The inguinal ligament (also ligamentum inguinale, arcus inguinalis or Pouparts’s ligament) is a band of connective tissue that extends from the anterior superior iliac spine of the ilium to the pubic tubercle on the pubic bone.
It is formed by the free inferior border of the aponeurosis of the external oblique muscle which attaches to these two points. The inguinal ligament is closely related to a number of structures and forms the superior boundary of the femoral triangle and contributes to the floor of the inguinal canal in the pelvic region.
It is also a site of attachment for the internal oblique and transversus abdominis muscles.
This article will discuss the anatomy and function of the inguinal ligament.
|Attachments||Anterior superior iliac spine, public tubercle|
|Extensions||Lacunar ligament, pectineal ligament|
|Function||Attach external oblique muscle to the pelvis, protect structure passing between the pelvis and thigh/external genitalia, forms boundary of femoral triangle and inguinal canal|
|Relations||Iliopsoas, pectineus, femoral artery, femoral vein, femoral nerve, lateral cutaneous nerve of thigh, lymphatics|
|Clinical notes||Inguinal hernia|
The inguinal ligament is formed by the thickened, reinforced free inferior edge of the aponeurosis of the external oblique muscle as this attaches to the bones of the pelvis. The superior attachment of the inguinal ligament is on the anterior superior iliac spine of the ilium. It courses obliquely in an inferomedial direction to insert onto the pubic tubercle of the pubic bone.
There are also a number of smaller ligaments formed from the extension of the medial end of the inguinal ligament. These reinforce the attachment of the inguinal ligament to the pubis. The lacunar ligament is a crescent shaped ligament that extends from the medial end of the inguinal ligament to the pecten pubis on the superior ramus of the pubic bone. A further extension of these fibres along the pecten pubis and pelvic brim forms the pectineal or Cooper’s ligament.
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The function of the inguinal ligament is to anchor the aponeurosis of the external oblique muscle to the pelvis. It also protects a number of important structures as they pass from the pelvic cavity into the thigh and inguinal canal. Additionally, the inguinal ligament forms the base of the femoral triangle and the floor of the inguinal canal.
For more information about the inguinal canal, including the inguinal ligament, take a look below:
As the inguinal ligament extends between its points of attachment, it crosses anterior to a number of structures that are passing between the pelvis and thigh. These are the iliopsoas and pectineus muscles, the femoral nerve, the lateral cutaneous nerve of the thigh and inguinal lymph nodes. The inguinal ligament is also the point where the external iliac artery becomes the femoral artery and the femoral vein becomes the external iliac vein.
The inguinal canal is a slit-like passage connecting the abdominal cavity to structures located in the groin. The medial half of the inguinal ligament forms the floor of the canal. There is an opening on either end of the canal allowing the entry and exit of the structures passing through.
The deep inguinal ring lies superior to the inguinal ligament at the mid-inguinal point. The superficial inguinal ring is located superior and slightly lateral to the pubic tubercle. Passing through the inguinal canal are the spermatic cord (males only), the round ligament of the uterus (females only), the ilioinguinal nerve and the genital branch of the genitofemoral nerve.
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An inguinal hernia is the abnormal protrusion of the peritoneal sac (with or without abdominal contents) through the abdominal wall in the groin. It is typically caused by a weakness in the abdominal wall at the point of the deep and superficial inguinal rings. The hernia usually begins as a saccular outpouching that contains extraperitoneal tissue. Over time, as the hernia gets larger, positive pressure from the abdominal cavity forces peritoneum into the sac. Eventually, abdominal viscus may enter the hernia sac as well.
Inguinal hernias may be congenital (in which case the hernia is associated with a patent processus vaginalis) or acquired (related to an imbalance of type I and type III collagen). Smoking, weight training and lifting heavy objects have also been identified as risk factors for developing hernias.
Inguinal hernias are classified as indirect or direct: Inguinal hernias that protrude through the deep inguinal ring and traverse the canal are known as indirect hernias. While direct hernias protrude through the superficial ring and emerge within the inguinal triangle (of Hesselbach, inferomedial aspect of anterior abdominal wall).
Symptoms of an inguinal hernia include:
- A noticeable bulge on either side of the pubic bone
- Pain and swelling of this region especially when coughing or lifting
- A heavy 'dragging' sensation in groin
- Weakness or pressure in groin
Inguinal hernias do not typically improve on their own and only resolve with surgical intervention. Surgery for the treatment of inguinal hernias involves pushing the peritoneal sac and contents back into the abdomen. The weakened area in the abdominal wall is then reinforced with a synthetic mesh to reduce the risk of re-herniation.
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