Abdominal muscles

Question 1

external oblique - proximal and distal attachments

Answer 1

proximal: external surface of ribs 5-12
distal: aponeurosis attaches to linea alba, iliac crest, pubic tubercle, folds to form inguinal ligament

Question 2

external oblique - function

Answer 2

compression of abdominal cavity
stabilization of pelvis
ipsilateral side bending
contralateral rotation
trunk flexion

Question 3

external oblique - innervation

Answer 3

intercostal nerves T7-T12

Question 4

what direction do the external oblique muscle fibers run?

Answer 4

superolateral to medio-inferior

“hands in pockets”

Question 5

internal oblique - proximal and distal attachments

Answer 5

proximal: inferior border ribs 10-12 & thoracolumbar fascia
distal: aponeurosis attaches to linea alba, anterior 2/3 iliac crest, continue in the inguinal ligament (cremaster muscle)

Question 6

internal oblique - function

Answer 6

core to support abdominal contents and stabilize pelvis
ipsilateral side bending and rotation
trunk flexion
elevate testes

Question 7

internal oblique - innervation

Answer 7

intercostal nerves T7-T12
2 branches of L1
- iliohypogatric: internal oblique
- ilioinguinal: cremaster part

Question 8

which way do the internal oblique muscle fibers run?

Answer 8

opposite external oblique

oh my direction

Question 9

transversus abdominis - proximal and distal attachments

Answer 9

proximal: thoracolumbar fascia
inner surface ribs 7-12

distal: aponeurosis attaches to linea alba, iliac crest, pubic tubercle, folds to inguinal ligament
- slip of muscle fibers interdigit with diaphragm

Question 10

transversus abdominis - function

Answer 10

increase intrabdominal pressure (compression)

rotate spine

Question 11

transversus abdominis - innervation

Answer 11

intercostal nerves T7-T12
2 branches of L1:
- iliohypogatric
- ilioinguinal

Question 12

between which muscle layers do the intercostal nerves run?

Answer 12

between transversus abdominis and internal oblique

Question 13

rectus abdominis (6 pack) - proximal and distal attachment

Answer 13

proximal: xiphoid process
5-7 costal cartilage

distal: pubic crest
tubercle
pubic symphysis

Question 14

rectus abdominis - function

Answer 14

compression and stabilizes the pelvis

trunk flexion

Question 15

rectus abdominis - innervation

Answer 15

intercostal nerves T7-T12

Question 16

what is the pyramidalis?

Answer 16

small triangular muscle in the distal anterior rectus abdominis

• doesn’t exist in all people
• isn’t on both sides all the time

Question 17

quadratus lumborum - proximal and distal attachments

Answer 17

proximal: inferior border of 12th rib
lateral transverse process of L1-L4

distal: posterior iliac crest
iliolumbar ligament

Question 18

quadratus lumborum - function

Answer 18

ipsilateral lumbar side bending (closed chain)
hip lift (open chain)
depress 12th rib to facilitate respiration

Question 19

quadratus lumborum - innervation

Answer 19

T12-L4 lumbar spinal nerves (ventral rami)

Question 20

psoas major - proximal and distal attachments

Answer 20

proximal: transverse process, body and discs of T12-L5
distal: lesser trochanter

Question 21

psoas major - function

Answer 21

hip flexion, external rotation, adduction (open chain)

trunk flexion, side bending (closed chain)

Question 22

psoas major - innervation

Answer 22

femoral nerve (L2-L4)