Shoulder Muscles Flashcards by Blake Miller

pec major

-origin

clavicular head
-anterior surface of sternal 1/2 of clavicle
sternocostal head
-anterior surface of sternum
-adjacent superior 6 costal cartilages
-aponeurosis of external oblique

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pec major

-insertion

common tendon to lateral lip of intertubercular groove

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pec major

-action

both heads
-adducts and internally rotates humerus
clavicular head
-flexes humerus
sternocostal head
-extends humerus

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pec major

-innervation

clavicular head
-lateral pectoral nerve (C5, C6)
sternocostal head
-medial pectoral nerve (C7-T1)
-C7 comes from communicating branch off lateral pectoral nerve

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pectoralis minor

-orign

ribs 3-5 near their costal cartilages

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pectoralis minor

-insertion

medial border and superior surface of coracoid process or scapula

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pectoralis minor

-actions

stabilized scapula by pulling it anteriorly and inferiorly against thoracic wall
protraction (minor) by moving scapula laterally and anteriorly around thoracic cage

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pectoralis minor

-innervation

medial pectoral nerve (C8, T1)

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subclavius

-origin

junction of rib 1 and its costal cartilage

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subclavius

-insertion

inferior surface of middle 1/3 of clavicle

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subclavius

-action

draws clavicle medially

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subclavius

-innervation

nerve to subclavius (C5, C6)

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serratus anterior

-origin

external surfaces of lateral parts of ribs 1-8

fascia overlying external intercostal muscles

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serratus anterior

-insertion

anterior surface of medial border of scapula

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serratus anterior

-action

protracts scapula and holds it against thoracic wall (along with subclavius)
rotates scapula (pulls on inferior angle of scapula; assists trapezius)

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serratus anterior

-innervation

long thoracic nerve (C5-C7)

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what are the pectoral muscles

pec major
pec minor
subclavius
serratus anterior

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what are the extrinsic muscles of the back?

trapezius
latissimus dorsi
levator scapulae
rhomboid major/minor

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trapezius

-origin

medial 1/3 of superior nuchal line
external occipital protuberance
ligamentum nuchae
spinous processes of C7-T12
lumbar and sacral spinous processes via pulling on thoracolumbar fascia

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trapezius

-insertion

lateral 1/3 of clavicle
acromion and spine of scapula
superior fibers extend more laterally, while inferior fibers insert on the spine as an aponeurosis, withous extending out to the acromion

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trapezius

-actions

superior fibers
-elevate
middle fibers
-retract
inferior fibers
-depress
superior and inferior fibers together
-superiorly rotate lateral angle (assisted by serratus anterior)

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trapezius

-innervation

spinal accessory nerve (CN XI)

ventral rami of cervical nerves C3, C4 (primarily sensory for proprioceptive and pain sensation)

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latissimus dorsi

-origin

spinous process of the inferior 6 thoracic vertebrae
thoracolumbar fascia
iliac crest
inferior 3-4 ribs (9-12)

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latissimus dorsi

-insertion

floor of intertubercular groove of humerus

latissimus dorsi | -actions

humerus extension humerus adduction humerus internal rotation raises body towards arms during climbing

latissimus dorsi | -innervation

thoracodorsal nerve (C6-C8)

levator scapulae | -origin

posterior tubercles of transverse process of C1-C4 vertebrae

levator scapulae | -insertion

superior part of medial border of scapula

levator scapulae | -action

elevates scapula | inferiorly rotates lateral angle of scapula

levator scapulae | -innervation

``` dorsal scapular nerve (C5) cervical nerve (C3, C4) ```

rhomboid minor/major | -origin

``` minor -ligamentum nuchae -spinous process of C7, T1 major -spinous processes of T2-T5 ```

rhomboid minor/major | -insertion

medial border of scapula from level of spine of scapula to inferior angle

rhomboid minor/major | -actions

retracts scapula inferiorly rotates lateral angle, depressing glenoid cavity fixes scapula to thoracic wall

rhomboid minor/major | -innervation

dorsal scapular nerve (C4, C5)

what are the scapular muscles (scapulohumeral muscles)

``` deltoid supraspinatus infraspinatus teres minor teres major subscapularis ```

deltoid | -origin

lateral 1/3 of clavicle acromion spine of scapula

deltoid | -insertion

deltoid tuberosity of humerus

deltoid | -actions

``` anterior part -arm flexion -arm medial rotation middle part -arm abduction posterior part -extends arm -laterally rotates arm ```

deltoid | -innervation

axillary nerve (C5, C6)

supraspinatus | -origin

supraspinous fossa of scapula

supraspinatus | -insertion

superior facet of greater tubercle of humerus

supraspinatus | -action

abducts arm (assists deltoid)

supraspinatus | -innervation

suprascapular nerve (C4-C6)

infraspinatus | -origin

infraspinous fossa of scapula

infraspinatus | -insertion

middle facet on greater tubercle of humerus

infraspinatus | -action

arm external rotation | helps hold head of humerus in glenoid cavity (as rotator cuff muscle)

infraspinatus | -innervation

suprascapular nerve (C5, C6)

teres minor | -origin

superior part of lateral border of scapula

teres minor | -insertion

inferior facet on greater tubercle of humerus

teres minor | -action

arm external rotation | helps hold head of humerus in glenoid cavity

teres minor | -innervation

axillary nerve (C5, C6)

teres major | -origin

dorsal surface of inferior angle of scapula

teres major | -insertion

medial lip of intertubercular groove of humerus

teres major | -action

arm adduction | arm internal rotation

teres major | -innervation

lower subscapular nerve (C5, C6)

subscapularis | -origin

subscapular fossa

subscapularis | -insertion

lesser tubercle of humerus

subscapularis | -action

arm internal rotation arm adduction helps hold head of humerus in glenoid cavity

subscapularis | -innervation

upper and lower subscapular nerve (C5-C7)