The midpoint of the inguinal ligament and the mid-inguinal point are two different anatomical landmarks in the inguinal region. In order to understand the difference, some simple anatomical knowledge must be clarified.
The inguinal ligament stretches from the anterior superior iliac spine (ASIS) to the pubic tubercle. The pubic symphysis lies just medial to the pubic tubercle and is the fibrous joint between the two halves of the pelvis.
Running under the inguinal ligament from medial to lateral are: femoral canal (a potential space that contains mainly lymphatics), femoral vein, femoral artery and femoral nerve.
The midpoint of the inguinal ligament is half way between the ASIS and the pubic tubercle and is the location of the femoral nerve. This landmark is used in femoral nerve blocks.
The mid-inguinal point is half way between the ASIS and the pubic symphysis and is the location of the femoral artery. This landmark is used in palpation of the femoral pulse.
In relation to each other, the mid-inguinal point is more medial than the midpoint of the inguinal ligament.