Iliohypogastric nerve
Introduction
The iliohypogastric nerve is a branch of the lumbar plexus, originating mainly from the L1 spinal nerve. It provides motor innervation to the lower abdominal muscles (such as the internal oblique and transversus abdominis) and sensory innervation to the skin over the lower abdomen and upper hip (gluteal) region. It plays a role in abdominal wall strength and sensation.
Together with the ilioinguinal nerve, it emerges as a single trunk from the anterior/ventral ramus of the L1 spinal nerve root. After emerging from the upper border of the psoas major muscle, the nerve begins its journey on the posterior abdominal wall. After that, it runs between the anterior abdominal muscles and crosses obliquely to the anterior abdominal wall.
The iliohypogastric nerve, being a mixed nerve, provides sensory innervation to the skin of the posterolateral gluteal and suprapubic areas in addition to motor and sensory innervation to the abdominal muscles.
Structure
Origin
The superior branch of the anterior ramus of spinal nerve L1 is where the iliohypogastric nerve begins. Additionally, T12 sends fibres to it through the subcostal nerve.
Course
The iliohypogastric and ilioinguinal nerves come from the anterior ramus of the L1 spinal nerve root of the lumbar plexus.
The iliohypogastric nerve travels anteriorly between the transversus abdominis muscle and the internal abdominal oblique muscles before puncturing the muscle just above the iliac crest as it moves in the direction of the anterior abdominal wall.
Function
Sensory function
The transversus abdominis muscle, internal abdominal oblique, and external abdominal oblique all receive sensory fibres from the nerve.
Motor function
Additionally, the transversus abdominis and internal abdominal oblique muscles get motor fibres from the iliohypogastric nerve. Additionally, it innervates the conjoint tendon, which is made up of the internal oblique muscles and the transversus abdominis’ shared aponeurosis.
Branches
Lateral cutaneous branch
To feed the posterolateral portions of the gluteal skin, the lateral cutaneous branch penetrates the external and internal abdominal oblique muscles above the iliac crest.
Anterior cutaneous branch
The transversus abdominis and internal abdominal oblique muscles are innervated by the anterior cutaneous branch, which runs anteriorly between them. It punctures the internal oblique muscle around 2 cm medial to the anterior superior iliac spine. This branch then supplies the skin above the pubic region by passing via the aponeurosis of the external abdominal oblique muscle, which is located around 3 cm above the superficial inguinal ring.
Variation
Rather, its fibres are transported by other nerves, such as the ilioinguinal nerve.
Clinical Importance
Other nerves may be impacted, and iliohypogastric nerve damage is seldom isolated. An oblique open approach to the appendix during surgery can sometimes result in injury. Transverse incisions in the lower abdomen, such as those made after a hysterectomy, can also cause damage to the iliohypogastric nerve. Since many nerves innervate the suprapubic area, a discernible sensory loss is uncommon.
Nerve injuries can be caused by:
either as a result of acute surgical damage or after the surgery, when the nerve becomes trapped in scar tissue.
Sport-related injuries like muscular tears or trauma can potentially harm the nerve.
Rarely, pregnancy-related nerve damage might also happen because of the third trimester’s fast abdominal growth. The term “idiopathic iliohypogastric syndrome” describes this condition.
The suprapubic and inguinal areas may experience a searing pain if the iliohypogastric nerve is injured or trapped. A local anesthetic injection, painkillers such as anti-inflammatory drugs, or physical therapy like cryotherapy are the available treatment options.
The posterior wall of the inguinal canal may become weaker if the iliohypogastric nerve divides above the level of the anterior superior iliac spine. This may increase the risk of developing a direct hernia.
FAQs
What is the main function of the iliohypogastric nerve?
The iliohypogastric, ilioinguinal, and genitofemoral nerves have a primary sensory function, innervating the lower abdomen, inguinal region, the upper and medial anterior thigh, and part of the genitalia.
What happens if the iliohypogastric nerve is damaged?
The iliohypogastric nerve, which passes through the lower abdominal muscles, provides sensation to the skin of the gluteal region and lower abdomen. Damage to this nerve may result in pain or sensory deficits in these areas.
What is iliohypogastric nerve dysfunction?
Iliohypogastric nerve neuralgia: This disorder is typified by a scorching, intense pain that usually starts right after surgery on the abdomen. The discomfort typically radiates from the location of the surgical incision into the suprapubic and inguinal regions and is frequently characterised as a constant burning or stabbing sensation.
How do you treat iliohypogastric nerve pain?
These regions may experience pain or sensory deficiencies as a result of damage to this nerve.
What are the complications of an iliohypogastric nerve block?
Vasovagal response (passing out), new or increased pain, infection, bleeding, lasting skin changes, allergic or unanticipated medication reaction with small or serious consequences, and unintentional nerve damage are some examples of potential dangers.
References
Iliohypogastric nerve – 2024 – https://en.wikipedia.org/wiki/Iliohypogastric_nerve
Iliohypogastric nerve – 2023-https://www.kenhub.com/en/library/anatomy/iliohypogastric-nerve
