Activity – Analyzing the Teres Major
In this activity we will use the "3 Rules of Muscles" to determine the joint actions of the teres
major. Answer the questions below:
Shoulder (Glenohumeral) Joint Actions Word Bank
Action
Plane
Flexion
Extension
Abduction
Adduction
Horizontal Abduction
Horizontal Adduction
Internal Rotation
External Rotation
Sagittal
Sagittal
Frontal
Frontal
Transverse
Transverse
Transverse
Transverse
© 2014 Brent Brookbush
1. Despite a different origin, this muscle nearly blends with the muscle we just discussed, including an
insertion at the same bony landmark. The teres major is very similar to which muscle?
Latissimus Dorsi
2. As this muscle follows a similar course from the scapula and around the medial side of the humerus
to the anterior humeral head, which joint actions do you expect it to contribute to?
Adduction, Extension and Internal Rotation
3. Re-write your answers into one succinct table?
Teres Major:
o Joint it crosses: Shoulder
o Actions: Adduction, Extension and Internal Rotation
Check your answers.

Study Note: Make a special note of the major in teres major. This muscle has a "little brother" who
does not share the same joint actions. As “major” is latin for "greater or larger", I try to remember
that the teres major muscle assists the large latissimus dorsi.
© 2014 Brent Brookbush