Muscles (Innervation and Action) Flashcards
What are the extrinsic shoulder muscles
Superficial posterior axioperpendicular muscles:
Trapezius
Latissimus Dorsi
Deep posterior axioperpendicular muscles:
Levator scapulae
Rhomboid minor and major
What are the intrinsic shoulders muscles
Deltoid Teres major Supraspinatus Infraspinatus Teres minor Subscapularis
Nerves innervating Trapezius
Accessory nerve (CN XI/11) - motor fibers Spinal Nerves (C3, C4) - pain and proprioceptive fibers
Action of trapezius
Descending part elevates
Ascending part depresses
Middle part or all parts retracts scapula
Ascending and Descending part act together to rotate glenoid cavity superiorly
Nerves innervating Latissimus dorsi
Thoracodorsal nerve (C6, C7, C8)
Action of Lats
Extends, adducts, medially rotates the humerus
Raises body towards arms when climbing or pull ups
nerves innervating levator scapulae
Dorsal scapular nerve (C5) Cervical nerves (C3,C4)
nerve innervating rhomboid minor and major
Dorsal scapular nerve (C4, C5)
action of levator scapulae
elevate scapula, tilts glenoid cavity of scapula inferiorly
rhomboid minor and major action
retract and rotate scapula
fix scapula to thoracic wall
nerve innervating deltoid
axillary nerve (C5,C6)
deltoid action
anterior part: flexes and medial rotation
middle part: abducts arm
posterior part: extends and lateral rotation
nerves innervating teres major
lower subscapular nerve (C5, C6)
action of teres major
adducts and medially rotates arm
what are the rotator cuff muscles
Subscapularis
Infraspinatus
Teres minor
Supraspinatus
nerves innervating supraspinatus
suprascapular nerve (C4,C5,C6)
supraspinatus action
initiates and assists deltoid in abduction
acts with other rotator cuff muscles
nerves innervating infraspinatus
suprascapular nerve (C5, C6)
infraspinatus action
Laterally rotates arm
help hold humeral head in glenoid cavity of scapula
nerve innervating teres minor
Axillary nerve (C5, C6)
teres minor action
laterally rotates arm
helps hold humeral head in glenoid cavity of scapula
nerves innervating subscapularis
upper and lower subscapular nerves (C5, C6, C7)
subscapularis action
adducts and medially rotates arm
helps hold humeral head in gelnoid cavity of scapula
what are the upper arm (humeral) muscles
biceps brachii brachialis coracobrachialis triceps brachii anconeus
nerves innervating biceps brachii
Musculocutaneous nerve (C5, C6)
biceps brachii action
supinates forearm
flexes forearm when supinated
short head resists dislocation of shoulder
nerves innervating brachialis
musculocutaneous nerve (C5, C6)
brachialis action
flexes forearm in all positions
nerves innervating coracobrachialis
musculocutaneous nerve (C5,C6,C7)
coracobrachialis actions
helps flex and adduct arm
resists dislocation of shoulder
nerves innervating triceps brachii
radial nerve (C6, C7, C8)
action of triceps brachii
chief extensor of forearm
long head resists dislocation of humerus
helps in abduction of arm
nerves innervating anconeus
radial nerve (C7, C8 , T1)
anconeus action
assists triceps in extending forearm
stabilizes elbow joint
abduct ulna during pronation
