Lab Manual - Anterior Leg & Foot

Assignments:

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Identify the muscles of the anterior and lateral compartments of the leg and give their functional significance in locomotion.
  2. Identify the vascular supply of the anterior and lateral compartments of the leg.
  3. Identify the nerves of the anterior and lateral compartments of the leg, the muscles and cutaneous regions supplied by them, so that given a functional and/or cutaneous loss one can predict the nerve and the probable level of injury.
  4. Describe the bony structure of the foot, including its arches, subtalar and transverse tarsal joints, and the bones and ligaments contributing to its strength and flexibility.
  5. Describe the arrangement, specializations, and compartments of the foot.
  6. Identify the muscles of the foot and give their functional significance in locomotion.
  7. Identify the vascular supply of the foot and give the regions supplied by each.
  8. Identify the nerves of the foot, and the muscles and cutaneous regions supplied by them, so that given a functional and/or cutaneous loss one can predict the nerve and the probable level of injury.

Procedure:

1. Review the bony landmarks. (Play movie; View images: N 513, 522, 523A, 523B, 524A, 524B, 525, 529, 530, TG 3-08, 3-09, 3-40A, 3-40B, 3-41A, 3-41B, 3-60)

Examine the articulated foot and note the arrangement of the tarsals. Note how this provides medial and lateral longitudinal arches and a transverse arch. Identify the tuberosity of the calcaneus and the sustentaculum tali. Note the tarsal sinus. Examine the articulation between the talus and calcaneus (subtalar joint) and study the transverse tarsal joint, a complex joint that comprises the talonavicular joint and the calcaneocuboid joint. What is its function?

Bones of the foot
Bones of the ankle
Bones of the foot

Remove the subcutaneous tissue of the anterior and lateral leg and dorsum of the foot and expose the crural fascia and the fascia of the dorsum of the foot. Carefully examine thickenings of these fascias: the extensor retinacula and the fibular (peroneal) retinacula.

2. Open the lateral compartment of the leg and identify its muscles. (Play movie; View images: N 521, 535, TG 3-32, 3-35, 3-36, 3-52)

Open the lateral compartment and dissect the fibularis (peroneus) longus and fibularis (peroneus) brevis muscles. Note their spiral course, their relations behind the lateral malleolus and the role of the fibular retinacula. Trace fibularis brevis to its insertion, but do not follow the fibularis longus into the foot.

3. Open the anterior compartment of the leg and identify the muscles within it; follow their tendons into the foot. (Play movie; View images: N 519, 521, 530, TG 3-36, 3-37, 3-45)

In the anterior compartment dissect the tibialis anterior, the extensor hallucis longus, the extensor digitorum longus, and the fibularis (peroneus) tertius muscles. Trace each of these muscles to its insertion in the foot, cutting through the superior and inferior extensor retinacula; note compartmentalization and the presence of synovial sheaths. Do not dissect the extensor expansions on the digits at this time.

4. Trace the vessels and nerves into the lateral and anterior compartments of the leg. (Play movie; View images: N 512, 518, 520, 522, 529, 531, 534, 535, 536, 541, 542, TG 3-32, 3-35, 3-38, 3-39A, 3-39B, 3-47, 3-50, 3-51, 3-53, 3-62, 3-65B, 3-65C, 3-66AB, 3-67A, 3-67B, 3-67C)

From the popliteal artery, follow the anterior tibial artery over the upper free edge of the interosseous membrane and into the anterior compartment. Trace the anterior tibial artery through the anterior compartment, noting muscular and malleolar branches. Does the anterior lateral malleolar artery communicate with the perforating artery?

Arteriogram of the popliteal artery
Foot arteriogram

Cut the origin of fibularis longus muscle in order to trace the common fibular (peroneal) nerve around the neck of the fibula and determine its point of division. Trace the deep fibular (peroneal) nerve into the anterior compartment with its accompanying artery and vein. Note how it innervates anterior compartment muscles and continues into the foot. What muscle does it supply there? To what area does it supply cutaneous innervation? Follow the superficial fibular (peroneal) nerve through the lateral compartment to the anterior intermuscular septum. Review its cutaneous distribution. Which nerve supplies the muscles of the lateral compartment?

5. Dissect the dorsum of the foot. (Play movie; View images: N 530, 531, 536, 542, TG 3-45, 3-46, 3-47, 3-65B, 3-65C)

Trace the extensor hallucis longus and the extensor digitorum longus muscles to their ultimate insertions, noting the similarity of the extensor expansions to those in the hand. Expose the extensor digitorum brevis muscle and its extensor hallucis brevis slip. Trace their insertions and note how they blend with the extensor expansions.

Follow the anterior tibial artery to the ankle, where it becomes the dorsalis pedis artery, its tarsal branches, the arcuate artery and the deep plantar artery. Note dorsal metatarsal arteries and dorsal digital branches. Note the relation of the dorsalis pedis artery to the tendon of extensor hallucis longus.

6. Remove the skin and subcutaneous tissue from the plantar foot. (Play movie; View images: N 532, 534, TG 3-48, 3-50)

Remove the skin and subcutaneous tissue from the plantar surface of the foot, exposing the plantar aponeurosis and the deep fascia that compartmentalizes and invests the muscles of the great toe (medial compartment) and little toe (lateral compartment). In the subcutaneous tissue note the medial and lateral plantar nerves and their digital branches.

7. Identify and dissect the medial, lateral and central compartments of the foot, identifying fascia, ligaments, muscles, vessels and nerves. (Play movie; View images: N 515, 529, 532, 533, 534, 535, 536, 537, 541, 542, TG 3-34, 3-48, 3-49, 3-50, 3-51)

Remove the deep fascia from the medial (great toe) compartment. Dissect the abductor hallucis muscle and reflect from the flexor retinaculum. Note the medial head of the flexor hallucis brevis and its common insertion with the abductor hallucis. Remove the flexor retinaculum to expose the tendons of tibialis posterior and flexor digitorum longus, the posterior tibial artery and vein, the tibial nerve and the flexor hallucis longus tendon passing into the foot in this order, anterior to posterior. Note the point of division of the posterior tibial artery into medial and lateral plantar arteries, and the division of the tibial nerve into medial and lateral plantar nerves. Trace the medial plantar nerve and artery into the medial compartment. Locate and trace the flexor hallucis longus tendon to the great toe.

Examine the deep fascia of the lateral compartment and identify the calcaneometatarsal ligament. Note that the lateral compartment contains an abductor, flexor and sometimes an opponens like the hand. Note branches of the lateral plantar nerve and artery to the lateral compartment.

Now remove the plantar aponeurosis by cutting the aponeurosis at its mid-point and reflecting it both proximally and distally. This exposes the contents of the central compartment. Dissect the flexor digitorum brevis and trace its tendons to the lateral three or four digits. Compare their insertion with the flexor digitorum superficialis of the forearm and hand. Note the fibrous flexor digital sheath with synovial lining for each digit. What innervates the flexor digitorum brevis? Reflect it from its origin and turn it forward.

Examine and trace the lateral plantar nerve, artery and vein. Now dissect the complex plane of the quadratus plantae muscle, flexor digitorum longus tendon and lumbrical muscles. Note the relations and attachment of the tendon of flexor hallucis longus. Trace the flexor digitorum longus tendons to the digits and note insertions comparable to those of the flexor digitorum profundus in the hand. Trace the lumbrical muscles, noting insertion and innervation.

8. Dissect the adductor-interosseous compartment of the foot, identifying fascia, ligaments, muscles, vessels and nerves. (Play movie; View images: N 515, 529, 532, 533, 534, 535, 536, 537, 541, 542, TG 3-30, 3-42, 3-43, 3-50, 3-51, 3-52, 3-53A, 3-53B, 3-61, 3-65)

Transect the quadratus plantae muscle and the flexor digitorum longus tendon to expose the adductor hallucis (with its transverse and oblique heads) and the flexor hallucis brevis. Identify the oblique head of the adductor hallucis muscle by following the lateral plantar artery and nerve; transect this head to expose the interosseous muscles. Define the axis of adduction and abduction in the foot and observe how each of the plantar and dorsal interosseous muscles fits into the plan.

Trace the lateral plantar artery, noting its plantar metatarsal branches, proper plantar digital arteries and its communication with the deep plantar artery from the dorsalis pedis. What is the plantar arterial arch? Organize your observations on the arterial supply to the foot.

Trace the lateral plantar nerve, noting its division into deep and superficial branches. Organize its motor and cutaneous branches. Now, review the entire innervation (sensory and motor) to the foot. Trace the tendon of tibialis posterior to its insertion by following it into the foot.