Shoulder Part 1
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Questions and Answers

Which joint is characterized as a synovial saddle joint in the shoulder complex?

  • Acromioclavicular joint
  • Glenohumeral joint
  • Coracoacromial joint
  • Sternoclavicular joint (correct)

    • Which ligament is considered the main stabilizing factor in the sternoclavicular joint?

  • Coraco-acromial ligament
  • Trapezoid ligament
  • Conoid ligament
  • Costo-clavicular ligament (correct)

    • What type of joint is the acromioclavicular joint classified as?

  • Synovial hinge joint
  • Synovial ball-and-socket joint
  • Fibrous joint
  • Synovial plane joint (correct)

    • Which of the following muscles is primarily responsible for movements of the scapula?

    <p>Serratus anterior</p> Signup and view all the answers

    Which anatomical feature is not a part of the shoulder girdle?

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

    Which region connects the upper limb to the thoracic wall?

    <p>Pectoral region</p> Signup and view all the answers

    The articulation between which structures forms the glenohumeral joint?

    <p>Humerus and scapula</p> Signup and view all the answers

    Which muscle group is primarily responsible for the elevation of the shoulder girdle?

    <p>Trapezius muscles</p> Signup and view all the answers

    What is the primary function of the upper fibers of the trapezius muscle?

    <p>Elevate the scapula</p> Signup and view all the answers

    Which muscles work together to rotate the scapula so that the glenoid cavity faces downward?

    <p>Levator scapulae and Rhomboids</p> Signup and view all the answers

    What is one of the primary actions of the pectoralis major muscle?

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

    What movement is primarily caused by the middle fibers of the trapezius?

    <p>Retraction of the scapula</p> Signup and view all the answers

    Injury to which nerve commonly results in paralysis of the trapezius muscle?

    <p>Accessory nerve</p> Signup and view all the answers

    Which muscle primarily assists in the protraction of the shoulder?

    <p>Serratus anterior</p> Signup and view all the answers

    What action does the latissimus dorsi perform for movement?

    <p>Adduction and medial rotation of the arm</p> Signup and view all the answers

    What is the consequence of injury to the nerve of serratus anterior?

    <p>Winging of the scapula</p> Signup and view all the answers

    Which of the following muscles is responsible for initiating arm abduction from 0 to 15 degrees?

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

    Which muscle is primarily responsible for the protraction of the scapula?

    <p>Serratus anterior</p> Signup and view all the answers

    Which muscle assists with elevation of the scapula alongside the upper fibers of the trapezius?

    <p>Levator scapulae</p> Signup and view all the answers

    What action does pectoralis minor perform when the scapula is fixed?

    <p>Pulls the ribs during inspiration</p> Signup and view all the answers

    What is one of the actions of the rhomboids?

    <p>Retract the scapula</p> Signup and view all the answers

    Which muscle acts to fix the medial border of the scapula to the chest wall?

    <p>Serratus Anterior</p> Signup and view all the answers

    What is the primary action of the infraspinatus muscle?

    <p>Rotates the arm laterally</p> Signup and view all the answers

    Which of the following muscles is deep to the pectoralis major?

    <p>Subclavius muscle</p> Signup and view all the answers

    Study Notes

    Shoulder Joint

    • The shoulder girdle connects the upper limb to the vertebral column.
    • Major back muscles involved:
      • Trapezius
      • Latissimus dorsi

    Muscles of the Back

    Superficial Layer

    • Trapezius:

      • Upper fibers: Elevate scapula
      • Middle fibers: Retract scapula
      • Lower fibers: Depress scapula
      • Functions in rotary motion of scapula during arm elevation.
      • Injury to the accessory nerve can result in shoulder drop and limited arm movement.

    • Latissimus dorsi:

      • Functions in adduction, extension, and medial rotation of the arm.
      • Assists in trunk elevation during climbing, swimming, and rowing.

    Second Layer

    • Levator Scapulae:

      • Elevates scapula alongside upper trapezius fibers.

    • Rhomboids (Minor and Major):

      • Actions include retraction of the scapula and maintaining shoulder stability.
      • Both contribute to downward rotation of the scapula.

    Movements of the Shoulder Girdle

    • Elevation & Depression: Muscles include trapezius and serratus anterior.
    • Upward & Downward Rotation of Glenoid Cavity: Involves trapezius and serratus anterior.
    • Protraction & Retraction of Scapula: Muscles include pectoralis minor and rhomboids.

    Pectoral Region

    • Muscles:

      • Connect upper limb to thoracic wall.
      • Includes pectoralis major, pectoralis minor, subclavius, and clavipectoral fascia.

    • Pectoralis Major:

      • Actions: Adduction, flexion, medial rotation of the arm; aids in climbing and rowing.

    • Pectoralis Minor:

      • Actions: Protracts and depresses the shoulder; assists in forced inspiration.

    • Serratus Anterior:

      • Originates from upper ribs; major role in scapular protraction and rotation.
      • Fixes scapula to thoracic wall; assists in respiration.

    Shoulder (Scapular) Region

    • Comprises six muscles connecting the scapula with the humerus:

      • Deltoid, Supraspinatus, Infraspinatus, Teres Minor, Teres Major, Subscapularis.

    • Deltoid:

      • Actions: Flexes, extends, medially and laterally rotates, and abducts the arm (15° to 90°).

    • Supraspinatus:

      • Initiates arm abduction (0° to 15°) and stabilizes shoulder joint.

    • Infraspinatus:

      • Laterally rotates arm and provides stability to the shoulder joint.

    Shoulder Skeleton

    • Key bones: Scapula, Humerus, Clavicle.
    • Movement facilitated by:
      • Sternoclavicular and Acromioclavicular joints.

    Shoulder Joints and Ligaments

    • Sternoclavicular Joint:

      • Synovial saddle joint; connects sternum, clavicle, and first costal cartilage.
      • Important ligaments include:
        • Anterior and posterior interclavicular ligaments
        • Sternoclavicular ligament
        • Costo-clavicular ligament, which stabilizes the joint.

    • Acromioclavicular Joint:

      • Synovial plane joint; unites acromion of scapula with clavicle.
      • Stabilized by coracoclavicular ligament components (trapezoid and conoid parts) and coracoacromial ligament.

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