shoulder Flashcards
describe the pectoral girdle
- formed of clavicle and scapula
- clavicle S shape allows 180 degrees lateral abduction
give an overview of pectoral girdle joint
- 3 true joints= sternoclavicular, acromioclavicular and glenohumeral
- 2 other joints= scapulothoracic, subacromial
what type of bones are the scapula and clavicle? how do they move?
- scapula is an irregular
- clavicle is a flat bone
- they move as a unit
what is the shoulder’s function?
- mobility i.e. place of hand in space
shoulder stability vs mobility
- stability compromised to increase mobility
- ROM in all 3 planes
- shallow socket, negative intra- articular pressure, weak ligaments and muscles
- labarum + rotator cuff reinforces joint
- stability and mobility needs to be in equilibrium to create movement
what is the only body link to axial skeleton?
- clavicle’s articulation with sternum (acromion process)
what is the sternoclavicular joint?
- conformed by articular surface of sternum (manubrium) and lateral end of clavicle will articulate with acromion of scapula
what ligaments provide stability for sternoclavicular joint?
- anterior sternoclavicular
- posterior sternocalvicular
- interclavicular
- costoclavicular
anterior sternoclavicular ligament of sternoclavicular
- provides anterior stability of the joint
posterior sternocalvicular ligament of sternoclavicular
- provides stability in posterior direction of the joint
interclavicular ligament of sternoclavicular
- provides superior stability as goes from superior part of joint
- links both articulations
costoclavicular ligament of sternoclavicular
- short but strong
- goes from cartilage of first rib to clavicle
- resists elevation of pectoral girdle
describe acromioclavicular joint
- joint at the top of shoulder where acromion meets lateral end of clavicle
- 3 axes
what are the 3 ligaments that provide stability for acromioclavicular joint?
- acromioclavicular, trapezoid (inferior) and conoid
what is the degree of movement in acromioclavicular joint?
- 20-30 degrees total gliding and rotational motion
trapezoid ligament of acromioclavicular
- underneath joint
- lateral distribution as inserted into inferior base of clavicle in trapezoidal line to provide stability for rotation
conoid ligaments of acromioclavicular joint
- medial distribution
- twists to insert into coracoclavicular inferior face
describe the glenohumeral joint
- articulation between spherical head of humerus and concave glenoid fossa (scapula)
- ball and socket joint
- 3 axes; f-e; a-a; l-m
what is the role of the labarum?
- increases articular surface for movement of head of humerus
what are the five ligaments of the glenohumeral joint?
- superior, medial and inferior glenohumeral
- transverse humeral and coracohumeral
what does glenohumeral joint contain lots of? what is the synovial membrane?
- contains lots of bursae
- synovial membrane is important as provides lubrication for movement of articular surfaces
what increases stability of humeral head during elevation movements?
- tendon of the long head of biceps
superior glenohumeral ligament
- provides stability in superior and anterior directions
medial glenohumeral ligament
- provides stability in anterior direction
inferior glenohumeral ligament
- provides inferior stability of the joint
transverse humeral ligament of glenohumeral
- keeps tendon on groove of humerus
coracle humeral ligament of glenohumeral
- superiorly located
- starts in base of coracoid process and is inserted into humerus laterally from greater to lesser tubercle
- stability in superior movements of head of humerus
coracle acromion ligament
- provides stability and reinforces the coracoid arch, which acts as a roof for movement of head of humerus and roof for subacromial joint
what is the point of bursas around joints? what is the bursa in fibrous layer?
- provide navigation for different muscles
- sub coracoid bursa
sub coracoid bursa function
- decreases friction of movement of tendons of coracobrachialis and other muscles
- important in fertility as if inflamed they can provoke pain, swelling and restrict movement
describe scapulothoracic articulation
- sliding junction between deep aspect of scapula and thoracic rib cage
- enables integration of movements of scapula against underlying chest wall
describe subacromial articulation
- space directly beneath acromion and directly above shoulder joint
what happens to structures as arm is lifted?
- humeral head and acromion draw nearer
- narrows space
what is elevation and depression?
elevation- moves up
depression- moves down
what is elevation performed by?
- trapezius and levator scapulae
what is depression performed by?
- ascending part of trapezius, transverse part, pectoralis minor and latissimus dorsi
- inserted into humeral bone so combined action depresses shoulder pulling down humerus
what is protraction and retraction?
- protraction involves moving away from midline
- retraction involves moving towards midline
what performs protraction?
- pectoralis minor and serratus anterior
- scapula glides around thorax in interior direction so medial border of scapula moved away from spine
what performs retraction?
- trapezius, latissimus dorsi and contribution of rhomboid major/ minor
what is upward rotation and downward rotation ?
- upwards> raising arms ; inferior angle moves laterally from spine
- downwards> drop arms; inferior angle moves medially towards spine
what is upward rotation performed by?
- upper fibres of trapezius and serratus anterior
- pulls inferior angle of scapula upwards
how is downward rotation performed?
- combo of scapula, rhomboids and pectoralis minor pulling the coracoid process
what is scaption ?
- moving the glenohumeral joint in scapula plane
- 60 degrees angle away from midline
what is the scapulohumeral rhythm?
- ratio of glenohumeral movement to scapulothoracic movement during arm elevation
- 2:1 ratio as 120 degrees of GH abduction and 60 degrees of ST rotation
inferior glenoid tuberosity
- provides insertion for long head of triceps brachii
supra glenoid tuberosity
- provides insertion for bicep brachii
what do you get if you follow the spine?
- blunt angle known as acromion angle
greater tuberosity
- lateral aspect of humerus
- close to head of humerus
lesser tuberosity
- anterior and medial aspect of humerus
where is the anatomical neck?
- between two tuberosities and head of humerus
intertuberosity groove
- found between crest of greater and lesser tuberosity
- provides pathway for long head of triceps brachii
deltoid tuberosity
- provides attachment for deltoid
- triangular roughening in surface
radial nerve groove
- shallow depression on posterior side of humerus
- insertion for biceps brachii
what is the glenoid fossa?
- hollow area that is the articular surface of scapula
what is infraspinous fossa?
- provides attachment for infraspinatus muscle
what is supraspinous fossa?
- provides attachment for supraspinatus muscle
subscapular fossa
- important for scapula stability and provides attachment for subscapularis
what does coracoid process provide?
- attachment for ligaments and tendons
what is olecranon?
- tuberosity that provides insertion for triceps
location, origin, insertion and action of descending part of trapezius
L= posterior side of pectoral girdle
O= occipital bone
I= (posterior) clavicle + acromion
A= elevation+ retraction
location, origin, insertion and action of transverse part of trapezius
L= posterior side of pectoral girdle
O= C7-T4
I= acromion scapula
A= elevation+ retraction
location, origin, insertion and action of ascending part of trapezius
L= posterior side of pectoral girdle
O= T5- 12
I= medial 1/2 of scapula
A= retraction+ depression
location, origin, insertion and action of levator scapulae
L= posterior side of pectoral girdle
O= C1-4
I= superior angle of scapula
A= elevation
location, origin, insertion and action of rhomboid minor
L= posterior side of pectoral girdle
O= nuclei ligament and spinous process C7-T1
I= medial border of scapula
A= retraction
location, origin, insertion and action of rhomboid major
L= posterior side of pectoral girdle
O= T2-T5
I= medial border of scapula
A= retraction
location, origin, insertion and action of latissimus dorsi
L= posterior side of pectoral girdle
O= T6-T12, L1-L5, crest of sacrum, iliac crest, inferior 4 ribs
I= intertubercular groove of humerus
A= depression, retraction
location, origin, insertion and action of subclavius
L= anterior side of pectoral girdle
O= costal end of first rib +costal cartilage
I= inferior surface of clavicle
A= stabilises pectoral girdle
location, origin, insertion and action of pectoralis minor
L= anterior side of pectoral girdle
O= anterior 3rd- 5th rib
I= coracoid process
A= protraction+ depression
location, origin, insertion and action of pectoralis major
L- anterior side of pectoral girdle
O= clavicle, sternum, costal cartilage
I= greater tuberosity of humerus
A= depression
location, origin, insertion and action of serratus anterior
L= anterior side of pectoral girdle
O= 1st- 9th rib
I= medial border of scapula
A= protraction
origin, insertion and action of supraspinatus
O= supraspinatus falsa
I= greater tuberosity of humerus
A= glenohumeral abductor
origin, insertion and action of middle deltoid (acromion part)
O= scapula acromion
I= deltoid tuberosity
A= glenohumeral abductor
origin, insertion and action of latissimus dorsi- adductor
O= T7-T12
I= intertubercular groove of humerus
A= glenohumeral adductor, extensor and medial rotator
origin, insertion and action of pectoralis major
O= clavicle, sternum, costal cartilage
I= greater tuberosity of humerus
A= glenohumeral adduction, flexion and medial rotator
origin, insertion and action of teres major
O= inferior angle of scapula
I= lesser tuberosity
A= glenohumeral adductor and medial rotator
origin, insertion and action of coracobrachialis
O= coracoid process
I= medial aspect of humerus
A= glenohumeral adductor and flexor
- lifts arm to 90 degrees abduction to allow horizontal movement
what is horizontal adduction performed by?
- pectorals major, anterior portion of deltoid and coracobrachialis
what is horizontal abduction performed by?
- teres minor and posterior fibres of deltoid
origin, insertion and action of anterior deltoid- flexor
O= clavicle
I= deltoid humeral tuberosity
A= glenohumeral flexor, transverse abductor and medial rotator
origin, insertion and action of posterior deltoid
O= spine of scapula
I= deltoid tuberosity
A= glenohumeral extender/horizontal abductor/ lateral rotation
origin, insertion and action of biceps brachii- flexor
O= long -supraglenoid tuberosity
short- coracoid process
I= radial tuberosity
A- glenohumeral flexor
origin, insertion and action of triceps long head
O= infraglenoid tuberosity
I= common tendon of ulna
A= glenohumeral extender
origin, insertion and action of triceps medial and lateral head
O= posterior humerus
I= common tenson of ulna
A= glenohumeral extensor
origin, insertion and action of subscapularis
O= subscapularis fossa
I= lesser humerus tuberosity
A= glenohumeral medial rotator
origin, insertion and action of infraspinatus
O= infraspinatus fossa
I= greater tuberosity of humerus
A= glenohumeral lateral rotator
describe rotator cuff muscles
- important for active stability of glenohumeral joint
- supraspinatus, infraspinatus and teres minor
where are rotator cuff muscles inserted? what is their role?
- inserted around humeral head and main action is to rotate humerus medially and laterally
- helps centralise head of humerus during movements