Thorax Structure Information: Muscles

Question 1

External intercostal

Answer 1

attachments- from rib to rib oriented from superior-lateral to inferior-medial [down and in]

actions- elevation of ribs

innervation- intercostal nerve (segmental)

Question 2

Internal and innermost intercostal

Answer 2

attachments- from rib to rib oriented superior-medial to inferior-lateral [down and out]

actions- depression of ribs

innervation- intercostal nerve (segmental)

Question 3

Transversus thoracis

Answer 3

attachments- from posterior sternum to costal cartilages

actions- depress ribs

innervation- intercostal nerves (segmental)

Question 4

Diaphragm

Answer 4

(C3-5)

attachments- from xiphoid process, inner surface of the lower ribs & costal cartilages, lumbar vertebrae via the crura to the central tendon

actions- inspiration (negative thoracic pressure by inferior displacement)

innervation- phrenic nerve