Muscles TRUNK

Question 1

Describe the orientation and location of the internal oblique muscle

Answer 1

• arises from the thoracolumbar fascia, iliac crest, & lateral 1/2 of inguinal ligament
• fibers course superiomedially at right angle to external oblique & continue into internal oblique aponeurosis
• medially splits around rectus abdominus & helps form anterior & posterior layers of rectus sheath above arcuate line
• fibers intersect at linea alba

Question 2

Describe the orientation & location of the transversus abdominis muscles

TA

Answer 2

• originates from costal cartilages 7-17, thoracolumbar fascia, iliac crest, & lateral 1/3 of inguinal ligament
• runs transversely
• lowest tendinous fibers arch downward to help form the conjoint tendon
• helps form posterior layer of recus sheath

Question 3

Describe the orientation and location of the internal oblique muscle

INT OBL

Answer 3

• arises from the thoracolumbar fascia, iliac crest, & lateral 1/2 of inguinal ligament
• fibers course superiomedially at right angle to external oblique & continue into internal oblique aponeurosis
• medially splits around rectus abdominus & helps form anterior & posterior layers of rectus sheath above arcuate line
• fibers intersect at linea alba

Question 4

Describe the orientation and location of the external oblique muscle

EXT OBL

Answer 4

• arises from lower 8 ribs & courses inferomedially
• posterior fibers insert into illiac crest & form external oblique aponeurosis (part of anterior rectus sheath)
• at midline aponeurotic fibers intersect from both sides (linea alba)
• most superior layer

Question 5

Describe the orientation & location of the rectus abdominis muscle

RA

Answer 5

• ascends vertically from pubic crest to cartilages 5-7
• 3 or more tendinous intersections = 6 pack
• enclosed w/i connective rectus sheath (formed by aponeuroses of 3 flat abdominal muscles)
• is seperated at midline by linea alba
• laterally bound to linea semilunaris

Question 6

https://www.cram.com/flashcards/anatomy-exam-5-anterior-abdomen-3635275

Answer 6

https://www.cram.com/flashcards/anatomy-exam-5-anterior-abdomen-3635275

Question 7

What is the movement of the external oblique?

Answer 7

EXT OBL

• Pulls chest dwn
• Compress the ab cavity
• Increases intra ab pressure
• Performs Same Side Bending
• Performs Opposite Side Rotation

Function.
The external oblique functions to pull the chest downwards and compress the abdominal cavity, which increases the intra-abdominal pressure as in a valsalva maneuver. It also performs ipsilateral (same side) side-bending and contralateral (opposite side) rotation.