Upper Limb Muscles


Upper Limb Muscles

      • Muscles of the Pectoral Region and Axilla


      • Pectoralis major
        • Origin
          • Medial half of clavicle
          • manubrium and body of sternum
          • upper sixcostal cartilages
        • Insertion
          • Lateral lip of inter- tubercular groove of humerus
        • Nerve
          • Lateral and medial pectoral
        • Action
          • Flexes, adducts, and medially rotates arm
      • Pectoralis minor
          • Origin
        • Third, fourth, and fifth ribs
          • Insertion
        • Coracoid process of scapula
          • Nerve
        • Medial (and lateral) pectoral
          • Action
        • Depresses scapula; elevates ribs
      • Serratus anterior (MCQ)
        • Origin -Upper eight ribs
        • Insertion–  Medial border of scapula
        • Nerve – Long thoracic
        • Action –Rotates scapula upward; abducts scapula with arm and elevates it above the horizontal

Muscles of the Shoulder


      1. Deltoid
        1. Origin :Lateral third of clavicle, acromion, and spine of scapula
        2. Insertion :Deltoid tuberosity of humerus
        3. Nerve :Axillary
        4. Action :Abducts, adducts, flexes, extends, and rotates arm medially and laterally
      2. Teres major
        1. Origin : Dorsal surface of inferior angle of scapula
        2. Insertion : Medial lip of intertuber- cular groove of humerus
        3. Nerve : Lower subscapular
        4. Action :Adducts and rotates arm medially
      3. Teres minor
        1. Origin Upper portion of lateral border of scapula
        2. Insertion : Lower facet of greater tubercle of humerus
        3. Nerve :Axillary
        4. Action : Rotates arm laterally

  Muscles of the Arm


      1. Coracobrachialis
        1. Origin –Coracoid process
        2. Insertion –Middle third of medial surface of humerus
        3. Nerve  –Musculocutaneous(MCQ)
        4. Action – Flexes and adducts arm
      2. Biceps brachii
        1. Origin Long head, supraglenoid tubercle; short head, coracoid process
        2. Insertion –Radial tuberosity of radius
        3. Nerve  –Musculocutaneous(MCQ)
        4. Action – Flexes arm and forearm, supinates forearm(MCQ)

 Muscles of the Anterior Forearm


      • Pronator teres
        • O: Medial epicondyle and coronoid process of ulna
        • I: Middle of lateral side of radius
        • N: Median
        • A: Pronates and flexes forearm
      • Flexor digitorumsuperficialis
        • O: Medial epicondyle, coronoid process, oblique line of radius
        • I: Middle phalanges of finger
        • N: Median
        • A: Flexes proximal interphalangeal joints, flexes hand and forearm(MCQ)
      • Flexor digitorumprofundus
        • O:Anteromedial surface of ulna, interosseousmem- brane
        • I:Bases of distal phalanges of fingers
        • N:Ulnar and median
        • A:Flexesdistal interphalangeal joints and hand (MCQ)

 Muscles of the Posterior Forearm


      • Brachioradialis
        • O:Lateral supracondylar ridge of humerus
        • I: Base of radial styloid process
        • N: Radial
        • A: Flexes forearm
      • Supinator
        • O: Lateral epicondyle, radial collateral and annular ligaments, supinator fossa and crest of ulna
        • I: Lateral side of upper part of radius
        • N: Radial
        • A: Supinates forearm
      • Abductor pollicislongus
        • O: Interosseous membrane, middle third of posterior surfaces of radius and ulna
        • I: Lateral surface of base of first metacarpal
        • N: Radial
        • A: Abducts thumb and hand
      • Extensor pollicislongus
        • O:Interosseous membrane and middle third of posterior surface of ulna
        • I:Base of distal phalanx of thumb
        • N: Radial
        • A: Extends distal phalanx of thumb and abducts hand
      • Extensor pollicisbrevis
        • O:Interosseous membrane and posterior surface of middle third of radius
        • I:Base of proximal phalanx of thumb
        • N:Radial
        • A: Extends proximal phalanx of thumb and abducts hand

Muscles of the Hand (High yield topic in MD Entrance)


      1. Abductor pollicisbrevis
        1. O: Flexor retinaculum, scaphoid, and trapezium
        2. I: Lateral side of base of proximal phalanx of thumb
        3. N: Median
        4. A: Abducts thumb
      2. Adductor pollicis
        1. O: Capitate and bases of second and third metacarpals (oblique head); palmar sur- face of third metacarpal (transverse head)
        2. I: Medial side of base of proximal phalanx of the thumb
        3. N: Ulnar (MCQ)
        4. A: Adducts thumb
      3. Flexor pollicisbrevis
        1. O: Flexor retinaculum and trapezium
        2. I; Base of proximal phalanx of thumb
        3. N: Median
        4. A: Flexes thumb
      4. Opponenspollicis
        1. O; Flexor retinaculum and trapezium
        2. I: Lateral side of first metacarpal
        3. N: Median
        4. A: Opposes thumb to other digits
      5. Lumbricals (4)
        1. O;Lateral side of tendons of flexor digitorumprofundus
        2. I; Lateral side of extensor expansion
        3. N; Median (two lateral) and ulnar (two medial)
        4. A: Flex metacarpophalangeal joints and extend interphalangeal joints
      6. Dorsal interossei (4)(bipennate)
        1. O: Adjacent sides of metacarpal bones
        2. I: Lateral sides of bases of proximal phalanges; extensor expansion
        3. N: Ulnar
        4. A: Abduct fingers; flex metacarpophalangeal joints; extend inter- phalangeal joints
      7. Palmar interossei (3) (unipennate)
        1. O: Medial side of second metacarpal; lateral sides of fourth and fifth metacarpals
        2. I: Bases of proximal phalanges in same sides as their origins; extensor expansion
        3. N: Ulnar
        4. A: Adduct fingers; flex metacarpophalangeal joints; extend interphalangeal joints

Summary of muscle actions of the upper limb (High yield Topic for MD Entrance)

      1. Movement of the Scapula
        1. Elevation—trapezius (upper part), levator scapulae
        2. Depression—trapezius (lower part), serratus anterior, pectoralis minor
        3. Protrusion (forward or lateral movement; abduction)—serratus anterior
        4. Retraction (backward or medial movement; adduction)—trapezius, rhomboids
        5. Anterior or inferior rotation of the glenoid fossa—rhomboid major
        6. Posterior or superior rotation of the glenoid fossa—serratus anterior, trapezius
      2. Movement at the Shoulder Joint (Ball-and-Socket Joint) (MCQ)
        1. Adduction—pectoralis major, latissimusdorsi, deltoid (posterior part)
        2. Abduction—deltoid, supraspinatus
        3. Flexion—pectoralis major (clavicular part), deltoid (anterior part), coracobrachialis, biceps
        4. Extension—latissimusdorsi, deltoid (posterior part)
        5. Medial rotation—subscapularis, pectoralis major, deltoid (anterior part), latissimusdorsi,teres major
        6. Lateral rotation—infraspinatus, teres minor, deltoid (posterior part)
      3. Movement at the Elbow Joint (Hinge Joint) (MCQ)
        1. Flexion—brachialis, biceps, brachioradialis, pronator teres
        2. Extension—triceps, anconeus
      4. Movement at the Radioulnar Joints (Pivot Joints) (MCQ)
        1. Pronation—pronator quadratus, pronator teres
        2. Supination—supinator, biceps brachii (MCQ)
      5. Movement at the Wrist (Radiocarpal) Joint (Condylar or Ellipsoidal Joint) (MCQ)
        1. Adduction—flexor carpi ulnaris, extensor carpi ulnaris
        2. Abduction—flexor carpi radialis, extensor carpi radialislongus and brevis
        3. Flexion—flexor carpi radialis, flexor carpi ulnaris, palmarislongus, abductor pollicislongus
        4. Extension—extensor carpi radialislongus and brevis, extensor carpi ulnaris
      6. Movement at the Metacarpophalangeal Joint (Condyloid Joint) (MCQ)
        1. Adduction—palmar interossei(MCQ)
        2. Abduction—dorsal interossei(MCQ)
        3. Flexion—lumbricals and interossei(MCQ)
        4. Extension—extensor digitorum(MCQ)
      7. Movement at the Interphalangeal Joint (Hinge Joint)
        1. Flexion—
          1. flexordigitorumsuperficialis (proximal interphalangeal joint)(MCQ)
          2. flexordigitorumprofundus (distal interphalangeal joint)(MCQ)
        2. Extension—
          1. lumbricals and interossei (when metacarpophalangeal joint is extended by extensor digitorum)(MCQ)
        3. Extension—
          1. extensordigitorum (when metacarpophalangeal joint is flexed by lumbricals and interossei)(MCQ)

Summary of muscle innervations of the upper limb(High yield Topic for MD Entrance)

      1. Muscles of the Anterior Compartment of the Arm: Musculocutaneous Nerve
        1. Biceps brachii(MCQ)
        2. Coracobrachialis(MCQ)
        3. Brachialis
      2. Muscles of the Posterior Compartment of the Arm: Radial Nerve
        1. Triceps
        2. Anconeus
      3. Muscles of the Posterior Compartment of the Forearm: Radial Nerve
        1. Superficial layer
          1. brachioradialis, extensor carpi radialislongus
          2. extensor carpi radialisbrevis, extensor carpi ulnaris
          3. extensordigitorumcommunis, extensor digitiminimi
        2. Deep layer
          1. Supinator(MCQ)
          2. abductorpollicislongus
          3. extensorpollicislongus, extensor pollicisbrevis
          4. extensorindicis
      4. Muscles of the Anterior Compartment of the Forearm: Median Nerve
        1. Superficial layer
          1. pronatorteres
          2. flexor carpi radialis
          3. palmarislongus
          4. flexor carpi ulnaris (ulnar nerve)*
        2. Middle layer
          1. flexordigitorumsuperficialis
        3. Deep layer
          1. flexordigitorumprofundus (median nerve and ulnar nerve),* (MCQ)
          2. flexorpollicislongus
          3. pronatorquadratus
      5. Thenar Muscles: Median Nerve
        1. Abductor pollicisbrevis(MCQ)
        2. Opponenspollicis
        3. Flexor pollicisbrevis (median and ulnar nerves)*(MCQ)
        4. Adductor Pollicis Muscle: Ulnar Nerve (MCQ)
      6. Hypothenar Muscles: Ulnar Nerve(MCQ)
        1. Abductor digitiminimi
        2. Opponensdigitiminimi
        3. Flexor digitiminimi
      7. Interossei (Dorsal and Palmar) Muscles: Ulnar Nerve(MCQ)
      8. Lumbrical Muscles (Medial Two): Ulnar Nerve (MCQ)
      9. Lumbrical Muscles (Lateral Two): Median Nerve(MCQ)

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