upper thoracic

O -First rib at junction between rib and costal cartilage

I -Groove on inferior surface of middle one-third of clavicle

In -Nerve to subclavius [C5, C6]

F -Pulls tip of shoulder down; pulls clavicle medially to stabilize sternoclavicular joint

O - Inferior margin of rib above

I - Superior margin of rib below

In - Intercostal nerves; T1-T11

F - Most active during inspiration; supports intercostal space; moves ribs superiorly

O -Lateral edge of costal groove of rib above

I -Superior margin of rib below deep to the attachment of the related external intercostal

In -Intercostal nerves; T1-T11

F -Most active during expiration; supports intercostal space; moves ribs inferiorly

O -Medial edge of costal groove of rib above

I -Internal aspect of superior margin of rib below

In -Intercostal nerves; T1-T11

F -Acts with internal intercostal muscles

O -Clavicular head-anterior surface of medial half of clavicle; sternocostal head-anterior surface of sternum; first seven costal cartilages; sternal end of sixth rib; aponeurosis of external oblique

I -Lateral lip of intertubercular sulcus of humerus

In -Medial and lateral pectoral nerves; clavicular head [C5, C6]; sternocostal head [C6, C7, C8, T1]

F -Flexion, adduction, and medial rotation of arm at glenohumeral joint; clavicular head-flexion of extended arm; sternocostal head-extension of flexed arm

O - Anterior surfaces and superior borders of ribs III to V; and from deep fascia overlying the related intercostal spaces

I -Coracoid process of scapula (medial border and upper surface)

In - Medial pectoral nerve [C5, C6, C7, C8, T1]

F -Pulls tip of shoulder down; protracts scapula

O -Lateral surfaces of upper 8-9 ribs and deep fascia overlying the related intercostal spaces

I -Costal surface of medial border of scapula

In -Long thoracic nerve [C5, C6, C7]

F -Protraction and rotation of the scapula; keeps medial border and inferior angle of scapula opposed to thoracic wall