Leg
Introduction
Overview of the anatomy of the leg consisting of various compartments and their functions.
Page 1: The Leg
Focus on understanding the different sections and functions of the leg.
Page 2: Dermatomes and Cutaneous Innervations in the Posterior Leg
S2: Innervates the posterior part.
Lateral Sural Cutaneous Nerve (L4, L5, S1): Supplies the lateral aspect.
L4: Involvement of the cutaneous nerves in the posterior leg.
Saphenous Nerve (L3, L4): Supplies the medial aspect of the leg and foot.
L5: Involvement with Sural Nerve (L5, S1, S2).
Medial Calcaneal Branches of Tibial Nerve (S1, S2): Supplies the medial heel region.
Page 3: Dermatomes and Cutaneous Innervations in the Anterior Leg
Infrapatellar Branch of Saphenous Nerve: Supplies the area below the patella.
Lateral Sural Cutaneous Nerve (L5, S1, S2): Supplies the lateral region of the anterior leg.
Superficial Fibular (Peroneal) Nerve (L4, L5, S1): Provides sensory innervation.
Sural Nerve: Sends branches to the anterior leg region.
Deep Fibular (Peroneal) Nerve (L5): Innervates deeper structures of the anterior leg.
Page 4: Bones in the Leg Region
Fibula:
Head, Neck, Shaft, Lateral Malleolus.
Tibia:
Medial Malleolus, Anterior Crest (Border), Medial Surface, Tibial Tuberosity, Apex.
Page 5: Description of Bone Features
Medial Malleolar Groove: Area for tendon passage.
Lateral Malleolar Groove & Fossa: Notable features for tendon and ligament attachment.
Soleal Line: Attachment site for muscles.
Articular Surfaces: Interaction points with fibula and talus.
Page 6: Superficial Aspect of the Anterior and Medial Leg
Superficial Fibular Nerve: Innervates lateral compartment.
Great Saphenous Vein: Major superficial vein of the leg.
Saphenous Nerve: Supplies medial aspect of the leg.
Page 7: Superficial Aspect of the Posterior and Lateral Leg
Small Saphenous Vein: Major drainage of the superficial lateral leg.
Lateral Sural Cutaneous Nerve: Supplies lateral aspect.
Sural Nerve: Contributes to sensory innervation.
Dorsal Venous Arch: A network of veins in the foot.
Page 8: Brief Review of Dorsum of the Foot
Superficial Fibular Nerve: Innervation framework.
Saphenous Nerve: Medial sensation.
Sural Nerve: Posterior sensation.
Deep Fibular Nerve: Supplies dorsum of the foot.
Page 9: Crural Compartments Overview
Compartments: Anterior, Lateral, Posterior (Superficial, Deep)
Nerves: Deep Fibular Nerve, Superficial Fibular Nerve, Tibial Nerve.
Arteries: Anterior Tibial A., Posterior Tibial A., Fibular A.
Muscle Groups:
Anterior Compartment: Extensor Digitorum Longus, Tibialis Anterior.
Lateral Compartment: Fibularis Longus, Fibularis Brevis.
Posterior Compartment: Gastrocnemius, Soleus, etc.
Actions: Dorsiflexion, Eversion, Plantarflexion.
Page 10: Anterior Crural Compartment
Muscles: Tibialis Anterior, Extensor Hallucis Longus, Extensor Digitorum Longus, Fibularis Tertius.
Retinacula: Extensor Retinaculum.
Innervation: Common Fibular Nerve, Deep Fibular Nerve.
Artery: Anterior Tibial A.
Page 11: Tibialis Anterior Muscle
Origin: Lateral condyle and proximal half of tibia, interosseous membrane.
Insertion: Medial and plantar surfaces of the 1st metatarsal and medial cuneiform.
Action: Dorsiflexion and inversion.
Innervation: Deep Fibular Nerve; Spinal Levels: L4, L5.
Page 12: Extensor Hallucis Longus Muscle
Origin: Medial surface of the fibula, interosseous membrane.
Insertion: Dorsal surface of the base of distal phalanx of the great toe.
Action: Extension of interphalangeal joint of hallux.
Innervation: Deep Fibular Nerve; Spinal Levels: L5, S1.
Page 13: Extensor Digitorum Longus Muscle
Innervation: Deep Fibular Nerve; Spinal Levels: L5, S1.
Origin: Lateral condyle of tibia, fibula, interosseous membrane.
Insertion: Distal phalanges of the lateral four digits.
Action: Dorsiflexion and extension of lateral four digits.
Page 14: Fibularis Tertius Muscle
Innervation: Deep Fibular Nerve; Spinal Levels: L5, S1.
Origin: Distal third of fibula, interosseous membrane.
Insertion: Dorsal surface of the base of the 5th metatarsal.
Action: Weak dorsiflexor; eversion.
Page 15: Lateral Crural Compartment
Components: Fibularis Longus, Fibularis Brevis.
Innervation: Superficial Fibular Nerve.
Page 16: Fibularis Longus Muscle
Origin: Head and proximal three-fourths of fibula.
Insertion: Lateral aspect of the base of the 1st metatarsal, medial cuneiform.
Innervation: Superficial Fibular Nerve; Spinal Levels: L5, S1, S2.
Action: Eversion.
Page 17: Fibularis Brevis Muscle
Innervation: Superficial Fibular Nerve; Spinal Levels: L5, S1, S2.
Action: Eversion.
Origin: Distal one-third of the lateral surface of fibula.
Insertion: Lateral surface of the base of the 5th metatarsal.
Page 18: Posterior Crural Compartment (Superficial Layer)
Components: Gastrocnemius, Plantaris, Soleus.
Page 19: Gastrocnemius Muscle
Spinal Levels: L5, S1.
Origin: Medial condyle and lateral condyle of femur.
Insertion: Calcaneal tuberosity via tendo calcaneus.
Actions: Plantarflexion; initiates knee flexion.
Innervation: Tibial Nerve.
Page 20: Soleus Muscle
Origin: Posterior surface of proximal third of fibula, soleal line of tibia.
Insertion: Same as gastrocnemius.
Action: Plantarflexion; provides postural support when bearing weight.
Innervation: Tibial Nerve; Spinal Levels: L5, S1.
Page 21: Plantaris Muscle
Origin: Lateral epicondyle of femur.
Insertion: Calcaneal tuberosity along medial edge of tendo calcaneus.
Action: Very weak plantarflexion.
Innervation: Tibial Nerve; Spinal Levels: L5, S1.
Page 22: Posterior Crural Compartment (Deep Layer)
Components: Popliteus, Flexor Digitorum Longus, Tibialis Posterior, Flexor Hallucis Longus.
Arteries: Fibular A., Posterior Tibial A.
Innervation: Tibial Nerve.
Page 23: Flexor Digitorum Longus Muscle
Origin: Medial aspect of tibia.
Insertion: Distal phalanges of the lateral four toes.
Spinal Levels: S2, S3.
Action: Flex distal interphalangeal joints of lateral four toes; assists in plantarflexion and inversion.
Innervation: Tibial Nerve.
Page 24: Tibialis Posterior Muscle
Origin: Posterior surface of interosseous membrane and medial tibia.
Insertion: Tuberosity of navicular, calcaneus, cuneiforms, and metatarsals.
Action: Inversion; plantarflexion.
Spinal Levels: L4, L5; Innervation: Tibial Nerve.
Page 25: Flexor Hallucis Longus Muscle
Origin: Lower half of fibula and interosseous membrane.
Insertion: Base of distal phalanx of great toe.
Action: Flex distal phalanx; plantarflex ankle; invert foot.
Spinal Levels: S2, S3; Innervation: Tibial Nerve.
Page 26: Popliteus Muscle
Origin: Lateral epicondyle of femur.
Insertion: Posterior surface of tibia, above soleal line.
Actions: Unlocks knee via lateral rotation of femur when fixed; allows tibia to medially rotate and flex knee.
Spinal Levels: L4, L5, S1; Innervation: Tibial Nerve.
Page 27: Blood Supply in the Leg
Arteries: Anterior Tibial A., Posterior Tibial A., Fibular A.