External Oblique Muscle Flashcards

Learn the external oblique muscle's attachments, fiber orientation, actions, innervation, aponeurosis, and inguinal relationships.

Card 1 of 24Question

What is the external oblique muscle?

The largest and most superficial of the three flat anterolateral abdominal wall muscles.

In This Section

1. What is the external oblique muscle?

The largest and most superficial of the three flat anterolateral abdominal wall muscles.

2. From which ribs does the external oblique muscle originate?

The external surfaces of ribs 5 to 12.

3. Where does the external oblique muscle insert?

The linea alba, pubic tubercle, and anterior half of the iliac crest.

4. What is the predominant fiber direction of the external oblique muscle?

Inferomedial, resembling the direction of hands placed in front pockets.

5. Which muscles interdigitate with the upper digitations of the external oblique?

The serratus anterior muscle.

6. Which posterior trunk muscle interdigitates with the lower digitations of the external oblique?

The latissimus dorsi muscle.

7. Which abdominal wall muscle lies immediately deep to the external oblique?

The internal oblique muscle.

8. Which spinal nerves provide motor innervation to the external oblique muscle?

The thoracoabdominal nerves T7 to T11 and the subcostal nerve T12.

9. What is the primary action of bilateral external oblique contraction?

Flexion of the trunk and compression of abdominal contents.

10. What trunk movement results from unilateral contraction of the external oblique?

Rotation of the trunk toward the opposite side.

11. Which external oblique muscle contracts to rotate the trunk toward the left?

The right external oblique muscle.

12. How does the external oblique contribute to forced expiration?

It compresses abdominal contents and helps depress the lower ribs.

13. What is the external oblique aponeurosis?

The broad, flat tendon formed by the anterior continuation of the external oblique muscle.

14. How does the external oblique aponeurosis contribute to the rectus sheath?

It forms the most superficial aponeurotic layer of the anterior rectus sheath.

15. Which midline fibrous structure receives fibers from the external oblique aponeurosis?

The linea alba.

16. Which ligament is formed by the thickened inferior border of the external oblique aponeurosis?

The inguinal ligament.

17. Between which bony landmarks does the inguinal ligament extend?

The anterior superior iliac spine and pubic tubercle.

18. Which ligament is formed by the medial reflection of fibers from the inguinal ligament?

The lacunar ligament.

19. Which opening in the external oblique aponeurosis forms the external exit of the inguinal canal?

The superficial inguinal ring.

20. What forms the medial and lateral margins of the superficial inguinal ring?

The medial and lateral crura of the external oblique aponeurosis.

21. Which wall of the inguinal canal is primarily formed by the external oblique aponeurosis?

The anterior wall.

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

The external spermatic fascia.

23. Which nerve emerges through the superficial inguinal ring after passing deep to the external oblique aponeurosis?

The ilioinguinal nerve.

24. Why is the external oblique aponeurosis important during open inguinal hernia repair?

It is opened to expose the inguinal canal and subsequently repaired to restore its anterior wall.