Foot & Ankle Revision

1. What bones form the medial longitudinal arch of the foot?The bones that form the longitudinal arch of the foot are:

Calcaneus Talus Navicular The 3 x cuneiforms & their metatarsals.

The pillars are: Calcaneus & 3 x metatarsal heads.

Stability: Bony congruity (little) Ligaments – plantar aponeurosis, spring ligament (Plantar-Calcaneonavicular Ligament), less

so the talocalconeal ligament, anterior fibers of the deltoid ligament. Muscles – FHL, less so FDL, AbH and medial half of Flexor Digitorum Brevis (FDB). (TP and TA

important in adducting and inverting the foot and help raise the med border)

2. What bones form the lateral longitudinal arch of the foot?The bones that form the lateral longitudinal arch of the foot are:

Calcaneus Cuboid 4th & 5th Metatarsals

3. What movements occur at the talo-crural joint? It’s a uni-axial hinge joint with the talus wider anteriorly. Dorsiflexion is the closed packed position. Articular surfaces are covered in hyaline cartilage. Movements are dorsiflexion & plantarflexion.

3 (b). Where does the fibrous capsule of the talo-crural joint attatch? It’s thin anteriorly & posteriorly. Attached proximally to borders of tibial and malleolar articular surfaces. Attached distally to talus, to the margins of the trochlear except ant where it reaches to the

dorsum of the talar neck. Strengthened by ligaments.

3 (c). What are the ligaments of the talo-crural joint?

Medial collateral (deltoid) a strong triangular band Lateral collateral discrete parts

4. What movement occurs at the sub-talar joint?

The functional unit between the ant and post articulations of the calcaneus and talus is known as the subtalar joint

Posterior articulation = talocalcaneal joint Anterior articulation = part of the talocalcaneonavicular joint

Talocalcaneonavicular Joint Regarded as 2 joints, made up of: Anterior part of the “subtalar” Talonavicular joint It is a compound, multi-axial articulation

5. What is the transverse tarsal joint?

The transverse tarsal joint or midtarsal joint or Chopart's joint is formed by the articulation of the calcaneus with the cuboid (the calcaneocuboid joint), and the articulation of the talus with the navicular (the talocalcaneonavicular joint).

The most important intertarsal joints are the subtalar, the talocalcaneonavicular, and the calcaneocuboid. The last two constitute the transverse tarsal, or midtarsal, joint. The transverse tarsal joint can be represented by a line from the posterior aspect of the tuberosity of the navicular to the midpoint between the lateral malleolus and the tuberosity of the fifth metatarsal. The other intertarsaljoints are the cuneocuboid, intercuneiform, and cuneonavicular, all of which are plane joints.

Some studies show that in biomechanical analysis suggest the navicular & cuboid move as one unit. Studies consistently demonstrate that the mid foot contributes to pronation & supination of the foot.

“TRANSVERSE TARSAL JOINT MOTION: Together the talonavicular and calcaneocuboid joints are quite mobileand amplify the motion of the ankle and subtalar joints. Dorsiflexion is a component of pronation and consequently, pronation of the transverse tarsal joint can provide additional “functional” dorsiflexion ROM in an individual with a flexible midfoot (Fig. 44.28). However, the use of large midfoot motion during activities that require dorsiflexion ROM such as squat- ting, jumping, walking, or running may lead to excessive stress to structures on the medial side of the foot such as the posterior tibialis tendon, or to abnormal loads to the knee”.(Kinesiology pp. 825).

6. What are the rays of the foot?

• The rays of the foot are the metatarsal and their corresponding cuneiforms.• The coupled movement of the rays help to maintain maximal contact between the foot and the

ground.

Subtalar Joint Metatarsal RaysMedial Lateral

Eversion / Pronation Extension FlexionInversion / Supination Flexion Extension

7. What movements constitute pronation in the foot & ankle?

Pronation = dorsiflexion, eversion and abduction.

8. What movements constitute supination in the foot & ankle?

• Supination = plantarflexion, inversion and adduction.

9. What structures are involved in supporting the medial longitudinal arch of the foot?

See question 1

10. What is the function of the interosseous membrane in the leg?

The interosseous membrane of the leg (middle tibiofibular ligament) extends between the interosseous crests of the tibia and fibula, helps stabilize the Tib-Fib relationship and separates the muscles on the front from those on the back of the leg.It consists of a thin, aponeurotic lamina composed of oblique fibers, which for the most part run downward and lateralward; some few fibers, however, pass in the opposite direction.It is broader above than below. Its upper margin does not quite reach the tibiofibular joint, but presents a free concave border, above which is a large, oval aperture for the passage of the anterior tibial vessels to the front of the leg.In its lower part is an opening for the passage of the anterior peroneal vessels.It is continuous below with the interosseous ligament of the tibiofibular syndesmosis, and presents numerous perforations for the passage of small vessels.It is in relation, in front, with the Tibialis anterior, Extensor digitorum longus, Extensor hallucis proprius, Peronæus tertius, and the anterior tibial vessels and deep peroneal nerve; behind, with the Tibialis posterior and Flexor hallucis longus.

11. Which nerve innervates the plantarflexors?

Tibial Nerve S1-S2

12. Which nerve innervates the anterior compartment of the leg?

Deep Fibular Nerve L4-5

Blood Supply: Anterior Tibial Artery

13.Which nerve innervates the lateral compartment of the leg?

Superficial Fibular Nerve

14.What are the attachments of peroneus longus?

in human anatomy, the peroneus longus (also known as fibularis longus) is a superficial muscle in the lateral compartment of the leg, and acts to evert and plantar flex the ankle.The muscle, the longest and most superficial of the three fibularis muscles, is attached proximally to the head of the fibula and its 'belly' runs down most of this bone. It becomes a tendon that goes posteriorly around the lateral malleolus of the ankle, then continues under the foot to attach to the medial cuneiform and first metatarsal.

15.What are the attachments of soleus?

Attatchments

It arises from the soleal line on the posterior surface of the tibia, the posterior surface of the upper third of the fibula (including the head) and a fibrous arch between these bony attachments. The fibres pass downwards, forming a belly about halfway down the calf to the deep surface of a membranous tendon, which faces posteriorly. This tendon glides over a similar one on the deep surface of gastrocnemius, thereby enabling independent movement of the two muscles. Inferiorly the two tendons fuse to form the upper part of the tendocalcaneus, which passes behind the ankle joint to insert into the middle part of the posterior surface of the calcaneus.

Nerve supply

By two branches from the tibial nerve (root value S1 and 2), one of which arises in the popliteal fossa and enters the superficial surface of the muscle, while the other arises in the calf entering the deep surface. The skin over the region of the muscle is predominantly supplied by root S2.

Action

Soleus is one of the two main plantarflexors of the ankle joint. It is so placed to prevent the body falling forwards at the ankle joint during standing, and as such is an important postural muscle. Intermittent contraction of the muscle during standing aids venous return (the soleal pump) due to the communicating vessels joining the deep and superficial venous systems which pass through its substance.

15 (b). What are the attachments of gastrocnemius?

Gastrocnemius

The shape of the calf is mainly due to the two fleshy bellies of gastrocnemius (Fig. 3.38A), being situated on the back of the leg with its muscle bulk mainly in the upper half. Together with soleus and plantaris, the gastrocnemius forms a composite muscle referred to as the triceps surae. The two heads of gastrocnemius form the lower boundaries of the popliteal fossa, which can only really be seen when the knee is flexed. The two heads arise from the medial and lateral condyles of the femur: the medial head, from behind the medial supracondylar ridge and the adductor tubercle on the popliteal surface of the femur, the lateral head from the outer surface of the lateral condyle of the femur just above and behind the lateral epicondyle. Each head has an additional attachment from the capsule of the knee joint and from the oblique popliteal ligament, below which each head is separated from the capsule by a bursa. The bursa associ- ated with the medial head often communicates with the knee joint; that under the lateral head rarely does. There is often a sesamoid bone, the fabella, in the lateral head as it crosses the lateral condyle of the femur. Less commonly there may be one associated with the medial head.

From each head a fleshy bulk of muscle fibres arise which gradually come together, although not actually blending with each other, to insert into the posterior surface of a broad membranous tendon which fuses with the tendon of soleus to form the upper part of the tendocalcaneus. This broad tendon gradually narrows, becoming more rounded until it reaches about three fingers’ breadth above the calcaneus, where it begins to expand again and continues to do so, until its insertion into the middle part of the posterior surface of the calcaneus. The fibres of the tendon spiral as they pass from the myotendinous junction to their insertion, so that the most medial fibres superiorly become posterior at the site of insertion. This helical arrangement results in less buckling when the tendon is lax and less de- formity of the individual strands when they are put under tension. A bursa lies between the tendon and the upper part of the calcaneus while a pad of fat lies between the tendon and the posterior aspect of the ankle joint. Inferior to the insertion is the fat pad of the heel.

Nerve supply

Each head by a branch from the tibial nerve (root value S1 and 2). The area of skin covering the muscle is supplied by roots L4, 5 and S2.

Action

Gastrocnemius, together with the soleus, is the main plan- tarflexor of the ankle joint. It provides the propelling force for locomotion. As it crosses the knee joint, gastrocnemius is also a powerful flexor of that joint. However, it is not able to exert its full power on both joints simultaneously. For example, if the knee is flexed, gastrocnemius cannot exert maximum power at the ankle joint and vice versa.

Functional activity

In running, walking and jumping gastrocnemius provides a considerable amount of the propulsive force. When one considers the power needed to launch the body into the air, the triceps surae must be one of the most powerful mus- cle groups in the body.

The habitual wearing of shoes with a high heel can cause considerable shortening of the fibres of gastrocnemius, as the two attachments of the muscle are brought closer to- gether. If shortening has occurred, difficulty in walking in flat shoes or bare feet may be experienced due to limited dorsiflexion at the ankle joint.

16.What is the main functional difference between soleus and gastrocnemius?

The gastrocnemius is a biarticular muscle:

Proximal attachment: Medial head: Upper and pos- terior part of the medial femoral condyle behind the adductor tubercle and from a slightly raised area on the popliteal surface of the femur above the medial condyle. Lateral head: Upper and posterior part of the lateral surface of the lateral femoral condyle and lower part of the corresponding supracondylar line

Distal attachment: Posterior surface of the calcaneus via the tendo calcaneus

Innervation: Tibial nerve (S1, S2)

Half muscle fibers are Type I & Type II.

The soleus is a monoarticular muscle:

Proximal attachment: Posterior surface of the head and proximal 1/4 to 1/3 of the shaft of the fibula, soleal line and middle 1/3 of the medial border of the tibia, and a fibrous band between the tibia and fibula

Distal attachment: Posterior surface of the calcaneus via the tendo calcaneus

Innervation: Tibial nerve (S1, S2)

Muscle fibers are Type I.

They both plantarflex the foot however soleus works better when the knee is in flexion. They both attach & form the Achilles tendon & together form the triceps surae. Both work together to lift the weight of the body when rising onto the forefoot. The soleus appears well suited to play a larger role

in such phasic activities as controlling upright posture, while the gastrocnemius is critical in high-velocity and forceful activities such as jumping [7,19]. Both the gastrocnemius and soleus muscles are active during the stance phase of gait, although the activity of the soleus begins earlier, and the activity of the gastrocnemius lasts longer [35,82]. The soleus and gastrocnemius both contribute to forward progression in stance, but the soleus helps to decelerate the leg as the body glides forward over the fixed foot during midstance [67]. Like the gastrocnemius, the soleus with its insertion into the Achilles tendon has a small inversion moment arm, suggesting that the soleus can contribute to inversion of the hindfoot.

17.Which has the greatest range of movement; inversion or eversion, why?

Inversion. This is be cause of the structure of the talo-crural joint with the lateral malleoli blocking any eversion. The deltoid ligament (the strongest of all foot ligaments) on the medial side of the foot also prevents eversion.

18.What are the functions of tibialis anterior and posterior?

Inverting the foot they both work together.

19.What are the functions of the foot and ankle?

Acts as a support base with minimal muscle activity. Provides a mechanism for rotation of the tibia and fibular during gait. Adapts to uneven terrain. Provides shock absorption. Acts as a lever during push off.

20.What is the main arterial blood supply to the foot?

The main artery carrying blood to the lower limb is named successively external iliac, femoral, and popliteal. The arrangement of this vessel and its branches is summarized in figure 13-5. The external iliac artery passes deep to the inguinal ligament and is then termed the femoral artery. The principal branch of this artery in the proximal thigh is the deep femoral. Femoral circumflex arteries either arise from the femoral or deep femoral artery and pass posteriorward around the hip joint to supply this joint and to contribute to an anastamosis with gluteal and posterior thigh vessels. The blood supply of the posterior thigh arises from perforating branches from the deep femoral artery. In the lower third of the thigh, the femoral artery passes posteriorward (through the adductor opening), where its name is changed to popliteal. This artery gives rise to several genicular braches around the knee. Inferior to the knee joint (at the inferior border of the popliteus muscle), the popliteal artery divides into the anterior and posterior tibial arteries. The posterior tibial artery gives off the fibular artery from its lateral side and, as it passes posterior to the medial malleolus, divides into medial and lateral plantar arteries, and the lateral plantar artery forms the plantar arch. The anterior tibial artery supplies the anterior leg and continues onto the dorsum of the foot as the dorsal artery of the foot

21. What is the plantar fascia?

The plantar fascia is a complex system of ligaments on the plantar side of the foot. It contributes to the shape & stabilization of the whole foot. The deepest portion is the plantar aponeurosis has remarkable tensile strength & is twice as strong as the deltoid ligament - the strongest of all ligaments in the foot. It spans the arches of the foot & helps support them. Weight bearing lowers the longitudinal arch of the foot & stretches the plantar aponeurosis. Studies show that when the aponeurosis is compromised there is a decrease of height within the arch.

22. What is the function of the arches of the foot?

The arches serve several purposes: they protect the nerves, blood vessels, and muscles on the plantar surface of the foot from compression during weight bearing; they help the foot to absorb shock during impact with the ground; and they help store mechanical energy then release it to improve the efficiency of locomotion.

Muscles plantarflexing the ankle joint

GastrocnemiusSoleus PlantarisFibularis longus Fibularis brevis Tibialis posterior Flexor digitorum longus Flexor hallucis longus

Muscles dorsiflexing the ankle joint

Tibialis anterior Extensor digitorum longus Extensor hallucis longus Fibularis tertius

Muscles inverting the foot

Tibialis posterior Tibialis anterior

Muscles everting the foot

Fibularis (peroneus) longus Fibularis (peroneus) brevis Fibularis (peroneus) tertius

Muscles extending the toes

Extensor hallucis longus Extensor digitorum longus Extensor digitorum brevis Lumbricals

Muscles flexing the toes

Flexor digitorum longus Flexor accessorius (quadratus plantae) Flexor digitorum brevisFlexor hallucis longus Flexor hallucis brevis Flexor digiti minimi brevis Interossei Lumbricals

Muscles adducting the toes

Adductor hallucis Plantar interossei

Chapter 17: The ankle and foothttps://www.dartmouth.edu/~humananatomy/part_3/chapter_17.html

The word ankle refers to the angle between the leg and the foot. The foot functions in support and in locomotion, whereas the hand is a tactile and grasping organ. The toes are numbered from one to five, beginning with the great toe, or hallux. Thus, the pre-axial digit in either the hand or the foot is numbered one. The terms abduction and adduction of the toes are used with reference to an axis through the second toe. Thus, abduction of the big toe is a medial movement, away from the second toe. The tendons around the ankle (similar to those at the wrist) are bound down by retinacula (see fig. 17-4).The fascia on the sole of the foot is a strong sheet termed the plantar aponeurosis, which acts as a mechanical tie. It extends anteriorly from the calcaneal tuberosity and divides into five processes, each of which is anchored at a metatarsophalangeal joint. Fascial "spaces" are situated superior to the plantar aponeurosis, and the big and little toes have special compartments. Synovial sheaths are found (1) anterior to the ankle (fig. 17-1) for the tendons of the (a) tibialis anterior, (b) extensor hallucis longus, and (c) extensor digitorum longus and fibularis tertius; (2) posterior to the medial malleolus for the tendons of the (a) tibialis posterior, (b) flexor digitorum longus, and (c) flexor hallucis longus; and (3) posterior to the lateral malleolus for the tendons of the fibularis longus and brevis. Some further sheaths are found in the sole and in relation to the toes.Muscles of foot (table 17-1)The extensor digitorum brevis is the only muscle on the dorsum of the foot. It and the extensor hallucis longus tendon can be felt and sometimes seen when dorsiflexing the proximal phalanges against resistance, and these actions are used to test the integrity of the fifth

lumbar nerve (L5) or the fibular nerve.The muscles of the sole are collectively important in posture and locomotion, and they provide strong support for the arches of the foot during movement. They may be considered in three groups: for the big toe (medially), the central portion of the sole, and the little toe (laterally). They may also be considered, however, in four layers (table 17-1 and fig. 17-2).The flexor digitorum brevis resembles the flexor digitorum superficialis of the upper limb, in that each muscle has four tendons (omitting the first digit), which are perforated by the long flexor tendons and then divide to be inserted into the sides of the middle phalanges.Although classified as dorsal and plantar, this is a relative position and both groups of interossei are actually more plantar. The lumbricals and interossei are arranged in a manner basically similar to those of the hand but are organized around the axis of the second toe as compared with that of the third finger. There are, however, some structural and functional differences between the interossei of the hand and of the feet. For example, the interossei of the foot are not inserted into the extensor aponeuroses, and they probably strengthen the metatarsal arch by holding the metatarsals together.

The plantar reflex is a superficial reflex that consists of (plantar) flexion of the toes when the skin of the sole is stroked slowly along its lateral border. In infants before they walk and in patients with certain disorders of the motor pathways of the brain and spinal cord, however, similar stimulation of the sole results in a slow dorsiflexion of the great toe and a slight spreading of the other toes. This response is known as the Babinski sign.Nerves of footThe medial plantar nerve, the larger terminal branch of the tibial nerve, arises posterior to the medial malleolus, deep to the flexor retinaculum and the abductor hallucis (see fig. 17-4A). It runs anteriorly between the abductor hallucis and the flexor digitorum brevis and supplies these muscles (see fig. 15-2) as well as the skin on the medial side of the foot. It ends as plantar digital nerves that supply the flexor hallucis brevis, the first lumbrical, and the skin of the medial toes, including their nail beds. The medial plantar nerve is comparable to the median nerve in the hand.The lateral plantar nerve arises posterior to the medial malleolus. It runs anteriorly and laterally, deep to the flexor digitorum brevis, and divides into superficial and deep branches. It supplies the quadratus plantae and abductor digiti minimi muscles, as well as the lateral side of the sole. The superficial branch supplies the flexor digiti minimi brevis muscle and gives rise to plantar digital nerves to the lateral toes. The deep branch turns medially and supplies the interossei, lumbricals 2 to 4, and the adductor hallucis. The lateral plantar nerve is comparable to the ulnar nerve in the hand.Vessels of foot (fig. 17-3)

The medial plantar artery, one of the terminal branches of the posterior tibial artery, arises deep to the flexor retinaculum and the abductor hallucis muscle. It runs anteriorly with its companion nerve and gives digital branches to the medial toes (fig. 17-4A).The lateral plantar artery, with its companion nerve, runs anteriorly and laterally, deep to the flexor digitorum brevis muscle. It then turns medially and forms the plantar arch, which lies between the third and fourth layers of the muscles of the sole. The arch gives off a series of metatarsal and digital arteries.The dorsal artery of the foot, variable in size and course, is the continuation of the anterior tibial artery at a point midway between the malleoli (fig. 17-4C). This artery extends to the posterior end of the first intermetatarsal space. The dorsal artery of the foot is important clinically in assessing peripheral circulation. Its pulsations should be sought, and can generally be felt, between the tendons of the extensor hallucis longus and extensor digitorum longus (fig. 17-4C). The artery is crossed by the inferior extensor retinaculum and extensor hallucis brevis. It lies successively on the capsule of the ankle joint, the head of the talus, the navicular, and the intermediate cuneiform. Its branches form an arterial network on the dorsum of the foot. The tendon of the extensor hallucis longus crosses either the anterior tibial artery or the dorsal artery of the foot and comes to lie on the medial side of the latter. The dorsal artery of the foot ends in a deep plantar branch, which passes to the sole between the heads of the first dorsal interosseus and completes the plantar arch.JointsTibiofibular Syndesmosis.A strong fibrous union exists between the lower ends of the tibia and fibula. It consists of an interosseous ligament, strengthened in its anterior and posterior aspects by anterior and posterior tibiofibular ligaments, and a transverse ligament from the malleolar fossa of the fibula to the posterior aspect of the tibia. A recess of the ankle joint often extends upward into the lower portion of the syndesmosis.Ankle Joint.

The ankle, or talocrural, joint is a hinge joint between (1) the tibia and fibula, which form a socket, and (2) the trochlea of the talus (see fig. 12-29). The jooint capsule is thickened on each side by a strong ligament. The medial, or deltoid, ligament (fig. 17-5) runs from the medial malleolus to the talus, navicular, and calcaneus. It is crossed by the tendons, vessels, and nerves that have entered the foot by passing posterior to the medial malleolus. The lateral ligaments (fig. 17-5) consists of (1) the anterior talofibular ligament, between the neck of the talus and the lateral malleolus; (2) the calcaneofibular ligament; and (3) the posterior talofibular ligament, between the talus and the malleolar fossa. The medial and lateral ligaments prevent anterior and posterior

slipping of the talus. They may be torn in injuries to the ankle, with the lateral ligaments being significantly weaker and more liable to sprain. If the ligaments do not yield, one or both malleoli may be broken off in dislocations of the ankle joint. The shape of the surfaces at the ankle is such that, aided by the ligaments of the tibiofibular syndesmosis, the malleoli grip the talus tightly in dorsiflexion. Therefore, most sprains of the ankle occur with the ankle in some degree of flexion.The ankle joint allows dorsiflexion and plantar flexion (fig. 17-6) around an axis that passes approximately through the malleoli. The range of movement varies. The triceps surae and fibularis longus muscles plantar-flex the foot. The tibialis anterior and extensor digitorum longus muscles dorsiflex the foot (see fig. 16-5). It should be appreciated that, physiologically, plantar flexion of the foot and toes is an extensor response, whereas dorsiflexion of the foot and toes is a flexor response.Intertarsal Joints.The talus moves with the foot during dorsiflexion and plantar flexion. However, during inversion and eversion, which occur at intertarsal joints, the talus moves very little. The most important intertarsal joints are the subtalar, the talocalcaneonavicular, and the calcaneocuboid. The last two constitute the transverse tarsal, or midtarsal, joint. The transverse tarsal joint can be represented by a line from the posterior aspect of the tuberosity of the navicular to the midpoint between the lateral malleolus and the tuberosity of the fifth metatarsal. The other intertarsaljoints are the cuneocuboid, intercuneiform, and cuneonavicular, all of which are plane joints.The subtalar joint.The subtalar joint (figs. 12-36 and 17-7) is a separate talocalcanean articulation lying posterior to the tarsal canal. The talocalcaneonavicular joint, a part of the transverse tarsal joint, lies in front of the tarsal canal. It resembles a ball-and-socket joint in that the head of the talus fits into a socket formed by the navicular on the anterior side, the calcaneus on the inferior side, and the plantar calcaneonavicular ligament in between (fig. 17-7). This band, frequently termed the spring ligament (figs. 17-5 and 17-8), connects the sustentaculum tali with the navicular, and the tibialis posterior tendon lies immediately inferior to it. The other part of the transverse tarsal joint is the calcaneocuboid, which resembles a limited saddle joint. A strong bifurcate ligament extends from the floor of the tarsal sinus (on the supeior aspect of the calcaneus) to the navicular and cuboid bones. (The tarsal sinus is the expanded anterolateral end of the tarsal canal, which runs obliquely between the talus and calcaneus.)The foot may be disarticulated at the ankle joint (Syme's amputation) or at the transverse tarsal joint (Chopart's amputation).The tension that develops during the support of body weight is taken up by strong ligaments on the plantar aspect of the tarsus (figs. 17-8 and 17-9). The long plantar ligament extends from the plantar aspect of the calcaneus to the tuberosity of the cuboid. The short plantar ligament,

also extending from the calcaneus to the cuboid, is more deeply placed. We have already discussed the plantar calcaneonavicular (spring) ligament that is involved in supporting the talus.

The chief movements of the foot distal to the ankle joint are inversion and eversion. In inversion, the sole of the foot is directed medially. In eversion, the sole is turned so that it faces laterally (see fig. 17-6). Inversion and eversion occur mainly at the subtalar and transverse tarsal joints. The axes of movement at these articulations are situated obliquely with reference to the standard anatomical planes. Hence, each movement is a combination of two or more primary movements. Inversion comprises supination, adduction, and plantar flexion. Eversion involves pronation, abduction, and dorsiflexion. Usage is unfortunately variable, but supination and pronation of the foot generally refer to medial and lateral rotation about an anteroposterior axis. Abduction and adduction refer to movements of the anterior part of foot about a vertical axis. The tibialis posterior and anterior muscles invert the foot. The fibularis and extensor digitorum longus muscles evert the foot (see fig. 16-5).Remaining Joints.The tarsometatarsal and intermetatarsal joints are plane articulations that allow gliding. The medial cuneiform and first metatarsal have an independent joint cavity (see fig. 12-31A). The second metatarsal fits into a socket formed by the three cuneiforms (see fig. 12-32). The metatarsophalangeal joints are ellipsoid, and the interphalangeal joints are hinge, but the ligamentous arrangements of both are similar. Collateral ligaments are present, as are fibrous or fibrocartilaginous pads termed plantar ligaments (cf. palmar ligaments of fingers). The pads are interconnected by the deep transverse metatarsal ligament, which helps to hold the metatarsal heads together. The metatarsophalangealjoints allow flexion, extension, abduction, and adduction. The interphalangeal joints permit flexion and extension. The metatarsophalangeal joint ofthe big toe is specialized. Two grooves on the plantar aspect of the head of the first metatarsal articulate with the sesamoids that are embedded in the plantar ligament (fig. 17-9). The sesamoids are attached to the plantar aponeurosis and anchored to the phalanx. The sesamoids of the big toe take the weight of the body, especially during the latter part of the stance phase of walking. The sesamoid mechanism is deranged in bunions and in hallux valgus. A bunion is a swelling medial to the joint, and it is due to bursal thickening. In hallux valgus the big toe is displaced laterally because of angulation at the metatarsophalangeal joint.Arches and flat feetThe arches of the foot (figs. 17-9, 17-10, 17-11 and 17-12) are the longitudinal and the transverse. The longitudinal arch is formed medially by the calcaneus, talus, navicular, cuneiforms, and first to third metatarsals and laterally by the calcaneus, cuboid, and fourth and fifth

metatarsals. The transverse, or metatarsal, arch is formed by the navicular, cuneiforms, cuboid, and first to fifth metatarsals. These osseous arches depend on the mechanical arrangement of the bones, but they are supported by ligaments and, during movement, by muscles, especially the invertors and evertors. The arches develop during fetal life, but they are masked by a fat pad, which makes the sole convex in the newborn. The medial arch can be recognized in the footprints of most adults, but the extent of contact between the sole and the ground does not necessarily indicate precisely the height of the bony arches. The term "flatfoot" (pes planus) is used for several conditions, including a simple depression of the longitudinal arch, which in many individuals is not pathological (fig. 17-10B). The converse is pes cavus, in which the longitudinal arch is very high (fig. 17-10C). The term "clubfoot" (talipes) is used for a foot that appears twisted out of shape or position. The commonest variety of congenital clubfoot comprises plantar flexion, supination, and adduction (talipes equinovarus).

Questions17-1 What is the plantar reflex?

17-1 The plantar reflex consists of plantar flexion of the toes (S1) when the skin of the sole is stroked slowly along its lateral border.

17-2 What is the Babinski sign?17-2 The Babinski sign, named after a French neurologist (1896), consists of dorsiflexion of the great toe on stroking the sole slowly along its lateral border. "There is perhaps no more important single physical sign in clinical neurology" (Walshe). It is found in lesions of the upper motor neuron. It may be accompanied by dorsiflexion of the foot and flexion at the knee and hip; i.e., it is part of a more extensive flexion response, or withdrawal of the limb. Hence it is incorrect to refer to Babinski's sign as the "extensor plantar response" although the trem "upgoing toe" may be applicable.

17-3 How far distally do (a) the femoral, (b) the obturator, and (c) the sciatic cutaneous territories extend?17-3 The territory of the femoral nerve extends (through the saphenous nerve) to the medial side of the foot; the obturator nerve may reach almost as far as the knee; the sciatic distribution (through the plantar nerves) proceeds to the toes. The sole is supplied by the tibial and medial and lateral plantar nerves (L4,5; S1,2).

17-4 In terms of dermatomes, which spinal nerves supply the hand and the foot?17-4 The following is a memory aid for the dermatomes of the hand and foot: L4,5 (foot); C6,7,8 (hand); S1,2 (foot). See figures 8-10 and 15-11.

17-5 Which vessels are used in seeking a pulse at the ankle and foot?17-5 A pulse at the ankle and foot is sought chiefly in the posterior tibial artery (see fig. 17-4A) and the dorsal artery of the foot (see fig. 17-4C).

17-6 Which structures are situated between the medial malleolus and the heel?17-6 Between the medial malleolus and the heel are the tibialis posterior and flexor digitorum longus tendons (which occupy a groove on the medial malleolus and lie against the medial, or deltoid, ligament of the ankle); the posterior tibial artery and tibial nerve; and the flexor hallucis longus tendon (see figs. 16-5 and 17-4A). These structures lie under cover of the flexor retinaculum.

17-7 Which structures cross the anterior aspect of the ankle joint?17-7 The following structures cross the anterior aspect of the ankle joint from lateral to medial: the extensor digitorum longus tendon, anterior tibial artery, deep peroneal nerve, and extensor hallucis longus tendon (see fig. 17-4C). These structures are anchored by the extensor retinacula.

17-8 Which structures are situated posterior to the lateral malleolus?17-8 The fibularis longus and, anterior to it, the fibularis brevis are situated posterior to the lateral malleolus (see fig. 17-4B). Both tendons wind around the lateral malleolus and lie on the lateral ligament (calcaneofibular part) under cover of the fibular retinacula.

17-9 What is the deltoid ligament of the ankle joint?17-9 The deltoid ligament is the medial ligament of the ankle joint. It extends between the medial malleolus and the navicular, calcaneus (sustentaculum tali), and talus (see fig. 17-5).

17-10 What is the clinical importance of the lateral ligament of the ankle joint?

17-10 The lateral ligament connects the lateral malleolus with the talus anteriorly and posteriorly and with the calcaneus in between (see fig. 17-5). Although a sprain is generally a minor ligamentous injury, forcible inversion may cause rupture of the lateral ligament without a fracture. The ankle may seem to be normal unless the foot is inverted by the examiner, when the talus becomes tilted out of the tibiofibular mortice. Immobilization is then indicated to avoid recurrent dislocation of the ankle joint.

17-11 Which are the most important intertarsal joints and which important movements occur at them?17-11 The subtalar and transverse tarsal (talocalcaneonavicular and calcaneocuboid) are the most important intertarsal joints (see fig. 17-7). The chief movements are (a) inversion and (b) eversion (see fig. 17-6), carried out by (a) the tibialis anterior and posterior muscles and (b) the fibularis (peronei) longus and brevis and the extensor digitorum longus muscles (see fig. 16-5).

17-12 Which is the most frequent type of clubfoot?17-12 The most frequent type of clubfoot is talipes equinovarus, a deformity in which the foot is plantar flexed (equinus, resembling the stance of a horse), supinated, and adducted (varus, bent medially).

17-13 What is the significance of the adjectives varus and valgus?17-13 Varus implies medial deviation; valgus indicates lateral deviation. For example, at the elbow, a more acute (accentuated) carrying angle is termed cubitus valgus, a more obtuse angle is cubitus varus. Similarly, at the hip, a more acute angle of inclination of the femur is termed coxa vara, a more obtuse angle is coxa valga. At the knee, increased angulation between the femur and tibia is genu valgum (liable to produce "knock-knee"), decreased angulation is genu varum (liable to cause "bowlegs").

The Foot

The primary functions of the foot are to provide a stable platform of support to attenuate impact load- ing of the extremity during locomotion, and to as- sist in the efficient forward propulsion of the body. To accomplish these tasks, the foot is made up of three sections. These sections—the hindfoot, the mid- foot, and the forefoot—are in turn composed of mul- tiple mobile and semirigid articulations that afford foot conformity to varying surface topographies. The bony elements of the foot are arranged to form a longitudinal and a transverse arch. These arches are spanned across the plantar aspect by soft-tissue ten- sion bands that act as shock absorbers during impact (Figure 13.3a).

The foot has 26 bones distributed among the hind- foot, midfoot, and forefoot (Figure 13.3b). The hind- foot represents one-third of the total length of the foot. It contains the two largest bones of the foot, the calcaneus and the talus. The larger is the calcaneus (heel bone). The calcaneus lies beneath and supports the body of the second bone, the talus. The talus (an- kle bone) is the only bony link between the leg and the foot. The tibia articulates with the talus in the middle of the hindfoot.

The midfoot contains the small, angular navicular, cuneiforms (medial, middle, and lateral), and cuboid bone. The midfoot makes up slightly more than one- sixth of the overall length of the foot. Little movement occurs within the midfoot articulations.

The forefoot represents the remaining one-half of the overall length of the foot. It is composed of minia- ture long bones, 5 metatarsals and 14 phalanges.

Structural integrity of the foot is dependent on the combination of articular geometry and soft-tissue support. All articulations of the foot are synovial. The soft-tissue support is provided by static (ligamentous) and dynamic (musculotendinous) stabilizers. The fail- ure of either articular or soft-tissue structural integrity will result in ankle dysfunction, foot dysfunction, re- duced efficiency, arthritis, and bony failure (fatigue fractures).

The support of the talus is afforded posteriorly by the anterior calcaneal facet and distally by the navicular bone. There is a void of bony support at the plantar aspect between the calcaneus and nav- icular, beneath the talar head. Support of the talar