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
pec major
-insertion
common tendon to lateral lip of intertubercular groove
pec major
-action
both heads -adducts and internally rotates humerus clavicular head -flexes humerus sternocostal head -extends humerus
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
pectoralis minor
-orign
ribs 3-5 near their costal cartilages
pectoralis minor
-insertion
medial border and superior surface of coracoid process or scapula
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
pectoralis minor
-innervation
medial pectoral nerve (C8, T1)
subclavius
-origin
junction of rib 1 and its costal cartilage
subclavius
-insertion
inferior surface of middle 1/3 of clavicle
subclavius
-action
draws clavicle medially
subclavius
-innervation
nerve to subclavius (C5, C6)
serratus anterior
-origin
external surfaces of lateral parts of ribs 1-8
fascia overlying external intercostal muscles
serratus anterior
-insertion
anterior surface of medial border of scapula
serratus anterior
-action
protracts scapula and holds it against thoracic wall (along with subclavius) rotates scapula (pulls on inferior angle of scapula; assists trapezius)
serratus anterior
-innervation
long thoracic nerve (C5-C7)
what are the pectoral muscles
pec major
pec minor
subclavius
serratus anterior
what are the extrinsic muscles of the back?
trapezius
latissimus dorsi
levator scapulae
rhomboid major/minor
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
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
trapezius
-actions
superior fibers -elevate middle fibers -retract inferior fibers -depress superior and inferior fibers together -superiorly rotate lateral angle (assisted by serratus anterior)
trapezius
-innervation
spinal accessory nerve (CN XI)
ventral rami of cervical nerves C3, C4 (primarily sensory for proprioceptive and pain sensation)
latissimus dorsi
-origin
spinous process of the inferior 6 thoracic vertebrae
thoracolumbar fascia
iliac crest
inferior 3-4 ribs (9-12)
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)
