Muscles of the Thoracic Wall Flashcards Preview

Anatomy - Thorax and Abdomen > Muscles of the Thoracic Wall > Flashcards

Flashcards in Muscles of the Thoracic Wall Deck (15)
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What direction do the external intercostal muscle fibers run?

Inferoanteriorly

1

What direction do the internal intercostal muscles fibers run?

Inferoposteriorly

2

Intercostal muscles and membrane

Start as muscles medially and then end up as membrane more lateral

3

External intercostals and membrane

Start as muscles laterally and then end as membrane more medially

4

Innermost intercostals and membrane

Sit laterally as muscles and do not contain a membrane

5

External intercostal

Origin: inferior border of the rib

Insertion: superior border of the rib below

Innervation: intercostal nerve

Action: during forced inspiration - elevates ribs

6

Internal intercostal

Origin: inferior border of the rib

Insertion: superior border of the rib below

Innervation: intercostal nerve

Action: during forced inspiration - interosseous part depresses rib and interchondral part elevates rib

7

Innermost intercostal

Origin: inferior border of the rib

Insertion: superior border of the rib below

Innervation: intercostal nerve

Action: during forced inspiration - interosseous part depresses rib and interchondral part elevates rib

8

Transverse thoracis

Origin: posterior surface of the lower sternum

Insertion: internal surface of costal cartilages of 2-6

Innervation: none

Action: weakly depresses ribs

9

Subcostal

Origin: internal surface of lower ribs near their angles

Insertion: superior border of 2-3 ribs below

Innervation: none

Action: same as internal intercostal

10

Levatores costarum

Origin: transverse processes of C7-T11

Insertion: subjacent ribs between their angles and tubercles

Innervation: posterior rami of C8-T11 nerves

Action: elevates ribs

11

External oblique

Origin: external surfaces of ribs 5-12

Insertion: anterior half of iliac crest, pubic tubercle, and linea alba

Innervation: thoracoabdominal nerve (anterior rami of C7-T11) and subcostal nerve

Action: compresses/supports abdominal viscera and flexes and rotates the trunk

12

Internal oblique

Origin: thoracocolumbar fascia, connective tissue deep to inguinal ligament, anterior 2/3 of iliac crest

Insertion: inferior borders of ribs 10-12, linea alba, pubis via conjoint tendon

Innervation: thoracoabdominal nerve (anterior rami of C7-T11) and first lumbar nerve

Action: compresses/supports abdominal viscera and flexes and rotates the trunk

13

Transverse oblique

Origin: connective tissue deep to inguinal ligament, thoracocolumbar fascia, iliac crest, and internal surfaces of 7-12th costal cartilages

Insertion: linea alba w/ aponeurosis of internal oblique, pubic crest, and pectin pubis via conjoint tendon

Innervation: thoracoabdominal nerve (anterior rami of C7-T11) and first lumbar nerve

Action: compresses/supports the abdominal viscera

14

Rectus abdominis

Origin: pubic symphysis and pubic crest

Insertion: xiphoid process and 5-7th costal cartilages

Innervation: thoracoabdominal nerve (anterior rami of inferior six thoracic nerves)

Action: flexes trunk (lumbar vertebrae), compresses abdominal viscera, and stabilizes/controls tilt of pelvis