Muscles of Thorax and abdomen

Question 1

Answer 1

Levator Costarum

• O: TPs C7-T11 (posterior lateral lip)
• I: ribs 1-12 (below the TP)
• A: elevation of ribs (inspiration)
• Spinal nerve Dorsal rami

Question 2

Answer 2

Serratus Posterior Superior

• O: SPs of C7-T3
• I: superior external border of ribs 2-5
• A: elevation of ribs
• N: intercostal & subcostal nerves

Question 3

Answer 3

Serratus Posterior Inferior

• O:SPs of T11-L3
• I: inferior external border of ribs 9-12
• A: depression of ribs 9-12; accessory muscle of expiration
• N: intercostal & subcostal nerves

Question 4

Answer 4

Quadratus Lumborum

• O: inferior border 12 rib & TP of L1-L4
• I: posterior iliac crest & iliolumbar ligament
• A: Unliateral: elevation of pelivs, lateral flexion of trunk, dpression of 12 rib; Bilateral: extension of lumbosacral spine
• N: Lumbar plexus T12-L3

Question 5

Answer 5

Rectus Abdominis

• O: Pubic crest and pubic symphysis
• I:costal cartilage of ribs 5-7 & xiphoid process
• A: flexion of trunk, posterior pelvic tilt, compression and stabilization of abdomen
• N: intercostal nerves T5- T12

Question 6

Answer 6

External Obliques

• O: Anterior 1/2 of iliac crest, inguinal ligament, pubic tubercle/crest & rectus sheath
• I: inferior border of ribs 6-12
• A: flexion, lateral flexion, and contralateral rotation of trunk; posterior pelvic tilt; compression and stabilization of abdomen
• N: intercostal nerves T7-T12

Question 7

Answer 7

Internal Obliques

• O: iliac crest, inguinal ligament, thoracolumbar fascia
• I: ribs 10-12 & rectus sheath
• A: flexion, LF, ipsilateral rotation of trunk, compression/stabilization of abdomen; posterior pelvis tilt
• N: intercostal nerves T7-L1

Question 8

Answer 8

Transverse Abdominis

• O: Iliac crest, inguinal ligament, thoracolumber fascia & lower ribs & costal cartilage
• I: abdominal aponeurosis
• A: compression/stabilization of abdomen
• N: intercostal nerves T7-L1

Question 9

Answer 9

External Intercostals

• O: inferior borber of ribs
• I: superior border of rib below
• A: elevation of ribs, fix intercostal spaces during respiration
• N: intercostal nerve

Question 10

Answer 10

Internal Intercostals

O: inferior borber of ribs

I: superior border of rib below

A: depression of ribs, fix intercostal spaces during exspiration

N: intercostal nerve

Question 11

Answer 11

Innermost Intercostals

O: interior inferior borber of ribs

I: interior superior border of rib below

A: depression of ribs, fix intercostal spaces during exspiration

N: intercostal nerve

Question 12

Answer 12

Subcostalis

• O: internal surface of ribs 10-12
• I: internal surface of ribs 8-10
• A: depress ribs
• N: Intercostal nerve

Question 13

Answer 13

Transverse Thoracis

• O: inferior 1/3 of inner aspect of sterum, xiphoid process & costosternal junctions of ribs 4-7
• I: costal cartilage of ribs 2-6
• A: depresses upper ribs
• N: intercostal nerves

Question 14

Answer 14

Diaphragm

• O: Sternal: Two fleshy slips from dorsum of xiphoid process
  
  • ​Costal: medial and lateral arcute ligaments, inner aspect of lower 6 ribs
  • Vertebral: by two muscular crura from the bodies of L1, L2 on the left L1-L3 on the right
• ​​​I: Central tendon of diaphragm, which is a thin strong aponeurosis w/no boney attachment
• A: inspiration (increase thoracic cavity volume) assists in raising intra-abdominal pressure
• N: Phrenic nerve

Question 15

Answer 15

Subclavius

• O: 1st rib junction of costocartilage
• I: middle 1/3 of clavicle inferior surface
• A: assists in stabilization of clavicle, depression of clavicle, elevation of 1st rib
• N: nerve to subclavius C5, C6