The groin is also referred to as the inguinal portion of the body. It is located anteriorly in the lower region within the abdominal wall, inferiorly surrounded by the thighs, with the pubic tubercle in the medial part and superolateral surrounded by the anterior superior iliac spine (ASIS). The inguinal canal has a tubular form that runs inferomedially. In males, it consists of the spermatic cord, whereas in females consist of the round ligament. The length of the inguinal canal is approximately 4-6 cm which changes from childhood to adulthood.
Inguinal ligament forms the floor of the inguinal canal, also called as Poupart ligament. This ligament is composed of the external oblique aponeurosis. It overlaps and attaches to the ASIS extending till the pubic tubercle. The folded edge is known as the shelving edge that plays an important role for clinicians in the management of hernia repairs.
Groin or the inguinal canal consists of an anterior wall, posterior wall, floor and roof. The anterior wall is composed of the external oblique aponeurosis. The transversalis muscle forms the posterior wall. The floor of the groin or inguinal canal is composed of the inguinal ligament. This ligament is a thickened portion formed by the external oblique aponeurosis. The roof is a complex structure formed by the combination of fibres of two muscles (transversus abdominis and internal oblique muscle) with the aponeurosis and the conjoint tendon. The conjoint tendon forms an important part of the posterior wall in the medial portion.
The adductor muscles in the groin are most commonly subject to injury, and there comprises the adductor longus, adductor magnus, adductor brevis, gracilis, and pectineus.
There are two openings through the inguinal canal:
- The deep or internal ring is present above the center of the inguinal ligament, and laterally surrounded by the epigastric vessels. This ring is made by the transversalis fascia, providing a posterior covering to the contents of the inguinal ring.
- The superficial or external ring constitutes the inguinal canal’s terminal end. This ring is present superior to the pubic tubercle. The external ring has a triangular shape which is formed by the fibres of the external oblique muscle. These fibres cover the inguinal contents and descend into the scrotal area.
It is important to understand the anatomy of the inguinal canal or groin so that the surgeon is well aware of different types of groin hernia arising in the region, and also for performing various kinds of surgical repair. The mid-inguinal point demarcates the region between the pubic symphysis and the anterior superior iliac spine. Deep to this location, there is a femoral artery that enters the lower limb. The palpation of the femoral artery is possible below the inguinal ligament. The groin acts as a gateway for structures between the intra- and extra-abdominal components. It transmits the gonadal vessels , spermatic cord and lymphatics in males, while in females allows the passage of the round ligament of the uterus.
The major role of the muscles of the inner thigh is to pull the legs towards the midline, with a movement known as adduction.
There are two important nerves that pass through the various structures of the inguinal canal. This includes the ilioinguinal, genitofemoral nerves, and iliohypogastric nerve. The iliohypogastric nerve does not pass through the inguinal canal, however, it supplies skin sensation above the genitalia. The ilioinguinal nerve, a branch of L1 passes through the deep inguinal openings in addition to the cord structures. It supplies sensation to the medial and upper thigh as well as the anterior perineum. The genitofemoral nerve is a branch of the L1-L2 spinal nerve roots. It divides into two branches namely, the genital branch and the femoral branch where the former passes through the deep inguinal ring and the latter passes below the inguinal canal.
The femoral artery supplies blood to the groin region. As a continuation of the external iliac artery, the common femoral artery is formed below the inguinal ligament. The artery is present medially to the middle portion of the inguinal ligament within the inguinal crease region.
Clinical Relevance and Associated Diseases
Inguinal hernias are associated with the inguinal area and canal. Groin hernia refers to the inguinal and femoral hernias, that show up as groin pain. Certain diseases are encountered within this area such as hydrocele and undescended testis and, if not treated in time, lead to chronic pain.
Groin strain, also known as a groin pull, refers to the damage of one of the muscles in the inner thigh due to excessive stretch or the muscle being torn.
This type of hernia occurs when the peritoneal sac enters into the inguinal canal through the deep inguinal ring. Through the external inguinal ring, there is the protrusion of the hernia that manifests as groin pain.
In this type of groin hernia peritoneal sac enters via the inguinal canal as a result of defect or impairment in the posterior portion of the inguinal canal, mostly the transversus abdominis.
In this type of injury, the hernial sac protrudes through the femoral ring. The femoral ring constitutes the medial portion of the femoral canal. There is a difference in the management of surgical repair of femoral hernia and inguinal hernia as the latter is conducted by an open approach.
A hydrocele happens due to the prolonged patency of the processus vaginalis which may occur along with indirect hernia. In hydrocele, there is an accumulation of fluid within the scrotum leading to persistent groin pain.
Malignancy of the groin
The inguinal area is also involved with the drainage of lymph nodes and therefore may result in lymphadenopathy from infections and malignancies. Certain malignancies of the groin area include lipoma of the spermatic cord and malignant tumours like rhabdomyosarcoma.
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