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

2. Groin Pain: A Neurologic and Musculoskeletal…
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abdominal wall, eventually passing through external oblique about
2.5 cm superior to the external ring, providing sensory innervation to the
suprapubic skin [ 3 ].
The lower branch of the L1 nerve is the ilioinguinal nerve , which
similarly pierces the transversus abdominus muscle to travel in the
neurovascular plane and then passes through the internal oblique to enter
the inguinal canal, providing motor innervation to the lower fibers of
both muscles. It runs with the cord structures and exits the canal via the
external ring to provide sensory innervation to the overlying skin of the
upper medial thigh, anterior scrotum, and base of the penis (or labium
majus and mons pubis).
The genitofemoral nerve arises from L1 and L2 within the substance
of psoas major and then courses downward on its anterior surface. It
divides into a genital and a femoral branch. The genital branch travels
along the external iliac artery and then ascends to meet the vas deferens
at the internal ring. Entering the inguinal canal, it becomes part of the
spermatic cord lying on its inferior surface with a companion vein. In the
male, it passes into the scrotum via the external ring and provides motor
innervation to the cremaster muscle (and therefore is responsible for the
cremasteric reflex), and sensory innervation to a small part of the scrotum.
In the female, it provides sensory innervation to the mons pubis.
The femoral branch passes deep to the inguinal ligament, lateral to the
femoral artery, supplying the skin of the upper anterior thigh immediately
inferior to the ligament.
The sympathetic nerves of the spermatic cord originate in the T10-11
spinal cord segments and travel with the greater and lesser splanchnic
nerves to the pre-aortic plexus. These autonomic fibers then run with the
gonadal artery to the testis. The sympathetic efferent fibers are vasomotor,
and the afferent fibers conduct testicular pain, which is thus referred
to the umbilical region, innervated by the tenth intercostal nerve.
Anatomy of the Femoral Ring
Immediately posterior and inferior to the inguinal ligament is the
femoral ring . It is bounded posteriorly by the pectineal ligament, medially
by the lacunar ligament, and laterally by the femoral vein.
Immediately below the inguinal ligament from lateral to medial lie the
femoral nerve, femoral artery and vein, both contained within the femoral
sheath, and most medially, the femoral canal with its contained fat
and lymphatic tissue.