Musculoskeletal: Anatomy - Muscles and fascia of the anterolateral abdominal wall

Question 1

Attachments, innervation and actions of rectus abdominis

Answer 1

Attachments: xyphoid process, 5-7th costal cartilages
Innervation: thoraco-abdominal nerve (anterior rami T6-12 spinal nerve)
Actions: trunk flexion and stabilisation of pelvis, increases intra-abdominal pressure to antagonist diaphragm and aid active expiration

Question 2

Attachments, innervation and actions of external obliques

Answer 2

Attachments: ribs 5-12; linea alba, pubic tubercle, anterior 1/2 iliac crest
Innervation: thoraco-abdominal nerve (T7-11), subcostal nerve
Actions: trunk flexion and rotation, increases intra-abdominal pressure to antagonise diaphragm and aid active expiration

Question 3

Attachments, innervation and actions of internal obliques

Answer 3

Attachments: thoracolumbar fascia and anterior 2/3 iliac crest; inferior ribs 10-12, linea alba and pecten pubis
Innervation: thoraco-abdominal nerve (anterior rami T6-12), first lumbar nerve
Actions: trunk flexion and rotation, increases intra-abdominal pressure to antagonise diaphragm and aid active expiration

Question 4

Attachments, innervation and actions of transversus abdominis

Answer 4

Attachments: internal surfaces ribs 7-12, thoracolumbar fascia, iliac crest; linea alba, pubic crest, pecten pubis
Innervation: thoraco-abdominal nerve (anterior rami T6-12), first lumbar nerve
Actions: increases intra-abdominal pressure to antagonise diaphragm and aid active expiration

Question 5

Orientation of fibres in external vs internal obliques

Answer 5

External obliques: fibres run infero-anteriorly
Internal obliques: fibres run infero-posteriorly