Shoulder, Arm And Forearm

Front 1

Trapezius

origin: skull and thoracic vertebrae
insertion: clavicle and scapula
shape: trapezium - divided into 3 sections (a) descending convergent fibres, superior; (b) transverse fibres, middle; (c) ascending convergent fibres, inferior
Layer: most superior layer of shoulder region

Group: superficial posterior (shoulder) group

Function:
1) descending part (superior) - elevate scapula
2) middle part - retracts scapula (pull posteriorly)
3) Ascending part (inferior) - descend scapula
4) ascending + descending = rotate glenoid cavity posteriorly

Back 1

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Front 2

Rhomboid minor

origin: cervical and thoracic vertebrae
insertion: medial border of scapula
shape: flat, rhomboid; descending parallel fibres
layer: superior to rhomboid major, under trapezius

Group: superficial posterior (shoulder) group
Function: retract scapula, rotate/depress glenoid cavity fix scapula to thoracic wall

Back 2

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Front 3

Rhomboideus Major

origin: cervical and thoracic vertebrae
insertion: medial border of scapula
shape: flat, rhomboid; descending parallel fibres

Group: superficial posterior (shoulder) group
position: inferior to rhomboid minor, under trapezius

Function: retract scapula, rotate/depress glenoid cavity fix scapula to thoracic wall

Back 3

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Front 4

Levator Scapulae

origin: cervical vertebrae
insertion: superior scapula

group: superficial posterior (shoulder) group
innervation:
position: next to subscapularis, under trapezius

joint:
function: + descending parts of trapezius = elevate scapula/fix against thoracic wall
extend neck (bilaterally with trapezius)
contribute to lateral flexion of neck (unilateral contraction)

Back 4

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Front 5

Latissimus Dorsi

origin: lumbar and thoracic vertebrae
insertion: anterior proximal humerus

group: superficial posterior group
innervation:
position: most superficial lower back muscle

Function: extends, retracts and rotates the humerus medially (directly at glenohumeral joint; indirectly at pectoral girdle - clavicle, scapula, scapulothoracic joint)

Back 5

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Front 6

Teres Major

origin: inferior angle of scapula (posterior surface)
insertion: anterior proximal humerus

group: superficial posterior (shoulder) group
innervation: Axillary nerve
blood supply:
drain into:
position: inferior to teres minor and infraspinatus, under or lateral to trapezius

Function: adducts and medially rotates the arm, important stabilizer of humerus head in glenoid cavity

Back 6

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Front 7

Teres Minor

origin: laterial border of scapula
insertion: greater tubercle of humerus

group: deep rotator cuff group; posterior
innervation: axillary nerve
blood supply:
drain into:
position: superior to teres major, under trapezius and superficial to infraspinatus

joint: glenohumeral joint
function:
1) dynamic ligament: keep head of humerus in socket and stabilize joint throughout wide range of movement
2) rotate humerus: lateral rotation (infraspinatus + teres minor)

Back 7

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Front 8

Supraspinatus

origin: supraspinous fossa of scapula
insertion: greater tubercle of humerus

group: deep rotator cuff group
innervation:
position: above the spine of of scapula (as named), under trapezius (but both anterior and posterior)

Function:
1) Dynamic ligament: keep head of humerus in socket and stabilize joint throughout wide range of movement
2) Assist abduction (away from midline)

Back 8

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Front 9

Subscapularis

origin: subscapular fossa of scapula
insertion: lesser tubercle of humerus

group: deep rotator cuff group
innervation:
position: anterior; under rhomboid minor and pectoralis major

Function:
1) Dynamic ligament - keep head of humerus in socket and stabilize joint throughout wide range of movement
2) rotate humerus - medial rotation (glenohumeral joint)

Back 9

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Front 10

Infraspinatus

origin: infraspinous fossa of scapula
insertion: greater tubercle of humerus

group: deep rotator cuff group; posterior
innervation:
position: posterior below spine of scapula, below teres minor, superior to teres major

Function:
1) Dynamic ligament - keep head of humerus in socket and stabilize joint throughout wide range of movement
2) rotate humerus - lateral rotation (infraspinatus + teres minor; glenohumeral joint)

Back 10

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Front 11

Serratus Anterior

origin: ribs
insertion: medial border of scapula

group: anterior and lateral group (superficial)
innervation:
position: superficial layer (from back to side of front)

Back 11

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Front 12

Pectoralis Minor

origin: 3 ribs (3-5)
insertion: coracoid process of scapula

group: anterior and lateral group
innervation:
position: under pectoralis major, superficial to subscapularis and intercostals (external)

Back 12

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Front 13

Deltoid

origin: lateral clavicles, acromion, spine of scapula
insertion: proximal, lateral humerus (deltoid tuberosity of humerus)

group: anterior and lateral group
innervation: Axillary nerve
blood supply:
drain into:
position: most superficial proximal humerus and shoulder region; divided in three sections - clavicular (anterior; superior, next to pectoralis major), acromial (middle) and spinal (posterior, on top of infraspinatus) part. Cephalic vein in deltopectoral groove

Function:
1) anterior (clavicular): flexes and medially rotates arm (glenohumeral joint)
2) middle ( acromial): abducts arm (away from midline)
3) posterior (spinal): extends and laterally rotates arm

Back 13

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Front 14

Pectoralis Major

origin: sternum, rib cartilages, clavicle
insertion: greater tubercle of humerus

Group: superficial anterior and lateral group
innervation:
blood supply:
drain into:
position: most superficial anterior muscle, inferior to clavicle and deltoid muscle. Cephalic vein in deltopectoral groove.

function: adducts and medially rotates humerus, draws scapula anteriorly and inferiorly

Back 14

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Front 15

Biceps Brachii

origin: long head - supraglenoid tubercle of scapula; short head - coracoid process of scapula
insertion: common - radial tuberosity (bicipital aponeurosis)

group: flexor (anterior) arm group
innervation: musculocutaneous nerve
blood supply: brachial artery
drain into:
position: most superficial anterior arm

function:
1) glenohumeral joint (long head only) flexion, stabilisation of humeral head during deltoid contraction; abduction of humerus
2) elbow joint (both long and short head) - flexor (forearm extended or supinated), supinator (forearm flexed and pronated)

Note: no attachment to humerus

Back 15

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Front 16

Coracobrachialis

origin: coracoid process of scapula
insertion: medial margins of the humerus shaft

group: flexor (anterior) arm group
innervation: musculocutaneous nerve
blood supply: brachial artery
drain into:
position: under biceps brachii, exposed at medial humerus close to armpit region

Function: flex and adduct arm (glenohumeral joint), stabilise glenohumeral joint (shunt muscle)

Back 16

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Front 17

Brachialis

origin: distal half of anterior surface of humerus
insertion: ulnar tuberosity

Group: flexor (anterior) arm group
innervation: musculocutaneous nerve
blood supply: brachial artery
drains into:
position: posterior and under biceps brachii, exposed close to lateral edge of humerus (close to lateral head of triceps brachii

Function: ONLY pure flexor of the arm

Back 17

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Front 18

Brachioradialis

origin:
insertion:

group: flexor arm (functional), extensor forearm (anatomical) compartment
innervation: radial nerve
blood supply:
drains into:

location: located anterior compartment of forearm (but actually flexor of arm)

Back 18

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Front 19

Triceps Brachii (lateral head, long head, medial head)

origin:
insertion:

group: extensor arm
innervation: radial nerve
blood supply: deep brachial artery
drain into:
location:

Function:

Back 19

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Front 20

Anconeus

Origin:
Insertion:

Group: extensor arm group (functional), extensor forearm group (anatomical)
innervation: radial nerve
blood supply:
drain into:
Location: elbow, between extensor carpi ulnaris and flexor carpi ulnaris

Function:

Back 20

Name muscle

Front 21

Flexor Carpi Radialis

origin: medial epicondyle of humerus
insertion: radial (lateral) palmar hand

group: superficial anteriomedial (flexor) forearm
innervation: median nerve
blood supply: radial artery
drain into:
location:

Function:

Back 21

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Front 22

Flexor Carpi Ulnaris

origin: medial epicondyle of humerus
insertion:

Group: superficial flexor (anteriomedial) forearm
innervation: ulna nerve
blood supply: ulnar artery
drain into:
location:

Function:

Back 22

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Front 23

Palmaris Longus

Origin: medial epicondyle of humerus
Insertion:

Group: superficial flexor (anteriomedial) forearm
Innervation: median nerve
blood supply: ulna artery
drain into:
location: most superficial forearm muscle

Back 23

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Front 24

Pronator Teres

origin: medial epicondyle of humerus
insertion:

Group: superficial flexor (anteriomedial) forearm
Innervation: median nerve
blood supply:
drain into:
location:

Function:

Back 24

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Front 25

Flexor digitorum superficialis

origin: medial epicondyle of humerus
insertion: middle phalanges of digits 2-5

group: anteriomedial (flexor) compartment of forearm
innervation: median nerve
supply: ulna artery
drain:
location: intermediate layer of forearm, tendons reach edges of middle phalanges

Function: weak flexor of elbow, flexor of wrist, MCP, and PIP joints of digits 2-5

Back 25

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Front 26

flexor digitorum profundus

origin:
insertion:

group: deep anteriomedial (flexor) of forearm
innervation: median nerve (radial side), ulna nerve (ulna side)
blood supply: ulnar artery
drain into:
location: deep layer, directly beneath flexor digitorum superficialis, tendons reach proximal edge of dital phalanges (digits 2-5)

Function: flexor of wrist, MCP, PIP and DIP of digits 2-5
Note: ONLY flexor of distal phalanges

Back 26

name

Front 27

flexor pollicus longus

origin:
insertion:

group: deep flexor (anteriomedial) forearm
innervation: median nerve
blood supply: radial artery
drain into:
location:

Function:

Back 27

name

Front 28

pronator quadratus

Origin:
Insertion:

Group: deep anteriomedial (flexor) forearm
innervation: median nerve
blood supply:
drain into:
location:

Function:

Back 28

name

Front 29

Extensor Carpi Ulnaris

origin:
insertion:

group: superficial extensor (posteriolateral) forearm
innervation: radial nerve
blood supply:
drain into:
location:

Function:

Back 29

Name the muscle

Front 30

Extensor Carpi Radialis Brevis

Origin:
Insertion:

Group: superficial extensor (posteriolateral) forearm
innervation: radial nerve
blood supply
drain into:
location:

Function:

Back 30

Name the muscle

Front 31

Extensor Carpi Radialis Longus

origin:
insertion:

group: superficial extensor (posteriolateral) forearm
innervation: radial nerve
blood supply:
drain into:
location:

Function:

Back 31

Name the muscle

Front 32

Extensor Digitorum

origin:
insertion:

group: superficial extensor (posteriolateral) forearm
innervation; radial nerve

Back 32

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Front 33

extensor digiti minimi

origin:
Insertion:

group: extensor forearm group
innervation: radial nerve
blood supply:
drain into:
location: tendon under extensor carpi ulnaris (intersect at wrist), between extensor capi ulnaris and extensor digitorum (muscle, elbow region)

Function: extend wrist

Back 33

name

Front 34

Supinator

origin:
insertion:

group: deep extensor (posteriolateral) forearm
innervation: radial nerve
blood supply:
drain into:
location:

Function:

Back 34

Name the muscle

Front 35

extensor pollicis brevis

origin: dorsal shaft of radius (and ulna), interosseous membrane
insertion: mid thumb

group: deep extensor forearm group
innervation: radial nerve
blood supply:
drain into:
location: under abductor pollicis longus, origin more distal and tendon more posterior (thumb) than abductor pollicis longus. Deepest layer on radius.

Function

Back 35

Brevis

Front 36

extensor pollicis longus

origin: dorsal shaft of ulna (and radius) and interosseous membrane
insertion: tip of thumb

group: deep extensor forearm
innervation: radial nerve
blood supply:
drain into:

location: tendon ends further than extensor pollicis brevis, under extensor digitorum, origin on ulna (medial to adductor pollicis longus origin) and cross at wrist, medial to adductor pollicis longus, lateral and partly superficial to extensor indicis

Function:

Back 36

Longus

Front 37

Abductor pollicis longus

origin: posterior shaft of radius and ulna, interosseous membrane
insertion: near base of thumb (metacarpal)

group: deep extensior (posterior) forearm
innervation: radial nerve
blood supply:
drain into:

location: from posterior radius to anterior thumb, crosses (and lateral to) extensor pollicis brevis, distal to supinator

Function:

Back 37

name

Front 38

Extensor indicis

origin:
insertion:

group: deep extensor forearm
innervation: radial nerve
blood supply:
drain into:
location:

Function:

Back 38

name

Front 39

opponens pollicis

innervation: median nerve

Back 39

opponens pollicis

Front 40

abductor pollicis brevis

innervation: median nerve

Back 40

name

Front 41

flexor pollicis brevis

innervation: median nerve

Back 41

flexor pollicis brevis

Front 42

adductor pollicis

innervation: median nerve

Back 42

adductor pollicis

Front 43

opponens digiti minimi

innervation: ulna nerve

Back 43

opponens digiti minimi

Front 44

abductor digiti minimi brevis

innervation: ulna nerve

Back 44

abductor digiti minimi brevis

Front 45

flexor digiti minimi brevis

innervation: ulna nerve

Back 45

flexor digiti minimi brevis

Front 46

palmaris brevis

innervation: ulna nerve

Back 46

palmaris brevis

Front 47

palmar interossei

innervation: ulna nerve

Back 47

name

Front 48

dorsal interossei

innervation: ulna nerve

Back 48

name

Front 49

lumbricals

Innervation: median nerve (1,2), ulna nerve (3,4)

Back 49

Lumbricals