Deltoid Muscle Anatomy Quiz

Questions and Answers

What is the primary action of the supraspinatus muscle?

Initiation of abduction of arm from 0-15° (correct)

Extension of the arm

Lateral rotation of arm

Medial rotation of arm

Which nerve supplies the infraspinatus muscle?

Suprascapular nerve (correct)

Lower subscapular nerve

Dorsal scapular nerve

Axillary nerve

Where does the teres major muscle insert?

Middle facet on the posterior surface of the greater tubercle of the humerus

Medial lip of the intertubercular sulcus on the anterior surface of the humerus (correct)

Tip of the greater tubercle of the humerus

Inferior facet on the greater tubercle of the humerus

Which muscle is responsible for lateral rotation of the arm?

Infraspinatus muscle Signup and view all the answers

What is the origin of the teres minor muscle?

Posterior surface of the lateral border of the scapula Signup and view all the answers

Which nerve supplies the teres minor muscle?

Axillary nerve Signup and view all the answers

Which muscle originates from the superior angle of the scapula?

None of the above Signup and view all the answers

What action is performed by the teres major muscle?

Medial rotation and extension of arm Signup and view all the answers

What is the common function of the rotator cuff muscles?

Stabilization of the shoulder joint Signup and view all the answers

Which of the following muscles is NOT a rotator cuff muscle?

Teres major Signup and view all the answers

Study Notes

Deltoid Muscle

Origin: Anterior border of lateral 1/3 of clavicle, lateral border of acromion process, inferior lip of crest of spine.
Insertion: Deltoid tuberosity on the humerus.
Nerve Supply: Axillary nerve, important for shoulder mobility.
Action:
- Anterior fibers: Flex and medially rotate the arm.
- Middle fibers: Abduct the arm from 15° to 90°.
- Posterior fibers: Extend and laterally rotate the arm.

Subscapularis Muscle

Origin: Medial 2/3 of subscapular fossa.
Insertion: Lesser tubercle of the humerus.
Nerve Supply: Upper and lower subscapular nerves.
Action: Causes adduction and medial rotation of the arm; part of the rotator cuff.

Rotator Cuff Muscles

Supraspinatus Muscle:
- Origin: Medial two-thirds of the supraspinous fossa of the scapula.
- Insertion: Tip of the greater tubercle of the humerus.
- Nerve Supply: Suprascapular nerve (C5, C6).
- Action: Initiates abduction of the arm from 0-15°.
Infraspinatus Muscle:
- Origin: Medial two-thirds of the infraspinous fossa of the scapula.
- Insertion: Middle facet on posterior surface of the greater tubercle of the humerus.
- Nerve Supply: Suprascapular nerve (C5, C6).
- Action: Lateral rotation of the arm.
Teres Minor Muscle:
- Origin: Upper two-thirds of posterior surface of the lateral border of the scapula.
- Insertion: Inferior facet on the posterior surface of the greater tubercle of the humerus.
- Nerve Supply: Axillary nerve (C5, C6).
- Action: Lateral rotation of the arm at the shoulder joint.
Teres Major Muscle:
- Origin: Posterior surface of the inferior angle of the scapula.
- Insertion: Medial lip of the intertubercular sulcus (bicipital groove) on the humerus.
- Nerve Supply: Lower subscapular nerve (C5, C6, C7).
- Action: Medial rotation and extension of the arm at the shoulder joint.

Description

Test your knowledge on the anatomy of the deltoid muscle, including its origin, insertion, nerve supply, and actions. This quiz is perfect for students of human anatomy and related fields to reinforce their understanding of muscle functions.