Brian P. Jacob, David C. Chen, Bruce Ramshaw, Shirin Towfigh (eds.) - The SAGES Manual of Groin Pain-Springer International Publishing (2016)

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A. Malhotra
steroid injections, therapeutic nerve blocks, pulsed radiofrequency neuromodulation
of peripheral nerves or dorsal root ganglia, cryoablation,
radiofrequency ablation, chemoneurolysis, and implantable peripheral
field stimulation. Identifying the nerve that is most likely to be injured
is the first step in pursuing an interventional approach. Groin pain by
definition occurs between the abdomen and thigh, and for this reason the
nerves supplying the skin and structures in this area are referred to as
“border nerves” [ 14 ]. These include the ilioinguinal, iliohypogastric,
genitofemoral, and lateral femoral cutaneous nerves arising from the
T12–L3 anterior rami as they form the upper lumbar plexus.
1. Iliohypogastric nerve—formed by L1 with contributions from
T12. Exits the lateral border of the psoas and runs in the retroperitoneum
along the quadratus lumborum before emerging
through the transversus abdominis plane at the iliac crest. It
innervates the infraumbilical skin to the inguinal ligament.
2. Ilioinguinal nerve—formed by L1 with contributions from T12.
Follows a similar course as the iliohypogastric nerve before
passing lateral to the internal inguinal ring, running anterior to
the spermatic cord to innervate the medial thigh, root of penis
and upper scrotum in men, and mons pubis and labia majora in
women.
3. Genitofemoral nerve—formed by L1 and L2. Pierces the psoas
and runs along its anterior surface before splitting into a genital
and femoral branch. The femoral branch runs with the external
iliac artery under the inguinal ligament and innervates the anterolateral
thigh. The genital branch passes through the inguinal canal
and runs along with the spermatic cord to innervate the testicle
and scrotum. It can run inside or outside the cord itself [ 14 ].
4. Lateral femoral cutaneous nerve—formed by L2 and L3. Exits
the lateral border of the psoas and runs inferolaterally to the anterior
superior iliac spine (ASIS) and then passes under the inguinal
ligament and over the sartorius, located between the fascia lata
and iliaca, providing innervation to the lateral thigh.
It should be noted that there is significant overlap and communication
between nerves in the groin. In particular, the ilioinguinal nerve distribution
may overlay that of the iliohypogastric, and, indeed, they are commonly
inverse in size. Similarly, the ilioinguinal nerve has been shown to
share innervation of the genital branch of the genitofemoral nerve in up
to one-third of cadaver dissections [ 14 ]. Due to this anatomical variability,
landmark-based techniques for nerve blockade are unlikely to be