Anatomy: anterolateral abdominal wall

Question 1

Functions of the abdominal muscles?

Answer 1

Assist in expiration - attach to the costal margin and depress the ribs
Increase intra abdominal pressure to facilitate the evacuation process –> urination, defecation, birth

Question 2

Label the layers of the anterolateral abdominal wall

Answer 2

Question 3

Above the arcuate line, how do the external oblique/internal oblique/transveralis aponeuroses relate to the rectus abdominis?
How about below the arcuate line?

Answer 3

Question 4

External oblique muscle
- Directin of muscle fibres?
- Superior muscle attachments?
- Inferior muscle attachments

Answer 4

Anteroinferior
Superior: interdigitate with serratus anterior and pectoralis major; spills over the costal margin
Inferior: anterior half of the iliac crest

Question 5

External oblique
- Superior tendon attachment?
- Medial tendon attachment?
- Inferior tendon attachment?

Answer 5

Superior: pectoralis fascia and xiphoid process
Medial: both tendons blend with the anterior rectus sheath and meet in the middle at the linea alba
Inferior: tendons bottom edge thicken to become/blend with the inguinal ligament, attaches to public crest and pubic tubercle

Question 6

Internal oblique
- Driection of muscle fibres?
- Posterior muscle attachment?
- Superior muscle attachment?
- Inferior muscle attachment?

Answer 6

Posteroinferior
Posterior: arises from the thoracolumbar fascia (fascia of the psoterior abdominal wall)
Superior: attaches to the costal margin and the linea alba
Inferior: arises from the lateral 2/3 of the inguinal ligament, then arch over and downwards

Question 7

Internal oblique
- Superior tendon attachment?
- Medial tendon attachment?
- Inferior tendon attachment?

Answer 7

Superior: costal margin
Medial: splits above arcuate line to contribute to anterior and posterior rectus sheath; only contributes to anterior rectus sheath below
Inferior: combined tendon inserts into the pubic crest

Question 8

Transversus abdominus
- What direction are the muscle fibres?
- What fascia does the muscle sit on?
- Posterior muscle attachment?
- Superior muscle attachment?
- Inferior muscle attachment?

Answer 8

Horizontal fibres
Transversalis fascia
Posteriorly: thoracolumbar fascia
Superiorly: underneath the costal margin
Inferiorly: fibres arise from the anterior 2/3 of the iliac crest and lateral ½ of the inguinal ligament, then arch over

Question 9

Transversalis fascia
- Superior tendon attachment?
- Medial tendon attachment?
- Inferior tendon attachment?

Answer 9

Xiphoid process
Above arcuate line –> posterior rectus sheath; below –> anterior rectus sheath
Combined tendon inserts into the pubic crest

Question 10

Rectus abdominis
- Superior muscle attachments?
- Medial muscle attachment?
- Lateral muscle attachments?
- Inferior muscle attachments?

Answer 10

Xiphoid process, pectoralis fascia and costal margin (spill over)
LInea alba
Linea semilunaris - confluence of abdominal tendons
Pubic crest

Question 11

Rectus abdominis
- Muscle bellies are contained within which tendinous structure?
- How many tendinous intersections normally? Can this vary?

Answer 11

Within the rectus sheath and its aponeurosis with the external/internal oblique, and transversus abdominis
3 - making the 6 pack; yes can vary

Question 12

Pyramidalis muscle
- Where is it found?

Answer 12

Between the anterior surface of the rectus abdominis muscle and the rectus sheath

Question 13

Arteries
- Label the branches of the internal thoracic artery (yellow) and the external iliac artery (blue)

Answer 13

Question 14

Arteries
- Anastamoses can occur between which branches of the internal thoracic artery (yellow) and the external iliac artery (blue)?

Answer 14

Superior epigastric artery + inferior epigastric artery
Musculophrenic artery + deep circumflex iliac artery

Question 15

Nerves
- Label the thoracic nerves (yellow)

Answer 15

Question 16

Nerves
- Label the L1 nerves (blue and green)

Answer 16

Question 17

Nerves:
- Which nerves supply the external/internal obliques and the transversus abdominis?

Answer 17

T7-T11
Subcostal nerve (T12)
Iliohypogastric nerve (L1)
Ilioinguinal nerve (L1)

Question 18

Nerves
- Which nerves supply the rectus abdominis muscle?

Answer 18

T7-T11
Subcostal nerve (T12)