Shoulder/Arm/Elbow Anatomy Flashcards
Glenohumeral Joint
- Dynamic Stabilizers*
- Long head of biceps: humeral head depressor
- Rotator cuff muscles: originate on the scapula, insert on the lesser or greater tuberosity of the humerus
- Supraspinatus (abductor)
- Subscapularis (internal rotator)
- Infraspinatus (external rotator)
- Teres minor (external rotator)
Ligaments of the AC & GH Joints
- Acromioclavicular
- Coracoacromial
- Coracoclavicular (trapezoid + conoid)
- Glenohumeral
Elbow Joint Ligaments
- Radial collateral
- Ulnar collateral
- Radial head annular
Impingement Syndrome
- Repeated compression of the humeral head and/or greater tubercle against the contents of the subacromial space
- Occurs in athletes/laborers who repeatedly abduct arm greater than 90 degrees or in sedentary individuals
- Injury to: subacromial bursa, supraspinatus tendon, long head of biceps, & superior capsule of GH joint
- Sign = “painful arc”
Predisposing Factors to Impingement Syndrome
- Inability of muscles to coordinate the GH joint motions of abduction
- Slouched thoracic posture
- Degeneration of thoracic muscles
- Instability of GH joint
- Tightness/adhesions of GH capsule
- Decreased volume in subacromial space
- Abnormal acromion shape
- Osteophytes around AC joint
- Swelling of structures in the subacromial space
Acromion Shape
Type I = flat
Type II = curved
Type III = hooked
XR Findings in Impingement Syndrome
- Greater tuberosity – enthesopathic changes, small cysts, sclerotic rings, osteoporotic, irregular, or osteophytes
- Acromion – sclerosis (sourcil sign) & bone spurs on the anterior acromion
- Acromiohumeral interval – humeral head subluxes upwards
Rotator Cuff Tear
- MCC = age-related degeneration & chronic mechanical impingement (lesser w/ acute injury)
- Originate in the supraspinatous tendon & progress posteriorly & anteriorly
- Full thickness tears are uncommon under age 40 years (present in ~25% of persons over 60 years)
- Most are asymptomatic or have only mild, non-disabling symptoms
Rotator Cuff Tear S/S
Hx: anterolateral shoulder pain x several months after specific injury; night pain; difficulty sleeping on affected side; weakness, catching or crepitus
PE: atrophy of supraspinatus & infraspinatus; limited active ROM, if large tear-can only shoulder shrug; “drop-arm” test; tenderness over greater tuberosity
Scapular Winging
- Due to weakness of the serratus anterior muscle (scapula cannot resist the pull of the deltoid muscle –> scapula downwardly rotates & the GH joint abducts)
- Exaggerated w/ resistance against a shoulder abduction effort
Supraspinatous M.
O-supraspinatous fossa
I-Greater tubercle of humerus (top)
A-Abducts arm
N-Suprascapular n.
Subscapularis M.
O-subscapular fossa
I-Lesser tubercle of humerus
A-Internally rotates humerus
N-Upper & lower subscapular n.
Infraspinatus M.
O-infraspinatus fossa
I-greater tubercle of humerus (middle)
A-externally rotates humerus
N-suprascapular n.
Teres Minor M.
O-superior lateral scapular border
I-greater tubercle of humerus (bottom)
A-externally rotates humerus
N-axillary n.
Deltoid M.
O-lateral 1/3 clavicle, acromion, scapular spine
I-deltoid tuberosity of humerus
A-abducts shoulder (flexes/extends/internally & externally rotates)
N-axillary n.
