Thoracic and Abdominal Wall Muscles

Question 1

Innervation of all Intercostal muscles

Answer 1

1st to 11th intercostal nn.

Question 2

Action of External Intercostal muscle

Answer 2

Raises ribs (inspiration); supports intercostal spaces; stabilizes chest wall

Question 3

Origin and Insertion of Internal Intercostal muscles

Answer 3

Lower margin of rib to upper margin of next lower rib ( courses obliquely forward and upward from costal angle to sternum)

Question 4

Action of Internal Intercostal muscle

Answer 4

Lowers ribs (expiration); supports intercostal spaces; stabilizes chest wall

Question 5

Origin of Transversus Thoracis muscle

Answer 5

Sternum and xiphoid process (inner surface)

Question 6

Insertion of Transversus Thoracis muscle

Answer 6

2nd to 6th ribs (costal cartilage, inner surface)

Question 7

Innervation of Transversus Thoracis muscle

Answer 7

2nd to 6th intercostal nn.

Question 8

Action of Transversus Thoracis muscle

Answer 8

Weakly lowers ribs (expiration)

Question 9

Origin of Diaphragm (Costal Part)

Answer 9

7th to 12th ribs (inner surface; lower margin of costal arch)

Question 10

Origin of Diaphragm (Lumbar Part)

Answer 10

Medial Part: L1-L3 vertebral bodies, intervertebral disks, and anterior longitudinal ligament as right and left crura

Lateral Part: lateral and medial arcuate ligaments

Question 11

Origin of Diaphragm (Sternal Part)

Answer 11

Xiphoid process (posterior surface)

Question 12

Insertion of the Diaphragm

Answer 12

Central Tendon

Question 13

Innervation of the Diaphragm

Answer 13

Phrenic n. (C3-C5)

Question 14

Action of the Diaphragm

Answer 14

Principal muscle of respiration (diaphragmatic and thoracic breathing): aids in compressing abdominal viscera

Question 15

Origin of Rectus Abdominis

Answer 15

Lateral head: Crest of pubis to pubic tubercle

Medial head: Anterior region of pubic symphysis

Question 16

Insertion of Rectus Abdominis

Answer 16

Cartilages of 5th to 7th ribs, xiphoid process of sternum

Question 17

Innervation of Rectus Abdominis

Answer 17

Intercostal nn. (T5-T12)

Question 18

Action of Rectus Abdominis

Answer 18

Flexes trunk, compresses abdomen, stabilizes pelvis

Question 19

Origin of External Oblique

Answer 19

5th to 12th ribs (outer surface)

Question 20

Insertion of External Oblique

Answer 20

Linea alba, pubic tubercle, anterior iliac crest

Question 21

Innervation of External Oblique

Answer 21

Intercostal nn. T7-T12

Question 22

Action of External Oblique

Answer 22

Unilateral: Bends trunk to same side, rotates trunk to opposite side

Bilateral: Flexes trunk, compresses abdomen, stabilizes pelvis

Question 23

Origin of Internal Oblique

Answer 23

Thoracolumbar fascia (deep layer), iliac crest (intermediate line), anterior superior iliac spine, iliopsoas fascia

Question 24

Insertion of Internal Oblique

Answer 24

10th to 12th ribs (lower borders), Linea alba (anterior and posterior layers)

Question 25

Innervation of Internal Oblique

Answer 25

Intercostal nn. (T7-T12)
Iliohypogastric n.
Ilioinguinal n.

Question 26

Action of Internal Oblique

Answer 26

Unilateral: Bends trunk to same side, rotates trunk to opposite side

Bilateral: Flexes trunk, compresses abdomen, stabilizes pelvis

Question 27

Origin of Transversus Abdominis

Answer 27

7th to 12th costal cartilages (inner surfaces), thoracolumbar fascia (deep layer), iliac crest, anterior superior iliac spine (inner lip), iliopsoas fascia

Question 28

Insertion of Transversus Abdominis

Answer 28

Linea alba, pubic crest

Question 29

Innervation of Transversus Abdominis

Answer 29

Intercostal nn. (T7-T12)
iliohypogastric n.
ilioinguinal n.

Question 30

Action of Transversus Abdominis

Answer 30

Unilateral: Rotates trunk to same side

Bilateral: Compresses abdomen

Question 31

Origin and Insertion of External Intercostal muscle

Answer 31

lower margin of rib to upper margin of next lower rib ( courses obliquely forward and downward from costal tubercle to chondro-osseous junction)