Chapter 5 - Shoulder Complex Flashcards
Shoulder Complex
involves the sternum, clavicle, ribs, scapula, and humerus
osteologic features of the sternum
manubrium
clavicular facets
costal facets
jugular notch
osteologic features of the clavicle
shaft sternal end costal facet costal tuberosity acromial end acromial facet
muscle attachments of the sternum
pectoralis major
subclavius
part of sternocleidomastoid
muscle attachments to the clavicle
pectoralis major
sternocleidomastoid
anterior deltoid
upper trapezius
orientation of the clavicle
about 20 degrees posterior to frontal plane
orientation of the scapula
deviated about 35 degrees anterior to the frontal plane
retroversion of the humeral head
about 30 degrees posterior to the medial-lateral axis at the elbow
attached to the coracoid process
short head of biceps coracobrachialis pectoralis minor trapezoid ligament conoid ligament coracohumeral ligament coracoacromial ligament
attachments to superior part of humerus
Greater tubercle = supraspinatus, infraspinatus, teres minor
lesser tubercle = subscapularis
pectoralis major - latissimus dorsi - teres major
deltiod
coracobrachialis
osteologic features of the proximal-to-mid humerus
head anatomic neck lesser tubercle greater tubercle facets on greater tubercle intertubercular groove deltoid tuberosity radial groove
shaft of humerus to humeral head comparison
135 degree angle of inclination
30 degree retroversion of the humeral head relative to the distal humerus
Primary movements of scapulothoracic joint
elevation & depression
protraction & retraction
upward & downward rotation
(pictures pg. 14 Ch 5)
Movements of the sternoclavicular joint
Elevation & Depression(frontal plane)
Protraction & depression(horizontal plane)
Axial rotation(sagittal plane)
structures stabilizing the SC joint
capsule
anterior and posterior sternoclavicular ligaments
interclavicular ligament
costoclavicular ligament
articular disc
sternocleidomastoid, sternothyroid, sternohyoid, subclavius
elevation of the clavicle
convex surface rolls superiorly and slides inferiorly
- costoclavicular ligament helps limit
depression of clavicle
convex surface rolls inferiorly and slides superiorly
- stretches the interclavicular ligament and superior capsule
retraction of clavicle
concave surface of clavicle rolls and slides posteriorly on the convex sternum
- stretch anterior costoclavicular ligament and anterior capsule
- 15-30 degrees
protraction of the clavicle
concave surface of clavicle rolls and slides anteriorly on convex surface of sternum
- stretch posterior of costoclavicular ligament, posterior capsule, scapular retractor muscles
- 15-30 degrees
axial rotation of the clavicle
longitudinal rotation
- occurs during shoulder abduction or flexion
- 20-35 rotation
acromioclavicular joint
3 degrees of freedom
- plane joint
- upwards & downward rotation
- horizontal plane rotational adjustments(scapula rotates)
- sagittal plane rotational adjustments(scapula rotates anterior/posterior)
tissues that stabilize the AC joint
superior and inferior AC joint capsular ligaments
coracoclavicular ligament(trapezoid and conoid)
- supports weight of upper extremity
articular disc(when present)
deltoid and upper trapeziusupward rotation of AC joint
occurs as scapula swings upwardly and outwardly
- component of shoulder abduction or flexion
- 30 degrees
downward rotation of AC joint
- component of shoulder adduction or extension
horizontal plane adjustments of the AC joint
evident as the medial border of the scapula pivots away and toward the posterior surface of the thorax(internal and external rotation)
sagittal plane adjustments of AC joint
medial-lateral axis
- inferior angle pivots away or toward the posterior surface of the thorax(anterior tilting and posterior tilting)
scapulothoracic joint
between anterior surface of scapula and posterior-lateral wall of thorax
- separated by subscapularis, serratus anterior, erector spinae
scapulathoracic elevation
elevation at SC joint and downward rotation at AC joint
scapulothoracic protration
protraction at SC joint and slight IR at AC joint
scapulothoracic retraction
retraction at SC joint and slight ER at AC joint
scapulothoracic upward rotation
elevation at the SC joint and upward rotation at AC joint
Scapulothoracic downward rotation
depression at SC joint and downward rotation at the AC joint
glenohumeral joint
3 degrees of freedom
- abduction and adduction(frontal)
- flexion and extension(sagittal)
- IR and ER(horizontal)
- humeral head is directed medially and superiorly, as well as posteriorly(scapular plane)
axillary pouch
slackened or redundant recess that is the inferior portion of the GH capsule
subluxation
incomplete separation of articular surfaces, followed by spontaneous realignment
dislocation
complete separation of articular surfaces without spontaneous realignment
passive mechanisms
1) restraint provided by capsule, ligaments, labrum, tendons
2) mechanical support predicated on scapulothoracic posture
3) negative intrascapsular pressure
GH ligaments
superior glenohumeral ligament
middle glenohumeral ligament
inferior glenohumeral ligament
- anterior band and posterior band
- connected axillary pouchsuperior glenohumeral ligament
stretched with adduction
- inferior and anterior-posterior translations of the humeral head
middle glenohumeral ligament
stretched with anterior translation
- 45-60 degrees of abduction
- external rotation
inferior GH ligament(axillary pouch)
stretched with 90 degrees of abduction
- combined with anterior-posterior and inferior translations
inferior GH ligament(anterior band)
stretched with 90 degrees of abduction
- full ER
- anterior translation
inferior GH ligament(posterior band)
stretched with 90 degrees of abduction
- full IR
coracohumeral ligament
stretched with adduction
- inferior translation
- ER
rotator cuff muscles
subscapularis, supraspinatus, infraspinatus, teres minor
rotator interval
between supraspinatus and subscapularis
- filled by tendon long head of biceps and coracohumeral ligament
- common site for anterior dislocation
tissues that reinforce/deepen the GH joint
joint capsule and capsular ligaments coracohumeral ligament rotator cuff muscles long head of biceps glenoid labrum
subacromial space
supraspinatus muscle and tendon
subacromial bursa
long head of biceps
part of the superior capsule
subacromial bursa
between supraspinatus and undersurface of the acromion
subdeltoid bursa
limits friction forces between the deltoid and supraspinatus tendon and humeral head
GH joint abduction
humeral head rolling superiorly and sliding inferiorly
1st kinematic principle of shoulder abduction
full arc of nearly 180 degrees is result of simultaneous 120 degrees abduction and 60 degrees of scapulothoracic upward rotation
2nd principle of abduction
60 degrees of upward rotation of scapula during full abduction is result of simultaneous elevation of clavicle at SC joint combined with upward rotation of scapula at the AC joint
3rd principle of abduction
clavicle retracts at the SC joint during full shoulder abduction
4th principle of abduction
during full abduction, scapula posteriorly tilts and externally rotates
5th principle of abduction
clavicle rotates posteriorly around its own long axis
6th principle of abduction
humerus naturally externally rotates during shoulder abduction
axillary nerve
C5, C6
deltoid and teres minor
thoracodorsal
C6-C8
latissimus dorsi
upper subscapular
C5, C6
upper subscapularis
lower subscapular
C5, C6
lower subscapularis
lateral pectoral
C5-C7
pectoralis major
medial pectoral
C8, T1
pectoralis major and pectoralis minor
suprascapular
C5, C6
supraspinatus and infraspinatus
subclavian
C5,C6
subclavius
dorsal scapular
C5
rhomboid major and minor
levator scapula
long thoracic
C5-C7
serratus anterior
Scapulothoracic joint Elevators
upper trapezius
levator scapulae
rhomboids
Scapulothoracic joint depressors
lower trapezius
latissimus dorsi
pectoralis minor
subclavius
scapulothoracic joint protractors
serratus anterior
scapulothoracic joint retractors
middle trapezius
rhomboids
lower trapezius
scapulothoracic joint upward rotators
serratus anterior
upper and lower trapezius
scapulothoracic joint downward rotators
rhomboids
pectoralis minor
abduction of GH joint
anterior deltoid
middle deltoid
supraspinatus
flexion of GH joint
anterior deltoid
coracobrachialis
long head of biceps brachii
IR of the GH joint
subscapularis anterior deltoid pectoralis major latissimus dorsi teres major
ER of the GH joint
infraspinatus
teres minor
posterior deltoid
Possible causes of shoulder impingement syndrome
1) abnormal kinematics at GH joint and scapulothoracic joints
2) “slouched” posture
3) fatigue, weakness, poor control, or tightness of muscles
4) inflammation and swelling of tissues within subacromial space
5) excessive wear and degeneration of tendons of rotator cuff muscles
6) instability of GH joint
7) adhesions within inferior GH joint capsule
8) excessive tightness of posterior capsule
9) osteophytes forming around the AC joint
10) abnormal shape of the acromion or coracoacromial arch
