Exam 4- arm muscles

Pectoralis Major

Pectoralis Major

Origin: -anterior border of medial have of clavicle (& head)

- anterior surface of sternum

-superior six costal cartilages

insertion: humerus

innervation: C5-T1

actions: -flex humerus

- adduct humerus

- medially rotate humerus

- draw scapula anterior and inferior

Pectoralis Minor

Origin: 3rd - 5th ribs

insertion: coracoid process of scapula

innervation: medial pectoral nerve (C8, T1)

action: -stabilize scapula by drawing inferiorly and anteriorly against thoracic wall

-protract/abduct scapula

-raise ribs in inspiration

Serratus Anterior

origin: outer surface ribs 1-8

insertion: costal aspect of medial margin of scapula

innervation: long thoracic nerve (from roots of brachial plexus C5-C7)

actions: -protract/abduct and stabilize scapula

-assist in upward rotation of scapula

Deltoid

origin: -anterior lateral third clavicle

-spine of scapula

insertion: deltoid tuberosity of humerus

innervation: axillary n.

action: -clavicular part: flexion and medially rotate arm

-acromial part: abducts arm beyond initial 15 degrees done by supraspinatus m.

-spinus part: extends and laterally rotates arm

Trapezius

origin: occipital protuberance and C7-T12 spinous processes

insertion: clavicle, acromion process, and scapula

innervation: accessory n.(CN XI), C3-C4

action: - retraction/adduction of scapula

-rotate scapula

-elevate scapula

-lower fibers- depress scapula

Rhomboid Major

origin: spinous processes of T2-T5

insertion: medial border of scapula

innervation: dorsal scapular n (C4-C5)

action: -retract/adduct scapula

-rotate scapula to depress glenoid cavity

-fix scapula to thoracic wall

Rhomboid Minor

origin: spinous processes of C7-T1

insertion: medial border of scapula

innervation: dorsal scapular n (C4-C5)

actions: -retract/adduct and rotate scapula

-fix scapula to thoracic wall

Teres Major

origin: posterior aspect of inferior angle of scapula

insertion: humerus

innervation: lower subscapular n. (C5-C6)

actions: -adduct humerus

-internal/medial rotation of humerus

-extend humerus from flexed position

-protract/abduct scapula

-depress shoulder

Teres Minor

origin: lateral border of scapula

insertion: greater tubercle of humerus

innervation: axillary nerve CN XI

actions: -laterally rotate arm

-stabilize humerus

Latissimus Dorsi

origin: T7-L5 spinous processes and iliac crest

insertion: humerus

innervation: thoracodorsal n (C6-C8)

action: -extend, adduct, and medially rotate humerus

-move body toward arms during climbing

Levator Scapulae

origin: C1-C4 transverse processes

insertion: scapula

innervation: C3-C5

action: elevate scapula

Rotator Cuff Muscles

supraspinatus

infraspinatus

teres minor

subscapularis

(Tendons of S.I.T.S)

Supraspinatus

origin: scapula

insertion: superior aspect of greater tubercle of humerus

innervation: suprascapular n. (C4-C6)

action: initiates abduction of arm (first 15 degrees)

Infraspinatus

origin: scapula

insertion: greater tubercle of humerus

innervation: suprascapular n (C4-C6)

action: -lateral rotation of arm

-stabilize humerus

Subscapularis

origin: subscapular fossa of scapula

insertion: lesser tubercle of humerus

innervation: upper and lower subscapular n (C5-C7)

action: -medially rotates arm

-adduct arm

-help hold humeral head in glenoid cavity

shoulder abduction muscles

supraspinatus (inital 15 degrees)

lateral part of deltoid (30-120 degrees)

shoulder adduction muscles

pec major

lat dorsi

coracobrachialis

teres major

anterior and posterior parts of deltoid

shoulder flexion muscles

anterior part of deltoid

coracobrachialis

long head of biceps brachii

shoulder extension muscles

posterior part of deltoid

lat dorsi

teres major

long head of triceps

shoulder medial rotation muscles

lat dorsi

subrascapularis

teres major

pec major

anterior part of deltoid

shoulder lateral rotation muscles

infraspinatus

teres minor

posterior part of deltoid

Shoulder elevation/depression

at SC joint with vertical gliding of scapula

Shoulder prime elevators

cervical portion of trapezius

levator scapula

rhomboid major and minor

shoulder depressors

pec minor

subclavius

thoracic portion of trapezius

shoulder protraction/retraction

at SC joint with horizontal gliding of scapula

shoulder protraction/abduction

pec minor

serratus anterior

shoulder retraction/adduction

rhomboid major and minor

trapezius

shoulder rotation

at AC joint and Sc joint

shoulder superior rotators

trapezius

serratus anterior

shoulder inferior rotators

pec mino

rhomboid major and minor

order of muscles involved în raising arms above head

1. supraspinatus

2. deltoid

3. serratus anterior

3 flexors of arm muscles

biceps brachii

brachialis

coracobrachialis

1 extensor of arm muscles

triceps brachii

Forearm flexors are _____ groups, forearm extensors are ______

anterior; posterior

Forearm flexion/extension

through trochlea

forearm flexors

biceps brachii (acts on radius)

brachialis (acts on ulna)

brachioradialis

forearm extensors

triceps

anconeus

forearm pronation/supination

through capitulum of humerus

forearm pronators

pronator teres (long and short head)

pronator quadratus

forearm supinators

supinator m.

biceps brachii n.

biceps brachii

long head tendon sits in bicipital groove

origin: -short head: coracoid process of scapula

-long head: supraglenoid tubercle of scapula

insertion: radial tuberosity

innervation: musculocutaneous n. (C5-C6)

action: -flex arm

-flex forearm

-supinate forearm

bracialis

origin: distal ½ of anterior surface of humerus

insertion: coronoid process of ulna and tuberosity of ulna

innervation: musculocutaneous n (C5-C6)

action: flex forarm at elbow

coracobrachialis

origin: coracoid process of scapula

insertion:medial aspect of humeral shaft (humerus)

innervation: musculocutaneous n (C5-C7)

action: flex and adduct arm

triceps brachii

origin: -long head: scapula

-lateral head: posterior humerus

-medial head: posterior humerus

insertion: posterior olecranon process of ulna

innervation: radial nerve (C6-C8)

action: -extend forearm at elbow

-long head: extend and adduct arm

anconeus

origin: posterior lateral epicondyle of humerus

insertion: lateral surface of olecranon and superior part of posterior surface of ulna

innervation: radial nerve (C7-T1)

action: -assists triceps in extending forearm

-stabilizes elbow joint

-abducts ulna during pronation

flexion/extension at wrist

through radoiocarpal and ulnocarpal joints

wrist prime flexors

flexor carpi radialis

flexor carpi ulnaris

palmaris longus

flexor digitorum superficialis

flexor digitorum profundus

wrist prime extensors

extensor carpi radialis longus

extensor carpi radialis brevis

extensor digitorum

palmaris longus

origin: medial epicondyle of humerus

insertion: flexor retinaculum and palmar aponeurosis

innervation: median nerve

action: flex wrist (hand at wrist joint)

flexor carpi ulnaris

origin: humeral head (from medial epicondyle of humerus), ulnar head (from medial aspect of olecranon process and posterior border of ulna)

insertion: pisiform bone, hook of hamate, base of 5th metacarpal

innervation: ulnar nerve

action: flex and adduct hand at wrist joint

Pronator teres

origin: humeral head (from medial epicondyle), ulnar head (from medial border of coronoid process of ulna)

insertion: lateral aspect of shaft of radius

innervation: median nerve

action: pronation and flexion of forearm

Flexor carpi radialis

origin: from medial epicondyle of humerus

insertion: bases of 2nd and 3rd metacarpals

innervation: median nerve

action: flex and abduct hand at wrist joint

flexor digitorum superficialis

origin: humeroulnar head from medial epicondyle of humerus and medial border of coronoid process of ulna, radial head from oblique line on anterior surface of shaft of radius

insertion: base of middle phalanx of 2-5 fingers

innervation: median nerve

action: flex middle phalanx of fingers and assist in flexing proximal phalanx at MCP joint

Flexor digitorum profundus

origin: anteromedial surface of shaft of ulna

insertion: distal phalanges of medial four fingers

innervation: medial half- ulnar nerve; lateral half- median nerve

action: flexes distal phalanx of fingers; assists in flexion of wrist

Flexus pollicis longus

origin: anterior surface of shaft of radius

insertion: distal phalanx of thumb

innervation: median nerve

action: flex distal phalanx of thumb

pronator quadratus

origin: anterior surface of ulna

insertion: anterior surface of radius

innervation: median nerve

action: pronate forearm

muscles that extend medial 4 digits

extensor digitorum

extensor indicis

extensor digiti minimi

muscles that extend or abduct thumb

abductor pollicis longus

extensor pollicis brevis

extensor pollicis longus

brachioradialis

origin: proximal lateral supra-epicondylar ridge

insertion: styloid process (distal end) of radius

innervation: radial nerve

action: flex forearm

extensor carpi radialis longus

origin: lateral supra-epicondylar ridge of humerus

insertion: base of 2nd metacarpal

innervation: radial nerve

action: extend and abduct wrist

extensor carpi radialis brevis

origin: lateral epicondyle of humerus

insertion: base of 3rd metacarpal

innervation: radial nerve

action: extend and abduct wrist

extensor carpi ulnaris

origin: lateral epicondyle of humerus and posterior border of ulna

insertion: base of 5th metacarpal

innervation: radial nerve

action: extend and adduct wrist

Extensor digitorum

origin: lateral epicondyle of humerus

insertion: extensor expansion medial 4 fingers

innervation: radial nerve

action:extend medial 4 fingers at MCP joints and IP joints

extensor digiti minimi

origin: lateral epicondyle of humerus

insertion: extensor expansion of 5th finger

innervation: radial nerve

action: extend 5th finger

extensor pollicis brevis

origin: distal 1/3 of radius

insertion: base of proximal phalanx of thumb

innervation: radial nerve

action: extend thumb at MCP joint, extend carpometacarpal joint

extensor pollicis longus

origin: middle 1/3 ulna and interosseous membrane

insertion: base of distal phalanx of thumb

innervation: radial nerve

action: extend thumb at IP joint, extend MCP and carpometacarpal joint

abductor pollicis longus

origin: posterior surface of ulna and middle aspect of radius

insertion: base of 1st metacarpal

innervation: radial nerve

action: abducts thumb and extends it at carpometacarpal joint

supinator

origin: lateral epicondyle of humerus and crest of ulna

insertion: upper 1/3 of radius

innervation: radial nerve

action: -supinate forearm

-rotate radius to turn palm anteriorly or superiorly (if elbow is flexed)

extensor indicis

origin: posterior surface of ulna

insertion: extensor expansion of index finger

innervation: radial nerve

action: -extend index finger

-help extend hand at wrist

Short intrinsic hand muscles

lumbrical

dorsal interossei

palmar interossei

Lumbricals I & II unipennate actions

action: flex the MCP joint and extend IP joints of 2 and 3

lumbricals III& IV bipennate actions

action: flex MCP joint and extend IP joints of 4 and 5

Dorsal Interossei (bipennate)

origin: adjacent sides of metacarpal

insertion: base of proximal phalanges; extensor expansions of 2-4 fingers

action: abduct 2-4 fingers from axial line, act with lumbricals in flexing MCP joints and extending IP joints

Palmar interossei (unipennate)

origin: palmar side of 2nd, 4th, and 5th metacarpals

insertion: base of proximal phalanges, extensor expansions of 2nd, 4th, and 5th fingers

innervation: ulnar nerve

action: adduct 2nd, 4th, and 5th fingers toward axial line, assist lumbricals in flexing MCP joint and extending IP joints