Podcast
Questions and Answers
Which muscle initiates abduction of the arm from 0-15°?
Which muscle initiates abduction of the arm from 0-15°?
The Teres Major muscle is responsible for lateral rotation of the arm.
The Teres Major muscle is responsible for lateral rotation of the arm.
False
What is the action of the Infraspinatus muscle?
What is the action of the Infraspinatus muscle?
Lateral rotation of the arm
The __________ muscle flexes and medial rotates the arm.
The __________ muscle flexes and medial rotates the arm.
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Match the shoulder muscles with their primary actions:
Match the shoulder muscles with their primary actions:
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Which muscle is primarily responsible for the abduction of the arm from 0 to 15 degrees?
Which muscle is primarily responsible for the abduction of the arm from 0 to 15 degrees?
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The teres minor muscle is responsible for medial rotation of the arm.
The teres minor muscle is responsible for medial rotation of the arm.
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What is the primary action of the infraspinatus muscle?
What is the primary action of the infraspinatus muscle?
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The greater tuberosity is the insertion point for the ______ and ______ muscles.
The greater tuberosity is the insertion point for the ______ and ______ muscles.
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Match the shoulder muscles with their corresponding nerve supply:
Match the shoulder muscles with their corresponding nerve supply:
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What condition is characterized by pain and swelling in the shoulder area, often seen in athletes?
What condition is characterized by pain and swelling in the shoulder area, often seen in athletes?
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Name the muscles that comprise the rotator cuff.
Name the muscles that comprise the rotator cuff.
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The subacromial bursa is located below the supraspinatus tendon.
The subacromial bursa is located below the supraspinatus tendon.
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Study Notes
Muscles Connecting Scapula with Humerus
-
Deltoid Muscle
- Origin: Anterior border of the lateral half of the clavicle, lateral border of acromion, lower border of the spine of scapula
- Insertion: Deltoid tuberosity
- Nerve Supply: Axillary nerve
- Action:
- Anterior fibers: Flexes and medially rotates the arm.
- Middle fibers: Abducts the arm (15-90 degrees).
- Posterior fibers: Extends and laterally rotates the arm.
- Paralysis: Atrophy of the shoulder, unable to abduct the arm to 90 degrees.
-
Supraspinatus Muscle
- Origin: Supraspinous fossa
- Insertion: Greater tuberosity of the humerus (upper impression)
- Nerve Supply: Suprascapular nerve
- Action: Initiates abduction of the arm (0-15 degrees)
-
Infraspinatus Muscle
- Origin: Infraspinous fossa
- Insertion: Greater tuberosity of the humerus (middle impression)
- Nerve Supply: Suprascapular nerve
- Action: Lateral rotation of the arm
-
Teres Minor Muscle
- Origin: Dorsal aspect of the lateral border of the scapula (upper 2/3)
- Insertion: Greater tuberosity of the humerus (lower impression)
- Nerve Supply: Axillary nerve
- Action: Adduction and lateral rotation of the arm
-
Teres Major Muscle
- Origin: Dorsal surface of the scapula above the inferior angle
- Insertion: Medial lip of the bicipital groove
- Nerve Supply: Lower subscapular nerve
- Action: Adduction, medial rotation
-
Subscapularis Muscle
- Origin: Subscapular fossa
- Insertion: Lesser tuberosity
- Nerve Supply: Upper and lower subscapular nerves
- Action: Adduction and medial rotation of the arm
Rotator Cuff
- Muscles attached to greater and lesser tuberosities
- Blend with capsule of the shoulder joint for strength
-
Muscles:
- Supraspinatus
- Infraspinatus
- Teres Minor
- Subscapularis
Subacromial Bursa
- Location: Between:
- Above: Coracoacromial arch and deltoid muscle
- Below: Supraspinatus tendon and greater tuberosity
- Function:
- Protection of the supraspinatus tendon
- Assists with abduction
Abduction of the Arm
-
0-90 degrees (movement of the humerus)
- 0-15 degrees: Supraspinatus
- 15-90 degrees: Deltoid
-
90-180 degrees (rotation of the scapula)
- Trapezius
- Serratus Anterior
Dawbarn's Test
- Arm by side: Pain
- Right angle abduction: No Pain
Rotator Cuff Tendinitis
- Symptoms: Pain and swelling in the shoulder area, limited motion or weakness of the arm
- Occurs in athletes who frequently lift their arm above their head (e.g., swimmers, pitchers)
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Description
This quiz covers the anatomy of the muscles that connect the scapula with the humerus, focusing on their origins, insertions, actions, and nerve supply. Explore key muscles like the Deltoid, Supraspinatus, and Infraspinatus, and understand their roles in arm movement.
