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.
what are the significance of shoulder bursae?
- subacromial bursa : facilitates supraspinatus tendon under coracoacromial arch and deltoid movement.
- subscapula bursa : facilitates subscapularis tendon over scapula
what does the aubacromial space contain?
- subacromial bursa, supraspinatous tendon, capsule, tendon of long head of biceps.
what nerves and arteries supply the shoulder joint?
- nerves : axillary, suprascapular, lateral pectoral nerve from brachial plexus C5, C6.
- blood : anterior circumflex humeral, posterior circumflex humeral, suprascapular artery.
what muscles are responsible for shoulder abduction?
think in 0-15, 15-90 and 90-150 degrees
first 90 : across glenohumeral joint.
- 0-15 : supraspinatus (suprascapular nerve)
- 15-90 : deltoid central fibres (axillary nerve)
90-150 : across scapulothoracic joint.
- rotation of scapula trapezius (upper fibres) and serratus anterior.
describe the deltoid muscle.
- origin : anterior and upper at clavicle, acromion of scapula, spine of scapula.
- insertion : deltoid tuberosity on lateral humerus.
- nerve supply : axillary (C5, C6)
what movements are the deltoid muscle a part of?
- anterior fibres : flex and medially rotate arm and shoulder.
- central and middle fibres : abduct arm from 15-90.
- posterior fibres : extend and laterally rotates arm at shoulder.
describe the features of the trapezius muscles.
origin : external occipital protuberance of skull, nuchal ligament, spinous processes of C7, T12.
insertion : clavicle, acromion, spine of scapula.
nerve : spinal accessory nerve, proprioceptive fibres from C3 and C4.
what movements are the trapezius muscle a part of?
- upper fibres : rotate acromion of scapula upwards during abduction of shoulder.
- lower fibres : rotate medial spine of scapula downwards.
describe the features and movements of the serratus anterior.
origin : lateral ribs of 1-8 / 1-9.
*fibres pass deep into scapula and insert into medial border.
nerve : long thoracic nerve (C5,6,7) prone to injury at mastectomy causing winging of scapula.
actions : protraction of scapula, scapula rotation during shoulder abduction from 90-150.
what muscles are responsible for extension of shoulder?
- posterior fibres of deltoid (axillary C5,6).
- latissimus dorsi (thoracodorsal nerve C6,7,8).
- teres major (lower subscapular nerve C5,6).
describe the features of the latissumus dorsi.
- origin : spinous processes of T6-T12, thoracolumbar fascia, illiac crest and 3 lower ribs.
- insertion : intertubucular sulcus of humerus.
action : extends, adducts and medially rotates shoulder.
describe the features of teres major.
- origin : posteriot surface of inferior scapula angle.
- insertion : medial lip of intertubecular groove humerus.
- action : adducts, extends and medially rotates the shoulder.
what muscles are responsible for shoulder flexion.
- clavicular head of pectoralis major. : medial and lateral pectoral nerves.
- anterior deltoid fibres : axillary.
- carocabrachialis : musculocutaneos nerve.
- biceps brachialis : musculacutaneous nerve.
describe the features of pectoralis major.
- origin : clavicular head, sternocostal head.
- insertion : lateral lip of intertubercular sulcus.
- actions : adducts shoulder, flexes shoulder, internally rotates shoulder.
describe the features of the caracobrachialis.
- origin : caracoid process of scapula.
- insertion : medial humeral shaft.
- nerve : musculocutaneous nerve.
- action : weak flexor and adductor of shoulder.
describe the features of biceps brachialis.
- origin : long head from supraglenoid tubercule of scapula and short head from caracoid process.
- insertion : radial tuberosirty via biceps tendon and deep fascia of forearm.
- actions : weak contribution to shoulder flexion, strong supinator, flexor of elbow.
what muscles are responsible for shoulder adduction?
- pectoralis major.
- latissimus dorsi.
- teres major.
what muscles are responsible for shoulder medial rotation?
- sternocostal head of pectoralis major, suscapularis, teres major, latissimus dorsi.
what muscles are responsible for shoulder external rotation?
- infraspinatues : subscapular nerve.
- teres minor : axillary.
