scapular region & the shoulder joint Flashcards
what is the clavicle?
- an s shaped bone that rests on the sternum across the upper part of the ribcage and the acromial end of the scapula
what is the costal tuberosity?
- located at the sternal end of the clavicle
- broad surface
- where the costoclavicular ligament attaches
what is the conoid tubercle?
- found closer to the acromial end of the clavicle
- coracoclavicular ligament joins
is the inferior or superior surface of the clavicle smooth ?
the superior surface - facing upwards
what 3 bones make up the ‘shoulder girdle’?
- scapula
- clavicle
- proximal end of the humerus
what is the scapula also called?
the shoulder blade
what 2 important bones does the scapula articulae with and as a result what joints are formed?
- humerus - glenohumeral joint / shoulder joint
- acromioclavicular joint
what are important features of the scapula in an anterior and posterior view?
anterior
* coracoid process - pec minor attaches here
* glenoid cavity
* lateral border, medial boarder, superior border
* acromion
* subscapular fossa
posterior view
* spine of scapula
* supraspinous fossa
* infraspinous fossa
*
what are important features on humerus (anterior) ?
Anterior view
* head of humerus
* **greater tubercle
* lesser tubercle **
* intertubercular groove
* **anatomical **neck
* surgical neck
* **deltoid tuberosity **- where deltoid muscle attache
what are important features of the humerus (posterior)?
posterior view
* radial groove
* olecranon fossa
what muscles attach to the greater tubercle of the humerus?
SIT
- supraspinatus
- infraspinatus
- teres minor
Describe the sternoclavicular joint
- atypical synovial joint - it contains fibrocartilage on articular surfaces
- only bony articulation between the upper limb and axial skeleton
- connects the sternum and clavicle
Describe the **acromioclavicular joint **
- atypical synovial joint - fibrocartilage on articular surfaces (and not hyaline like normal)
- articulation between the clavicle and the scapula
- multi axial joint
describe the** coracoclavicular joint **
- extends between the acromial end of the clavicle and coracoid process of the scapula
- it has 2 parts - a conoid and trapezoid part
what is the trapezius muscle?
- large triangular diamond shaped muscle at the posterior aspect of the neck and thorax
- extrinsic muscle of the back
what are the origins and insertions of the trapezius muscle?
- O: external occipital protuberance to T12 vertebrae,
- I: lateral clavicle, acromion and spine of scapula
what are the actions of the trapezius on the scapula and the shoulder joint?
- scapula - elevation retraction and lateral rotation
- shoulder joint - abduction - past 90 degrees, it helps to laterally rotate the scapula
where does the levator scapulae originate and insert onto?
- O: C1-C4 vetrebrae (traneverse processes)
- I: superior angle of scapula
where does the rhomboid minor muscle originate and attach onto?
- O : C7 & T1 vertebrae
- I: medial scapula
where does the rhomboid major muscle originate and attach onto?
- O: T2-T5 vertebrae
- I: medial scapula
what are actions of levator scapulae, rhomboid maj and minor muscles?
- to retract and medially rotate scapula
what muscles protact the scapula (ie push forward like pushing against a wall)?
- serratus anterior
- pec minor
what muscles retract or pull back the scapula?
- trapezius
- rhomboids
what muscles elevate the scapula?
shrug
- trapezius
- levator scapulae
what muscles depress the scapula?
- trapezius
- latissimus dorsi
what muscles laterally rotate the scapula?
- trapezius
- serratus anterior
what muscles medially rotate the scapula?
- levator scapulae
- rhomboids
what are the 4 rotator cuff muscles?
SSIT
- Supraspinatus
- subscapularis
- infraspinatus
- teres minor
where does the deltoid muscle originate and insert onto?
- O: lateral clavicle, acromion and spine of scapula
- I: deltoid tuberosity
what nerve innervates the deltoid muscle?
the axillary nerve
what are the actions of the deltoid muscle?
and posterior vs anterior fibres
- abduction
- posterior fibres extend arm
- anterior fibres flex arm
where does the** teres major **originate and insert onto?
- O: inferior angle of scapula and lower medial border
- I: intertubercular groove
what nerve innervates the teres major muscle?
lower subscapular nerve
what are the actions of the teres major muscle?
- adduction of the arm
- medial rotation of the arm
where does the supraspinatus muscle originate and insert onto?
- O: supraspinous fossa
- I: greater tuberosity of humerus
what nerve innervates the supraspinatus muscle?
suprascapular nerve
what is the main action of the supraspinatus muscle?
abduction of the arm
where does the infraspinatus muscle originate and insert onto?
- O: infraspinous fossa
- I: greater tuberosity/ tubercle of humerus
what** nerve** innervates the** infraspinatus muscle** and what is the** muscles main actions?**
- nerve - suprascapular nerve
- actions : adduction, lateral rotation & stabilisation
where does teres minor muscle originate and insert onto?
- O: lateral scapula
- I: greater tubercle / tuberosity of humerus
what nerve innervates the teres minor muscle?
axillary nerve
what are the main actions of the teres minor muscle?
- adduction
- lateral rotation
- stabilisation
where does the subscapularis originate and insert onto?
- O: subscapular fossa
- I: lesser tuberosity of humerus
what nerves innervate the subscapularis muscle?
- upper and lower subscapular nerves
what type of joint is the shoulder joint?
synovial ball and socket
what are the articulating surfaces of the shoulder joint
- head of humerus (convex) - this is the moving part
- glenoid cavity & labrum (concave)
what are the main supporting ligaments of the shoulder joint?
- sup, middle and inf glenohumeral ligaments
- coracohumeral ligament
- transverse humeral ligament
what is the function of the coracohumeral ligament?
- prevents excessive external rotation of the humerus
what are the 3 bursae of the shoulder joint?
* subacromial bursa
* infraspinatus bursa
* subscapularis bursa
due to the shoulders high mobility, what can be a problem?
- the shoulder is not a stable joint
- there is a poor fit between bones - ie the head of humerus is 4 times larger than the glenoid cavity - ie they are incongruent
what is the most common type of dislocation of the shoulder?
- anteroinferior dislocation
- prominent acromion
what is suprascapular nerve entrapment syndrome?
- supraspinatus weakness - difficulty or inability to abduct first 10%
how can rotator cuff injuries occur?
- wear and tear over time
- overhead motions
