All About #SCIATIC_NERVE (SN) ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ⠀⠀The SN is a major nerve of the lower limb. It is a thick flat band, approximately 2cm wide – the largest nerve in the body. ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● #Sciatica_Nerve_ANATOMICAL_COURSE:- The SN is derived from the lumbosacral plexus (Nerve roots: L4-S3). After its formation, it leaves the pelvis and enters the gluteal region via greater sciatic foramen. It emerges inferiorly to the piriformis muscle and descends in an inferolateral direction. As the nerve moves through the gluteal region, it crosses the posterior surface of the superior gemellus, obturator internus, inferior gemellus and quadratus femoris muscles. It then enters the posterior thigh by passing deep to the long head of the biceps femoris. Within the posterior thigh, the nerve gives rise to branches to the hamstring muscles and adductor magnus. When the sciatic nerve reaches the apex of the popliteal fossa, it terminates by bifurcating into the tibial and common fibular nerves. In approximately 12% of people they separate as they leave the pelvis, that’s why the SN can be described as 2 individual nerves bundled in the same connective tissue sheath. ●●●●●●●●●●●●●●●◆◆◆◆●●●●●●●●●●● #Sciatica_nerve_MOTOR_FUNCTION:- Although the SN passes through the gluteal region, it does not innervate any muscles there. However, the SN does directly innervate the muscles in the post. compartment of the thigh (biceps femoris, semimembranosus and semitendinosus) and the hamstring portion of the adductor magnus. The SN also indirectly innervates several other muscles, via its two terminal branches: TIBIAL NERVE - the muscles of the posterior leg (calf muscles), and some of the intrinsic muscles of the foot. COMMON FIBULAR NERVE - the muscles of the anterior leg, lateral leg, and the remaining intrinsic foot muscles. In total, the SN innervates the muscles of the posterior thigh, entire leg and entire foot. ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● #Sciatica_Nerve_SENSORY_FUNCTION The SN does not have any direct cutaneous functions. It does provide indirect sensory innervation via its terminal branches: TIBIAL NERVE - innervates the posterolateral and anterolateral sides of the leg, and the plantar surface of the foot. COMMON FIBULAR NERVE - innervates the lat. leg and the dorsal surface of the foot.