MSK Exam 3

sternoclavicular joint, acromioclavicular joint, scapulothoracic joint, glenohumeral joint

What are the 4 joints that make up the shoulder complex?

sternocalvicular (SC) joint

connects sternum and clavicle

acromioclavicular (AC) joint

connects clavicle and scapula

scapulothoracic joint

connects scapula and rib cage

glenohumeral joint

connects scapula and humerus

clavicle

connects upper extremity with axial skeleton

scapula

triangular flat bone that overlies ribs 2nd-7th posteriorly

superior, medial, and axillary borders

what are the three main borders of the scapula?

- attachment for upper appendicular and axial skeleton
- serve as the base for upper extremity movement

What are the 2 primary purposes of the pectoral girdle?

sternum (manubrium), clavicle, scapulae

what bones form the partial ring of the pectoral girdle?

humerus

what is the longest bone in the body?

sternoclavicular joint

the articulation between manubrium of the sternum and medial end of the clavicle

the sternoclavicular joint

what the only direct connection of the upper limb to the axial skeleton

articular disc

what improves joint congruency at the sternoclavicular joint?

fibrocartilage

what is the articular disc made of?

improve joint congruency and absorb shock

what is the purpose of the articular disc?

saddle joint (triaxial)

what kind of joint is the sternoclavicular joint?

elevation/depression, protraction/retraction, upward/downward rotation

what motions occur at the sternoclavicular joint?

anterior sternoclavicular ligament, posterior sternoclavicular ligament, interclavicular ligament, costoclavicular ligament

What ligaments support the sternoclavicular joint?

prevents excessive retraction and elevation

what actions occur at the anterior sternoclavicular ligament?

prevents excessive protraction and elevation

what actions occur at the posterior sternoclavicular ligament?

prevents excessive retraction and depression

what actions occur at the interclavicular ligament?

costoclavicular ligament

what actions occur at the costoclavicular ligament

during abduction or flexion of glenohumeral joint, the clavicle rotates upwardly. Opposite occurs during extension and adduction

what happens at the long axis of clavicular rotation

acromioclavicular joint

articulation between acromion process of scapula and lateral end of clavicle

plane synovial joint

what kind of joint is the acromioclavicular joint?

gliding, clavicle rotates when scapula elevates and depresses

What kind of actions occur at acromioclavicular joint?

acromioclavicular ligaments, coracoclavicular ligaments, and coracoacromial ligments

what 3 types of ligaments occur at the acromioclavicular joint?

- superior and inferior thickening in the joint capsule
- holds AC joint together

What is the purpose of acromioclavicular ligaments?

conoid ligament and trapezoid ligament

What 2 ligaments make up the coracoclavicular ligaments?

inferior aspect of clavicle to coracoid process of scapula

Where are the coracoclavicular ligaments located?

prevent excessive elevation of the clavice

What is the purpose of the coracoclavicular ligaments?

the coracoid process to the acromion process of the scapula

Where does the coracoacromial ligament run?

- provides stability on superior aspect of GH joint
- forms roof of coracoacromial arch

What is the purpose of the coracoacromial ligament?

coracoacromial arch

Osteoligamentous structure formed by acromion process, coracoacromial ligament, and coracoid process

prevents superior translation of humerus

what is the purpose of the coracoacromial arch?

glenohumeral joint

articulation between head of humerus and glenoid fossa of scapula

multi-axial ball and socket joint

what kind of joint is the glenhumeral joint?

sacrifices stability for mobility

What compromise does the glenhumeral joint make?

sagittal, frontal, transverse planes

what planes of motion does the glenhumeral joint act in?

flexion/extension, abduction/adduction, internal/external rotation, horizontal abduction/adduction, circumduction

what actions occur at the glenhumeral joint?

anterior, posterior, and inferior capsule

what are the main parts of the glenohumeral joint capsule?

3

how many distinct thickenings does the anterior capsule have?

none

how many thickenings does the posterior capsule have?

glenoid labrum

fibrocartilaginous rim around the perimeter of the glenoid cavity

deepens the socket

what is the primary function of the glenoid labrum

anterior glenhumeral ligaments

fibrous bands that run from glenoid to anatomical neck

superior, middle, and inferior

what are the 3 distinct bands of the anterior glenhumeral ligaments

prevents humerus from displacing anteriorly

what is the main function of the anterior glenhumeral ligaments?

runs from the lateral aspect of the coracoid process to greater tuberacle of the humerus

Where does the coracohumeral ligament run?

provides anterior stability to GH joint

what is the primary function of the coracohumeral ligament?

runs from the greater to the lesser tuberacles over the intertubercular groove and superficial to the long head of the biceps tendon

Where does the transverse humeral ligament run?

holds tendon in place

what is the primary function of the transverse humeral ligament?

bursa

flattened sac containing synocial fluid that reduces friction between two moving structures in the body

between the subscapularis tendon and the coracoid process

Where is the subscapular bursa located?

inferior to the coracoacromial arch and superior to the supraspinatus tendon

what is the subacromial bursa located?

subdeltoid bursa

what other bursa is the subacromial bursa continuous with?

atop the 2nd and 7th ribs

where does the scapulothoracic joint lie?

- no joint capsule
- no ligaments
- muscles on anterior scapula prevent articulation of bones

why is the scapulothoracic joint not a true joint?

elevation/depression, protraction/retraction, upward/downward rotation

what motions occur at the scapulothoracic joint?

scapulohumeral rhythm

coordination of movements between the scapula, clavicle, and humerus

GH joint, ST joint, SC joint, and AC joint

what 4 joints must work together to ensure scapulohumeral rhythm?

2:1 ratio of GH:ST

what is the ratio of movement between glenohumeral and scapulothoracic joints?

120 degrees abduction/flexion of humerus

during 180 degrees of abduction of the arms, what happens at the glenohumeral joint?

60 degrees upward rotation of scapula

during 180 degrees of abduction of the arms, what happens at the scapulothoracic joint?

30 degrees elevation of clavicle

during 180 degrees of abduction of the arms, what happens at the sternoclavicular joint?

30 degrees upward rotation of clavicle

during 180 degrees of abduction of the arms, what happens at the acromioclavicular joint?

thoracoappendicular muscles

muscles that move the pectoral girdle

subclavius, pectoralis minor, serratus anterior

What are the anterior muscles that move the pectoral girdle?

serratus anterior

dysfunction of what muscle causes winging of the scapula?

trapezius, levator scapulae, rhomboid major, rhomboid minor

what posterior muscles move the pectoral girdle?

humerus

what bone does the rotator cuff muscles work to move?

supraspinatus, infraspinatus, teres minor, subscapularis

what muscles make up the rotator cuff?

external/internal rotation, abduction

what actions do rotator muscles help with?

dynamic stabilizer to pull humeral head into socket when raising the arm

what is the main function of the rotator cuff muscles?

pectoralis major, deltoid, coracobrachialis, biceps brachii

what are the anterior muscles that move the humeus?

latissimus dorsi, teres major, triceps brachii

what are the posterior muscles that move the humerus?

pectoralis major, coracobrachialis, latissimus dorsi, teres major

what muscles are involved in adduction?

supraspinatus, deltoid

what muscles are involved in abduction?

subscapularis, pectoralis major, latissimus dorsi, teres major

what muscles are involved in internal rotation

infraspinatus, deltoid

what muscles are involved in external rotation?

supraspinatus-deltoid force couple

Supraspinatus initiates abduction by elevating the humeral head and pulling it snugly into the glenoid fossa (with other rotator cuff muscles)

Deltoid has a mechanical advantage to abduct humerus once humeral head is stabilized in glenoid

upper trapezius-serratus anterior force couple

Upper trapezius contracts to upwardly rotate the scapula

Serratus anterior contracts to pull the scapula away from the midline of the body

Resultant vector causes the scapula to protract around the circumference of the rib cage

flexion/extension

what motions occur at the elbow?

olecranon process

where on the elbow does motion occur?

supination/pronation

what motions occur at the forearm?

radioulnar joint

where do motions at forearm occur?

humerus, ulna, radius

what bones make up the elbow and forearm?

radius

what bone moves during pronation and supination?

capitulum

part on humerus that articulates with radius

trochlea

part on humerus that articulates with ulna

radial fossa

part of the humerus that fits the radial head during flexion

coronoid fossa

part of the humerus that fits coronoid process during flexion

olecranon fossa

part of the humerus that fits olecranon process during extension

right behind medial epicondyle of humerus

where does ulnar nerve run?

trochlear notch

articulates with trochlea of humerus

olecranon process

proximal end of ulna and lip of trochlear notch

coronoid process

distal lip of trochlear notch

radial notch of ulna

articulates with radial head, proximal

ulnar head

articulates with ulnar notch of radius, distal