Podcast
Questions and Answers
What are the articulating bones of the glenohumeral joint?
What are the articulating bones of the glenohumeral joint?
Head of humerus and glenoid fossa of scapula
What is the joint classification of the glenohumeral joint?
What is the joint classification of the glenohumeral joint?
Ball and socket
What is the relationship between mobility and stability in the glenohumeral joint?
What is the relationship between mobility and stability in the glenohumeral joint?
More mobile than stable
Name three stabilizing structures associated with the glenohumeral joint.
Name three stabilizing structures associated with the glenohumeral joint.
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What joint does the rotator cuff provide dynamic stability to?
What joint does the rotator cuff provide dynamic stability to?
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What muscles are included in the rotator cuff?
What muscles are included in the rotator cuff?
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What is the most important function of the rotator cuff?
What is the most important function of the rotator cuff?
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Which rotator cuff muscles are most commonly injured?
Which rotator cuff muscles are most commonly injured?
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What is impingement syndrome?
What is impingement syndrome?
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What is the labrum?
What is the labrum?
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What is the function of the bursae?
What is the function of the bursae?
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What is the brachial plexus?
What is the brachial plexus?
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Which glenohumeral muscles are extrinsic?
Which glenohumeral muscles are extrinsic?
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Which glenohumeral muscles often work together?
Which glenohumeral muscles often work together?
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What is the exception to the muscle pairs working together?
What is the exception to the muscle pairs working together?
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What is the function of the pectoralis major?
What is the function of the pectoralis major?
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What is the function of the subscapularis?
What is the function of the subscapularis?
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What is the function of the supraspinatus?
What is the function of the supraspinatus?
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What is the function of the latissimus dorsi?
What is the function of the latissimus dorsi?
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What is the function of the infraspinatus?
What is the function of the infraspinatus?
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What is the proximal attachment of the pectoralis major?
What is the proximal attachment of the pectoralis major?
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What is the distal attachment of the pectoralis major?
What is the distal attachment of the pectoralis major?
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What is the proximal attachment of the subscapularis?
What is the proximal attachment of the subscapularis?
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What is the distal attachment of the subscapularis?
What is the distal attachment of the subscapularis?
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What is the proximal attachment of the supraspinatus?
What is the proximal attachment of the supraspinatus?
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What is the distal attachment of the supraspinatus?
What is the distal attachment of the supraspinatus?
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What is the proximal attachment of the latissimus dorsi?
What is the proximal attachment of the latissimus dorsi?
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What is the distal attachment of the latissimus dorsi?
What is the distal attachment of the latissimus dorsi?
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What is the proximal attachment of the teres major?
What is the proximal attachment of the teres major?
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What is the distal attachment of the teres major?
What is the distal attachment of the teres major?
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What is the proximal attachment of the teres minor?
What is the proximal attachment of the teres minor?
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What is the distal attachment of the teres minor?
What is the distal attachment of the teres minor?
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What is the proximal attachment of the infraspinatus?
What is the proximal attachment of the infraspinatus?
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What is the distal attachment of the infraspinatus?
What is the distal attachment of the infraspinatus?
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What is the proximal attachment of the anterior deltoid?
What is the proximal attachment of the anterior deltoid?
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Study Notes
Glenohumeral Joint Overview
- Articulating bones: head of the humerus and glenoid fossa of the scapula
- Joint classification: ball-and-socket
- High mobility characterized by reduced stability
- Stabilizing structures: ligaments, rotator cuff, glenoid labrum
Rotator Cuff
- Provides dynamic stability to the scapulothoracic joint
- Composed of four muscles: subscapularis, infraspinatus, teres minor, and supraspinatus
- Primary function: holds the humeral head in place
- Most commonly injured muscles: supraspinatus and infraspinatus, particularly during high diagonal movements
- Impingement syndrome: inflammation caused by the compression of rotator cuff muscles between the humeral head and the spine
Glenoid Labrum
- Specialized rim made of fibrocartilage
- Enhances stability of the glenohumeral joint
- Deepens the glenoid fossa for improved fit with the humeral head
Bursae
- Small fibrous sacs that secrete fluid to cushion joints and reduce friction
- Key bursae: subscapularis bursa (associated with the subscapularis muscle) and subacromial bursa (protecting supraspinatus)
- Bursitis: inflammation of bursae, can cause pain and limited motion
Innervation and Muscle Classification
- All glenohumeral muscles innervated by the brachial plexus
- Intrinsic muscles: primarily associated with joint movement
- Extrinsic muscles: pectoralis major and latissimus dorsi not classified as intrinsic
Muscle Collaborations
- Common muscle partnerships: pectoralis major and anterior deltoid; latissimus dorsi and teres major; infraspinatus and teres minor
- Exception: during horizontal abduction, other muscle combinations may not work together
Pectoralis Major
- Categorized as an extrinsic muscle
- Works closely with anterior deltoid
- May become overdeveloped due to imbalance with posterior trunk muscles
- Strengthening exercises include push-ups and bench press; can be tight from poor posture (relieved by stretching like doorway stretch)
Subscapularis
- Contributes dynamic stability to both scapulothoracic and glenohumeral joints
- Noted as the only anteriorly located rotator cuff muscle
- Strengthening through internal rotation exercises
Supraspinatus
- Positioned beneath the subacromial bursa for protection
- Most frequently injured rotator cuff muscle, particularly in activities like swimming and throwing
- Strengthening exercise: full can
Latissimus Dorsi
- The broadest back muscle, referred to as the "swimmer's muscle"
- Often partners with teres major, except during horizontal abduction
- Strengthening exercises include lat pulldowns and straight-arm pulldowns
Infraspinatus
- Collaborates with teres minor
- Most powerful external rotator among the rotator cuff muscles
- Second most frequently injured rotator cuff muscle; strengthening exercises include external rotations
Muscle Attachments
- Pectoralis Major: proximal attachment at the anteromedial clavicle; distal attachment at intertubercle groove
- Subscapularis: proximal attachment at the subscapular fossa; distal attachment at the lesser tubercle
- Supraspinatus: proximal attachment at supraspinous fossa; distal attachment at greater tubercle of the humerus
- Latissimus Dorsi: proximal attachment spans T6-L5, sacrum, ilium, and last 3 ribs; distal attachment at intertubercle groove
- Teres Major: proximal attachment at the inferolateral scapular border; distal attachment at intertubercle groove
- Teres Minor: proximal attachment at the posterolateral scapular border; distal attachment at the greater tubercle of the humerus
- Infraspinatus: proximal attachment at infraspinous fossa; distal attachment at the greater tubercle of the humerus
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Description
Explore the anatomy and function of the glenohumeral joint and its associated structures, including the rotator cuff and glenoid labrum. This quiz delves into joint classification, stability mechanisms, and common injuries affecting the shoulder. Test your knowledge on these critical components of shoulder anatomy.