Lecture 6 - Muscles Of The Anterior Trunk

Question 1

What is the general function of the anterior trunk muscles?

Answer 1

• Trunk movement; Flexion, Side Flexion, Rotation
• Transfer point of energy
• Protection for vital abdominal organs

Question 2

What mechanisms are involved in the trunk?

Answer 2

• Assisting with Valsalva manoeuvre and increasing abdominal pressure
• Assisting with Compression of abdominal contents
• Assisting with respiration

Question 3

What are the main actions of the obliques ?

Answer 3

• rotation
• side flexion

Question 4

What is rotation?

Answer 4

• Contraction of external & internal obliques on OPPOSITE sides
• I.e., trunk rotation to the right — left EAO & Right IAO

Question 5

What is side flexion?

Answer 5

• Contraction of external & internal obliques on the SAME side
• I.e., trunk side flexion to the right — right EAO & right IAO

Question 6

What is the linea alba?

Answer 6

• Extends from xiphoid process to pubic symphysis

Question 7

What are the 5 muscles of the Anterolateral Abdominal Wall?

Answer 7

• external abdominal obliques (EAO)
• internal abdominal obliques (IAO)
• tranversus abdominis (TA)
• Rectus abdominis (RA)
• pyramidalis

Question 8

What is the origin/insertion/Innervation/main action of the external abdominal obliques (EAO)?

Answer 8

• O: External surfaces of ribs 5-12
• I: Linea alba & anterior half of iliac crest
• Inn: Segmental
• MA: Trunk rotation & side flexion

Question 9

What is the origin/insertion/Innervation/main action of the internal abdominal obliques (IAO)?

Answer 9

• O: Thoracolumbar fascia, anterior 2/3 iliac crest, & lateral half inguinal ligament
• I: Inferior borders of ribs 10-12 & Linea alba
• Inn: Segmental
• MA: Trunk rotation & side flexion

Question 10

What is the origin/insertion/Innervation/main action of the transversus abdominis (TA)?

Answer 10

• O: Internal surface costal cartilages of ribs 7-12, Thoracolumbar fascia, iliac crest, connective tissue deep to lateral 1/3 inguinal ligament
• I: Linea alba
• Inn: Segmental
• MA: Acts as a corset to stabilize the spine & increase intra-abdominal pressure

Question 11

What is the origin/insertion/Innervation/main action of the Rectus abdominis (RA)?

Answer 11

• O: Pubic symphysis & pubic crest
• I: Costal cartilages of ribs 5-7 & xiphoid process
• Inn: Segmental
• MA: Trunk flexion

Question 12

What is the pyramidalis & what is its main action?

Answer 12

• Lies anterior to the inferior end of Rectus abdominis
• MA: Tenses Linea alba

Question 13

What are the muscles that facilitate respiration?

Answer 13

• diaphragm
• intercostals (3): external, internal, & innermost intercostal

Question 14

What is the diaphragm?

Answer 14

• a muscle for respiration

Question 15

What is the origin of the diaphragm?

Answer 15

• 3 divisons based on peripheral attachments:
• Sternal - xiphoid process
• Costal - inferior surfaces of ribs 6-12
• Lumbar - medial & lateral arcuate ligaments, L1-L3

Question 16

What is the insertion/Innervation of the diaphragm?

Answer 16

• I: Central tendon
• Inn: Phrenic nerve (C3, C4, C5)

Question 17

What is the main action of the diaphragm?

Answer 17

• facilitates respiration

Question 18

What is the external intercostal?

Answer 18

• Extends down & anterior (i.e., hands in pocket)
• Movement - inspiration

Question 19

What is the internal intercostal?

Answer 19

• extends down & posteriorly
• movement - expiration

Question 20

What is the innermost intercostal ?

Answer 20

• incomplete, thin & closely adhered to the internal intercostals

Question 21

How can you train the 4 abdominal muscles?

Answer 21

• external abdominal obliques = side bend
• internal abdominal obliques = Russian twist
• Rectus abdominis = crunch
• transversus abdominis = isometric hold