Thoracic Anatomy: Musculature

Question 1

What are the 5 “True Muscles” of the thoracic wall?

Answer 1

serratus posterior
levatores costarum
transversus thoracis
subcostals
intercostals

Question 2

Name the 2 serratus posterior muscles.

Answer 2

Serratus posterior superior (C7-T3)

Serratus posterior inferior (T11-L2)

Question 3

Action of serratus posterior superior muscle.

Answer 3

elevate superior 4 ribs

Question 4

Action of serratus posterior inferior.

Answer 4

depress inferior ribs (prevents diaphragm from pulling ribs upward)

Question 5

Which triangular muscles have a proximal attachment of the transverse processes of C7-T11

Answer 5

Levatores Costarum

Question 6

Main action of levatores costarum muscles…

Answer 6

elevate ribs (C7-T11)

Question 7

Name the three layers of intercostal muscles from superficial to deep…

Answer 7

External intercostal
Internal intercostal
Innermost intercostal

Question 8

the intercostal nerves and vessels run between fibers of which muscles?

Answer 8

internal and innermost intercostal muscles

Question 9

Fiber orientation of external intercostal muscles…

Answer 9

inferoanteriorly (“hands in pockets” orientation)

Question 10

Fiber orientation of internal and innermost intercostal muscles…

Answer 10

inferposteriorly

Question 11

The innermost intercostal muscle is a group of fibers from the _______ muscle

Answer 11

internal intercostal

Question 12

The external intercostals extend to the abdomen to make up which muscles?

Answer 12

External Oblique (“hands in pockets” orientation)

Question 13

Action of external intercostal muscles

Answer 13

elevate ribs during FORCED inspiration

Question 14

This group of muscles originates at the INTERNAL surface of ribs and attaches distally to the superior border of the ribs 2-3 inferior from origin…

Answer 14

Subcostal muscles

Question 15

Fiber orientation of subcostal muscles

Answer 15

same as internal intercostals (inferoposteriorly)

Question 16

origin of this muscle is the posterior surface of the lower sternum, sitting on the interior of thoracic cage…

Answer 16

transversus thoracis (analogous to transversus abdominus)

Question 17

Attachment site of transversus thoracis…

Answer 17

Internal costal cartilage surface of ribs 2-6

Question 18

This nerve provides innervation to:

• Intercostals
• Transversus Thoracis
• Subcostals

Answer 18

intercostal nerves

Question 19

What band of fibrous tissue sits between the thoracic cage and the lining of pulmonary cavities?

Answer 19

endothoracic fascia

Question 20

This structure attaches the costal parietal pleura to the thoracic wall…

Answer 20

endothoracic fascia

Question 21

at the apices of the lungs, the endothoracic fascia becomes more dense, and is called…

Answer 21

suprapleural membrane

Question 22

Name the three large muscles which overly the anteiror thoracic cage, but do not directly exert an action on it…

Answer 22

pectoralis major
pectoralis minor
serratus anterior

Question 23

small muscle that runs vertically in some people along the sternum…

Answer 23

sternalis muscle

Question 24

Which nerves innervate the levator costorum?

Answer 24

posterior rami of C8-T11

Question 25

Which fascia invests the pectoralis minor?

Answer 25

clavipectoral fascia