lecture 9: the shoulder Flashcards
which 2 bones form the glenohumeral joint
scapula and humerus
know all the landmarks of the scapila
.
what are the 2 tubercles of the humerus
lesser and greater
which tubercle facest more laterally
greater tubercke
which neck is more superior: anatomical or surgical
anatomical
what sits between the 2 tubercles
intertubercular groove
what is the orientation of the deltoid tuberocity
lateral
be able to name the landmarks on the hum
,
what type of joint is the glenohum joint
multiaxial ball and socket jt
what are the directins of the multiaxial ball and socket gleno joint
in both direcitons in 3 planes and the combo of these
what makes the gleno jt so mobile
it is a big ball (humeral head) in a small, shallow socket (glenoid fossa)
how much smaller is the glenoid fossa in comparison to the humeral head
3-4 times smaller
what are the motions of the glenohumeral joint
flexion, extension
abduction/adduciton
lateral/medial rotation
explain the cost of a highly mobile shoulder
multiaxial, large ROM with a shallow/ill fititng ball and socket
=instabilitiy
explain the cost of a highly mobile shoulder
multiaxial, large ROM with a shallow/ill fititng ball and socket
=instabilitiys
since there isso much instability of the gleno joint, what is needed
passive and active stab structures
what are the general passive stabilizers of the glenohum jt
glenoid labrum and ligaments
what is the glenoid labrum and its fucntion
the rim of fibrocartilage around the edge of the glenoid fossa that deepens the fossa and increases contact area
true or false: other mammals lack the gelnoid labrum
true
what surface do the glenohumeral ligaments reinforce
reinforce on the anterior/intferior surface
what surface do the coracohumeral ligaments support
the siperior aspect
true or false: the posterior surface of the gleno jt has many ligaments
false, has no ligaments
what are the important ligaments of the gleno jt
coracohum
glenohum
how many glenohumeral ligamnets are there
3
where does to the coracohumeral ligament attach
the greater tubercle of the huemrus
true or false: the shoudler is th emost commonly dislocated large jt
true
are there more anterior or posterior shoulder dislocations
95% are anterior dislocations
when there is an anterior discloation, what is the postion of the humeral head
in the subcoracoid position
what causes shoulder dislocations (MOI)
blunt force to abducted, extended and/or laterally rotated arm (ex: contact sports and overhead sports)
=torque applied to distal which causes rotation (ant lig acts as a hinge)
what is the main active stabilization of the shoulder
rotator cuff muscles
what are the 4 RC muscles
4 muscles that originate on scapula, wrap around shoulder joint capsule and insert on the tubercles of proximal humerus
where do the RC insert
the tubercles of the humerus
explain how the RC muslcles provide shoulder mobility and active stability
by pulling the humeral head against the glenoid fossa
true of false: the RC cause passive stabilization
false, active
what are the 4 RC muslces (sits)
supraspinatus
infraspinatus
teres minor
subscapularis
which RC lkes anterior
subscapularis
what is the origin of the supraspinatus m
supraspinous fossa
what is the insertion of the supraspinatus m
greater tubercle (sup facet)
where does the supraspinatus run
beneath acromion and over the glenoid fossa
what is the function of the supraspinatus
abduction (esp. early/initiation)
where is supraspinatus most commonly used
overhead sports and occupations
what is the origin of the infraspinatus
infraspinous fossa
what is the orogin of the teres minor
inferior border of the scapula
what is the insterion of the infraspinatus
greater tubercle (middle facet)
what is the insertion of the teres minor
greater tubercle (inf facet)
what is the motion/action of the tere minor and infraspinatus
lateral rotation
adduction (teres=weak)
what is the origin of the subscap
subscapular fossa
what is the insertion of the subscap
lesser tubercle of the humerus
what is the action of the subscap
medial rotation (primary)
adduction (weak)
what is RC tendinitis
inflammation of the RC tendons
what are the main causes of RC tendinitis
wear and tear, age, often due to overuse and friction of overhead motions
where is RC tendinitis most common
supraspinatus
why is RC tendinitis most common in supraspinatus
it is bounded superiorly by acromion and coracoacromial ligament
(very narrow subacromial space)
RC tendinitis is assocaited with what other condition
shoulder impingement syndrome
what is shoulder impingement syndrome
irritation due to the pinching of the supraspinatus tendon in motion
what is the painful arc test
abduction painful between 60 and 120 degrees
which ligament forms a roof over the supraspinatus
coracoacromial
be able to explain RC tendinitis
.
true or false: Rc muscles are considered scapulohumeral muscles
true
is deltoid a scapulohumeral muscles
yes
what is the origin of the deltoid muscles
clavicle, acromial and spinal
what is the insertion of the deltoid m
deltoid tuberocity of hum
what is the action of the anterior/clavicular fibers of the detloid
flexion
what is the action of the lateral/acromial fibers of the detloid
abduction
what is the action of the psoterior/spinal fibers of the detloid
extension
what is a common condition assocaited withdeltoid m
subacromial/subdeltoid m
what are bursea
thin, fluid filled sacs between tisses (ex: muscles, bones and ligs)
what is the function of bursae
reduces friction between the tissues
what is SA/SD bursitis
inflammation and swelling of bursa, further narrowing subacromial space
what is another expression of impingement syndrome (with sim symptoms)
SA/SD bursitis
what are the subacromial and subdeltoid bursae
large, connected shoudler bursae, superior and lateral to humeral head
=b/w deltoid m and tendon of supraspinatus
what is the anatomical position of the SA and SD bursa
superior and lateral
where are the SA and SD bursae located
between deltoid m and tendon of supraspinatus
what is the scapulohumeral SH rhythm
collaborative movement between the scapulothoracic and glenohum jtn
what is SH ryhtm ration
2:1 ratio of glenohum to scapulothoracic movement respectively
where does most os shoulder movement come from
the glenohum joint (aided by the scapulothoracic jt)
explain the scapulohumeral (SH) rhythm
first 30 degrees of abduction: movement occurs at glenohum jt
beyond 30 degrees: further shoudler abduction is possible due to the concurrent movemetns at the sternoclav and scapulothoracic jts
true or false: teres major is not a scapulohumeral muscle
false, it is
what is the origin if the teres major
inferior angle of the scapula
what is the insertion of the teresm= major
crest of lesser tubercle of humerus (medial)
why does teres major do medial rotation
because it begins posteiror and crosses anterior
what are the actions of the teres major
adduction, medial rotation
extension (when shoudler flexed)
when does teres major do extension
when shoulder is flexed
what are the scapulohumeral muscles
RC,deltoid
teres major
coracobrach
what is the origin of the coracobrach
tip of the coracoid process
what is the isnertion of the coracobrach
medial humerus
(1/2 way down)
what is the action of the coracobrach
flexion,
adduction
medial rotation (weak)
is the coracobrach a primary medial rotator
no false
what are the thorax muscles with shoulder actions
lat dorsi
pectoralis major
what is the orogin of the lat dorsi
iliac crest, thoracolumbar fascia
T7-T12 vert
what is the insertion of the lat dorsi
floor of humerus intertubercular groove
what is the origin of the pec major
clavicle, sternum, and ribs
what is the insertion of the pec major
crest of greater tubercle (most lateralO)
what are the actions of the pec major and lat dorsi at the shoulder
adduction
medial rotation
(extension when shoulder flexed)
true or false: the pec major and lat dorsi only have action at the shoulder and back
false, they also cross the scapulothoracic joint therefore move the scapula too
what motion at the scap does the pec major do
protraction
(downward rot)
what motion at the scap does the lat dorsi do
retraction
(downward rot)
what are the 3 muscles that insert into the intertub groove (lat to medial )
pec major
lat dorsi
teres major
