Exam 3 Flashcards
what is the sternoclavicular jt
clavicle like a strut holding the scapula
what is the acromioclavicular jt
firmly attaches the scapula to clavicle
what is the scapulothoraic jt
not a true jt
interface between bones
link to SC and AC
base of GH jt
what is the glenohumeral jt
most distal and mobile portion of the whole complex
what can happen to the shoulder complex when weakened or painful
decreases effectiveness of the entire UE
what are the slides of elevation and depression
ele- sup slide
dep- inf slide
where does the medial border of scapula slide in protraction and retraction
pro- ant and lat
re- post and med
describe the SC jt
basilar jt of UE
large ROM
irregular saddle shape
convex and concave with sternal facet reciprocally shaped
what is the longitudinal diameters in the SC jt
frontal plane
sup and inf points
what is the transverse diameters of SC jt
horizontal plane
ant and post points
what muscle can restrict the clavicle movement
subclavius
what muscles can affect the movement of SC jt
SCM
sternothyroid
sternohyoid
subclavius
where does the costoclavicular lig attach to
clavicle to 1st rib
what movements does the clavicle do
3 DOF- all 3 with UE elevation
ele/dep
protract/retract
rotates
what is the goal of SC
to place scapula in optimal position for head of humerus
what is the osteo of the SC joint
axis= AP
35-45 elevation
10 depression
clavicular promotes scapula motions
what is the arthro for SC elevation
convex surface rolls sup and slides inf
CCL ligament stretches
what is the arthro for SC depression
convex surface rolls inf and slides sup
ICL lig stretches
what is the osteo of SC protraction
axis- vertical
15-30 degrees
associated with scapula pro/re
what is the arthro of SC retraction
concave surface of clavicle rolls and slides post
stretches ant CCL and ant capsule
what is the arthro of SC protraction
concave surface of clavicle rolls and slides ant
stretches post CCL and post capsule
what is the osteo of SC rotation
longitudinal axis
20-35 degrees
what is the arthro of rotation of SC
spin of sternal end relative to lateral surface
linked with flx and abd
what is the coracoclavicular lig
extrinsic stability for AC
trapezoid and concoid
coracoid process to clavicle
what are the kinematics of AC jt
3 DOF
up/down rotation
secondary motion= rotational adjustment
describe upward rotation of scapula at AC
swings up and out
up to 30 degrees
contributes to scapulothoracic motion
describe the downward rotation of scapula at AC
return to anatomical position
describe the rotation of AC in horizontal plane
vertical axis
medial border moves away (IR)
describe the rotation of AC in sagittal plane
Tilting
ML axis
inferior angle moves away- ant or post tilting
describe the protraction of AC jt
internally rotates in horizontal plane
align ant surface of scapula and thorax
what happens to the scapula with IR
ant tilting
upward rotation
where does the scapula sit
between 2-7 ribs
medial border 6 cm lateral to spine
what are the ranges for the scapulathoracic jt
ant tilt- 10 degrees
upward rotation- 5-10
IR- 30-40
how is the motion for protraction/retraction of scapulothoracic jt
SC pro/re plus AC IR/ER
how is the motion of upward/downward rotation of scapulothoracic jt
SC elevation plus AC upward rotation
60 degrees upward rotation
how is the humeral head postioned
medial, superior, posterior
how is the glenoid fossa positioned
anterior-lateral in scapula
what is the axillary pouch
anatomic postion inferior portion of capsule is slackened
what lines the humeral head and glenoid fossa
articular cartilage
what is the potential size of the GH jt
2x humeral head
describe the fibrous capsule of GH jt
rim of glenoid fossa to anatomic neck
loose fitting
allows mobility and reinforced by ligaments
what allows for GH jt stability
passive tension of lig
active forces- RTC
long head of biceps crosses sup over head
describe GH superior capsular lig
resists ER and ant/inf translation
describe the GH middle capsular lig
stabilizes most motion
ant restraint of 45-90 abd and ER
describe the GH inf capsular lig
3 bands
taut in 90 abd
resists inf/ant-post translations
what is the coracohumeral lig
blends with sup capsule
taut in anatomical position
restrain inf translation and ER
what is the RTC interval
common site of dislocation
reinforced by LHB, coracohumeral lig and sup/mid capsule
describe the LHB
supraglenoid fossa and labrum
intratubercle groove on ant humerus
resists ant translation
ABD
describe the labrum
fibrocartilage
stabilzer
describe the coracoacromial arch and bursa
arch= coracoacromial lig and acromion process
roof of GH jt
1 cm in adults
what is contained in the coracoacromial arch and bursa
supraspinatus
subacromial bursa
LHB
sup capsule
where is the subacromial space
between arch and humeral head
what is the subacromial bursa
protects SS from acromial bone
what is the subdeltoid bursa
limites friction between deltoid and SS tendon and humeral head
describe the ABD and ADD of humerus
frontal A-P
120 degrees, also with 60 deg scap RT
convex rolls sup and slides inf on concave
opposite in ADD
what is dynamic stability
supraspinatus tendon blends with superior capsule
contraction pulls capsule tight=no pinching
what is adhesive capsulitis
excessive thickening or stiffness in ICL
limits inferior slide of humeral head (sup roll)
what is impingement syndrome
unnatural and repeated compression/abrasion damaging the SS tendon, subacromial bursa, LHB tendon or sup capsule
describe FLX of humerus
sagittal M-L
120 deg/180 with scap
most structures are taut
tension in post capsule= ant translation
describe EXT of humerus
65 deg active/ 80 passive
slight ant tilt of scap= stretch capsular lig
describe IR of humerus
horizontal plane SI
75-85 deg
rolls ant slides post
describe ER of humerus
horizontal SI
60-70 deg(can be up to 90)
rolls post and slides ant
at 90 deg ER is all spinning
what is scapulohumeral rhythm
natural rhythm between GH ABD and ST upward RT
after 30 degrees ABD= rhythm consistent
2 deg GH + 1 deg ST = 3 deg
full arc = 120 GH/60 ST
what is the result of 60 deg of scapula with ABD at SC and AC jt
SC= elevation (30 deg)
AC= upward RT
what does the clavicle do at the SC jt during full ABD
retract (15-20 deg)
how is the scapula positioned at full ABD
tilts posteriorly (20 deg) and rotates outward
how does the post tilt and ER of scapula in ABD help
keeps scapula flush with thorax
orients fossa
how is the scapula normal positioned
ant tilt (10 deg)
IR (30-40 deg)
what does the clavicle do during ABD
posteriorly RT along axis
20-35 deg
most predominant motion
what happens to the clavicle during ABD if there is an subacromial impingement
reduced RT
what happens to the humerus during ABD (beside the Arthro)
ER
allows to pass post acromion
25-50 deg before 70-80 deg of ABD
what is the sensory innervation of the SC jt
C3-4
what is the sensory innervation of the AC and GH jt
C5-6
suprascapular and axillary n
what nerves come from the posterior cord
upper subscapular n
thoracodorsal n
lower subscapular n
axillary n
what n come from the proximal segments of the brachial plexus
dorsal scapular
long thoracic
pectoral
suprascapular
what are proximal stabilizers
originate from spine/ribs/cranium and insert on the scapula and clavicle
what are distal mobilizers
originate on scapula and clavicle and insert on humerus or forearm
what muscles elevate the ST
UT (CN 11)
levator scapulae (dorsal scapular)
rhomboids (dorsal scapular)
what muscles retract ST
MT (cn 11)
rhomboids (dorsal scapular)
LT (cn 11)
what muscles depress ST
LT (cn 11)
Lat dorsi (thoracodorsal)
Pec minor (medial pectoral)
subclavius (subclavian)
what muscles protract ST
SA (long thoracic)
pec minor (medial pectoral)
what muscles upward rotate ST
SA (long thoracic)
U/MT (cn 11)
what muscles downward rotate ST
rhomboids (dorsal scapular)
pec minor (medial pectoral)
what is the function of the elevators
support the posture of the sh girdle
what can happen if elevator m support is lost
can damage underlying structures
how is the Lat dorsi a depressor
pulls humerus inf leading to indirect depression
what can the pec minor limit if tight
retraction
what are the retractors main function
proximal stabilizers anchoring scapula to axial skeleton
essential for pulling activities
what 3 groups of m help elevate the arm and their function
muscles that elevate the humerus at GH
scapular m that control up RT of ST
RTC m that control dynamic stability and arthro of GH
what muscles elevate the humerus
ant/mid deltoid (axillary)
supraspinatus (supraclavicular)
coracobrachialis (musculocutaneous)
biceps brachii (musculocutaneous)
when are the m that elevate the humerus activated with ABD
between 60-90 deg
ant/mid deltoid and SS share equally
what are the roles of the upward RT of ST
drive up RT and RT adjustments
provide stable attachments for distal mobilizers (deltoid and RTC)
what can happen if you have paralysis of the trap
with full ABD (very difficult) = T spine extends 10-15 deg
control of scapula changes
excessive protraction
what can happen if you have paralysis of the SA
downward RT position
abnormal ant tilt and IR
can not resist the deltoid and SS pull in ABD
what is scapular dyskinesis
abnormal position or movement of the scapula
reduced up RT
excessive down RT, IR, ant tilt/elevation
what are type 1 and 2 prominences of the inf and med border of the scapula indicating
labrial lesions
what does type 3 prominence of superomedial border of scapula indicating
impingement and RTC lesions
what is function of RTC m during elevation of arm
regulators of dynamic jt stability and control jt arthro
compensates for natural laxity
RT, compress, and stabilize in fossa
what m FLX the humerus
ant deltoid (axillary)
coracobrachialis (musculocutaneous)
biceps brachii (musculocutaneous)
what m ABD the humerus
mid deltoid (axillary)
supraspinatus (suprascapular)
where does the RTC distally attach
blends into capsule before attaching to humerus
what is the action of the SS when ABD of GH
rolls humeral head sup while compressing for stability
what is the action of the IS, SubS, and TMin when ABD of GH
downward translation on humeral head due to SS sup translation
what other action is IS and Tmin doing during ABD of GH
ER humerus to create clearance
what m ADD and EXT the sh
post delt (axillary)
lat dorsi (thoracodorsal)
LH triceps (radial)
pec major (med and lat pectoral)
IS (supraclavicular)
Tmin (axillary)
what is required for the sh to ADD/EXT
scapula stabilization with rhomboids
what m IR the sh
subscapularis (lower subscapular)
pec major (med and lat pectoral)
lat dorsi (thoracodorsal)
teres major (lower and upper subscapular)
ant deltoid (axillary)
what m ER the sh
infraspinatus (suprascapular)
Tmin (axillary)
post deltoid (axillary)
what m has the greatest moment arm of IR and which has the least
subscapularis
ant deltoid
which movement (IR or ER) has the greatest mass and torque
IR by 40-70% of torque
in throwing sports what movement (IR or ER) has the most internal torque and which has the strongest deceleration force
IR largest torque
ER largest deceleration
what muscle contraction has peak force
eccentric forces
