shoulder and arm Flashcards
pectoral girdle: describe the anatomy of the pectoral girdle, explain the movements of the pectoral girdle; identify the muscles and joints responsible for these movements and list the main attachments and nerve supply of these muscles
3 bones of region
scapula, clavicle, humerus
sections of scapula
spine on posterior surface separating suprapinous and infraspinous fossa; lateral end is acromion; coracoid process protrudes forward; lateral arch bone widened into glenoid cavity and rim (socket for ball and socket joint); superior, lateral and inferior angles
sections of clavicle, including when it becomes calcified
first bone to start becoming calcified during foetal development, and one of the last to finish; S-shaped, flattened at acromial-end; sternal end has flattish sternal facet that articulates with manubrium and first costal cartilage
sections of humerus
long bone with relatively straight shaft; proximal and distal ends are widened out; smooth rounded head; radial groove; deltoid tuberosity (irregular) where proximal part of deltoid attaches; epicondyles above sections of condyles (capitulum and trochlea)
2 necks of humerus
surgical, anatomical (true)
what humerus neck is more commonly damaged
surgical
location of proximal attachments in general
closer to trunk
5 muscular anatomy compartments of shoulder and arm
anterior pectoral girdle muscles, posterior pectoral girdle muscles, intrinsic shoulder muscles, anterior compartment of [“upper”] arm, posterior compartment of [“upper”] arm
4 anterior pectoral girdle muscles
pectoralis major, pectoralis minor, subclavius, serratus anterior
orientation serratus anterior runs
posterior to anterior
proximal and distal attachments of pectoralis major
proximal attachments to medial 1/3 clavicle (clavicular head), sternum, costal cartilages (sternocostal head); distal attachment to lateral lip of intertubercular sulcus (groove) in anterior part of humerus
nerves supplying pectoralis major
medial and lateral pectoral nerves
functions of pectoralis major
adducts and medially rotates humerus (lesser actions on scapula)
pectoralis minor proximal attachment
coracoid process of scapula
pectoralis minor distal attachment
finger-like parts which attach to 2-5th ribs (close to costrochondral joints)
pectoralis minor function
pulls scapula forward and possibly down
subclavius attachments
proximal to first rib close to costochondral joint; distal to clavicle
subclavius function
stabilising clavicle
serratus anterior attachments
runs from medial border of scapula, anteriorly over surface of thoracic cage, to anterior attachments on ribs (typically 1-9)
serratus anterior nervous supply
long thoracic nerve
serratus anterior function
holds scapula to wall
4 posterior pectoral girdle muscles
trapezius, latissimus dorsi, levator scapulae, rhomboids
trapezius attachments
attachments most superiorly to nuchal line of skull, cervical and thoracic vertebrae; descending (superior fibres), middle fibres come across, ascending (inferior fibres); curls round to front (very large muscle); attach to spine, clavicle and acromion
trapezius function
stabilise and move scapula
nerve innervation of trapzius
spinal accessory nerve (CN XI)
latissimus dorsi movements
extends adducts and rotates humerus e.g. pulls body up to arm during climbing
latissimus dorsi supply
thoracodorsal nerve
location and attachments of rhomboids
medial border of scapula; form quadrilateral parallelogram of muscle which attaches to spinous process of C7-T5 vertebrae
rhomboid nevrous supply
dorsal scapular nerve
rhomboid movement of scapula
retracts, rotates and fixes scapula
levator scapulae attachements
C1-C4 transverse process and superior angle of scapula
levator scapulae nervous supply
dorsal scapula nerve and C3,4
levator scapulae movement of scapula
elevates and rotates scapula
3 intrinsic shoulder muscles
deltoid, teres major, rotator cuff muscles
4 rotator cuff muscles
supraspinatus, infraspinatus, teres minor, subscapularis
deltoid nervous supply, attachments and movement
supplied by axillary nerve; attachments to spine of scapula, acromion and anterior to lateral clavicle (clavicular, middle and spinal/posterior part); abducts arm after 15 degrees
rotator cuff muscles, nervous supply, attachments and movement
cover scapula; supraspinatus in supraspinous fossa and infraspinatus in infraspinous fossa (supplied by siprascapular nerve); teres minor is straight and supplied by axillary nerve; broad subscapularis muscle is in deep surface (anterior surface of scapula); all run towards head of humerus, cross over shoulder joint to attach; main activity is to fix head of humerus in glenoid fossa, but with supraspinatus important in initiating abduction of arm for first 15 degrees
teres major nerve supply, attachments and function
innervated by lowest subscapular nerve; proximal attachment to inferior angle and distal to medial lip of interrubercular sulcus of humerus (latissimus dorsi attaches here too); adducts and medially rotates arm
3 muscles of anterior compartment of arm
biceps brachii, brachialis, coraco-brachialis
nerve supplying muscles in anterior compartment of arm
musculocutaneous nerve (C5,6,7), lying close to subscapularis tendon anterior to shoulder
biceps brachii proximal and distal attachments
short head more lateral (coracoid process), and long head more medially (goes through intertubercular groove held in place by ligament); crosses over shoulder joint and attaches to rim of glenoid fossa; both merge distally and form distal attachments at elbow, forming tendon attaching to radius (radial tuberosity) and bicepital aponeurosis
coracobrachialis proximal and distal attachments and function
corachoid process; spindle-shaped that broadens distally and attaches to humerus, acting across shoulder joint; adducts arm
brachialis location, function and proximal and distal attachments
underneath biceps; flexion of elbow joint; attaches to middle shaft of humerus proximally; distally has broad attachment at lower parts of shaft and attaches to coronoid process of ulna
2 muscles of posterior compartments of arm
triceps brachii, anconeus
nerve supply of posterior compartment of arm
radial nerve (C5,6,7,8 T1); lies on humerus in radial groove
triceps brachii proximal and distal attachments
proximally the lateral and medial head attach to posterior shaft of humerus, and long head attaches to infraglenoid tubercle of scapula; distally forms triceps tendon which crosses elbow and attaches to olecranon process of ulna
anconeus proximal and distal attachments
small muscle attaching to humerus proximally at lateral epicondyle, then broadens out and attaches distally to posterior ulna at olecranon process
4 joints of pectoral girdle
sterno-clavicular joint, acromio-clavicular joint, gleno-humeral joint (shoulder joint), scapulo-thoracic “joint”
other joint of arm
elbow joint
sterno-clavicular joint type
synovial joint composed of 2 portions separated by fibrocartilage articular disc
what gives sterno-clavicular joint strength
very strong sterno-clavicular ligaments (injury causes subluxation and dislocation)
what does sternal end of clavicle articulate with
sternum at manubrium, first costal cartilage
how many planes does the sterno-clavicular joint allow movement of the clavicle and girdle
3
acromio-clavicular joint type and where is it between
synovial joint, between acromial end of clavicle and acromion process of scapula
3 ligaments involved in connecting and stabilising acromio-clavicular joint
acromio-clavicular ligament, coraco-clavicular ligament, coraco-acromial ligament
where does the coraco-clavicular ligament run
from coracoid process of scapula to clavicle
2 main sections of coraco-clavicular ligament
conoid, trapezoid
what can the coraco-acromial ligament often cause
impingement of gleno-humeral joint
what ligament of the acromio-clavicular joint is torn in minor dislocations
acromio-clavicular ligament
what 2 ligaments of the acromio-clavicular joint are torn in severe dislocations
acromio-clavicular ligament, coraco-clavicular ligament
what does the scapulo-thoracic “joint” represent
“articulation” between scapula and chest wall
4 movements of scapula at scapulo-thoracic “joint”
elevation and depression of scapula, protraction of scapula (forward and lateral against chest wall), retraction of scapula (backward and medial against chest wall), rotation of scapula
