Thoracic Muscles

Question 1

pec major

Answer 1

origin: mid 1/2 of clavicle and ant surface of sternum, 1st 7 costal cartilages, aponeurosis of external oblique

insertion: lateral lip intertubercular sulcus of humerus

innervation: med and lat pec nerves

function: adduction, med rotation, and flexion of humerus at shoulder joint

Question 2

subclavius

Answer 2

origin: rib 1 at junction b/w rib and costal cartilage

insertion: groove on the inf surface of middle third of clavicle

innervation: nerve to subclavius

function: pulls the clavicle medially to stabilize SC joint and depresses the tip of the shoulder

Question 3

pec minor

Answer 3

origin: ant surface of 3rd, 4th, and 5th ribs and deep fascia overlying the related intercostal spaces

insertion: coracoid process of the scapula

innervation: med pec nerve

function: depresses the tip of the shoulder and protracts the scapula

Question 4

external intercostals

Answer 4

origin: inf margin of the rib above

insertion: sup margin rib below

innervation: intercostal nerves T1-T11

function: most active during inspiration, supports, intercostal space, and moves the ribs superiorly

Question 5

internal intercostals

Answer 5

origin: lat edge of costal groove of rib above

insertion: sup margin of the rib below deep to the attachment of the related external intercostals

innervation: intercostal nerves T1-T11

function: most active during expiration, supports intercostal space, and moves ribs inferiorly

Question 6

innermost intercostals

Answer 6

origin: med edge of costal groove of the ribs above

insertion: internal aspect of sup margin of the ribs below

innervation: intercostal nerves T1-T11

function: acts w/internal intercostals muscles

Question 7

subcostals

Answer 7

origin: internal surface (near angle) of the lower ribs

insertion: internal surface of the 2nd or 3rd rib below

innervation: related intercostal nerves

function: may depress the ribs

Question 8

transverse thoracis

Answer 8

origin: inf margins and internal surfaces of costal cartilages of the 2nd to 6th ribs

insertion: inf aspect of deep surface of body of sternum, xiphoid process, and costal cartilages of ribs 4-7.

innervation: related intercostal nerves

function: depresses costal cartilages

Question 9

intercostal muscles

Answer 9

• external intercostal (superficial)
• internal intercostals (intermediate)
• innermost intercostals (deepest and least distinctive)
• internal obliques - post membrane
• external obliques - ant membranes

Question 10

subcostales info

Answer 10

same plane as intermost intercostals

spans multiple ribs

internal surface to internal surface of the ribs

fibers run parallel to the internal intercostals

depress the ribs in exhalation

Question 11

transverse thoracis muscles

Answer 11

deep surface of the anterior thoracic wall

same plane as the innermost intercostals

og on inf sternum, travels super lateral and inserts on costal cartilage

depress costal cartilage