The four main abdominal muscles from deep to superficial are: 1. Transversus abdominis - draws the abdominal wall inward toward the spine protecting internal organs 2. Internal oblique - rotates the torso to the same side and side bends the spine 3. External oblique - rotates the torso to the opposite side and side bends the spine 4. Rectus abdominus - causes the spine to bow forward and tucks the pelvis under

1. ABDOMINAL
Anatomy

2. 4 ABDOMINAL MUSCLES
Listed deep to superficial:
1. Transversus Abdominus
2. Internal Oblique
3. External Oblique
4. Rectus Abdominus

3. Transversus Abdominus
The TVA Attaches to the ribs,
pelvis, and lower back
creating a corset to protect the
organs and support the spine.
When engaged, TVA pulls
the abdominal wall inward
toward the spine.
Action: Drawing in

4. The Internal Oblique
Abdominals rotate
the spine and rib cage
to the same direction.
This is called
ipsilateral rotation.
Do you see how
the muscle fibers are
arranged on a upward
diagonal?
Pictured here are the
Left Internal Obliques,
so they would rotate
the torso to the left.
This muscle along with some
of the back muscles side
bend the spine, which is
also known as lateral flexion.
This muscle can also assists
with drawing the abdominal
wall toward the spine
(along with the TVA).
Actions: ipsilateral rotation,
lateral flexion, drawing in

5. External Obliques
This muscle rotates the spine and rib
cage to the opposite direction. This
is called contralateral rotation.
This muscle along with some of the
back muscles side bend the spine,
which is also known as lateral
flexion.
Do you see how the muscle fibers
are arranged on a Downward
diagonal? Pictured here are the
Left External Obliques, so they
would rotate the torso to the
right.
Actions: contralateral rotation,
lateral flexion

6. Pictured here are the Internal
& External Oblique
Abdominals.
Notice how the fibers run on a
diagonal into one other.
When paired up, they
become a powerful team.
Right Rotation =
Left External Oblique &
Right Internal Oblique
Left Rotation =
Right External Oblique &
Left Internal Oblique

7. Rectus Abdominus This muscle causes the spine
to bow forward, more
formally known as spinal
flexion.
This muscle can also cause
the pelvis to tuck under,
which is known as a
posterior tilt.
If one does not engage the
TVA, this muscle often
pops up creating a
“mountain.”
Actions: Spinal Flexion &
Posterior Pelvic Tilt