Muscles of the Thoracic and Abdominal Walls

Question 0

internal intercostals

Answer 0

Origin: inferior border of ribs
Insertion: superior border of ribs below
Innervation: intercostal nerve
Action: during forced respiration: interosseus part depresses ribs; interchondral part elevates ribs

Question 1

external intercostals

Answer 1

Origin: inferior border of ribs
Insertion: superior border of ribs below
Innervation: intercostal nerve
Action: during forced inspiration: elevates ribs

Question 2

innermost intercostals

Answer 2

Origin: inferior border of ribs
Insertion: superior border of ribs below
Innervation: intercostal nerve
Action: during forced respiration: interosseus part depresses ribs; interchondral part elevates ribs

Question 3

transversus thoracis

Answer 3

Origin: posterior surface of lower sternum
Insertion: internal surface of costal cartilages 2-6
Innervation: intercostal nerve
Action: weakly depresses ribs

Question 4

external oblique

Answer 4

Origin: external surfaces of 5th-12th ribs
Insertion: linea alba, pubic tubercle, and anterior half of iliac crest
Innervation: thoraco-abdominal nerves (anterior rami of T7-T11) and subcostal nerve
Action: compress and support abdominal viscera; flex and rotate trunk

Question 5

internal oblique

Answer 5

Origin: thoracolumbar fascia, anterior 2/3s of iliac crest, and connective tissue deep to the inguinal ligament
Insertion: inferior borders of 10th-12th ribs, linea alba, and pubis via conjoint tendon
Innervation: thoraco-abdominal nerves (anterior rami of T7-T11), subcostal and first lumbar nerve
Action: compress and support abdominal viscera; flex and rotate trunk

Question 6

transversus abdominus

Answer 6

Origin: Internal surfaces of 7th-12th costal cartilages, thoracolumbar fascia, iliac crest, and connective tissue deep to inguinal ligament
Insertion: linea alba with aponeurosis of internal oblique, pubic crest, and pubis via conjoint tendon
Innervation: thoraco-abdominal nerves (anterior rami of T7-T11), subcostal and first lumbar nerve
Action: compresses and supports abdominal viscera

Question 7

rectus abdominus

Answer 7

Origin: pubic symphysis and pubic crest
Insertion: Xiphoid process and 5th-7th costal cartilages
Innervation: thoraco-abdominal nerves (anterior rami of T7-T12 spinal nerves)
Action: flexes trunk (lumbar vertebrae) and compresses abdominal viscera, stabilizes and controls tilt of pelvis (antilordosis)

Question 8

diaphragm

Answer 8

Origin:
Insertion:
Innervation:
Action: