T2 l3: anatomy of the shoulder region Flashcards
what does the pectoral girdle consist of
Clavicle and scapula
what 2 joints are in the pectoral girdle
- glenohumeral
- acromioclavicular
function of ligaments
Stabilize the shoulder region
what are the 4 ligaments of the shoulder region
coracoclavicular
acromioclavicular
coracoacromial
glenohumeral:
- Superior
- middle
- inferior
describe the coracoclavicular ligament
- 2 parts
- major stabilizing ligament
describe the coracoacromial ligament
- Forms arch
- Provides support for head of humerus
- prevents superior dislocation
Glenohumeral joint:
describe type of joint
describe its function:
ball and socket joint
- Abduction/Adduction
- Flexion/Extension
- Lateral/Medial rotation
- Circumduction
Deltoid muscle
Spine of scapula+clavicle + acromion
deltoid tuberosity
post fibres: -extension + lateral rotation
anterior fibres: -flexion and medial rotation
supplied by axillary nerve
overall: arm abduction
what 2 muscles help the arm adduct
Latissimus dorsi, pec major
what are the 2 structural components that allows the arm to abduct/adduct
- glenohumeral joint
- the scapula
what muscles act on the scapula and in what direction n
Abduction : Upper fibres trapezius
serratus anterior
lower fibres trapezius
Adduction :
levator scapulae
rhomboids
what muscles perform arm flexion
Coracobrachialis
biceps brachii
what muscles perform arm extension
Triceps brachii
post fibres deltoid
latissimus dorsi
what contributes to glenohumeral joint stability
large humeral head
shallow glenoid fossa
what is most common type of dislocation of the glenohumeral joint
anterior dislocation common
what are the 5 factors that increase stability of glenohumeral joint
Coracoacromial arch
- Glenohumeral ligaments
- Deepening of glenoid fossa by glenoid labrum
- Long heads of biceps (above) and triceps (below)
- Tendons of rotator cuff muscles
what is the function of the coracoacromial arch
prevents superior dislocation
whay is the function of the glenohumeral ligaments
- Supports anterior of joint (sup mid and inferior )
what is the function of the glenoid labrum
deepens the glenoid fossa
what is the structural function of the long head of the biceps and triceps
Splint joint- passes through its origin-jo capsule- transverse humeral ligament- intertubercular sulcus
triceps- origin helps stabilise it
what are the structural function of the rotator cuff muscles
4 muscles - insert close to glenohumeral joint- fuse with the capsule and forms a cuff around the joint
what are the rotator cuff muscles
Supraspinatous
infraspinatous
teres minor
subscapularis
where do the SIT muscles insert
Greater tubercle
where does the subscapular muscle insert
lesser tubercle
describe the action of the teres major and why it can be considered a rotator cuff muscle
Performs medial rotation
Stabilises the humerus during
abduction - Eccentric contraction
describe an injury to the rotator cuff muscles
Supraspinatus impingement
:Supraspinatus most commonly injured
Limited space for tendon under coracoacromial arch
- Impingement due to repetitive overhead activities
- Common in athletes (throwers)
what is the blood supply to the shoulder
Scapula anastomosis- via subclavian and axillary arteries
describe scapula anastomosis
From subclavian :
upwards- thyrocervical trunk- suprascapular
downwards- dorsal scapula r- subscapular
describe the nerve supply to the shoulder
superior trunk-suprascapular nerve- infr and supraspinatous muscles
posterior cord:
- axilla-teres minor & deltoid
- radial- triceps brachii
- upper/lower subscapular nerves- subscapularis, teres major
Thoracodorsal nerve- latissimus dorsi
lateral cord:
- musculocutaneous - arm flexors
lateral pectoral nerve - pectoralis major
Medial cord: medial pectoral nerve - pectoralis major/minor
and to cutaneous nerves to arm and forearm
what is the quadrangular space and its importance
made up of teres major and minor as well as the humerus and the long head of the biceps
axllary nerve & post circumflex humeral artery passes through trough to supply deltoid and teres minor and badge area
fracture of surgical neck can damage nerve and vessel
