Posterior Shoulder - Muscles and Bones Flashcards Preview

Anatomy > Posterior Shoulder - Muscles and Bones > Flashcards

Flashcards in Posterior Shoulder - Muscles and Bones Deck (30):
1

Scapula

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Attachment sites for rotator cuff muscles 

Greater & Lesser tubercles

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Humerus 

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Shoulder movements 

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Scapula movements 

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scapular sliding along thoracic wall occurs along...

scapulothoracic joint (hypothetical joint)

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abduction of humerus above head cuases...

lateral rotation of scaupla

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Serratus Anterior Muscle

Origin: lateral parts of ribs 1-8

Insertion: anterior surface of medial border of scapula

Function: Stabilizes scapular, laterally rotates scapula, protracts scapula

Innervation: Long thoracic nerve (C5-C7)

 

 

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Winged Scaupla

  • Long thoracic nerve trauma
  • unable to clamp/stabilize scaupla against thoracic wall
  • unable to abduct arm above head b/c glenoid cavity cannot be laterally rotated

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General groups of shoulder muscles

  1. Superficial posterior shoulder muscles
  2. Deep posterior shoulder muscles
  3. Scapulohumeral muscles

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Superficial posterior shoulder muscles (Extrinsic shoulder muscles)

  1. Trapezius
  2. Latissimus

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Deep Posterior Shoulder Muscles

  1. Levator scapula
  2. Rhomboids (major/minor)

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Levator Scapula

Function: elevates, rotates scapula; tilts glenoid cavity inferiorly 

Innervation: dorsal scapular nerve (C5)

 

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Rhomboids (major and minor)

Function: retract and rotate scapula; tilt glenoid cavity inferiorly

Innervation: dorsal scapular nerve (C5)

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Scapulohumeral muscles

  1. Deltoid
  2. Teres Major
  3. Supraspinatus
  4. Infraspinatus
  5. Subscapularis
  6. Teres Minor

 

  • All muscles pass from scapula to humerus and act on shoulder joint
  • stabilize humerus head in glenoid cavity
     

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Deltoid

Origin: Clavicle, acromion, spine of scapula

Insertion: deltoid tuberosity of humerus

Function: principal abductor of arm

Innervation: Axillary nerve (C5-C6)

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Teres Major

Origin: Scapula

Insertion: intertubercular groove (bicipital groove) of humerus

Function: adducts and medially rotates arm

Innervation: lower subscapular nerve (C5-C6)

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Muscles of Rotator Cuff

  1. Supraspinatus
  2. Infraspinatus
  3. Teres minor
  4. Subscapularis 
  • Insertion: musculotendinous rotator cuff
  • Function: protect shoulder joint; stabilize humeral head 
  • Mnemonic: SITS

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Supraspinatus Muscle

Origin: supraspinous fossa

Insertion: superios facet of greater tubercule

Function: arm abduction

Innervation: suprascauplar nerve (C5&C6)

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Infraspinatus Muslce

Origin: Infraspinous fossa

Insertion: middle facet of greater tubercle

Function: Lateral rotation of arm

Innervation:  suprascauplar nerve (C5&C6)

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Teres Minor

Origin: Lateral border of scaupla

Insertion: inferior facet of greater tubercle

Function: Laterally rotates arm

Innervation: Axillary nerve 

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Subscapularis

Origin: Subscapular fossa

Insertion: Leser tubercle

Function: Medially rotates and adducts arm

Innervation: Upper and lower subscapular nerves (C5 & C6)

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Subacromial Bursae (subacromial and subdeltoid bursae)

  • synovial fluid filled sacs that helps reduce friction btwn muscles/bone during shoulder movements 

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Gateways to Posterior Scapular Region

  1. Suprascapular notch/foramen
  2. Quadrangular space
  3. Trigangular Space
  4. Triangular interval
  • These allow neurovascular structures to move between anterior and posterior scapular/arm regions

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Suprascapular Notch

  • located on superior border of scapula
  • superior transverse scapular ligament spans the roof of this forming a foramen
  • Suprascapular nerve passes through foramen and innervates infraspinatus muscles 
  • Subscapular artery passes over this ligament
  • ligament can ossify and compress scauplar nerve --> shoulder pain
     

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Quadrangular Space

  • Bounded by
    • Teres Major
    • Teres Minor
    • Long head of triceps
    • Surgical neck of humerus
  • Contains Axillary nerve and Posterior circumflex humeral artery

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Triangular Space

  • Bounded by
    • Teres Major
    • Teres Minor
    • Long head of triceps
  • Contains circumflex scapular artery (branch of subscauplar artery)

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Dermatome

  • Representations of which spinal nerve root innervates which region of skin
  • tell you which level dorsal root accepts sensory information from a particular part of body
  • cell bodies of these sensory neurons reside in dorsal root ganglion

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Shingles

  • Herpes zoster is virus that makes chicken pox in children
  • in some patients remains dormant in dorsal root ganglion 
  • can become active, travel along nerve fibers to dermatome supplied by that nerve
  • rash erupts --> painful shingles

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Important Dermatomes to Remember