Shoulder Anatomy

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  1. Acromioclavicular Separation Grades
    • I: AC ligament sprain
    • II: AC tear, CC intact
    • III: AC & CC ligament tears </= 100% superior displacement
    • IV: Grade III with posterior displacement
    • V: Grade III with </= 300% superior displacement
    • VI: Grade III with inferior displacement
  2. Shoulder Joint: General
    • Shoulder made up of 4 separate articulations (SC joint, GH joint, AC joint, scapulothoracic articulation) 
    • Static stabilizers = glenoid, labrum, articular congruity, GH ligaments & capsule, negative intraarticular pressure
    • Dynamic stabilizers = RC muscles/tendons, biceps tendon, scapular stabilizers (periscapular muscles), proprioception
  3. SC Joint
    • Diarthrodial/double gliding joint
    • Clavicle rotates in joint up to 50 degrees on fixed sternum
    • Sternoclavicular ligament: primary stabilizer of SC joint; posterior stronger, anterior dislocation more common
    • Costoclavicular ligament: strongest SC ligament
    • Interclavicular ligament: secondary stabilizer
  4. Scapulothoracic Articulation
    • (not an actual joint)
    • Scapula slides/rotates along posterior ribs 2-7
    • 2:1 ratio of GHJ to scapulothoracic motion during flexion and abduction
  5. Glenohumeral Joint
    • Ball & socket joint
    • GH Ligaments: thickenings of anterior and inferior capsule that provide stability to jt (there are no ligaments posteriorly or superiorly) 
    • Superior GHL: resists inferior translation & ER in shoulder adduction, resists posterior translation in 90 deg of forward flexion
    • Middle GHL: resists anteroposterior translation in 45 deg of abduction, secondary restraint to translation & ER in adduction
    • Inferior GHL: most important ligament, forms sling that tightens in and & ER (ant band)/IR (post band)
  6. Inferior Glenohumeral Ligament
    • Anterior Band: resists anterior & inferior translation in abduction & ER
    • Posterior Band: resists posterior translation in IR & 90 deg flex
  7. Coracohumeral Ligament
    With SGHL, resists inferior translation in adduction
  8. Labrum
    • Circumferentially attached to glenoid
    • Fibrocartilage
    • Deepens glenoid
    • Provides more contact area
    • Adds stability
    • Insertion site for some GH ligaments (SGHL
  9. Capsule
    • Surrounds joint
    • Maintains intraarticular negative pressure
    • Thin posteriorly
  10. AC Joint
    • Diarthrodial (plane/gliding) joint
    • Very limited motion (5 deg rotation)
    • AC Ligament: provides ant->post stability and axial stability
    • CC Ligament: provides vertical stability to clavicle at AC joint
  11. Coracromial Ligament
    • Key component of coracromial arch
    • Prevents humerus migration in rotator cuff-deficient shoulder
  12. Superior Transverse Scapular Ligament
    • Suprascapular nerve travels under ligament
    • Suprascapular artery crosses over it
  13. Transverse Humeral Ligament
    Stabilizes biceps tendon within bicipital groove
  14. Neurovascular: Sensory
    • Supraclavicular Nerve (C4): superior shoulder/clavicular area 
    • Axillary Nerve (C5): lateral shoulder
    • T2 Segmental Nerve: axilla

    *Deficits indicate corresponding nerve/root lesion
  15. Neurovascular: Motor
    • Spinal Accessory (CN11): resisted shoulder shrug (trap or corresponding nerve lesion)
    • Suprascapular (C5-6): resisted abd (supraspinatus or nerve/root lesion) and ER (infraspinatus or nerve/root lesion) 
    • Axillary (C5): resisted abd (deltoid or corresponding nerve root/lesion) and ER (teres minor or nerve/root lesion) 
    • Dorsal Scapular Nerve (C5): shoulder shrug (levator scap/rhomboid or corresponding nerve/root lesion)
    • Thoracodorsal Nerve (C7-8): resisted add (lat dorsi or nerve/root lesion)
    • Lateral Pectoral Nerve (C5-7): resisted add (pec major or nerve/root lesion
    • U/L Subscapular Nerve (C5-6): resisted IR (subscap or nerve/root lesion)
    • Long Thoracic Nerve (C5-7): scap protraction/reach (serratus ant or nerve/root lesion)
  16. Triangular Space Borders
    • Teres minor
    • Teres major
    • Triceps (long head)
  17. Triangular Space Structures
    Circumflex scapular artery
  18. Quadrangular Space Borders
    • Teres Minor
    • Teres Major
    • Triceps (long head)
    • Humerus (medial border)
  19. Quadrangular Space Structures
    • Axillary nerve
    • Posterior circumflex artery
    • Humeral artery
  20. Brachial Plexus
    • Derived from ventral rami of C5-T1
    • Subdivisions: rami (roots), trunks, divisions, cords, branches (Rob Taylor Drinks Cold Beer
    • Rami exit between anterior and middle scalene muscles and travel with subclavian artery in axillary sheath
    • Rami & trunks (superior, middle & inferior) are supraclavicular
    • There are 2 nerves from the rami and 2 nerves from the trunks (upper)
    • Divisons (3 ant and 3 post) are under (posterior to) the clavicle
    • Anterior divisions innervate flexors, posterior innervate extensors
    • Cords (lateral, posterior, and medial) & branches (MARMU) are infraclavicular 
    • Cords named for relationship with axillary artery
    • Terminal branches of cords are peripheral nerves to shoulder region & upper extremity
  21. Brachial Plexus: Roots
    • Dorsal Scapular (C3-5): sensory = none, motor = levator scap, rhomboid major & minor
    • Long Thoracic (C5-7): sensory = none, motor = serratus anterior
  22. Brachial Plexus: Upper Trunk
    • Suprascapular (C5-C6): sensory = shoulder jt capsule, motor = supraspinatus and infraspinatus
    • Nerve to Subclavius (C5-6): sensory = none, motor = subclavius
  23. Brachial Plexus: Lateral Cord
    • Lateral Pectoral (C5-7): sensory = none, motor = pec majro (clavicular portion) and pec minor
    • Lateral root to median nerve
  24. Brachial Plexus: Medial Cord
    • Medial Pectoral (C5-7): sensory = none, motor = pec minor and pec major (sternal portion)
    • Medial root to median nerve
  25. Brachial Plexus: Posterior Cord
    • Upper Subscapular (C5-6): sensory = none, motor = upper subscapularis
    • Thoracodorsal (C6-8): sensory = none, motor = lat dorsi
    • Lower Subscapular (C5-6): sensory = none, motor = lower subscapularis and trees major
    • Axillary (C5-6): sensory = lateral proximal arm via superior lateral cutaneous nerve, motor = deltoid and teres minor
Card Set:
Shoulder Anatomy
2015-02-08 23:19:21
Shoulder Anatomy
I3 Review
Netter's Anatomy: Shouder
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