Clinical Aspects of Traumatic Peripheral Nerve Lesions in the Lower Limb

Keywords: lumbosacral plexus, sciatic nerve, peroneal nerve, tibial nerve, obturator nerve, femoral nerve, saphenous nerve

Yuval Shapira and Shimon Rochkind

Abstract

Knowledge of neuroanatomy and the clinical exam is of paramount importance for accurate diagnosis and optimal management of nerve injuries in the lower extremity. When evaluating patients with peripheral nerve lesions in the lower limb, it is important to exclude differential diagnosis. In cases where the injured nerves do not recover spontaneously, the surgeon has several treatment modalities. Selecting the correct treatment depends on the diagnosis and other specific factors such as the level of injury, the current neurological status, the existence of neuropathic pain, the time since the injury, and other specific factors related to the expected recovery.

5.1 Introduction

When evaluating patients with peripheral nerve lesions in the lower limb, it is important to exclude spinal lumbar radiculopathy and nonstructural neuropathies. ¹^, ²^, ³^, ⁴^, ⁵^, ⁶^, ⁷ Generally, femoral neuropathy should be differentiated from L2–L4 radiculopathy. L5 radiculopathy should be excluded in patients presenting with symptoms related to peroneal neuropathy, whereas S1 radiculopathy should be excluded from symptoms related to tibial neuropathy. Other nonsurgical processes such as lumbosacral plexitis (amyotrophic neuralgia), proximal diabetic neuropathy, and neoplastic and postradiation neuropathy should also be considered. The diagnosis and management are based on the clinical history and physical examination together with imaging studies and electrodiagnostic findings. The extent of injury and distance to the target, together with the interval of time since the injury, are the most important prognostic factors for recovery.

Here, we briefly describe applicable neuroanatomy and clinical aspects to support the management and surgical treatment of peripheral nerve lesions in the lower limb.

5.2 Lumbosacral Plexus

All motor and sensory innervation of the lower limbs originate from the lumbar and sacral nerve roots, which together form the lumbosacral plexus. Anatomy of the lumbar and sacral plexus and corresponding nerves are presented in ▶ Fig. 5.1, ▶ Table 5.1, and ▶ Table 5.2.

Fig. 5.1 Lumbosacral plexus illustration depicting the major components of the lumbosacral plexus with its spinal nerve root segments. Note relationship of the lumbar and sacral plexus through the lumbosacral trunk.

**Table 5.1** Nerves of the lumbar plexus
Nerve (spinal root)	Muscle innervation	Sensory branch
Iliohypogastric (T12–L1)	Internal and transverse abdominal	Lateral cutaneous (iliac) Anterior cutaneous (hypogastric)
Ilioinguinal (L1)	Internal oblique	Anterior scrotal/labial
Genitofemoral (L1–L2)	Cremaster (male)	Femoral Genital
Lateral femoral cutaneous (L2–L3)	–	LFCN
Femoral (L2–L4)	Iliopsoas Pectineus Sartorius Quadriceps femoris (RF, VL, VM, VI)	Anterior cutaneous Saphenous
Obturator (L2–L4)	External obturator Adductor (longus, brevis, magnus) Gracilis	Medial cutaneous
Accessory obturator (30%)	Pectineus	–
Abbreviations: LFCN, lateral femoral cutaneous nerve; RF, rectus femoris; VI, vastus intermedius; VL, vastus lateralis; VM, vastus medialis.

**Table 5.2** Nerves of the sacral plexus
Nerve (spinal root)	Muscle innervation	Sensory branch
Superior gluteal (L4–S1)	Gluteus medius Gluteus minimus Tensor fasciae latae	–
Inferior gluteal (L5–S2)	Gluteus maximus	–
Common peroneal (L4–S2)	Biceps femoris SH Tibialis anterior (DPN) EDL and EDB (DPN) EHL and EHB (DPN) PT (DPN) Peroneus longus (SPN) Peroneus brevis (SPN)	Lateral sural cutaneous Lateral dorsal cutaneous (DPN) Intermediate dorsal cutaneous (DPN) Medial dorsal cutaneous (SPN)
Tibial (L4–S3)	Semitendinosus Semimembranosus Biceps femoris LH Adductor magnus Gastrocnemius Popliteus Soleus Plantaris Tibialis posterior FDL and FHL Abductor hallucis (MP) FDB and FHB (MP) Lumbricals (MP) Quadratus plantae (LP) FDM (LP) Adductor hallucis (LP) Interossei and lumbricals (LP) ADM foot (LP)	Medial sural cutaneous Calcaneal Medial plantar Lateral plantar
Posterior femoral cutaneous (S1–S3)	–	Inferior cluneal Perineal branch
Abbreviations: ADM, abductor digiti minimi of foot; DPN, deep peroneal nerve; FDL and FDB, flexor digitorum longus and brevis; FHL and FHB, flexor hallucis longus and brevis; LH, long head; SH, short head; SPN, superficial peroneal nerve.