Surface Markings on anterior abdominal wall

1. Linear alba: midline where rectus sheath fuses
2. Linea semilunaris: lateral edge of rectus sheath on each side
3. Arcuate line: 5-6cm below umbilicus - level where posterior wall of rectus sheath finishes and where all 3 anterior wall muscles (external and internal oblique and transversalis abdominis) lie anterior to the rectus abdominis
4. Transpyloric plane: 1/2 between suprasternal notch and pubic symphysis

   

   • L1 vertebral body
   • Termination of spinal cord
   • 9th costal cartilage tips
   • Pylorus
   • Neck of pancreas
   • Origin of portal vein
   • Hilum of kidney
   • 2nd part of duodenum
   • Fundus of gallbladder
   • DJ flexure
   • Superior mesenteric artery

Inguinal Ligament and Canal

1. Inguinal ligament: lower free edge of external oblique
2. Lacunar ligament: medial curved fibres of inguinal ligament that pass upwards and backwards to attach to pectineal line
3. Inguinal canal: 4cm tunnel in lower, anterior abdominal muscles that runs downwards and medially between the deep and superficial rings
4. Deep inguinal ring: hole in transversalis fascia lying 3cm superior to the midpoint of the inguinal ligament
5. Superficial inguinal ring: V-shaped defect in the lower medial fibres of the external oblique just superior and lateral to the pubic tubercle

Inguinal (Hasselbach's) triangle

Site of direct inguinal herniation

Borders

1. Lateral: inferior epigastric artery
2. Medial: lateral edge of rectus abdominis
3. Inferior: inguinal ligament

Posterior Abdomen and back

• Supracrista plane: transverse line along upper aspects of the iliac crests passing through spinous process of L4 vertebra
• Useful aid in lumbar puncture for either L3/4 or L4/5 spaces