Lab Manual - Ankle and Foot
Upon completion of this session, the student will be able to:
- 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. (explanation)
- Describe the arrangement, specializations, and compartments of the foot. (explanation)
- Identify the muscles of the foot and give their functional significance in locomotion. (explanation)
- Identify the vascular supply of the foot and give the regions supplied by each. (explanation)
- 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. (explanation)
- Identify the structure of the ankle and foot joints and describe how the joints and ligaments provide firm footing but flexibility of movement. (explanation)
- Describe the arches of the foot and how the bony structure and ligaments form and support them. (explanation)
Readings and Modules:
- Introduction to Joints
- Prelab Learning Module and the Prelab Images
- Moore's Clinically Oriented Anatomy: (Ankle) p. 647, (Foot) pgs. 609-622
- Joints module
Plastinated specimens are available for this dissection.
1. Review the bony landmarks. (Play movie; View images: N 513, 522, 524, 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?
Carefully examine thickenings of these fascias: the extensor retinacula and the fibular (peroneal) retinacula.
2. 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.
3. 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.
4. 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, 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.
5. 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, 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.
6. Review the joints on plastinated specimens, if available. If you wish to perform joint dissections, you may do so on one limb only.
Open the ankle by removing the anterior and posterior capsules. (Play movie; View images: N 496 , 515, 516, 521, 525, 527A, 527B, 529A, 529B, 530, TG 3-30A, 3-30B, 3-33, 3-35, 3-37, 3-45, 3-60A, 3-60B)
Ankle and foot joints. Strip away all of the muscles that cross the ankle joint. Examine the interosseous membrane between the tibia and fibula. Identify the anterior and posterior tibiofibular ligaments and look for the transverse tibiofibular ligament. What does the latter do?
Clear the deltoid ligament and identify its tibionavicular, anterior tibiotalar (deep to tibionavicular), tibiocalcaneal, and posterior tibiotalar parts.
On the lateral side examine the isolated anterior talofibular, calcaneofibular, and posterior talofibular ligaments. Relate the arrangements of the malleoli and ligaments to the prevalence of ankle sprains.
Remove the capsule from the anterior and posterior side of the joint and flex and extend the joint. Note how the trochlea of the talus articulates with the distal end of the tibia and fibula to provide dorsi and plantar flexion. How is stability of this joint provided? Which position is the most stable? Why this position? Note that the lateral ligaments function for both ankle and subtalar joints. What muscles provide action? Stability? Open the joint and examine the articular surfaces of all elements forming this articulation.
7. Remove the overlying tissue and clean the ligaments of the plantar surface of the foot. (View images: N 523, 524A, 524B, 525, 527, 528, 535, 536, TG 3-40, 3-41, 3-51, 3-52, 3-60A, 3-60B, 3-61A, 3-61B, 3-61C)
Remove the muscles of the foot to expose the long plantar, the short plantar, and the plantar calcaneonavicular (spring) ligaments. Cut through the long plantar ligament and trace the fibularis longus tendon to its insertion. Cut through the plantar calcaneonavicular ligament to expose the head of the talus. Observe how the arches of the foot are formed. What is the function of the plantar ligaments dissected?
Observe the subtalar articulation. What are its actions? What is the tarsal sinus? What is the interosseous talocalcaneal ligament? Now examine the transverse tarsal joint. What are its two parts and its actions? Observe strengthening by the bifurcate ligament on the dorsum of the foot. Organize the structure of the foot, its arches and its major articulations. What are the actions of the foot?
Bones of the foot
Updated: 14 November 2011
|Copyright© 2000 The University of Michigan. Unauthorized use prohibited.|