Internal Oblique Flashcards

Study the internal oblique muscle, including its attachments, fiber direction, actions, nerve supply, rectus sheath, and inguinal anatomy.

Card 1 of 26Question

What is the internal oblique muscle?

The intermediate layer of the three flat anterolateral abdominal wall muscles.

In This Section

1. What is the internal oblique muscle?

The intermediate layer of the three flat anterolateral abdominal wall muscles.

2. Which muscle lies immediately superficial to the internal oblique?

The external oblique muscle.

3. Which muscle lies immediately deep to the internal oblique?

The transversus abdominis muscle.

4. What are the principal origins of the internal oblique muscle?

The thoracolumbar fascia, anterior two-thirds of the iliac crest, and lateral half of the inguinal ligament.

5. Where do the superior fibers of the internal oblique insert?

The inferior borders of ribs 10 to 12.

6. Where do the medial fibers of the internal oblique insert?

The linea alba through the internal oblique aponeurosis.

7. Where can the inferior aponeurotic fibers of the internal oblique insert?

The pubic crest and pecten pubis, sometimes through a conjoint tendon.

8. What is the predominant fiber direction of the upper and middle internal oblique?

Superomedial, approximately perpendicular to the external oblique fibers.

9. How are the inferior fibers of the internal oblique oriented?

They arch medially and inferiorly toward the pubic region.

10. Which nerves provide motor innervation to the internal oblique?

Thoracoabdominal nerves T7 to T11, the subcostal nerve T12, and the iliohypogastric and ilioinguinal nerves from L1.

11. What is the primary action of bilateral internal oblique contraction?

Flexion of the trunk and compression of abdominal contents.

12. What trunk movement results from unilateral internal oblique contraction?

Rotation of the trunk toward the same side.

13. Which internal oblique muscle contracts to rotate the trunk toward the right?

The right internal oblique muscle.

14. How does the internal oblique assist forced expiration?

It compresses abdominal contents and helps depress the lower ribs.

15. What is the internal oblique aponeurosis?

The broad, flat tendon through which the muscle contributes to the rectus sheath and linea alba.

16. How does the internal oblique aponeurosis contribute to the rectus sheath above the arcuate line?

It divides into anterior and posterior laminae that pass around the rectus abdominis.

17. How does the internal oblique aponeurosis pass relative to rectus abdominis below the arcuate line?

It passes entirely anterior to the rectus abdominis.

18. What is the conjoint tendon?

A variable common aponeurotic insertion of the internal oblique and transversus abdominis near the pubis.

19. Which part of the inguinal canal is reinforced by the conjoint tendon when present?

The medial portion of the posterior wall.

20. How does the internal oblique contribute to the anterior wall of the inguinal canal?

Its muscular fibers reinforce the lateral portion of the anterior wall.

21. How does the internal oblique contribute to the roof of the inguinal canal?

Its lower fibers arch over the canal with fibers of the transversus abdominis.

22. Which covering of the spermatic cord is derived from the internal oblique?

The cremasteric muscle and fascia.

23. Which nerve passes through the internal oblique muscle to enter the inguinal canal?

The ilioinguinal nerve.

24. Between which muscles does the principal abdominal wall neurovascular plane lie?

Between the internal oblique and transversus abdominis.

25. How does internal oblique contraction contribute to the inguinal canal shutter mechanism?

Its arching fibers descend toward the inguinal ligament, helping compress the canal.

26. Why is the internal oblique important during abdominal wall surgery?

Its muscle fibers, nerves, and aponeurotic attachments must be preserved or repaired to maintain abdominal wall function.