Posterior Shoulder Flashcards
_____ a common site of humeral fractures
Surgical neck
Lesser tubercle projects anteriorly/posteriorly
anteriorly
Greater tubercle projects laterally/anteriorly
laterally
As one abducts and adducts the humerus- note how the scapula slides along the thoracic wall
This scapular motion occurs at the conceptual ____
Abduction of the arm above the head requires lateral/medial rotation of the scapula
“scapulothoracic joint”; lateral
Action of the serratus anterior
Action: Stabilizes the scapula, laterally rotates the scapula, and protracts the scapula (Boxer’s Muscle)
nerve of the serratus anterior
nInnervated by long thoracic nerve (C5, C6 & C7)
Long thoracic nerve trauma (i.e. surgical procedures [mastectomy] or traumatic knife wound) can render the serratus anterior paralyzed (Step1)
Condition known as “winged scapula”
Unable to clamp or stabilize scapula against thoracic wall
Reduced ability to abduct arm above head because scapula cannot be sufficiently laterally rotated
nLevator scapula- true to its name…
is a “levator” or elevator (“lifter”) of the scapula
Rhomboids _____ the scapula medially/laterally
retract; medially…toward the spine
leavtor scapula and Rhomboids are innervated by
All these muscles innervated by the dorsal scapular nerve (C5) (minor contribution from C4)
Scapulohumeral Muscles
- Deltoid
- Teres Major
- Supraspinatus
- Infraspinatus
- Subscapularis (not shown here)
- Teres Minor
nPrincipal abductor of the arm (supraspinatus muscle initiates the 1st 15° of abduction)
Deltoid
deltoid is innervated by
nInnervated by Axillary nerve (C5 & C6)
_____can be injured in surgical neck fractures of humerus and can result in
Axillary nerve can be injured in surgical neck fractures of humerus
Result in atrophy of deltoid (loss of shoulder contour)
Inability to abduct the arm
Loss of sensation lateral aspect of shoulder
teres major is innervated by
Innervated by the lower subscapular nerve (C5 & C6)
teres major function
Adducts, extends, and medially (internally) rotates the arm
The tendons of the 4 muscles of the rotator cuff insert onto and reinforce the shoulder joint capsule – forming a strong _____
musculotendinous rotator cuff
Supraspinatus Muscle- arises from supraspinous fossa and inserts into the greater tubercle- initiates ______ of arm (~first 15о)
abduction
Infraspinatus Muscle- arises from infraspinous fossa and inserts into the greater tubercle- laterally/medially rotatesthe arm
laterally (externally)
Supraspinatus Muscle- arises from supraspinous fossa and inserts into the greater tubercle- initiates ______ of arm (~first 15о)
abduction
nBoth spinatus muscles are innervated by the
suprascapular nerve (C5 & C6)
Teres Minor- arises from lateral border of scapula and inserts into the greater tubercle- laterally rotates the arm, innervated by _____
axillary nerve
Subscapularis Muscle is innervated by
Innervated by the upper & lower subscapular nerves
(C5 & C6)
nDeltoid and supraspinatus muscles are separated from the acromion of the scapula by the ______ and ______
subacromial and subdeltoid bursae
the subacromial and subdeltoid bursa- synovial fluid-filled sacks helps reduce friction between the muscles/bone and allows the supraspinatus tendon to glide smoothly beneath the acromion (within the small subacromial space) during shoulder movements
Collectively…these two bursae are often referred to as the ____
Subacromial bursa