Week 3-4 Joints of the pectoral girdle & Glenohumeral (shoulder) joint Flashcards
all type of joints and classification of the pectoral glide
sternoclavicular (SC) joint - synovial saddle joint (function as ball and socket joint) - atypical
acromioclavicular (AC) joint - synovial plane joint - atypical since wedge shaped and incomplete fibrocartilage disc
scapulothoracic joint - functional joint
glenohumeral (shoulder) joint - ball and socket joint
feature of clavicle
convex medial 2/3
concave lateral 1/3
clavicle - sternal (medial) end
sternal (articular) facet
clavicle - acromial (lateral) end
deltoid tubercle
acromial (articular) facet
bone and articular surfaces of sternoclavicular (SC) joint
sternum (clavicular notch)
clavicle (medial end)
1st costal cartilage (medial surface)
intra articular capsule of sternoclavicular (SC) joint
fibrocartilage
ligaments of sternoclavicular (SC) joint
anterior sternoclavicular - lay on capsule
posterior sternoclavicular - lay on capsule
interclavicular
costoclavicular - accessory ligament
movements of sternoclavicular (SC) joint
elevation/ depression
protraction/ retraction
posterior axial rotation
bone and articular surfaces of acromioclavicular (AC) joint
acromion (scapula)
clavicle (lateral end)
covered by fibrocartilage
intra-capsular disc of acromioclavicular (AC) joint
wedge shaped and incomplete fibrocartilaginous disc
ligaments of acromioclavicular (AC) joint
acromioclavicular - superior and inferior capsular thickenings
coracoclavicular - conoid & trapezoid
movements (stability) of acromioclavicular (AC) joint
3 degrees of freedom
passively - occurs with scapular movement
will adjust in any direction to allow scapular keep contact with chest wall
bone and articular surfaces of scapulothoracic joint
chest wall
body of scapula
serratus anterior acting as a disc
why scapulothoracic joint is a functional joint
- no fibrous cartilaginous and synovial tissue
- relies on muscles
resting position of the scapula on thorax - base of spine of scapula & inferior angle
base of spine of scapula - T3
inferior angle - T7
functions of scapulothoracic joint
- scapular motion increases overall shoulder movement (keep humeral head in contact with glenoid fossa)
- maintains scapulohumeral rhythm
- movement relies of AC and SC joint movement
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movements of scapulothoracic joint
elevation/ depression
protraction/ retraction
upward/ downward rotation
bone and articular surfaces of glenohumeral (shoulder) joint
glenoid fossa of scapula
head of humerus (held by rotator cuff)
fibrous capsule and attachments of glenohumeral (shoulder) joint
fibrous capsule: loose cylindrical sleeve
attachments: margin of articular surfaces
reinforcements of glenohumeral (shoulder) joint
dynamic ligaments (distal attachment of the rotator tendons)
deficiencies of glenohumeral (shoulder) joint
top of bicipital groove
inferior to coracoid process
synovial membrane and communications with bursae
subscapular (communicating)
subacromial (non-communicating)
intrinsic, extrinsic and accessory ligaments of glenohumeral (shoulder) joint
intrinsic:
glenohumeral - superior, middle, inferior
transveral humeral
extrinsic: coracohumeral
accessory: coracoacromial
nerve supply of glenohumeral (shoulder) joint
suprascapular
subscapular
axillary
lateral pectoral
musculocutaneous
special structures of glenohumeral (shoulder) joint
glenoid labrum
long head of biceps tendon
movements of glenohumeral (shoulder) joint
flexion/ extension
abduction/ adduction
medial/ lateral rotation
circumduction
blood supply of glenohumeral (shoulder) joint
suprascapular vessels
- above suprascapular notch
anterior circumflex humeral vessels - from axillary artery extend
posterior circumflex humeral vessels - from axillary artery extend
what structures help to support the superior aspect of the glenohumeral joint
- coracohumeral ligament
- long head of biceps brachii tendon
- supraspinatus tendon
typically, the glenohumeral joint is prone to dislocation in which direction?
anterioinferiorly
what are the two muscles of scapular stabilization
serratus anterior and trapezius
scapulohumeral rhythm
- scapula and humeral to achieve UL elevation
- positioning glenoid fossa to serve UL function
- contributes to enough length tension of muscles (eg: deltoid) to cross GH joint
- loss of movement leads to shoulder dysfunction
- 180 degrees elevation = 120 degrees GH: 60 degrees scapulothoracic (30 AC & 30 SC)
muscles that contributes downward rotation of the scapula
rhomboid major/ minor - retracts scapula
levator scapulae - elevates scapula
pectoralis minor - depress scapula, protracts scapula
muscles that contributes upward rotation of the scapula
trapezius (upper, middle, lower) - retracts scapula
serratus anterior - protracts scapula