thorax muscles

Question 1

some info about the diaphragm

Answer 1

dome shaped, for breathing, separates the abdominal cavity from thoracic.
Contracts (drops) and increases thoracic cavity volume. Makes abdominal cavity volume smaller when it drops for breathing.
It is assymetrical.

Question 2

diaphragm

Answer 2

O: internal surfaces and costal cartilage of ribs 7-12; xiphoid process of sternum, vertebral bodies and discs of L1-L2.
I: central tendon
A: expands thoracic cage during inhalation.

Question 3

external intercostals

Answer 3

fibers of this muscle run laterally to medial (obliquely)
O: inferior border of the rib below.
I: superior border of the rib below.
A: elevates ribs during inhalation
They are the muscles between the ribs

Question 4

Internal intercostals

Answer 4

fibers run obliquely (medial to lateral)
O: superior border of the rib below.
I: inferior border of the rib above
A: depresses the ribs during forced exhalation
these muscles are near the sternum on the inside.

Question 5

serratus posterior superior

Answer 5

O: spinous processes of C7-T3 and ligamentum nuchae
I: posterior surfaces of Ribs 2-5
A: elevation of ribs during inhalation.
Same function as external intercostals

Question 6

serratus posterior inferior

Answer 6

O: spinous processes of T11-L3
I: posterior surfaces of Ribs 9-12
A: depresses ribs during forced inhalation

Question 7

what are the pairs of the muscles of the thorax that serve the same function?

Answer 7

external intercostals & serratus posterior superior - elevate ribs in inhalation.

Internal intercostals & serratus posterior inferior - depress ribs during forced exhalation

Question 8

what are the 2 breathing processes?

Answer 8

1. inspiration (inhale)
2. Expiration (exhale)

Question 9

inspiration

Answer 9

1. inspiratory muscles contract (diaphragm descends, rib cage rises)
2. thoracic cavity volume increases
3. lungs are stretched
4. pressure drops as volume increases
5. air flows into lungs until the pressure is 0.

Ribs are elevated and sternum flares as external intercostals contract. Diaphragm moves inferiorly during contraction.

Question 10

Expiration

Answer 10

1. inspiratory muscles relax, diaphragm rises, rib cage descends due to recoil of costal cartilages.
2. thoracic cavity volume decreases.
3. elastic lungs recoil passively and volume decreases.
4. pressure rises due to lower volume
5. gas flows out of lungs to the lower pressure as gas flows from high to low pressure.
   Ribs and sternum are depressed as external intercostal muscles relax. The diaphragm moves up (superiorly) as it relaxes.