Sacral Plexus, Tibial and Common Peroneal Nerves - Vocabulary Flashcards

Vocabulary flashcards covering key terms and definitions related to the sacral plexus, tibial nerve, and common peroneal nerve from the lecture notes.

Nerve plexuses

Networks of ventral rami that exchange fibers (crisscross) and mainly innervate the limbs; thoracic ventral rami do not form nerve plexuses.

Sacral plexus

Network formed by the union of the lumbosacral trunk and the anterior rami of S1–4; supplies motor and sensory innervation to the posterior thigh, leg, and foot; located on the posterolateral wall of the lesser pelvis, in front of the piriformis.

Lumbosacral trunk

Contribution to the sacral plexus formed by L4–L5.

Anterior rami S1–S4

Sacral spinal nerve roots that form the sacral plexus; divide into anterior (flexors) and posterior (extensors/abductors) divisions.

Greater sciatic foramen

Opening through which branches of the sacral plexus leave the pelvis to innervate the gluteal region.

Piriformis

Muscle in the buttock; the sacral plexus lies in front of it as nerves exit the pelvis.

Sciatic nerve

Largest nerve in the body; continuation of the sacral plexus (L4–S3); leaves the pelvis via the greater sciatic foramen below piriformis and divides into tibial and common peroneal nerves.

Tibial nerve

Medial, larger terminal branch of the sciatic nerve; supplies the calf and sole; travels through the popliteal fossa and tarsal tunnel; divides into medial and lateral plantar nerves.

Common peroneal (fibular) nerve

Lateral branch of the sciatic nerve; supplies the extensor and peroneal compartments of the leg; winds around the neck of the fibula and divides into deep and superficial peroneal nerves.

Sural nerve

Cutaneous nerve of the leg/foot formed by branches of the tibial and common peroneal nerves; supplies the posterolateral leg and lateral foot.

Posterior femoral cutaneous nerve

Sensory nerve supplying the skin of the posterior thigh.

Pelvic splanchnic nerves

Parasympathetic nerves from S2–S4 that supply pelvic viscera.

Pudendal nerve

Major nerve of the perineum; fibers from S2–S4; supplies perineal muscles and external genitalia.

Perineal branch of pudendal nerve

Branch of the pudendal nerve (S4) to the perineal region.

Nerve to obturator internus

Innervates obturator internus; fibers from L5–S1–S2.

Nerve to quadratus femoris

Innervates quadratus femoris; fibers from L4–5–S1.

Nerve to piriformis

Motor branch to the piriformis muscle (S1–S2).

Perforating cutaneous nerve

S2–S3 cutaneous nerve supplying skin over the gluteal/perineal region.

Medial calcaneal nerve

A branch of the tibial nerve supplying the skin of the heel.

Medial plantar nerve

Medial terminal branch of the tibial nerve; supplies the medial sole and toes.

Lateral plantar nerve

Lateral terminal branch of the tibial nerve; supplies the lateral sole.

Superior gluteal nerve

Nerve (L4–S1) that innervates gluteus medius, gluteus minimus, and tensor fasciae latae.

Inferior gluteal nerve

Nerve (L5–S1–S2) that innervates gluteus maximus.

Deep peroneal nerve

Branch of the common peroneal; supplies the anterior compartment of the leg and the skin between the first and second toes.

Superficial peroneal nerve

Branch of the common peroneal; supplies the lateral compartment of the leg and dorsum of the foot; divides into medial and lateral branches.

Foot drop

Inability to dorsiflex the foot, commonly caused by common peroneal nerve injury; produces a stamping gait.

Sciatica

Pain, tingling, or numbness along the distribution of the sciatic nerve; caused by disc prolapse, intrapelvic tumor, or inflammation.

Tibial nerve injury

Injury to the tibial nerve causing paralysis of plantarflexors and intrinsic foot muscles; sensory loss lateral leg and foot; possible trophic ulcers.

Common peroneal nerve injury

Injury causing paralysis of the anterior and lateral compartments of the leg; foot is plantarflexed and inverted; sensory loss on the dorsum of the foot and across the first web space.

Genicular nerves

Upper and lower medial/lateral and middle genicular branches that supply the knee joint.

Saphenous nerve

Branch of the femoral nerve; provides sensory innervation to the medial leg and foot (not a sacral plexus/sciatic branch).

Adductor hiatus

Passage within adductor magnus for femoral vessels to reach the popliteal fossa.

Tarsal tunnel

Passage behind the medial malleolus where the tibial nerve travels to the sole of the foot.