flexes and rotates

trunk

Transversus

abdominis

Internal surfaces of 7-12 costal

cartilages, thoracolumbar

fascia, iliac crest, and lateral

third of inguinal ligament

Linea alba with

aponeurosis of internal

oblique, pubic crest, and

pecten pubis via conjoint

tendon

Ventral rami of

inferior six

thoracic and

1st lumbar

nerves

Deep circumflex

iliac, and inferior

epigastric arteries

Compresses and

supports

abdominal viscera

Rectus

abdominis

Pubic symphysis and pubic

crest

Xiphoid process and costal

cartilages 5-7

Ventral rami of

inferior six

thoracic nerves

Superior and

interior epigastric

arteries

Flexes trunk and

compresses

abdominal viscera

Pyramidalis Body of pubis, anterior to rectus

abdominis

Linea alba Inferior epigastric

artery

Tenses the linea

alba

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Nerve supply
Neurovascular plane
Found between the internal abdominal oblique and the transversus abdominis
Contains the vessels and nerves supplying the skin and muscles of the anterior and lateral abdominal wall.
Nerves and vessels are transversely oriented and segmental
Nerves
Thoracoabdominal nerves
Anterior cutaneous branches of the ventral primary rami of T7-T11
a. T7-T9 supply skin above the umbilicus
b. T10 supplies skin around the umbilicus
c. T11 (plus subcostal and ilioinguinal and iliohypogastric nerves) supplies skin below umbilicus