Diaphragm muscles

Question 1

what is the diaphragm?

Answer 1

The diaphragm is a double-domed sheet of skeletal muscle

Question 2

where is the diaphragm located?

Answer 2

located at the inferior-most aspect of the rib cage

Question 3

what are the functions of the diaphragm?

Answer 3

1. Separates the thoracic cavity from the abdominal cavity

2. Undergoes contraction and relaxation

Question 4

why does the diaphragm need to undergo contraction and relaxation?

Answer 4

altering the volume of the thoracic cavity and the lungs, producing inspiration and expiration

Question 5

where is the diaphragm located?

Answer 5

at the inferior-most aspect of the ribcage

Question 6

what does the diaphragm fill?

Answer 6

the inferior thoracic aperture

Question 7

what does the diaphragm act as?

Answer 7

the floor of the thoracic cavity and the roof of the abdominal cavity

Question 8

what can the attachments of the diaphragm be divided into?

Answer 8

peripheral and central attachments

Question 9

how many peripheral attachments does the diaphragm have? what are they?

Answer 9

3 peripheral attachments:
Lumbar vertebrae and arcuate ligaments
Costal cartilages of ribs 7-12
Xiphoid process of the sternum

Question 10

which are parts of the diaphragm that arise from the vertebrae like in structure?

Answer 10

tendinous in structure

Question 11

which are parts of the diaphragm that arise from the vertebrae known as?

Answer 11

right and left crura

Question 12

where does the right crus arise from?

Answer 12

Arises from L1-L3 and their intervertebral discs

Question 13

what do some fibres from the right crus surround? what does it act as?

Answer 13

the oesophageal opening, acting as a physiological sphincter to prevent reflux of gastric contents into the oesophagus

Question 14

where does left crus arise from?

Answer 14

L1-L2 and their intervertebral discs

Question 15

what do the muscle fibres of the diaphragm combine to form?

Answer 15

combine to form a central tendon

Question 16

what does the tendon ascend to fuse with?

Answer 16

This tendon ascends to fuse with the inferior surface of the fibrous pericardium

Question 17

what does the diaphragm form either side of the pericardium?

Answer 17

Either side of the pericardium, the diaphragm ascends to form left and right domes

Question 18

at rest, which dome lies slightly higher? why>

Answer 18

At rest, the right dome lies slightly higher than the left – this is thought to be due to the presence of the liver

Question 19

what does the diaphragm divide?

Answer 19

The diaphragm divides the thoracic and abdominal cavities

Question 20

what happens to vessels that pass between the thoracic and abdominal cavities?

Answer 20

any vessels that pass between the two cavities will pierce the diaphragm

Question 21

how many openings are there in the diaphragm for vessels that pass between the 2 cavities? what are they?

Answer 21

three openings that act as conduit:
Oesophageal opening (T10 level)
Aortic opening (T12 level)
Caval opening (T8 level)

Question 22

what does the oesophageal opening at T10 transmit?

Answer 22

the oesophagus, vagus nerves, and oesophageal branches of the left gastric vessels

Question 23

what does the aortic opening at T12 transmit?

Answer 23

the aorta, thoracic duct (a large lymphatic vessel) and azygous vein

Question 24

what does the Caval opening (T8 level) transmit?

Answer 24

the inferior vena cava

Question 25

what is the diaphragm’s main function?

Answer 25

The diaphragm is the primary muscle of respiration

Question 26

what happens to the diaphragm during inspiration?

Answer 26

it contracts and flattens, increasing the vertical diameter of the thoracic cavity

Question 27

what does contraction of the diaphragm produce?

Answer 27

This produces lung expansion, and air is drawn in

Question 28

what happens to the diaphragm during expiration?

Answer 28

the diaphragm passively relaxes and returns to its original dome shape

Question 29

what does relaxation of the diaphragm produce?

Answer 29

reduces the volume of the thoracic cavity

Question 30

what do the halves of the diaphragm receive motor innervation from?

Answer 30

from a phrenic nerve

Question 31

what is the left half of the diaphragm known as?

Answer 31

a hemidiaphragm

Question 32

what is the different halves of the diaphragm innervated by?

Answer 32

the left phrenic nerve, and right phrenic nerve for right diaphragm

Question 33

where is each phrenic nerve formed?

Answer 33

in the neck within the cervical plexus

Question 34

what does each phrenic nerve contain?

Answer 34

contains fibres from spinal roots C3-C5

Question 35

where is the majority of the arterial supply to the diaphragm delivered via?

Answer 35

the inferior phrenic arteries

Question 36

where do the inferior phrenic arteries arise from?

Answer 36

directly from the abdominal aorta

Question 37

where is the remaining blood supply to the diaphragm from?

Answer 37

from the superior phrenic, pericardiacophrenic, and musculophrenic arteries

Question 38

what are the draining veins of the diaphragm?

Answer 38

The draining veins follow the arteries which supply the diaphragm