Distribution of the lateral cutaneous nerve of the thigh in the area of intramuscular injection

Abstract

The technique of intramuscular injection (IM) into the antero-lateral region of the thigh is widely used. Nevertheless, despite this area being indicated as the second best location for this practice, the technique is still observed to be very painful for both adult and child patients. OBJECTIVE: To study the localization, distribution and course of the lateral cutaneous nerve of the thigh, and its topographic relationship with the area recommended for the practice of intramuscular injection, relating these characteristics to the pain resulting from such procedures. METHOD: By means of exposing the antero-lateral region by classical dissection, the lateral cutaneous nerve of the thigh was identified and isolated in 20 fixed adult male cadavers, giving emphasis to the viewing of its nerve rami across the iliotibial tract. RESULTS: In 100% of the cases, the lateral cutaneous nerve emerged medially in relation to the upper anterior iliac spine. After this, it issued three wide-caliber rami in 70% of the specimens and only two in the remaining 30%. In the upper third and in the upper portion of the middle third of the thigh, a network of numerous small nerve rami was observed, enveloped in a variable quantity of adipose tissue. However, in the lower portion of the middle third of the thigh and in the lower third, no significant nerve rami were seen. CONCLUSION: Based on our data, we recommend whenever possible that the distal half of the region displayed by the classical technique be utilized as the location of choice for the practice of intramuscular injection into the antero-lateral region of the thigh. This is because this region is less innervated by the lateral cutaneous nerve of the thigh, which will cause less pain in this area during such procedures, thereby affording greater comfort to the patient.