Podcast
Questions and Answers
What is the primary action of the supraspinatus muscle?
What is the primary action of the supraspinatus muscle?
Which nerve supplies the infraspinatus muscle?
Which nerve supplies the infraspinatus muscle?
Where does the teres major muscle insert?
Where does the teres major muscle insert?
Which muscle is responsible for lateral rotation of the arm?
Which muscle is responsible for lateral rotation of the arm?
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What is the origin of the teres minor muscle?
What is the origin of the teres minor muscle?
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Which nerve supplies the teres minor muscle?
Which nerve supplies the teres minor muscle?
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Which muscle originates from the superior angle of the scapula?
Which muscle originates from the superior angle of the scapula?
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What action is performed by the teres major muscle?
What action is performed by the teres major muscle?
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What is the common function of the rotator cuff muscles?
What is the common function of the rotator cuff muscles?
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Which of the following muscles is NOT a rotator cuff muscle?
Which of the following muscles is NOT a rotator cuff muscle?
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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.
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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
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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°.
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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.
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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.
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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.
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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.
