Trapezius Flashcards

Explore trapezius anatomy, including its three fiber groups, attachments, innervation, blood supply, scapular actions, and clinical relevance.

Card 1 of 30Question

What type of back muscle is the trapezius?

A superficial extrinsic back muscle that acts primarily on the scapula.

In This Section

1. What type of back muscle is the trapezius?

A superficial extrinsic back muscle that acts primarily on the scapula.

2. What is the general shape of the trapezius muscle?

A broad, flat, triangular muscle covering the posterior neck and upper thoracic region.

3. What are the three functional divisions of the trapezius?

Upper, middle, and lower fibers.

4. Which cranial and cervical structures provide origins for the upper trapezius?

The medial superior nuchal line, external occipital protuberance, and nuchal ligament.

5. Which thoracic vertebrae provide spinous process attachments for the trapezius?

The spinous processes of T1 to T12 and their associated supraspinous ligaments.

6. Where do the upper fibers of the trapezius insert?

The lateral third of the clavicle.

7. Where do the middle fibers of the trapezius insert?

The acromion and superior lip of the spine of the scapula.

8. Where do the lower fibers of the trapezius insert?

The medial end of the spine of the scapula near its root.

9. What is the general direction of the upper trapezius fibers?

Inferolaterally from the occipital and cervical regions toward the clavicle.

10. What is the general direction of the middle trapezius fibers?

Approximately horizontally toward the acromion and scapular spine.

11. What is the general direction of the lower trapezius fibers?

Superolaterally toward the medial end of the scapular spine.

12. Which cranial nerve provides the primary motor innervation of the trapezius?

The spinal accessory nerve (cranial nerve XI).

13. Where do the motor neurons supplying the trapezius through the accessory nerve originate?

The spinal accessory nucleus in the upper cervical spinal cord.

14. Which spinal nerves contribute proprioceptive fibers to the trapezius?

The anterior rami of C3 and C4 spinal nerves.

15. What is the principal action of the upper trapezius fibers on the scapula?

Elevation of the scapula.

16. What is the principal action of the middle trapezius fibers?

Retraction of the scapula toward the vertebral column.

17. What is the principal action of the lower trapezius fibers?

Depression of the scapula.

18. What rotational movement is produced by the combined upper and lower trapezius fibers?

Upward rotation of the scapula, turning the glenoid cavity superiorly.

19. Which muscle works with the trapezius to produce upward rotation of the scapula?

The serratus anterior.

20. Why is the trapezius important during elevation of the arm above shoulder level?

It helps upwardly rotate and stabilize the scapula during overhead movement.

21. What movement can bilateral contraction of the upper trapezius assist when the shoulder girdle is fixed?

Extension of the head and cervical spine.

22. What head movement can unilateral upper trapezius contraction assist?

Ipsilateral lateral flexion with contralateral rotation of the head.

23. Which artery is an important blood supply to the upper and middle trapezius?

The superficial branch of the transverse cervical artery.

24. Which artery commonly contributes to the blood supply of the lower trapezius?

The dorsal scapular artery.

25. Which superficial neck muscle lies anterior to the trapezius at the posterior triangle of the neck?

The sternocleidomastoid, which forms the anterior boundary of the posterior triangle.

26. Which intrinsic and extrinsic back muscles lie deep to the trapezius?

The levator scapulae, rhomboids, splenius muscles, and portions of the erector spinae.

27. Why is the spinal accessory nerve vulnerable during surgery in the posterior triangle of the neck?

It courses relatively superficially across the posterior triangle before entering the trapezius.

28. What clinical findings may occur after spinal accessory nerve injury affecting the trapezius?

Shoulder drooping, weak shoulder shrugging, and impaired overhead arm elevation.

29. How is upper trapezius motor function commonly tested clinically?

By asking the patient to shrug the shoulders against resistance.

30. What scapular abnormality can occur with significant trapezius paralysis?

Lateral scapular winging due to loss of scapular stabilization.