Upper limb : Shoulder joint Flashcards
what are the features of the scapula?
- irregular bone.
what are the features of the humerus?
specifically what is the difference in anatomical vs surgical neck.
- anatomical neck : site of attachment to capsule, site of epiphyseal plate.
- surgical neck : between tubercles and shaft, and more fractures than anatomical neck.
what are some features of the clavicle?
- sternal end articulates with manubrium of sternum towards midline of body : sternoclavicular joint.
- acromial end articulates with acromion of scapula : acromioclavicular joint.
what are some features of the glenohumeral joint?
- the shoulder joint is a synovial joint, with ball and socket design.
- most mobile with wide range of movement over multiple planes.
- least stable joint in body : most common dislocations.
- articular surfaces head of humerus to glenoid fossa, 4:1 disproportional.
what is the significance of the glenoid labrum?
- deepens glenoid fossa, with loose anterosuperior attachment and inferior firm attachment.
- proprioceptive nerve endings ( perceiving movement ) found in GH ligaments and labrum so disruption leads to decrease in that.
- site of GH ligament attachment.
what is responsible for the mobility of the shoulder joint?
- shallow glenoid fossa.
- disproportion of articular surface.
- lax capsule : relaxed.
name some static stabilisers of the shoulder joint.
- glenoid labrum.
- joint capsule.
- intracapsular ligaments.
- extracapsular ligaments.
name some dynamic shoulder stabilisers.
- rotator cuff muscles.
- other muscles : deltoid, corabrachialis, long head of biceps and triceps.
what are the features of the capsule at the shoulder?
- attached to glenoid labrum, margining fossa and anatomical neck of humerus from other side.
- medially dips to surgical neck.
- tough but lax to allow movement.
- small opening with synovial membrane.
what is the significance of the synovial membrane?
- lines the capsule, intracapsular bone to articular cartilage, covers tendon of long head of bicep within joint cavity.
what are the intracapsular ligaments?
- 3 glenohumeral ligaments : superior, middle or inferior glenohumeral ligament.
- 3 fibrous band from glenoid labrum to humerus, reinforces capsule anteriorly.
- can be seen from inside the capsule.
what are the extracapsular ligaments?
- caracoacramial : caracoid to acromion.
- carocohumeral : caracoid to anteior greater tubercule.
- transverse HL : holds tendon of long biceps head in place when shoulder moves.
what is the caracoacromial arch?
- structure comprises caracoid process, caracoacromial ligament and acromian process.
- prevents superior dislocation of humerus.
- IMPINGEMENT SYNDROME.
what muscles make up the rotator cuff? and whats the significance?
- supraspinatus, infraspinatus, teres minor, subscapularis (dorsal unlike others).
- important in contributing to stability as the cuff fuses with capsule and strengthens it holding humeral head in glenoid cavity.
- subacromial bursa separates suprapinatus from caracoacromial arch.
what are the actions of the rotator cuff muscles?
- supraspinatus : initiation and first 15 of abduction.
- infraspinatus : lateral.external rotation of arm.
- teres minor : lateral arm rotation.
- sunscapularis : medial/ internal rotation.
*also stabilised by deltoid, long biceps head, long biceps head, caracobrachialis.