Shoulder Joint Movements and Stability
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Questions and Answers

What is the primary function of the Glenohumeral ligaments?

  • To stabilize the shoulder and prevent anterior dislocation (correct)
  • To support the weight of the arm
  • To provide flexibility during shoulder movements
  • To connect the scapula to the rib cage

    • Which muscles are primarily responsible for shoulder extension?

  • Pectoralis major and coracobrachialis
  • Infraspinatus and teres minor
  • Anterior deltoid and supraspinatus
  • Posterior deltoid, latissimus dorsi, and teres major (correct)

    • Which ligament attaches the base of the coracoid process to the greater tubercle of the humerus?

  • Coracohumeral ligament (correct)
  • Coracoacromial ligament
  • Coraco-clavicular ligament
  • Transverse humeral ligament

    • What is a unique feature of the Coracoacromial ligament compared to other ligaments?

    <p>It forms the coraco-acromial arch overlying the shoulder joint</p> Signup and view all the answers

    Which factors could negatively affect shoulder mobility?

    <p>Tightening of the joint capsule due to injury or overuse</p> Signup and view all the answers

    Which muscle initiates the first 15 degrees of abduction of the upper limb?

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

    Which factors contribute to the stability of the shoulder joint?

    <p>Rotator cuff muscles</p> Signup and view all the answers

    Which pair of muscles is primarily responsible for medial and lateral rotation of the shoulder joint?

    <p>Teres major and teres minor</p> Signup and view all the answers

    What is the role of the glenoid labrum in shoulder stability?

    <p>It deepens the glenoid cavity and reduces dislocation risks</p> Signup and view all the answers

    Which of the following muscles is NOT involved in medial rotation of the shoulder joint?

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

    What anatomical characteristic of the shoulder joint contributes to its mobility?

    <p>Ball and socket joint configuration</p> Signup and view all the answers

    Which muscle primarily facilitates lateral rotation of the shoulder?

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

    What is the primary role of the biceps brachii regarding shoulder movement?

    <p>Weakly assists in forward flexion</p> Signup and view all the answers

    Which ligament is primarily responsible for preventing excessive upward movement of the humeral head during shoulder abduction?

    <p>Coracohumeral ligament</p> Signup and view all the answers

    What is the primary movement allowed by the glenohumeral joint?

    <p>All of the above</p> Signup and view all the answers

    Which muscle is NOT considered part of the rotator cuff that contributes to shoulder stability?

    <p>Teres major</p> Signup and view all the answers

    What structural feature of the glenoid cavity helps improve joint stability?

    <p>Glenoid labrum</p> Signup and view all the answers

    Which factor is most likely to contribute to shoulder joint instability?

    <p>Disproportion between humeral head and glenoid fossa</p> Signup and view all the answers

    Which bursa in the shoulder joint primarily reduces friction for the supraspinatus tendon?

    <p>Subacromial bursa</p> Signup and view all the answers

    Which movement is primarily limited by the laxity of the shoulder joint capsule?

    <p>Medial rotation</p> Signup and view all the answers

    How does the structure of the shoulder joint affect its mobility compared to its stability?

    <p>High mobility leads to increased risk of dislocation;</p> Signup and view all the answers

    Study Notes

    Shoulder Joint Movements

    • Abduction: Moving the upper limb away from the midline in the coronal plane.
      • 0-15 degrees: Initiated by the supraspinatus muscle.
      • 15-90 degrees: Produced by the middle fibers of the deltoid muscle.
      • Past 90 degrees: Requires scapular rotation, facilitated by the trapezius and serratus anterior muscles.
    • Adduction: Moving the upper limb towards the midline in the coronal plane.
      • Produced by the pectoralis major, latissimus dorsi, and teres major muscles.
    • Medial Rotation: Rotating the humerus towards the midline (thumb pointing medially).
      • Produced by the subscapularis, pectoralis major, latissimus dorsi, teres major, and anterior deltoid muscles.
    • Lateral Rotation: Rotating the humerus away from the midline (thumb pointing laterally).
      • Produced by the infraspinatus and teres minor muscles.

    Mobility and Stability of the Shoulder Joint

    • Factors contributing to mobility:

      • Ball and socket joint: Allows for a wide range of motion.
      • Disproportionate surfaces: The shallow glenoid cavity and large humeral head contribute to mobility.
      • Laxity of the joint capsule: Provides flexibility for movement.

    • Factors contributing to stability:

      • Rotator cuff muscles:
        • Supraspinatus, infraspinatus, teres minor, and subscapularis muscles form a bundle around the shoulder joint.
        • Act as dynamic stabilizers by keeping the humeral head in the glenoid cavity.
        • Their resting tone compresses the humeral head into the glenoid cavity.
      • Glenoid labrum:
        • Fibrocartilaginous ridge surrounding the glenoid cavity.
        • Deepens the cavity and creates a seal with the humeral head, reducing dislocation risk.
      • Ligaments:
        • Primarily thickenings of the joint capsule.
        • Provide strength to the capsule and stabilize the joint, particularly the anterior aspect.

    Ligaments of the Shoulder Joint

    • Glenohumeral ligaments (superior, middle, inferior):
      • Thickenings of the joint capsule.
      • Connect the humerus to the glenoid fossa, providing significant stability and preventing anterior dislocation.
    • Coracohumeral ligament:
      • Attaches the base of the coracoid process to the greater tubercle of the humerus.
      • Supports the superior part of the joint capsule.
    • Transverse humeral ligament:
      • Extends between the two tubercles of the humerus.
      • Holds the tendon of the long head of the biceps in the intertubercular sulcus (bicipital groove).
    • Coracoclavicular ligament:
      • Composed of the trapezoi and conoid ligaments.
      • Connects the clavicle to the coracoid process of the scapula.
      • Works with the acromioclavicular ligament to keep the scapula attached to the clavicle.
    • Coracoacromial ligament:
      • Extends between the acromion and coracoid process of the scapula, forming the coraco-acromial arch.
      • Overlies the shoulder joint, providing some protection.

    Movements in the Sagittal Plane

    • Extension (backward):
      • Produced by the posterior deltoid, latissimus dorsi, and teres major muscles.
    • Flexion (forward):
      • Produced by the anterior deltoid, pectoralis major, and coracobrachialis muscles.

    Shoulder Joint (Glenohumeral Joint)

    • Ball and socket joint: Allows for a wide range of motion.
    • Articulating surfaces:
      • The head of the humerus articulates with the glenoid cavity of the scapula.
      • Covered in hyaline cartilage for smooth movement.
      • The humeral head is larger than the glenoid cavity, increasing instability.
    • Glenoid labrum:
      • A fibrocartilaginous rim that deepens the glenoid cavity and reduces instability.
    • Joint capsule:
      • A fibrous sheath enclosing the joint structures.
      • Extends from the anatomical neck of the humerus to the border of the glenoid fossa.
      • Relatively lax, allowing for greater mobility, especially abduction.
    • Synovial membrane:
      • Lines the inner surface of the joint capsule.
      • Produces synovial fluid, which lubricates the joint.

    Bursae of the Shoulder Joint

    • Subacromial bursa:
      • Located beneath the deltoid and acromion, superior to the supraspinatus tendon and joint capsule.
      • Facilitates smooth movement by minimizing friction between the deltoid, supraspinatus tendon, and joint capsule.
    • Subscapular bursa:
      • Lies between the subscapularis tendon and the scapula.
      • Reduces wear and tear on the subscapularis tendon during shoulder movement.
    • Other bursae:
      • Subcoracoid, coracoclavicular, and supra-acromial bursae.

    Ligaments in Shoulder Joint Stability

    • Ligaments:
      • The ligaments are thickenings of the joint capsule.
      • They play a critical role in stabilizing the bony structures of the shoulder joint.

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    The Shoulder Joint (Glenohumeral Joint) - 2023 PDF

    Description

    This quiz covers the various movements of the shoulder joint, including abduction, adduction, medial and lateral rotation, as well as the factors contributing to the joint's mobility and stability. Test your knowledge on the muscles involved and their functions. Perfect for students of anatomy and kinesiology.

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