Abdominal wall muscles

Question 1

What are the layers of the abdominal wall?

Answer 1

• Skin
• Superficial and deep fascia/fat
• Muscles
• Transversalis fascia
• Peritoneum

Question 2

Which abdominal muscles have an aponeurosis?

Answer 2

• External obliques
• Internal obliques
• Transverse abdominis
• The aponeuroses of these muscles envelope the midline rectus abdominus muscles.

Question 3

What is an aponeurosis?

Answer 3

Thin sheet like tendon

Question 4

What is the key information for the external obliques?

Answer 4

• Origin: ribs 5-12
• Insertions: iliac crest, pubic tubercle, linea alba
• Actions: compress abdominal viscera, flex trunk, rotate trunk.

Question 5

What is the inguinal ligament?

Answer 5

A band of connective tissue formed by the aponeurosis of the external oblique muscle that stretches from the ASIS to the pubic tubercle.

Question 6

What is the key information for the internal obliques?

Answer 6

• Origins: lateral portion of inguinal ligament, iliac crest, thoracolumbar fascia
• Insertions: lower 3-4 ribs, linea alba (via aponeurosis), pubic crest
• Action: compresses abdominal viscera, flexes trunk, ipsilateral rotator of the trunk.
• Direction of fibres runs perpendicular to those of external obliques.

Question 7

What is the key information for the transverse abdominis muscles?

Answer 7

• Origins: costal cartilages of lower ribs, thoracolumbar fascia, medial lip of iliac crest, inguinal ligament
• Insertions: linea alba (aponeurosis blends with linea alba), lower fibres insert onto pubic crest
• Actions: compresses abdominal viscera, important for core stability
• Fibres run horizontally

Question 8

What is the nerve supply to the external obliques, internal obliques, and transverse abdominis muscles?

Answer 8

• External obliques are innervated by the anterior rami T7-T12.
• Internal obliques and transverse abdominis supplied by anterior rami T7-&12, L1.

Question 8

What is the nerve supply to the external obliques, internal obliques, and transverse abdominis muscles?

Answer 8

• External obliques are innervated by the anterior rami T7-T12.
• Internal obliques and transverse abdominis supplied by anterior rami T7-&12, L1.

Question 9

What is the key information for the rectus abdominus muscle?

Answer 9

• Origins: pubic tubercle, pubic crest, pubic symphysis

-Insertions: costal cartilages of ribs 5-7, xiphoid process

• Actions: compresses abdominal viscera, stabilises pelvis during walking, depresses ribs

-Innervation: T7-T11

Question 10

What forms the rectus sheath?

Answer 10

• The aponeuroses of the lateral muscles.
• It surrounds the rectus abdominis muscles.
• The anterior wall is formed by the aponeuroses of the external oblique, and of half of the internal oblique.
• The posterior wall is formed by the aponeuroses of half the internal oblique and of the transversus abdominis.