Thoracic muscles Flashcards
What are the five muscles that make up the thoracic cage?
external intercostals, internal intercostals, innermost intercostals, subcostals, transverse thoracis
Which muscles attach to the thoracic cage?
pectoralis major, pectoralis minor, serratus anterior, scalene muscles
How many pairs of external intercostals are there?
11
Which muscle of the abdomen are external intercostals continuous with?
external oblique
What are the attachments of the external intercostals?
Originate at the lower border of the rib, inserting into the superior border of the rib below.
What is the function of the external intercostals?
Elevates ribs, increasing thoracic volume
The innervation of the intercostals if from_______
Intercostal nerves, T1-11
Which of the intercostals runs inferoposteriorly?
Internal intercostals
Which of the intercostals runs inferoanteriorly?
External intercostals
Which muscle of the abdominal wall are the internal intercostals continuous with?
Internal intercostals
What are the attachments of the internal intercostals?
Originates from the lateral edge of the costal groove and inserts into the superior surface of the rib below
What is the action of the interosseous part of the internal intercostals?
reduces thoracic volume by depressing the ribcage
What is the action of the interchondral part of the internal intercostals?
Elevate the ribs
What spearates the innermost intercostals from the internal intercostals?
intercostal neurovascular bundle
Where are the innermost intercostals found?
in the most lateral portion of the intercostal spaces
What is the action of the innermost intercostals?
same as internal
Which abdominal muscle is tranversus thoracic continuous with?
transversus abdominis
What are the attachments of transversus thoracis?
From the posterior surface of the inferior sternum to the internal surface of costal cartilages 2-6.
What is the action of transversus thoracis?
Weakly depresses the ribs
Where are the subcostals found?
in the inferior portion of the thoracic wall
Describe the subcostals
They comprise of thin slips of muscle, which run from the internal surface of one rib, to second and third ribs below. The direction of the fibres parallels that of the innermost intercostal.
What is the action of the subcostals?
share the action of the internal intercostals
