Muscles Of Thoracic Wall

Front 1

Transverse Thoracic

Back 1

Innervation: Intercostal n.
Action: Weakly depresses ribs

Front 2

Subcostal

Back 2

Innervation: Intercostal n.
Action: Same manner as internal intercostal muscles

Front 3

Levator costarum

Back 3

Innervation: Posterior rami of C8-T11 nerves
Action: Elevate ribs

Front 4

Serratus posterior inferior

Back 4

Innervation: 9th-11th inercostal n.; subcostal (T12) n.
Action: Depress ribs

Front 5

Serratus posterior superior

Back 5

Innervation: 2nd-5th intercostal n.
Action: Elevate ribs

Front 6

Intercostal Muscles (External, Internal and Innermost)

Back 6

Innervation: Intercostal n.
Action: elevate ribs during forced inspiration; interosseus part depresses ribs and interchondral part elevates ribs during forced expiration

Front 7

Pectoralis major

Back 7

Innervation: Lateral & Medial pectoral nerves
Action: adducts and medially rotates humerus; draws scapula anteriorly and inferiorly; clavicular head flexes humerus; sternocostal head extends humerus from flexed position

Front 8

Pectoralis minor

Back 8

Innervation: Medial pectoral nerve
Action: stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall

Front 9

Subclavius

Back 9

Innervation: nerve to subclavius
Action: Anchors and depresses clavicle

Front 10

Serratus anterior

Back 10

Innervation: Long thoracic n.
Action: Protracts scapula and holds it against thoracic wall; rotates scapula