Anatomy of the Anterior Leg Compartment

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Questions and Answers

What is the primary action performed by the Extensor digitorum longus?

Plantarflexion of the foot

Dorsiflexion of the ankle joint and extension of lesser toe phalanges (correct)

Eversion of the foot and stabilizing the hallux

Flexion at the proximal interphalangeal joint

Which muscle is closely related to the Extensor digitorum longus and acts as an almost fifth tendon?

Tibialis anterior

Peroneus longus

Peroneus tertius (correct)

Flexor digitorum longus

Which artery supplies the anterior compartment of the leg?

Femoral artery

Posterior tibial artery

Popliteal artery

Anterior tibial artery (correct)

What is the function of the retinacula around the ankle joint?

Maintain tendon position and act as modified pulleys Signup and view all the answers

Where does the anterior tibial artery enter the anterior compartment of the leg?

Through an opening in the interosseous membrane Signup and view all the answers

What is the primary action of the Tibialis Anterior muscle?

Dorsiflexion of the ankle Signup and view all the answers

Which of the following is NOT a muscle found in the anterior compartment of the leg?

Peroneus longus Signup and view all the answers

What type of joint is formed by the lower end of the fibula and the tibia?

Syndesmosis joint Signup and view all the answers

Which nerve innervates the Extensor Hallucis Longus?

Deep peroneal nerve Signup and view all the answers

What is the main function of the fibula?

To provide attachment for muscles Signup and view all the answers

Which action is NOT performed in the sagittal plane regarding foot motion?

Inversion Signup and view all the answers

What anatomical feature assists in the connection between the tibia and fibula?

Interosseous membrane Signup and view all the answers

Which compartment of the leg does the muscle Peroneus Tertius belong to?

Anterior compartment Signup and view all the answers

What anatomical structure protects and supports the medial tendons, vessels, and nerves in the leg?

Flexor retinacula Signup and view all the answers

Which nerve is responsible for supplying the anterior fascial compartment of the leg and originates from the common peroneal nerve?

Deep peroneal nerve Signup and view all the answers

What differentiates intrinsic muscles of the foot from extrinsic muscles?

They originate outside of the foot and insert into it. Signup and view all the answers

Which of the following describes the dorsal aspect of the foot?

It is less complicated anatomically than the plantar aspect. Signup and view all the answers

What is a dermatome?

An area of skin supplied by a single spinal nerve segment. Signup and view all the answers

Which nerve is responsible for innervating the muscles in the lateral compartment of the leg?

Superficial peroneal nerve Signup and view all the answers

What is the primary action of the Peroneus Longus muscle?

Eversion of the foot Signup and view all the answers

Where does the dorsalis pedis artery branch off from?

Anterior tibial artery Signup and view all the answers

The Great Saphenous vein primarily drains blood into which structure?

Dorsal venous arch Signup and view all the answers

Which muscle is innervated by the lateral branch of the deep peroneal nerve?

Extensor digitorum brevis Signup and view all the answers

Which artery is responsible for supplying the dorsal digital arteries?

Dorsalis pedis artery Signup and view all the answers

What is the location of the origin for the Peroneus Brevis muscle?

Lower 2/3 of the fibula Signup and view all the answers

What is the primary function of the deep peroneal nerve in the foot?

Sensory innervation to the first and second toe web Signup and view all the answers

Which of the following veins does not drain into the dorsal venous arch?

Great Saphenous vein Signup and view all the answers

The main action of the Extensor Hallucis Brevis muscle is to extend which joint?

MTP joint of the hallux Signup and view all the answers

Study Notes

Anterior Leg, Dorsum of Foot & Lateral Leg

Outline: The session covers Tibia & fibula osteology, anterior compartment of the leg, dorsum of the foot, lateral compartment of the leg, and a surface anatomy session.

Motion of the Foot

Sagittal Plane: Dorsiflexion and plantarflexion.
Frontal Plane: Inversion and eversion.
Transverse Plane: Abduction and adduction.
Tri-planar Motion: Pronation and supination.

Osteology & Surface Anatomy

Bones: Tibia, fibula, and foot bones.

The Tibia

Characteristic: Largest leg bone.
Proximal End: Articulates with the femur; distal end is the medial malleolus (part of the ankle joint). Includes medial/lateral condyles and tibial tuberosity.
Shaft: Triangular shape with anterior, medial, and interosseous borders.

The Fibula

Characteristic: Lateral leg bone.
Parts: Head (common peroneal nerve), shaft, and lateral malleolus (part of the ankle joint).
Connection: Syndesmosis (joint) at the lower end that connects to the tibia.
Shaft Surfaces: Anterior/extensor, lateral/peroneal, and posterior/flexor.

Compartments of the Leg

Structure: Three compartments: anterior, lateral, and posterior.
Features: Each compartment has its own muscles, blood supply, and nerve supply.
Connection: The interosseous membrane connects the interosseous border of the tibia and fibula.

Anterior Compartment of the Leg

Muscles: Tibialis anterior, extensor hallucis longus, extensor digitorum longus, and peroneus tertius are present in this area.

Tibialis Anterior (TA)

Origin/Insertion: Lateral shaft of tibia, intermuscular septa, medial cuneiform, and base of 1st MT.
Innervation: Deep peroneal nerve.
Action: Dorsiflexor, foot supinator (STJ and long axis of MTJ).
Function: Decelerates pronation and plantarflexion from HC, toe clearance during swing phase.
Pathology: Weak: foot drop, excessive foot pronation; contracture: supinated foot.

Extensor Hallucis Longus (EHL)

Origin/Insertion: Middle half of medial surface of fibula, intermuscular septa, dorsal surface of base of distal phalanx of the hallux, and into the extensor hood.
Innervation: Deep peroneal nerve.
Action: Dorsiflexion, extends/stabilizes hallux phalanges.

Extensor Digitorum Longus (EDL)

Origin/Insertion: Lateral tibial condyle, upper medial fibula, interosseous membrane, retinaculum, base of distal phalanges of lesser toes (and base of intermediate phalanx).
Innervation: Deep peroneal nerve.
Action: Dorsiflexion, extends lesser toe phalanges, contributes to extensor hood.

Peroneus Tertius

Characteristics: Closely related to the EDL tendon.
Origin/Insertion: Distal 1/4 of fibula, intermuscular septa, deep to ext retinaculum, dorsal surface of base of 5th MT.
Innervation: Deep peroneal nerve.
Action: Foot eversion, AJ dorsiflexion, and weak foot pronator.

Arterial Supply to Anterior Leg

Artery: Anterior tibial artery (branch of the popliteal artery).
Course: Enters the compartment through the interosseous membrane, goes behind the superior extensor retinaculum, and becomes the dorsalis pedis artery in front of the ankle joint.

Retinacula

Superior Extensor Retinaculum: Located on the anterior border of the fibula and tibia, and continuous with the deep fascia of the leg.
Inferior Extensor Retinaculum: Y-shaped band connecting calcaneus to tibia/plantar aponeurosis.
Flexor Retinacula: Medial malleolus to medial tuberosity of calcaneus. Protects/supports medial tendons, vessels, and nerve; includes a lacinate ligament.
Peroneal Retinacula: Superior – lateral malleolus to lateral calcaneus, continuous with the inferior extensor retinaculum. Inferior – peroneal tubercle to plantar aponeurosis..

Nerve of the Anterior Fascial Compartment of the Leg

Nerve: Deep peroneal nerve - a branch of the common peroneal nerve.
Course: Arise near the neck of the fibula; extend deep to the anterior leg muscles; run behind the extensor retinacula; supply branches to muscles (TA, EDL, peroneus tertius and EHL) and an articular branch to the ankle joint.

Dermatomes

Definition: Area of skin supplied by a single spinal nerve and spinal segment.

Cutaneous Nerve Distribution of the Lower Extremity

Distribution: Shows various nerves and their areas of skin supply.

Dorsum of the Foot

Structure: Less anatomically complicated than the plantar aspect.
Skin: Thinner than the plantar foot.
Muscle Types: Extrinsic (origin outside, insertion inside the foot), and intrinsic (origin and insertion inside the foot) muscles.

Dorsal Nerve Supply

Sensory Nerves: Superficial peroneal nerve, deep peroneal nerve, saphenous nerve, and sural nerve supply the dorsum of the foot and toes.

Dorsal Venous Arch

Location: Subcutaneous tissue over the metatarsal heads.
Drainage: Deep veins of the foot and communicating veins within the foot.
Importance: Main drainage avenue for blood from the foot.

Dorsalis Pedis Artery

Origin: Continuation of the anterior tibial artery.
Course: Passes deep into sole between 1st and 2nd metatarsals and joins the lateral plantar artery.
Distinguishing Characteristics: Easily palpable, superficial, branches into lateral tarsal, arcuate, and first dorsal metatarsal arteries.

Extensor Digitorum Brevis

Origin/Insertion: Anterior dorsal calcaneus and inferior extensor retinaculum; splits into 4 tendons that attach to the proximal phalanx of hallux and the 2-4 lesser toes (lateral side of EDL tendons and to the middle and distal phalanges of the toes).
Innervation: Lateral branch of deep peroneal nerve.
Action: Extension of the hallux МТРЈ, 2, 3, and 4 МТРЈs and IPJs.

Arteries of the Dorsal Foot

Components: Anterior tibial artery, dorsalis pedis artery, arcuate artery, and dorsal digital arteries.

Lateral Compartment of the Leg

Contents: Peroneus longus, Peroneus brevis muscles.
Blood Supply: Branches from the peroneal artery.
Nerve Supply: Superficial peroneal nerve.

Peroneus Longus

Origin/Insertion: Upper 2/3 of lateral fibula and intermuscular septa; passes behind lateral malleolus and inserts onto the base of 1st MT and medial cuneiform.
Innervation: Superficial peroneal nerve.
Action: Eversion (pronation) of the foot, foot flexor, stabilizes 1st ray and forefoot.

Peroneus Brevis

Origin/Insertion: Lower 2/3 of lateral fibula and intermuscular septa, peroneal retinaculum, base of 5th MT.
Innervation: Superficial peroneal nerve.
Action: Eversion (pronation) of the foot about the STJ and oblique axis of MTJ.

Surface Anatomy

Marking Points: Patella, tibial tuberosity, lateral collateral ligament, head of fibula, anterior crest of tibia, lateral malleolus, medial malleolus, styloid process, 1–5 MTPJs (dorsally & plantarly), tuberosity of the navicular, insertion point of the tendo achilles.
Palpation: Dorsalis pedis pulse.
Assessment: Simple muscle testing of anterior and lateral leg compartments (differentiate TA/EHL/EDL and PL/PB).

Questions

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Description

Test your knowledge on the anatomy and functions of the muscles in the anterior compartment of the leg. This quiz covers important muscle actions, innervations, and anatomical structures relevant to this region. Perfect for those studying human anatomy or preparing for a medical exam.