L7: Musculo-neuro-vascular systems of arm and glenohumeral joint Flashcards
scapulohumeral (shoulder) muscles
Rotator cuff:
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
Deltoid
teres major
Rotator cuff
Supraspinatus
Infraspinatus
Teres Minor
Subscapularis
Together, their tendons form a sheath as they insert onto the proximal humerus (greater and lesser tubercles)
Active stabilisers of the glenohumeral joint
supraspinatus; origin + insertion
origin: supraspinous fossa of scapula
insertion: greater tubercle of humerus ( superior facet)
Supraspinatus; innervation + actions
innervation: suprascapular nerve [C5,6] from superior trunk
actions: abducts arm 0-15, assists deltoid with abduction from 15-90
rotator cuff tear [especially supraspinatus] common in:
overhead athletes
Infraspinatus; origin + insertion
origin: infraspinous fossa of scapula
insertion: greater tubercle of humerus (middel facet)
Infraspinatus; innervation + actions
innervation: suprascapular nerve [C5,6] from superior trunk
actions: externally rotates arm at GH joint
suprascapular nerve
Origin: C5, C6
Course:
*Arises from superior trunk of brachial plexus
*Passes inferiorly through the scapular notch into the supraspinous fossa innervates supraspinatus
*Curves around the spine of the scapula entering the Infraspinous fossa > innervates infraspinatus
Structures innervated:
*Supraspinatus
*Infraspinatus
*Glenohumeral joint
Teres minor; origin + insertion
origin: infraspinatus fossa (inferior to infraspinatus)
insertion: greater tubercle of humerus (inferior facet)
Teres minor; innervation + actions
innervation: axillary nerve C5
actions: external rotation of humerus at GH joint, adduction of the GH joint
axillary nerve
Origin: Terminal branch of posterior cord (C5, C6)
Course:
*Passes laterally through quadrangular space reaching the posterior of the surgical neck
*Quadrangular Space Borders:
*Teres Minor
*Surgical Neck (Humerus) *Teres Major
*Long head of triceps
Structures innervated:
*Glenohumeral joint
*Teres minor
*Deltoid muscles
*Skin of superolateral arm
Subscapularis; origin + insertion
origin: subscapular fossa of scapula
insertion: lesser tubercle of humerus (anterior)
Subscapularis; innervation + actions
innervation: upper and lower subscapular nerves from posterior cord (C5,C6)
actions: internal rotation of humerus at GH joint, stabilises GH joint
Subscapularis tear results in:
weak internal rotation of the humerus
subscapular nerve
Origin: Posterior cord
Upper: C5
Lower: C6
Course:
*Upper: passes posteriorly to enter subscapularis directly
*Lower: Passes inferolaterally, deep to subscapular artery and vein
Structures innervated:
*Subscapularis (Upper and Lower)
*Teres major (Lower)
rotator cuff tears
Tears of one or more rotator cuff tendons
Supraspinatus most frequently injured
Acute (sudden, powerful movement) tear
Chronic (tendon rubs against bone) tearing
MRI of joint might show tendon tear
Operative/non-operative treatment
deltoid; origin + insertion
overlies rotator cuff
origin: lateral 1/3 clavicle, acromion, lateral 1/3 spine of scapula
insertion: deltoid tuberosity on humerus
deltoid; innervation + action
innervation: axillary nerve [C5,C6]
actions on GH joint: anterior fibres; flexion, middle fibres; abduction, posterior fibres; extension
Teres major; origin + insertion
origin: inferior 1/3 of lateral border of scapula
insertion: medial lip of bicipital groove (intertubercular sulcus)
Teres major; innervation + actions
innervation: lower subscapular nerve [C5,C6]
actions on GH joint: internal rotation, adduction, extension