WS 1 bones & joints of the shoulder girdle, muscles of the shoulder girdle

Pectoral/shoulder girdle

Bones = clavicle, scapula, manubrium of sternum, proximal humerus

Joints = Sternoclavicular (SC), acromioclavicular (AC), glenohumeral (GH)

Clavicle

connects upper limb to axial skeleton

long bone

articulates ac and sc joints

Clavicle labelling

Superior surface = smooth

inferior = rough

medial end (sternal) = convex anteriorly

lateral end (acromial end) = concave anteriorly

Scapula posterior aspect

spine of scapula

supraspinous fossa

infraspinous fossa

scapula notch

Scapular anterior aspect

subscapular fossa (subscapularis muscle is on this)

three angles - superior, inferior, lateral

three borders - medial, lateral, superior

Scapula - processes, cavity, tubercle

acromial process/acromion - participates in ac joint

coracoid process - lig and muscle attachment

glenoid fossa

supragenoid & infraglenoid tubercle - muscle attachment sites

Humerus

articulates w scapula at gh joint and radius + ulnar at elbow joint

largest bone of upper limb

Humerus - proximal aspect

head of humerus

anatomical neck

greater + lesser tubercle

Intertubercular/ bicipital groove

surgical neck

Humerus - distal aspect

shaft

deltoid tuberosity

radial groove

lateral and medial epicondyles

lateral and medial supracondylar ridges

capitulum and trochlea

fossa - radial, coronoid and olecranon

Scapula movements

protractions, retraction, elevation, depression, rotation of the scapula cannot occur in isolation

Glenohumeral movements

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

Sternoclavicular joint (SC)

articulation between the clavicle and the sternum

saddle synovial joint - functions like ball and socket

articular disc- shock absorber, fibrocartilage

SC joint ligaments

Anterior and posterior Sternoclavicular ligaments

Interclavicular ligament

Costoclavicular ligament

SC joint movements

elevation/depression, protraction/retraction, rotation, circumduction

SC NS

Medial supraclavicular nerve, Nerve to subclavius

Acromioclavicular joint (AC)

articulation between acromion process of scapula and lateral end of clavicle

plane synovial joint

articular disc - fibrocartilage

AC joint ligaments

Acromioclavicular ligament

Coracoclavicular ligament

Coracoacromial ligament

AC joint movements

Acromion of the scapula glides on the acromial end of the clavicle

Axioappendicular muscles move the scapula which in turn moves the acromion on the clavicle

AC NS

lateral supraclavicular nerve, lateral pectoral nerve, axillary nerve

AC joint disclocation

= step defect

Glenohumeral joint (GH)

articulation between the humeral head and the glenoid cavity/fossa of the scapula

ball and socket synovial joint

GH joint ligaments

Glenohumeral ligaments

Transverse humeral ligament

Coracohumeral ligament

Coracoacromial ligament

GH movements

all of them

GH bursa

subacromial bursa, subscapular bursa

bursa - synovial membrane sac which prevents friction

GH NS

axillary nerve, suprascapular nerve, lateral pectoral nerve

Glenoid labrum

fibrocartilaginous, lines glenoid fossa, increases stability

Coracoacromial arch

formed by coracoid process, acromial process (acromion), coracoacromial ligament

Coracoacromial arch function

protection of gh ligament, prevents dislocation

Scapulothoracic joint

not an actual joint

area where scapula moves on the thoracic cage due to contraction of the axioappendicular muscles e.g elevation/depression, protraction/retraction, upward and downward rotation

Muscles of pectoral/shoulder girdle

anterior axioappendicular muscles, posterior axioappendicular muscles, scapulohumeral muscles which cointains the rotator cuff muscles

Anterior axioappendicular muscles/pectoral muscles

connect axial skeleton to upper limb

move pectoral girdle

four muscles, pec major, pec minor, subclavius, serratus anterior

Posterior axioappendicular muscles/extrinsic shoulder muscles

5 muscles

superficial muscles = trapezius, latissimus dorsi

deep muscles = levator scapulae, rhomboid major, rhomboid minor

Scapulohumeral muscles/intrinsic shoulder muscles

attach between scapula and humerus

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

Rotator cuff

SITS

S=supraspinatus

I=infraspinatus

T=teres minor

S=subscapularis

note: all except supraspinatus are rotators of the glenohumeral joint (supraspinatus does not medially or laterally rotate the humerus, it only abducts it)

Fascia of upper limb

Pectoral fascia - chest region

Brachial fascia - arm

Antebrachial fascia - forearm

Palmar aponeurosis - palm of hand

Function of fascia

protect body structures, limits spread of infection, aids the musculovenous pump by limiting outward expansion of muscles, holds tendons in place (retinaculae)

Fascia of upper limb - arm

fascia between muscle compartments, often called intermuscular septa

arm = lateral & medial intermuscular septa form the anterior and posterior compartments of the arm

Fascia of upper limb - forearm

forearm has interosseous membrane which attaches to the bones of the forearm - separates anterior and posterior forearm muscles

Flexor retinaculum (palmar surface of hand/wrist)

Extensor retinaculum (dorsum of hand/wrist)

Fascia of upper limb - hand

Palmar aponeurosis - central, triangular, thickened area of the fascia of the palm