Shoulder Intrinsic Muscles
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Questions and Answers

Through which gap do the axillary nerve and posterior circumflex humeral artery pass?

  • Triangular space
  • Subscapular space
  • Quadrangular space (correct)
  • Intertubercular groove

    • Which nerve innervates the teres major muscle?

  • Axillary nerve
  • Subscapular nerve
  • Lower subscapular nerve (correct)
  • Suprascapular nerve

    • What is the collective function of the rotator cuff muscles?

  • To adduct the arm
  • To abduct the arm
  • To pull the humeral head into the glenoid fossa (correct)
  • To rotate the arm laterally

    • Which muscle originates from the supraspinous fossa of the scapula?

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

    What is the action of the infraspinatus muscle?

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

    Which muscle attaches to the lesser tubercle of the humerus?

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

    What is the action of the teres major muscle?

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

    What is the primary function of the middle fibres of the deltoid muscle?

    <p>Abducting the arm at the shoulder</p> Signup and view all the answers

    Which of the following muscles is NOT part of the rotator cuff group?

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

    What is the origin of the intrinsic muscles of the shoulder?

    <p>Scapula and/or clavicle</p> Signup and view all the answers

    What is the innervation of the deltoid muscle?

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

    What is the function of the anterior fibres of the deltoid muscle?

    <p>Flexing the arm at the shoulder</p> Signup and view all the answers

    How many muscles are part of the intrinsic muscles of the shoulder?

    <p>6</p> Signup and view all the answers

    What is the attachment of the deltoid muscle?

    <p>Deltoid tuberosity on the lateral surface of the humerus</p> Signup and view all the answers

    What is the primary action of the Teres Minor muscle?

    <p>Laterally rotates the arm</p> Signup and view all the answers

    What is the most common muscle affected in rotator cuff tendonitis?

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

    What is the primary cause of rotator cuff tendonitis?

    <p>Repetitive use of the shoulder joint</p> Signup and view all the answers

    What is the nerve responsible for innervating the Teres Minor muscle?

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

    What is the common site of injury in rotator cuff tendonitis?

    <p>Coraco-acromial arch</p> Signup and view all the answers

    What is the primary treatment for mild cases of rotator cuff tendonitis?

    <p>Rest, analgesia, and physiotherapy</p> Signup and view all the answers

    What is the origin of the Teres Minor muscle?

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

    What is the attachment site of the Teres Minor muscle?

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

    What is the consequence of repetitive use of the shoulder joint in rotator cuff tendonitis?

    <p>Inflammation and degenerative changes in the tendon</p> Signup and view all the answers

    What is the characteristic shape of the shoulder produced by?

    <p>The intrinsic muscles of the shoulder</p> Signup and view all the answers

    What is the function of the posterior fibres of the deltoid muscle?

    <p>Extend the arm at the shoulder</p> Signup and view all the answers

    What is the role of the middle fibres of the deltoid muscle?

    <p>They are the primary abductors of the arm</p> Signup and view all the answers

    Which of the following muscles is NOT part of the intrinsic muscles of the shoulder?

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

    How many degrees of abduction is the arm taken over by the middle fibres of the deltoid muscle?

    <p>15 degrees</p> Signup and view all the answers

    What is the innervation of the deltoid muscle?

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

    What is the attachment site of the deltoid muscle on the humerus?

    <p>Deltoid tuberosity</p> Signup and view all the answers

    Which muscle forms the inferior border of the quadrangular space?

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

    What is the common action of the rotator cuff muscles?

    <p>Pull the humeral head into the glenoid fossa</p> Signup and view all the answers

    Which nerve innervates the Supraspinatus muscle?

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

    What is the action of the Infraspinatus muscle?

    <p>Laterally rotate the arm</p> Signup and view all the answers

    What is the attachment site of the Teres Major muscle?

    <p>Medial lip of the intertubercular groove of the humerus</p> Signup and view all the answers

    Which muscle originates from the infraspinous fossa of the scapula?

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

    What is the action of the Subscapularis muscle?

    <p>Medially rotate the arm</p> Signup and view all the answers

    What is the primary action of the muscle that originates from the posterior surface of the scapula and attaches to the greater tubercle of the humerus?

    <p>Laternally rotates the arm</p> Signup and view all the answers

    What is the common location of inflammation in rotator cuff tendonitis?

    <p>Tendons of the rotator cuff muscles</p> Signup and view all the answers

    What is the role of the supraspinatus muscle in rotator cuff tendonitis?

    <p>It is the most commonly affected muscle</p> Signup and view all the answers

    What is the function of the muscle that is innervated by the upper and lower subscapular nerves?

    <p>Medially rotates the arm</p> Signup and view all the answers

    What is the purpose of steroid injections in the treatment of rotator cuff tendonitis?

    <p>To reduce inflammation</p> Signup and view all the answers

    What is the effect of repetitive use of the shoulder joint on the tendon?

    <p>It causes inflammation and degenerative changes</p> Signup and view all the answers

    What is the significance of the coraco-acromial arch in rotator cuff tendonitis?

    <p>It causes inflammation of the tendon</p> Signup and view all the answers

    What is the purpose of physiotherapy in the treatment of rotator cuff tendonitis?

    <p>To improve joint mobility</p> Signup and view all the answers

    What is the consequence of severe rotator cuff tendonitis?

    <p>Surgery may be required</p> Signup and view all the answers

    What is the primary action of the middle fibres of the deltoid muscle?

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

    What is the common characteristic of the intrinsic muscles of the shoulder?

    <p>They originate from the scapula and/or clavicle and attach to the humerus</p> Signup and view all the answers

    What is the shape of the deltoid muscle?

    <p>Greek letter delta - Δ</p> Signup and view all the answers

    How many muscles are part of the intrinsic muscles of the shoulder?

    <p>6</p> Signup and view all the answers

    What is the function of the anterior fibres of the deltoid muscle?

    <p>Flexion of the arm at the shoulder</p> Signup and view all the answers

    What is the attachment site of the deltoid muscle on the humerus?

    <p>Deltoid tuberosity</p> Signup and view all the answers

    What is the nerve that innervates the deltoid muscle?

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

    What is the primary function of the Teres Major muscle?

    <p>Adducts at the shoulder and medially rotates the arm</p> Signup and view all the answers

    What is the collective function of the Rotator Cuff muscles?

    <p>Adds stability to the glenohumeral joint</p> Signup and view all the answers

    Which muscle attaches to the medial lip of the intertubercular groove of the humerus?

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

    What is the innervation of the Infraspinatus muscle?

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

    What is the action of the Supraspinatus muscle?

    <p>Abducts the arm 0-15o</p> Signup and view all the answers

    Which muscle originates from the posterior surface of the inferior angle of the scapula?

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

    What is the common function of the Rotator Cuff muscles, in addition to their individual actions?

    <p>Pulls the humeral head into the glenoid fossa</p> Signup and view all the answers

    Which muscle is most commonly affected in rotator cuff tendonitis?

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

    What is the primary treatment for mild cases of rotator cuff tendonitis?

    <p>Rest, analgesia, and physiotherapy</p> Signup and view all the answers

    What is the role of physiotherapy in the treatment of rotator cuff tendonitis?

    <p>To strengthen surrounding muscles</p> Signup and view all the answers

    What is the consequence of repetitive use of the shoulder joint?

    <p>Inflammation of the tendons</p> Signup and view all the answers

    What is the function of the Teres Minor muscle?

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

    What is the nerve responsible for innervating the Teres Minor muscle?

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

    What is the consequence of severe rotator cuff tendonitis?

    <p>Surgery is required</p> Signup and view all the answers

    What is the common location of inflammation in rotator cuff tendonitis?

    <p>Tendons of the rotator cuff muscles</p> Signup and view all the answers

    What is the primary cause of rotator cuff tendonitis?

    <p>Repetitive use of the shoulder joint</p> Signup and view all the answers

    Study Notes

    The Shoulder Muscles

    • The shoulder muscles are associated with movements of the upper limb and produce the characteristic shape of the shoulder.
    • They can be divided into two groups: Extrinsic (originate from the torso and attach to the bones of the shoulder) and Intrinsic (originate from the scapula and/or clavicle and attach to the humerus).

    Intrinsic Muscles

    • The intrinsic muscles (also known as the scapulohumeral group) originate from the scapula and/or clavicle and attach to the humerus.
    • There are six muscles in this group: deltoid, teres major, and the four rotator cuff muscles (supraspinatus, infraspinatus, subscapularis, and teres minor).

    Deltoid Muscle

    • The deltoid muscle is shaped like the Greek letter delta (Δ) and can be divided into an anterior, middle, and posterior part.
    • Attachments: Originates from the scapula and clavicle, and attaches to the deltoid tuberosity on the lateral surface of the humerus.
    • Innervation: Axillary nerve.
    • Actions: The anterior fibers flex the arm at the shoulder, the posterior fibers extend the arm at the shoulder, and the middle fibers are the major abductor of the arm.

    Teres Major Muscle

    • The teres major forms the inferior border of the quadrangular space, which is the 'gap' that the axillary nerve and posterior circumflex humeral artery pass through to reach the posterior scapula region.
    • Attachments: Originates from the posterior surface of the inferior angle of the scapula, and attaches to the medial lip of the intertubercular groove of the humerus.
    • Innervation: Lower subscapular nerve.
    • Actions: Adducts at the shoulder and medially rotates the arm.

    Rotator Cuff Muscles

    • The rotator cuff muscles are a group of four muscles that originate from the scapula and attach to the humeral head.
    • Collectively, the resting tone of these muscles acts to 'pull' the humeral head into the glenoid fossa, giving the glenohumeral joint additional stability.
    • Each muscle has its own individual actions:
      • Supraspinatus: Abducts the arm 0-15° and assists deltoid for 15-90°.
      • Infraspinatus: Laterally rotates the arm.
      • Subscapularis: Medially rotates the arm.
      • Teres minor: Laterally rotates the arm.

    Clinical Relevance: Rotator Cuff Tendonitis

    • Rotator cuff tendonitis refers to inflammation of the tendons of the rotator cuff muscles.
    • This usually occurs secondary to repetitive use of the shoulder joint.
    • The muscle most commonly affected is the supraspinatus.
    • Treatment involves rest, analgesia, and physiotherapy, and in more severe cases, steroid injections and surgery can be considered.

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    Shoulder Muscles Anatomy PDF

    Description

    Learn about the intrinsic muscles of the shoulder, their origins and attachments, and how they produce the characteristic shape of the shoulder. Understand the difference between intrinsic and extrinsic muscles of the shoulder.

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