Muscles of Respiration

Question 1

From superficial to deep, what are the intercostal muscles?

Answer 1

external, internal, innermost

Question 2

How many pairs of muscles does each intercostal have?

Answer 2

11

Question 3

What are the attachments of the intercostals?

Answer 3

superior attachment: ribs 1-11

inferior attachment: ribs 2-12

Question 4

Where are the fixed attachments for the intercostals?

Answer 4

• external: ribs 1-11 (superior ribs)

- internal and innermost: ribs 2-12 (inferior ribs)

Question 5

What are the fibre directions of the intercostals?

Answer 5

• external: inferomedial (same as external obliques)

- internal and innermost: superomedial (same as internal obliques)

Question 6

What are the actions of the intercostals?

Answer 6

• external: quiet and forced inspiration (through elevation of the ribs)
• internal and innermost: forced expiration
• all intercostals: keep the intercostal spaces rigid

Question 7

How many levator costarum mm are there?

Answer 7

12 pairs

Question 8

What are the attachments of levator costarum?

Answer 8

S: TVPs of C7-T11
I: ribs (immediately inferior)

Question 9

What’s the action of levator costarum?

Answer 9

elevate the ribs (during quiet and forced inspiration)

Question 10

What are the attachments of subclavius?

Answer 10

M: 1st rib and its costal cartilage
L: middle 1/3rd of the inferior surface of the clavicle

Question 11

What are the actions of subclavius?

Answer 11

• anchors, depresses and draws the clavicle medially

- serves as cushion between broken/fractured clavicle and subclavian structures

Question 12

What’s the principal muscle of respiration?

Answer 12

(thoracic) diaphragm

Question 13

What areas does the diaphragm divide?

Answer 13

thoracic and abdominal cavities

Question 14

Where does the top of the dome shape of the diaphragm sit?

Answer 14

• approx the 4th intercostal space during expiration

- approx the 6th intercostal space during inspiration

Question 15

What are the attachments of the muscular component of the diaphragm?

Answer 15

• posterior surface of xiphoid
• internal surfaces of lower 6 ribs (and their costal cartilages)
• upper lumbar vertebrae via 2 muscular crura
• medial arcuate ligaments (upper lumbar vertebral bodies to TVPs - travels over psoas)
• lateral arcuate ligaments (L1 TVP to 12th rib - travels over QL)

Question 16

What’s a general description of the central tendon component of the diaphragm?

Answer 16

• muscular fibres converge radially into a strong aponeurotic tendon called the central tendon
• has a C-shaped appearance with a central, left and right ‘leaflet’

Question 17

What’s the action of the diaphragm?

Answer 17

with contraction, the diaphragm moves inferiorly so that it is flattened

Question 18

What innervates the diaphragm?

Answer 18

• phrenic nerve (C3, 4, 5), one on either side

- remember: “C3, 4 and 5 keep the diaphragm alive!”

Question 19

Describe the “bucket-handle movement”

Answer 19

the ribs are raised and move laterally which increases the transverse dimension of the thorax and thus increases thoracic volume

Question 20

Describe the “pump-handle” movement

Answer 20

as the ribs are raised, the anterior parts of the ribs and the sternum move anteriorly which increases the anteroposterior dimension of the thorax and thus increases thoracic volume

Question 21

What’s the anatomical term for hiccup?

Answer 21

singultus

Question 22

What’s apical breathing?

Answer 22

• the diaphragm remains relatively relaxed
• accessory muscles of respiration lift the chest up and out
• this is an inefficient means of respiration

Question 23

Where’s the Perineum?

Answer 23

• the region below the pelvic cavity
• floor: skin
• roof: pelvic diaphragm

Question 24

What are the actions of the pelvic diaphragm?

Answer 24

supports the pelvic viscera, helps maintain control of bodily functions

Question 25

What muscles compose the pelvic diaphragm?

Answer 25

• levator ani (2)

- coccygeus muscles (2)