GROSS ANATOMY

Detailed explanation-1: -The lumbar plexus arises from all the lumbar spinal nerves (L1 to L5) and gives rise to nerves innervating the pelvic region and the anterior leg. The femoral nerve is one of the major nerves from this plexus, which gives rise to the saphenous nerve as a branch that extends through the anterior lower leg.

Detailed explanation-2: -The lumbar enlargement gives attachment to the nerves which supply the lower limbs. It commences about the level of the ninth thoracic vertebra, and reaches its maximum circumference, of about 33 mm, opposite the last thoracic vertebra, below which it tapers rapidly into the conus medullaris.

Detailed explanation-3: -[4] Similarly, the lower thoracolumbar enlargement gives rise to a plexus of nerves supplying the lower limb muscles in the form of the lumbosacral plexus. This second enlargement extends from the second lumbar segment to the third sacral segment of the spinal cord.

Detailed explanation-4: -The supply motor and sensory innervation to the lower limb and pelvic girdle. The nerves arising from the lumbar plexus are important for functioning of the lower extremity function and movement allowing knee extension, hip flexion and adduction of the thigh.

Detailed explanation-5: -Two regions of the spinal cord are enlarged to accommodate the greater number of nerve cells and connections needed to process information related to the upper and lower limbs (see Figure 1.10B).