1. Flavia Lombardi Period: 5
Trunk Muscles
Flavia Lombardi
Period: 5

2. Trunk Muscles
Trunk muscles are the muscles that move the vertebral column, the muscles that form the thoracic and abdominal walls and those that cover the pelvic outlet.

3. Anterior Muscles Pectoralis Major
Large superficial muscle located in the upper chest, going across the chest from the shoulder to the breast bone.
The two major muscles in the Pectoralis Major are the “Pecs” which are muscles that create the bulk of the chest.
Abducts and flexes the arm.

4. Intercostal Muscles Deep muscles between the ribs
Help form and move chest wall
Essential in movement of the chest when you are breathing

5. External & Internal Intercostal
External Intercostal Muscles are important because they help raise the ribcage to let air in.
Fibers are running downward toward the Sternum.
Internal Intercostal Muscles depress the ribcage
Helps let out air when you exhale

6. Muscles of The Abdominal Girdle
The four anterior abdominal muscles form a natural “girdle” that reinforces the body trunk.
Rectus abdominis, external and internal obliques, and Transversus abdominis
The fibers of each muscle or muscle pair run in a different direction.

7. Rectus & Transversus Abdominis
The Rectus Abdominis is the most superficial muscles of the abdomen.
Main function is to flex the vertebral column
Compresses the abdominal contents during defecation and child birth.
The Transversus Abdominis is the deepest muscle in the abdominal wall
Has fibers that run horizontally and wraps around your spine for protection and stability.

8. External & Internal Oblique
The lateral walls of the abdomen are composed of the External Oblique muscles, which are paired superficial muscles.
Flex the vertebral column but also laterally bend and rotate the trunk.
The Internal Oblique are deep to the External Oblique and are paired muscles
Fibers run at right angles to those of the external Oblique’s
Same function as the External Oblique

9. Posterior Muscles
Trapezius muscles are the most superficial muscles of the posterior neck and upper trunk
Diamond/Kite shaped
Lower fibers depress and help upper fibers elevate and upwardly rotate scapula.
Latissimus Dorsi is a large and flat muscle
Covers the lower back
Extends, adducts and medially rotates the arm
Important muscles when you move your arm downward like when you’re swimming.

10. Erector Spinae & Delatoid
Deep muscles of the back
Each Erector Spinae is composed of 3 muscle columns; Longissimus, Iliocostalis & Spinalis
Deltoids are triangle-shaped muscles that form the rounded shaped of your shoulders
Deltoid is widest at the top of the shoulder and narrows to the bottom as it travels down the arm
Good place for injections because they are so bulky

11. Questions Which of the following is the Pectoralis Major? 1 2 3 4 4 1

12. True or false?
Internal Intercostals Muscles are important because they help raise the ribcage to let air in. A) True, Internal Muscles are important because they help raise the ribcage to let air in. B) False, Internal Intercostals Muscles are important because they help let out air when you exhale.

13. What are the three muscle columns in the Erector Spinae called. Hint:
What are the three muscle columns in the Erector Spinae called? Hint: *(Lo_______us, ili_____is, S_____is)*

14. Bibliography Page Works Cited
"Anterior Muscles - Boundless Open Textbook." Boundless. N.p., n.d. Web. 11 Dec
”Axial Muscles: Trunk Muscles Anatomy & Support - Video & Lesson Transcript | Study.com."
Study.com. N.p., n.d. Web. 11 Dec "Essentials of Human Anatomy & Physiology, 9th Edition." Essentials of Human Anatomy & Physiology, 9th Edition. Benjamin Cummings, n.d. Web. 11 Dec

15. Answer Key
1. A.
2. B.
3. Longissimus, iliocostalis, and spinalis