Abdominal + Breathing Muscles

Question 1

General purpose of anterior abdominal muscles

Answer 1

support and protect abdominal viscera

allow for upright posture and balance

Question 2

Rectus abdominus

Answer 2

origin = pubic crest, pubic symphysis
insertion = pubis, cartilage of ribs 5-7, xiphoid process
action = flexion of spine, compression of abdominal viscera
innervation = spinal nerves (T7-T12)

Question 3

External oblique

Answer 3

origin = sternum, ribs 5-12
insertion = linea alba, iliac crest
action =
bilateral: flexion of spine, compression of abdomen
unilateral: flexion of trunk to same side, rotation to opp. side
innervation = lower intercostal, ilioinguinal nerves

Question 4

Internal oblique

Answer 4

origin = iliac crest, lumbodorsal fascia
insertion = inferior ribs, linea alba
action = compresses abdomen, depresses ribs, flexes spine
innervation = lower intercostal, ilioinguinal nerves

Question 5

Transverse abdominus

Answer 5

origin = lateral inguinal ligament, inner iliac crest
insertion = linea alba, pubis
action = compression of abdomen
innervation = first lumbar nerve (T7-L1), iliohypogastric (T12-L1), ilioinguinal (T12-L1)

Question 6

Diaphragm

Answer 6

origin = ribs 7-12 cartilage, xiphoid process, lumbar vert
insertion = anterior longitudinal ligament (of vert. column)
action = expands thoracic cavity, compresses abdominal cavity for quiet inspiration
innervation = phrenic nerve (C3-5)

Question 7

Internal Intercostals

Answer 7

origin = superior border of ribs 2-12
insertion = inferior of ribs above (1-11)
action = depresses ribs for forced expiration
innervation = intercostal nerves

Question 8

External Intercostals

Answer 8

origin = inferior border of ribs 1-11
insertion = superior border of ribs 2-12 
action = elevates ribs during normal inspriation
innervation = intercostal nerves