1. Muscles of the Anterior Abdomen

2. External abdominal oblique m. (133)
Internal abdominal oblique m. (134)
Transversus abdominis m.
Rectus abdominis m. (135)
Pyramidalis m.
Cremaster m. (136)
Quadratus lumborum m. (137)

3. Generalized motions of the abdominal muscles
In general, muscle have two attachment sites:
Origin
Insertion

4. For abdominal muscles, one set of attachment sites is often on the pelvis, while the other is on the trunk
For some of the abdominal muscles, either the attachment on the trunk OR the attachment on the pelvis can be the fixed site, while the other attachment site moves.
For that reason, we will talk about distal and proximal attachments for some of these muscles, rather than origin and insertion

5. Flexion (anterior) or extension (posterior) of the trunk on the pelvis
Anterior or posterior tilt of the pelvis
Lateral flexion of the trunk on the pelvis
Lifting up of one side of the pelvis

6. Rotation of the trunk on the pelvis
Rotation of the pelvis
Ipsilateral rotation – when a muscle contracts, an anterior point on the moving region rotates toward the side of the muscle
Contralateral rotation – The anterior surface of the body region rotates away from the contracting muscle

7. Iliac Crest
Three lips
Each lip is an attachment site for one of the three lateral abdominal muscles

8. Ext. Abd. Oblique m. Proximal and distal attachment sites T7-T12
Stabilizes trunk
Compresses abdominal viscera
Bilateral and unilateral actions
Trunk movements
Pelvic movements

9. Int. Abd. Obllique m. Proximal and distal attachment sites T7-T12, L1
Stabilizes trunk
Compresses abdominal viscera
Bilateral and unilateral actions
Trunk movements
Pelvic movements

10. Transversus Abd. m. Origin and insertion T7-T12, L1 Stabilizes trunk
Compresses abdominal viscera

11. Rectus Abd. M. Proximal and distal attachments 3 Tendinous insertions
Muscle can contract in segments
T5-T12
Stabilizes Trunk
Compresses abdominal viscera
Bilateral actions
Trunk movement
Pelvic movement

12. Quad. Lumb. M. Proximal and distal attachments T12, L1-L3
Unilateral and bilateral actions
Pelvis stable
Trunk stable

13. Stabilizing actions Limit movement of the trunk
Which muscles do this and which movements do they limit?
Why is this important?

14. Compress Viscera
Increases abdominal pressure
What is this needed for?

15. Pyramidalis muscle

16. Cremaster muscle