Gross Anatomy L12

what does shoulder complex do

connects upper limb to thorax, provides dynamic stability

two muscular regions of shoulder

scapulohumeral and axioappendicular

static stabilizers

boney and ligamentous structures that strengthen a joint to maintain it’s stability

dynamic stabilizers

muscles that both move a joint and contribute to it’s stability

three bones of the shoulder

clavicle, scapula, proximal humerus

three joints of shoulder

sternoclavicular, acromioclavicular, glenohumeral, scapulothoracic

four muscle groups of the shoulder

scapulohumeral, anterioraxioappendicular, posterior axioappendicular (superficial extrinsic back), arm

what bones make up the pectoral girdle

clavicle, scapula

where does clavicle articulate

acromion at acromial end (acromioclavicular joint), manubrium at sternal end (sternoclavicular joint)

what does clavicle do in pectoral girdle

attach shoulder girdle to thorax

what does scapula do for pectoral girdle

attach pectoral girdle to humerus (glenohumeral joint)

facets of greater tubercle of the humerus

superior, middle, inferior

what muscle attaches to superior facet of greater tubercle

supraspinatus

what muscle attaches to middle facet of greater tubercle

infraspinatus

what muscle attaches to inferior facet of greater tubercle

teres minor

what muscle attaches to lesser tubercle

subscapularis

parts of intertubercular sulcus

medial lip, lateral lip, floor

what muscle attaches to the medial lip of the intertubercular sulcus

teres major

what muscle attaches to the floor of the intertubercular sulcus

latissimus dorsi

what muscle attaches to the lateral lip of the intertubercular sulcus

pectoralis major

what muscle attaches to the deltoid tuberosity

deltoid

sternoclavicular joint

shallow saddle joint, elevation and depression, protraction and retraction, anterior and posterior rotation, strong joint capsule

four ligaments of the sternoclavicular joint

anterior and posterior sternoclavicular ligaments, interclavicular ligament, costoclavicular ligament

what do the anterior and posterior sternoclavicular ligaments do

support for the articular disc, increases joint stability

what does the interclavicular ligament do

limits excessive depression

what does the costoclavicular ligament do

limit elevation

acromioclavicular joint

synovial plane joint, upward and downward rotation of scapula, anterior and posterior tilting of scapula, internal and external rotation of scapula, weaker capsule prone to degeneration

ligaments of the acromioclavicular joint

superior acromioclavicular ligament, inferior acromioclavicular ligament, inferior acromioclavicular ligament, coracoclavicular ligament

superior acromioclavicular ligament

restraint to anterior forces

coracoclavicular ligament

unites clavicle and scapula, conoid ligament and trapezoid ligament

what type of joint is the glenohumeral joint

synovial ball and socket, most mobile joint in the body

what actions does the glenohumeral joint do

flexion and extension, abduction and adduction, medial and lateral rotation, circumduction

what is the ring of fibrocartilage that extends the depth of the glenoid fossa called

glenoid labrum

how much of the humeral head fits in the glenoid fossa

less than 1/3

what are the ligaments of the glenohumeral area

superior glenohumeral ligament, middle glenohumeral ligament, inferior glenohumeral ligament, coracohumeral ligament

superior glenohumeral ligament attachments

superior glenoid labrum to upper humeral neck

middle glenohumeral ligament attachments

anteriorsuperior glenoid labrum to anterior aspect of proximal humerus

inferior glenohumeral ligament attachments

anterior and posterior ligament bands with an axillary pouch in between

coracohumeral ligament attachment

inserts on base of coracoid process, forms two bands, upper band inserts onto greater tubercle and lower band inserts onto lesser tubercle, long head biceps brachii passes through the two bands

what is scapulohumeral rhythm

scapula movement and positioning of the glenoid fossa influence glenohumeral joint function

anterior shoulder dislocation

inferior and anterior parts of glenohumeral joint capsule loose, forced abduction and lateral rotation can cause head of humerus to slide out of glenoid fossa anteriorly

coracoacromial arch

osteoligamentous arch formed by coracoid process, acromion and AC joint, and coracoacromial ligament, protects subacromial space

what does the subacromial space contain

subacromial bursa, rotator cuff tendons, tendon of long head of biceps brachii

scapulohumeral muscles

deltoid, teres major, supraspinatus, infraspinatus, teres minor, subscapularis

where do all scapulohumeral muscles originate and insert

originatet from scapula, insert onto the humerus (deltoid has clavicular origin)

what muscles are part of the rotator cuff

supraspinatus, infraspinatus, teres minor, subscapularis

supraspinatus action and innervation

abduction, suprascapular nerve

infraspinatus action and innervation

lateral rotation, suprascapular nerve

teres minor action and innervation

lateral rotation, axillary nerve

subscapularis action and innervation

medial rotation, upper and lower subscapular nerves

parts of the deltoid and innervation

anterior, medial, posterior, axillary nerve

anterior deltoid action

flexion, medial rotation, abduction

medial deltoid action

abduction

posterior deltoid action

extension, lateral rotation

teres major action and innervation

extension, adduction, medial rotation, lower subscapular nerve

what do the anterior axioappendicular muscles do

act to move pectoral girdle and support shoulder during movement, all attach proximally to ribs or costal cartilage, all attach distally to scapula or clavicle

four muscles of the anterior axioappendicular muscles

pectoralis major, pectoralis minor, subclavius, serratus anterior

two heads of pectoralis major

clavicular and sternocostal

what innervates pectoralis major

lateral and medial pectoral nerves

actions of pectoralis major

adduct and medially rotate humerus, depress and protract scapula, flex arm, extend arm from flexed position

pectoralis minor actions

depression, protraction, downward rotation

what innervates pectoralis minor

medial pectoral nerve

subclavius action

stabilizes sternoclavicular joint, pulls clavicle inferiorly

subclavius innervation

nerve to subclavius

serratus anterior action

boxers muscle, protract scapula, upward rotation, stabilization of scapula during abduction of arm

what innervates serratus anterior

long thoracic nerve

serratus anterior paralysis

scapular winging, loss of elevation, deltoid cannot produce abduction

posterior axioappendicular muscles (superficial extrinsic back muscles)

trapezius, latissimus dorsi, levator scapulae, rhomboid major, rhomboid minor

parts of the trapezius

descending, middle, ascending

descending trapezius actions

elevates scapula

ascending trapezius action

depresses scapula

middle trapezius action

retracts scapula

descending + ascending trapezius action

rotate glenoid superiorly

trapezius innervation

spinal accessory nerve

latissimus dorsi action

extends, adducts, medially rotates shoulder joint, raises trunk toward arms when upper limb is fixed

latissimus dorsi innervation

thoracodorsal nerve

rhomboid major action

retract scapula and rotate glenoid cavity inferiorly, fix scapula to thoracic wall

rhomboid major innervation

dorsal scapular nerve

rhomboid minor actions

retracts scapula and rotates glenoid cavity inferiorly, fix scapula to thoracic wall

rhomboid minor innervation

dorsal scapular nerve

levator scapulae actions

elevate scapula, rotate glenoid cavity inferiorly

levator scapulae innervation

dorsal scapular

axillary nerve innervates…

deltoid, teres minor

suprascapular nerve innervates

supraspinatus, infraspinatus

upper subscapular nerve innervates

subscapularis

lower subscapular nerve innervates

subscapularis, teres major

lateral pectoral nerve innervates

pectoralis major

medial pectoral nerve innervates

pectoralis minor, pectoralis major

long thoracic nerve innervates

serratus anterior

nerve to subclavius/subclavian nerve innervates

subclavius

spinal accessory nerve innervates

trapezius

C3 C4 ventral rami innervate

proprioception and nociception for trapezius

thoracodorsal nerve innervates

latissimus dorsi

dorsal scapular nerve innervates

levator scapulae and rhomboids