Glenohumeral Joint and Rotator Cuff Overview
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Questions and Answers

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?

Ball and socket

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.

<p>Ligaments, rotator cuff, glenoid labrum</p> Signup and view all the answers

What joint does the rotator cuff provide dynamic stability to?

<p>Scapulothoracic joint</p> Signup and view all the answers

What muscles are included in the rotator cuff?

<p>Subscapularis, infraspinatus, teres minor, and supraspinatus</p> Signup and view all the answers

What is the most important function of the rotator cuff?

<p>Holds humeral head in place</p> Signup and view all the answers

Which rotator cuff muscles are most commonly injured?

<p>Supraspinatus and infraspinatus</p> Signup and view all the answers

What is impingement syndrome?

<p>Inflammation of rotator cuff muscles (gets squeezed between humeral head and spinous process)</p> Signup and view all the answers

What is the labrum?

<p>Specialized rim of fibrocartilage pad</p> Signup and view all the answers

What is the function of the bursae?

<p>Provides cushioning and reduces friction</p> Signup and view all the answers

What is the brachial plexus?

<p>A network of nerves that innervates the muscles of the upper limb</p> Signup and view all the answers

Which glenohumeral muscles are extrinsic?

<p>Pectoralis major and latissimus dorsi</p> Signup and view all the answers

Which glenohumeral muscles often work together?

<p>Pectoralis major and anterior deltoid, latissimus dorsi and teres major, infraspinatus and teres minor</p> Signup and view all the answers

What is the exception to the muscle pairs working together?

<p>During horizontal abduction</p> Signup and view all the answers

What is the function of the pectoralis major?

<p>Works closely with anterior deltoid, can be overdeveloped in comparison to posterior trunk muscles</p> Signup and view all the answers

What is the function of the subscapularis?

<p>Provides dynamic stability to scapulothoracic joint along with the serratus anterior, provides dynamic stability to the glenohumeral joint</p> Signup and view all the answers

What is the function of the supraspinatus?

<p>Most often injured rotator cuff muscle, strengthening exercise includes full can</p> Signup and view all the answers

What is the function of the latissimus dorsi?

<p>Extrinsic muscle, broadest muscle of back, swimmer's muscle, often works with teres major</p> Signup and view all the answers

What is the function of the infraspinatus?

<p>Works with teres minor, most powerful external rotator cuff, second most commonly injured rotator cuff muscle</p> Signup and view all the answers

What is the proximal attachment of the pectoralis major?

<p>Anteromedial clavicle</p> Signup and view all the answers

What is the distal attachment of the pectoralis major?

<p>Intertubercle groove</p> Signup and view all the answers

What is the proximal attachment of the subscapularis?

<p>Subscapular fossa</p> Signup and view all the answers

What is the distal attachment of the subscapularis?

<p>Lesser tubercle</p> Signup and view all the answers

What is the proximal attachment of the supraspinatus?

<p>Supraspinous fossa</p> Signup and view all the answers

What is the distal attachment of the supraspinatus?

<p>Greater tubercle of humerus</p> Signup and view all the answers

What is the proximal attachment of the latissimus dorsi?

<p>T6-L5, sacrum, ilium, last 3 ribs (9-12)</p> Signup and view all the answers

What is the distal attachment of the latissimus dorsi?

<p>Intertubercle groove</p> Signup and view all the answers

What is the proximal attachment of the teres major?

<p>Inferolateral scapular border</p> Signup and view all the answers

What is the distal attachment of the teres major?

<p>Intertubercle groove</p> Signup and view all the answers

What is the proximal attachment of the teres minor?

<p>Posterolateral scapular border</p> Signup and view all the answers

What is the distal attachment of the teres minor?

<p>Greater tubercle of humerus</p> Signup and view all the answers

What is the proximal attachment of the infraspinatus?

<p>Infraspinous fossa</p> Signup and view all the answers

What is the distal attachment of the infraspinatus?

<p>Greater tubercle of humerus</p> Signup and view all the answers

What is the proximal attachment of the anterior deltoid?

<p>Anterolateral</p> Signup and view all the answers

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.

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