MSK!! Flashcards
deltoid
abduction (after initiated by supraspinatus), axillary n.
supraspinatus
initiates abduction of humerus
N: suprascapular n.
most common cause of intrinsic shoulder pain!
source of pain
- Originates on superior aspect of scapula
- Inserts on greater tubercle of humerus
- Passes through narrow area between acromion and head of humerus
suceptible to repetitive motion: baseball, house painters, UPS — often pinched by abduction
- only protected by the subacromail (sub-deltoid bursa)
infraspinatus
lateral rotation of humerus, suprascapular n.
teres minor
lateral rotation of humerus, axillary n.
teres major
medial rotation of humerus, lower subscapular n.
subscapularis
medial rotation of humerus, upper and lower subscapular n.
rotator cuff mm?
SITS: subscapularis, supraspinatus, infraspinatus, teres minor
supraspinatus is the most common to have problems!!!
- Weakness of the cuff muscles allow upward migration of the humeral head during use which irritates the supraspinatus tendon and/or muscle from impingement on the acromion.
- This results in tendinopathy which can lead to a tear. Acute tears can happen with more forceful injury mechanisms.
- Disuse atrophy of supraspinatus or deltoid seen, crepitus or grating noise when lifting arm.
- In complete supraspinatus tear, when abducting arm the shoulder shrugs upward from the effort of the deltoid in early abduction. There is a positive drop arm test = inability to hold 90 deg abduction when arm released.
serratus anterior
scapula protraction, fixes scapula to thoracic wall
long thoracic n.
biceps brachii
flexes forearm, supinates hand (most powerful supinator)
musculocutaneous n.
brachialis
flexion of forearm (most powerful flexor)
musculocutaneous n.
brachioradialis
flexion of forearm, radial n.
coracobrachialis
flexion and adduction of humerus
musculocutaneous n.
triceps brachii
extend forearm - radial n.
extrinsic causes of shoulder pain? neuro?
cervical nn. root compression (C5,6)
supraspinatus nn. compression
herpes zoster
cervical spine disease
abdominal/cardio/thoracic causes of shoulder pain?
abdominal: hepatobiliary disease, diaphragm irritation (ectopic pregnancy)
CV: MI, axillary vein thrombosis, thoracic outlet syndrome
thoracic: upper lobe pneumo, apical lung tumor, PE
intrinsic shoulder path?
Pain with specific movement or palpation Stiffness Weakness/loss of function Atrophy Pain Instability
supraspinatus test?
empty can
OR
resist elbow abduction at 90 degrees
subscapularis test
have patient rotate forearm medially against pressure – resist wrist going in
or
“lift off test”
infraspinatus/teres minor test?
patient rotates forearm laterally against resistance – resist wrist going out
or
place patients arms flexed 90 degrees with thumbs up - provide resistance as patient presses outward
drop arm test
patients arm is abducted to 90, gently push on arm - pain shows rotator cuff tear
disuse atrophy of supraspinauts
hear crepitus/grating when raise arm
complete supraspinatus tear?
when abducting arm the shoulder shrugs upward from the effort of the deltoid in early abduction. There is a positive drop arm test = inability to hold 90 deg abduction when arm released.
impingement
- Can cause a rotator cuff tear.
- Night pain common, gradual onset. Atrophy of superior and posterior muscles possible.
- Localized tenderness not common, but pain, crepitus or sudden pain while abducting the arm common.
Test: Hawkins and Near impingement signs.
- tip of acromion becomes a jammed up region
- Weakness of the rotator cuff can lead to superior subluxation of the humeral head when the shoulder is abducted beyond 90 degrees, predisposing to impingement syndromes.
Surgical treatment options often necessary for satisfactory results - take tip of acromion off
“Hawkin’s impingement sign”
shows if there is impingment of the subscapularis mm, d/t the acromion process
flex patients shoulder and elbow to 90 degrees, palm facing down
- then rotate arm internally by applying upward force at the elbow, and downward force at forearm
- this compresses the greater tuberosity against the coracoacromial libmament
Neer’s impingement sign
press on the scapula, raise patients arm— this compresses the greater tuberosity of the humerus against the acromion
acriomioclavicular separation
“fall on the tip of the shoulder” - results in driving the shoulder down, doesn’t take clavicle with it
involve both AC and coracoclavicular ligaments
5 grades of separations.
Tender right over AC joint:
- visual inspection confirmation typically at or above type 3
- Surgical care threshold varies, more type 4-6. - Otherwise conservative care: physical therapy