Anatomy Lecture Notes: Abdominal Wall and Inguinal Canal

Introduction

• Speaker: Dr. Alsup
• Focus: Muscles of the abdominal wall, inguinal canal structures, and related areas.

Abdominal Wall Muscles

External Obliques

• Most superficial of the anterolateral abdominal wall muscles.
• Muscle fibers run directionally similar to external intercostal muscles.
• Direction: Like putting hands in front pockets.
• Superficial dissection: Identifiable without reflecting internal structures.

Rectus Sheath

• Formed by tendons/aponeuroses of oblique muscles and transversus abdominis.
• Dominant white, opaque structure in anterior abdominal wall.
• Linea alba: Midline, more opaque than rest of the sheath.

Rectus Abdominis

• Long muscle, extends from xiphoid process to pubic symphysis.
• Contains tendinous intersections, typically three.
• Reflected to see posterior rectus sheath.
• Ends about 3/4 down, inferior portion of transversalis fascia begins.
• Arcuate line: Line of demarcation of posterior rectus sheath.

Inguinal Canal

• Traditionally complex region.
• Structures: Deep inguinal ring (not visible superficially) and superficial inguinal ring.
• Superficial inguinal ring: Exit of inguinal canal, formed by external oblique aponeurosis.

Round Ligament of Uterus

• Exits superficial inguinal ring.
• Tubular collection of adipose tissue, hard to differentiate.
• Ilioinguinal nerve runs superficial to the round ligament.
• Connects uterus to labia majis, remnant of gubernaculum.

Spermatic Cord

• Exits superficial inguinal ring with ilioinguinal nerve superficial.
• Components shown upon dissection.

Inguinal Ligament

• Floor of the inguinal canal.
• Extends from anterior superior iliac spine to pubic tubercle.
• Longer than the inguinal canal.
• Composed of external oblique aponeurosis.

Deep Surface of Abdominal Wall

• Reflecting anterior wall shows peritoneal cavity and omenta.
• Inferior epigastric vessels visible (paired veins and artery).
• Round ligament entering deep inguinal ring.
• Inferior epigastric vasculature medial to deep inguinal ring (important for inguinal hernias).

Diaphragm

• Major subdivision between thoracic and abdominal cavity.
• Left hemidiaphragm above the stomach, right above the liver.
• Three openings: Esophagus, vagal trunks, inferior vena cava, aorta.

Conclusion

• Review lecture material and reach out with questions.
• End of session.