Thorax

Question 1

Thoracic Musculature

Answer 1

• Intercostal Muscles (External, Internal, Innermost)
• Subcostal Muscles
• Transversus thoracis muscle
• Levator costarum muscle
• Diaphragm

Question 2

External Intercostal Muscles Origin

Answer 2

Superior attachments - inferior margin of rib above

Question 3

External Intercostal Muscles Insertion

Answer 3

Inferior attachment - superior margin of rib below

Question 4

External Intercostal Muscles Innervation

Answer 4

Intercostal nerves T1-T11

Question 5

External Intercostal Muscles Action

Answer 5

Moves ribs superiorly; most active during inspiration

Question 6

Internal Intercostal Muscles Origin

Answer 6

Inferior attachment: Superior margin of ribs below deep to attachment sits of external intercostals

Question 7

Internal Intercostal Muscles Insertion

Answer 7

Superior attachment - Lateral edge of costal groove of rib above

Question 8

Internal Intercostal Muscles Innervation

Answer 8

Intercostal nerves T1-T11

Question 9

Internal Intercostal Muscles Action

Answer 9

Moves ribs inferiorly; most active during expiration

Question 10

Innermost Intercostal Muscles Origin

Answer 10

Inferior attachment - Internal aspect of superior margin of rib below

Question 11

Innermost Intercostal Muscles Insertion

Answer 11

Superior attachment - Medial edge of costal groove of rib above

Question 12

Innermost Intercostal Muscles Innervation

Answer 12

Intercostal nerves T1-T11

Question 13

Innermost Intercostal Muscles Action

Answer 13

Moves ribs inferiorly; most active during expiration

Question 14

Transverse Thoracis Muscles Origin

Answer 14

Posterior xiphoid process and body of sternum

Question 15

Transverse Thoracis Muscles Insertion

Answer 15

Into inner aspect of costal cartilages of ribs 2-6

Question 16

Transverse Thoracis Muscles Innervation

Answer 16

Intercostal nerves T2-T6

Question 17

Transverse Thoracis Muscles Action

Answer 17

Depress costal cartilages of ribs 3-6 and at in exhalation; secure internal thoracic blood vessels to the anterior wall

Question 18

Diaphragm Muscle Origin

Answer 18

1. Origin (three parts:
   - Sternal: Part dorsal to xiphoid process
   - Costal: Part from inner surface of lower 6 ribs
   - Lumbar: Part by two cura (crus Singular)
2. Dome shaped musculotendinous septum between thorax and abdominal cavities
3. Right is longer attached to sides of vertebral bodies L1-L3
4. Left is shorter attached to sides of vertebral bodies L1-L2
5. Connected across the midline by Median Arcuate ligament, passing anterior to the aorta
6. Medial lumbocostal arch (medial arcuate ligament) attached medially to L1 and L2 and laterally to L1 (Psoas major involvement)
7. Lateral Lumbocostal arch (lateral arcuate ligament) attached medially to L1 and laterally to rib 12 (quadratus Lumborum involvement)

Question 19

Diaphragm Muscle Innervation

Answer 19

Phrenic Nerve (C3, C4, C5)

Question 20

Diaphragm Muscle Action

Answer 20

• flattens during inhalation to increase thoracic volume

- Relaxes during exhalation to decrease thoracic volume

Question 21

Subcostal Muscle (Intracostal) Origin

Answer 21

Internal surface of rib

Question 22

Subcostal Muscle (Intracostal) Insertion

Answer 22

Internal surface of rib on the 2nd or 3rd rib above

Question 23

Subcostal Muscle (Intracostal) Innervation

Answer 23

Intercostal nerves T1-T11

Question 24

Subcostal Muscle (Intracostal) Action

Answer 24

Move ribs inferiorly; act with internal interncostals