Thorax Muscles

pectoralis major sternocostal head origin

anterior surface of sternum
costal cartilages 1-7
6th rib

pectoralis major insertion

lateral border of intertubercular sulcus of humerus

pectoralis major innervation

medial and lateral pectoral nerve

pectoralis major function

flexion at glenohumeral joint
adduction at glenohumeral joint
medial rotation at glenohumeral joint
flexion of extended arm at glenohumeral joint (clavicular head)
extension of flexed arm at glenohumeral joint (sternocostal head)

pectoralis major clavicular head origin

medial half of anterior surface of clavicle

pectoralis minor origin

anterior surface of ribs 3-5

pectoralis minor insertion

coracoid process of scapula

pectoralis minor innervation

medial pectoral nerve

pectoralis minor function

protraction/abduction of scapula
depression of lateral angle of scapula

subclavius origin

rib 1 between bony portion and costal cartilage 1

subclavius insertion

inferior surface of clavicle

subclavius innervation

nerve to subclavius

subclavius function

stabilization of sternoclavicular joint by pulling clavicle medially

external intercostal origin

inferior margin of rib above

external intercostal insertion

superior margin of rib below

external intercostal innervation

intercostal nerve

external intercostal function

moves ribs superiorly
most active during inspiration
supports intercostal space

internal intercostal origin

lateral edge of costal groove of rib above

internal intercostal insertion

superior margin of rib below
deep to attachment of external intercostal

internal intercostal innervation

intercostal nerve

internal intercostal function

moves ribs inferiorly
most active during expiration
supports intercostal space

innermost intercostal origin

medial edge of costal groove of rib above

innermost intercostal insertion

internal aspect of superior margin of rib below

innermost intercostal innervation

intercostal nerve

innermost intercostal function

acts with internal intercostals

subcostales origin

internal surface of lower ribs near angle

subcostales insertion

internal surface of second or third rib below

subcostales innervation

intercostal nerve

subcostales function

depresses ribs

transversus thoracis origin

inferior aspect of deep surface of sternum
xiphoid process
costal cartilages 4-7

transversus thoracis insertion

inferior margins and internal surface of costal cartilages on ribs 2-6

transversus thoracis innervation

intercostal nerve

transversus thoracis function

depress costal cartilages

respiratory diaphragm origin

muscle fibers arise from margins of inferior thoracic aperture

respiratory diaphragm insertion

converge onto central tendon

respiratory diaphragm innervation

phrenic nerve

respiratory diaphragm function

contraction→inspiration

relaxation→expiration

serratus anterior origin

lateral surfaces of upper 8-9 ribs

serratus anterior insertion

medial border of scapula on anterior surface

serratus anterior innervation

long thoracic nerve

serratus anterior function

protraction.abduction of scapula
rotation of scapula
fix scapula

serratus posterior superior origin

spinous process of c7-t3
lower portion of ligamentum nuchae
supraspinous ligament

serratus posterior superior insertion

upper border ribs 2-5

serratus posterior superior innervation

anterior rami of upper thoracic nerve

serratus posterior superior function

elevation of ribs 2-5

serratus posterior inferior origin

spinous process t11-l3
supraspinous ligament

serratus posterior inferior insertion

lower border ribs 9-12

serratus posterior inferior innervation

anterior rami of lower thoracic nerve

serratus posterior inferior function

depression of ribs
prevention of lower ribs from elevating when diaphragm contracts

levatores costarum origin

transverse processes c7-t11
rib below vertebra of origin

levatores costarum insertion

rib below vertebra of origin

levatores costarum innervation

posterior rami of spinal nerves

levatores costarum function

elevate of rib