Shoulder and Upper Arm Muscles

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Please view the main muscle page to learn about foundational information relating to muscles (such as origins, insertions, actions, innervations):

https://sites.google.com/d/12VYvBt8J570d3MvRrzm_VwT4F88BXH84/p/1ooXqej1AW94rkDsWT8RczWdN-4tV9Fvo/edit

Anterior view of superficial muscles

Anterior view of deeper muscles

The deltoid, pectoralis major, sternocleidomastoid, and external oblique muscles are removed
The pectoralis minor, subscapularis, and subclavius are now visible

Anterior view of deeper muscles with trunk removed

Anterior view of even deeper muscles

Coracobrachialis and brachialis now clearly visible

Posterior view of superficial muscles

Posterior view of deeper muscles

The 3 posterior rotator cuff muscles now visible (supraspinatus, infraspinatus, and teres minor)

Posterior view of deeper muscles with trunk removed

Note how the triceps brachii has 3 heads (origins)

Posterior view of even deeper muscles

Various views of the 4 rotator cuff muscles

Note how the subscapularis is on the anterior side
Note how they all insert onto the head of the humerus

Quiz Questions - please watch the videos and view the Kenhub link before taking

1. Which muscle is the primary abductor of the shoulder joint?

a. Deltoid

b. Infraspinatus

c. Supraspinatus

d. Teres minor

2. Which muscle originates from the supraspinous fossa?

a. Subscapularis

b. Infraspinatus

c. Teres major

d. Supraspinatus

3. The deltoid muscle inserts on which bony landmark?

a. Greater tubercle of the humerus

b. Deltoid tuberosity

c. Bicipital groove

d. Deltoid groove

4. What is the main action of the subscapularis muscle?

a. Lateral rotation of the humerus

b. Abduction of the arm

c. Medial rotation of the humerus

d. Extension of the elbow

5. Which of the following muscles is NOT part of the rotator cuff group?

a. Teres minor

b. Infraspinatus

c. Supraspinatus

d. Teres major

6. What is the primary action of the triceps brachii?

a. Elbow flexion

b. Elbow extension

c. Shoulder flexion

d. Supination of the forearm

7. Which head of the triceps brachii crosses both the shoulder and elbow joints?

a. Medial head

b. Long head

c. Lateral head

d. Deep head

8. What is the action of the coracobrachialis muscle?

a. Flexion and weak abduction of the shoulder

b. Lateral rotation of the shoulder

c. Flexion and weak adduction of the shoulder

d. Extension of the shoulder

9. What is a shared action of both the biceps brachii and the brachialis?

a. Shoulder extension

b. Elbow flexion

c. Elbow flexion and shoulder flexion

d. Shoulder lateral rotation

10. Which nerve innervates the biceps brachii, brachialis, and coracobrachialis?

a. Axillary nerve

b. Radial nerve

c. Musculocutaneous nerve

d. Median nerve

Quiz Answers

References

Images from: Atlas of Anatomy 4th Edition, Gilroy et al., 2020, Thieme Medical Publishers

Information based on lecture content from professor Dr. Earl Mayhew, DPT, BIO 634 - Human Anatomy course, University of Michigan-Flint, Fall 2022

Page updated

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