The psoas quartus muscle

Iliacus minor and psoas quartus muscles traversing the femoral nerve

Anatomical variations of the nerves of the body can be relevant to surgical approaches anesthetic blockade, and other region procedures. Herein, we report a case of three muscle fascicles of the variant psoas quartus and iliacus minor muscles traversing the femoral nerve. Salient literature is reviewed regarding this phenomenon. Variations in the femoral nerve, such as illustrated in the current case, could also help explain hip and thigh pain, and failure of traditional anesthetic placement to block sensation from the femoral nerve completely. Given the procedural relevance of variations in the femoral nerve, further characterizations of nontraditional courses could help to avoid nerve injury during interventions.

Relationship of the Obturator Nerve and Psoas Major: Anatomic Study with Application to Avoiding Iatrogenic Injuries

BACKGROUND

The proximal course of the obturator nerve as related to the psoas major has been described differently among various authors. Because this relationship is important for better understanding of clinical presentations and during surgical approaches, this study aimed to elucidate this anatomy via cadaveric dissection.

METHODS

Twenty obturator nerves from 10 white cadaveric specimens underwent dissection. Observations were made of the relationship between the nerve and psoas major muscle.

RESULTS

On all sides, the obturator nerve descended posterior to the psoas major and never through it.

CONCLUSIONS

These results might be important to clinicians who interpret radiology of this region, to clinicians who treat patients with presumed obturator compression syndromes, or to surgeons who operate near the intracavitary part of the obturator nerve.

A multiply split femoral nerve and psoas quartus muscle

The femoral nerve is the largest branch of the lumbar plexus. It is normally composed of the ventral rami of spinal nerves L2 to L4. The psoas major has proximal attachments onto the T12 to L5 vertebrae and related intervertebral discs, fuses with the iliacus deep to the inguinal ligament and then attaches onto the lesser trochanter of the femur. Normally, the anatomical relationship is that the femoral nerve is located between the iliacus and psoas major. Herein, we report a case of the psoas quartus muscle related to several splits of the femoral nerve within the pelvis. Although the embryology for this is unclear, surgeons and physicians should be aware of such anatomical variants in order to better understand pain and entrapment syndromes and during surgical maneuvers in this region such as lateral transpsoas approaches to the lumbar spine.