Features of the Intramuscular Femoral Nerve Branching in Human Fetuses

Patients seeking medical care due to periodically arising asymmetric numbness and/or paresthesiae in the pelvic area and lower limbs tend to suffer from tunnel neuropathies caused by compression and impairment of the microcirculation of peripheral nerves in anatomically narrow fibrous and fibro-osseous canals (tunnels). Tunnel neuropathies constitute 1/3 of lesions in the peripheral nerves. We have not found any information on the features of the femoral nerve branching in the iliopsoas, sartorius and pectineus muscles, as well as in the quadriceps femoris in human fetuses of different ages. The purpose of the study was to establish the features of the topography of muscular branches in the lumbar plexus and in the femoral nerve of human fetuses aged 4-7 months. Materials and methods. Macroscopic examination of the intramuscular distribution of the muscular branches of the lumbar plexus and the femoral nerve in the thickness of some pelvic and femoral muscles was carried out on 28 specimens of human fetuses with 81.0-270.0 mm of crown-rump length (CRL). Results and discussion. Using the method of anatomical preparation, we established features of the intramuscular distribution of the muscular branches in the lumbar plexus and femoral nerve in 4-7 month-old fetuses. It was also found out that 6-13 branches arise from the lumbar plexus towards the psoas major muscle crossing the muscular fascicles at different angles and, at the same time, the intramuscular branches tend to be concentrated within proximal sections of the muscle. The distribution of muscle branches (2-7) from the femoral nerve in the stratum of the iliac muscle is uneven, the branching of the nerves is concentrated mainly within the upper and middle third of the muscle. As a rule, only one nervous trunk, which enters the muscle belly within its upper third and branches out into 4-11 branches, goes away to the sartorius muscle from the femoral nerve. The front and back branches, which enter the thickness of the muscular belly predominantly in the region of its upper, rarely middle third, go to the rectus femoris muscle. The anterior branch gives 2-9 branches in the main pattern, and the posterior one is branched out both in the main and in the scattered patterns and gives 2-6 branches. The segmental type of the nerve distribution is best expressed in the medial vastus muscle and the worst – in the lateral vastus muscle, while there was no segmental distribution of nerves in the intermediate vastus muscle. In the medial vastus muscle the scattered pattern of branching prevails, while in the lateral and intermediate vastus muscles, the intramuscular nerves branch out in a mixed type. In two fetuses 1-2 muscular branches were heading to the medial third of the belly of the right long adductor muscle, which branched out in a mixed pattern in its depth. The pectineus muscle is innervated by a branch from the femoral nerve and the anterior branch of the obturator nerve. Conclusions. The branches of the femoral nerve enter the thickness of the muscles at an acute angle relative to the longitudinal axis of the muscle. The hilum for the femoral nerve entrance, as a rule, are in the area of the upper third, less frequently in the middle third of the muscular belly and are placed on both its anterior and posterior surfaces. In the thickness of the muscles of the femur anterior group the branching of the femoral nerve is unevenly distributed. In the picture of the intramuscular branching of the femoral nerve, three patterns can be distinguished: scattered, main and mixed. The nature of the intramuscular distribution of the nerves depends on the muscle's structure and function. The largest number of intramuscular nerves branch out in the sartorius muscle. There are connecting branches between separate branches of the nerves within the upper two-thirds of the iliac muscle and in the paramedian parts of the psoas major muscle. T