Muscles of Thoracic Wall

Question 1

Pectoralis Major

Answer 1

A: medial half of clavicle, ribs 2-6, costal margin of sternum, intertubercular groove of humerus

A: adduction, medial rotation of humerus; extension of flexed limb (sternocostal); flexion of extended limb (clavicular)

N: medial and lateral pectoral nerves

Question 2

Pectoralis Minor

Answer 2

A: ribs 3 to 5 and deep fascia overlying the related intercostal spaces, coracoid process of scapula

A: pulls tip of shoulder down, protracts scapula, accessory breathing muscle

N: medial pectoral nerve

B: pectoral branch of the thoracoacromial trunk

Question 3

Serratus Anterior

Answer 3

A: upper 8-9 ribs and deep fascia overlying related intercostal spaces, costal surface of medial border of scapula

A: protraction and retraction of scapula, stabilizes scapula, accessory breathing muscle when pectoral girdle locked

N: Long thoracic vein

B: lateral thoracic artery

Question 4

Subclavius

Answer 4

A: first rib and groove on inferior surface of middle 1/3 of clavicle

A: pulls tip of shoulder down, pulls clavicle medially to stabilize sternoclavicular joint

N: Nerve to subclavius (C5, C6)

B: thoracoacromial trunk, clavicular branch

Question 5

External Intercostals

Answer 5

A: lower border of a rib above, upper border of rib below [W/i intercostal space, each extends from tubercle of rib dorsally to the cartilage of rib ventrally]

A: moves ribs superiorly, most active during inspiration

N: intercostal nerves (T1 to T11)

Question 6

Internal Intercostals

Answer 6

A: lateral edge of costal groove of rib above, upper border of rib below
[W/i intercostal space, each extends from sternum ventrally to angle of rib dorsally]

A: moves ribs inferiorly, most active during expiration

N: intercostal nerves (T1-T11)

Question 7

Innermost Intercostals

Answer 7

A: inner margin of costal groove of rib above, superior border of rib below

A: Acts with internal intercostal muscles

N: intercostal nerves (T1-T11)

Question 8

Transversus Thoracis

Answer 8

A: dorsal surface of the xiphoid process and the body of the sternum. Ribs/ costal cartilage of the 2nd to 6th ribs

A: depresses costal cartilages

N: intercostal nerves

SPAN MORE THAN ONE INTERCOSTAL SPACE

Question 9

Subcostales

Answer 9

A: Internal surface of lower ribs, Internal aspects of superior margin of ribs two to three levels below

A: depresses lower ribs

N: subcostal nerve

SPAN MORE THAN ONE INTERCOSTAL