Groin

The groin refers to the area on the lower front of the abdomen, where the torso meets the inner thigh. It is a term commonly used to describe the region that encompasses various muscles, tendons, and ligaments, as well as the inguinal canal.^[2] This area is essential for a wide range of movements, particularly those involving the legs and lower abdomen. Groin injuries, often involving strain or tearing of the muscles, are common in sports and physical activities.

Location

The groin is located in the lower part of the abdomen, between the pubic region and the upper inner thigh. Anatomically, it is situated just below the inguinal ligament, extending from the pelvic bones towards the thigh. The inguinal canal, a key feature in this area, passes through the groin region.

Structure and Anatomy

The groin is a complex anatomical region that involves muscles, ligaments, tendons, blood vessels, and nerves. It plays a vital role in movements that involve the hip, thigh, and lower abdomen. Below is a detailed description of the structures that make up the groin.

Muscles of the Groin

The groin region is home to several key muscles, primarily responsible for hip flexion, adduction, and stabilization.

a. Adductor Muscles

• Adductor Longus: Originates from the pubic bone and inserts into the femur (linea aspera). It is the most prominent adductor in the groin.^[3]
• Adductor Brevis: Positioned beneath the adductor longus, this muscle assists in adduction and internal rotation of the thigh.
• Adductor Magnus: A large, triangular muscle with origins from the pubic bone and ischial tuberosity, inserting into the femur. It is the strongest adductor in the group.
• Gracilis: A long, thin muscle that originates from the pubic symphysis and inserts into the tibia, contributing to hip adduction and knee flexion.

b. Iliopsoas Muscle

• Iliacus: Originates from the iliac fossa of the pelvis and inserts into the lesser trochanter of the femur.
• Psoas Major: Originates from the lumbar vertebrae and combines with the iliacus to form the iliopsoas, which is crucial for hip flexion.

c. Sartorius

• The longest muscle in the human body, the sartorius runs diagonally across the front of the thigh. It originates from the anterior superior iliac spine (ASIS) and inserts on the tibia, assisting in hip flexion and lateral rotation.^[5]

d. External Oblique

• The external oblique muscle runs along the sides of the lower abdomen, contributing to the stability of the groin and assisting in lateral flexion and rotation of the trunk.

Inguinal Ligament

• Structure: The inguinal ligament is a band of fibrous tissue that extends from the anterior superior iliac spine (ASIS) to the pubic tubercle.
• Function: It forms the lower border of the inguinal canal and plays a role in stabilizing the lower abdomen.

Inguinal Canal

• Location: The inguinal canal runs through the groin region, slightly above and parallel to the inguinal ligament. It serves as a passageway for various structures, including the spermatic cord in males and the round ligament in females.^[7]
• Content: The inguinal canal contains the spermatic cord in men, which includes the vas deferens, blood vessels, nerves, and lymphatics. In females, it contains the round ligament of the uterus.

Blood Supply

a. Femoral Artery

• The femoral artery, which is a continuation of the external iliac artery, supplies blood to the groin and thigh regions.
• It passes through the femoral triangle, an area bordered by the inguinal ligament, sartorius muscle, and adductor longus muscle.^[8]

b. Obturator Artery

• The obturator artery is another blood vessel that supplies the muscles of the inner thigh, including the adductor group. It originates from the internal iliac artery and passes through the obturator foramen.

Nerve Supply

The groin region is innervated by several important nerves that provide sensation and motor function.

a. Femoral Nerve

• The femoral nerve, arising from the lumbar plexus (L2-L4), innervates the anterior thigh muscles, including the iliopsoas and quadriceps. It also provides sensation to the anterior and medial thigh and part of the leg.

b. Obturator Nerve

• The obturator nerve (L2-L4) supplies the adductor muscles of the thigh and provides sensation to the medial thigh.

c. Genitofemoral Nerve

• Arising from the lumbar plexus, the genitofemoral nerve provides sensation to the skin over the groin and the genitalia.

d. Ilioinguinal Nerve

• The ilioinguinal nerve (L1) provides sensory innervation to the skin over the lower abdomen and upper thigh, including the groin area.

Lymphatic Drainage

Lymph nodes in the groin, particularly the inguinal lymph nodes, are part of the body’s immune system. These nodes drain lymph from the lower limb, external genitalia, and lower abdomen, filtering out bacteria and other pathogens.^[1]

Tendons and Ligaments

a. Pubic Symphysis

• The pubic symphysis is a cartilaginous joint that connects the left and right pubic bones. It provides stability to the pelvic girdle and is located at the center of the groin region.

b. Tendons of the Adductors

• The tendons of the adductor muscles (longus, brevis, and magnus) attach to the pubic bone and the femur. These tendons contribute to the adduction and stabilization of the hip joint.

Skin and Fascia

• Skin: The skin over the groin is relatively thin and contains numerous sweat glands.
• Superficial Fascia: Beneath the skin, the superficial fascia contains fat and connective tissue, providing protection and cushioning for the underlying muscles and structures.

Other Features

• Groin Hernias: Occur when a portion of the intestine or fatty tissue pushes through a weakness in the abdominal wall, often within the inguinal canal.
• Femoral Triangle: The femoral triangle, an anatomical area located in the upper inner thigh, is bordered by the inguinal ligament, sartorius muscle, and adductor longus muscle. It contains vital structures such as the femoral artery, vein, and lymph nodes.

Function

The groin region, with its various muscles, tendons, ligaments, and nerves, performs several key functions related to movement, stability, and overall bodily function:

Hip and Thigh Movement

The muscles of the groin, particularly the adductors (adductor longus, adductor magnus, adductor brevis, and gracilis), play a crucial role in the adduction (movement towards the midline) of the thigh.^[4]

The iliopsoas and sartorius muscles contribute to hip flexion, enabling actions such as lifting the leg or bringing the knee towards the body.

Pelvic Stabilization

The muscles of the groin, including the adductors and external oblique, help stabilize the pelvis and support movements that involve the lower abdomen and legs. This stabilization is essential for maintaining posture and balance during various activities, such as walking, running, and jumping.

Facilitating Gait

The groin muscles are essential for a smooth and efficient gait. The adductors help to control the swing of the leg, ensuring it moves properly during walking or running.

Supporting the Inguinal Canal

The inguinal ligament and canal provide support to the structures that pass through them, such as the spermatic cord in men and the round ligament in women. This support helps maintain proper positioning and function of the abdominal and pelvic contents.

Movement of the Abdomen and Trunk

The external oblique muscles assist in trunk rotation, lateral flexion, and compression of the abdomen. These actions are important for activities like bending, twisting, and lifting.

Conduit for Blood Vessels and Nerves

The groin serves as a passage for key blood vessels (femoral and obturator arteries) and nerves (femoral, obturator, and genitofemoral nerves) that supply the lower body. These structures are vital for motor control and sensation in the legs and pelvis.

Clinical Significance

The groin region is clinically significant due to its involvement in various injuries, conditions, and surgical procedures.^[6] Some of the key clinical issues associated with the groin include:

• Groin Strains
  • Groin strains are common injuries, particularly in athletes involved in sports that require quick changes in direction, running, or kicking. The adductor muscles are particularly prone to strain, leading to pain, swelling, and difficulty with movement.
• Inguinal Hernia
  • An inguinal hernia occurs when a portion of the intestine or fatty tissue pushes through a weakness in the abdominal wall in the groin area. This condition can cause pain and discomfort, especially during activities that increase intra-abdominal pressure. Surgical intervention is often required.
• Femoral Hernia
  • Less common than inguinal hernias, femoral hernias occur when tissue protrudes through the femoral canal, located near the groin. These hernias are more common in women and may require surgical repair to avoid complications such as strangulation of the intestine.
• Groin Pain Syndromes
  • Groin pain can result from various causes, including muscle strains, ligament injuries, hip joint pathologies, or conditions like osteoarthritis. Diagnosis can be challenging as groin pain often overlaps with issues in the lower abdomen, pelvis, and hip.
• Sports-Related Injuries
  • The groin area is highly susceptible to injuries during sports that involve repetitive movements, such as running, soccer, or hockey. These injuries may include muscle strains, tears, and tendonitis, which can lead to chronic pain and functional impairment if not properly managed.
• Hip and Groin Osteoarthritis
  • Osteoarthritis in the hip joint can present with pain and stiffness that radiates into the groin area. This condition may require medical management or, in severe cases, hip replacement surgery.
• Femoral Artery Access
  • In medical procedures such as angiograms or catheter insertions, the femoral artery is often accessed through the groin. This can lead to complications such as bleeding, hematomas, or infection if not properly managed.
• Pelvic and Inguinal Lymphadenopathy
  • Swelling or enlargement of lymph nodes in the groin area can indicate infections, cancers, or inflammatory conditions. Evaluation of these lymph nodes is critical in diagnosing conditions such as sexually transmitted infections, lymphoma, or metastasis from pelvic malignancies.