Dissector Answers - Ankle and Foot

 

Learning Objectives:

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

  1. 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.
  2. Describe the arrangement, specializations, and compartments of the foot.
  3. Identify the muscles of the foot and give their functional significance in locomotion.
  4. Identify the vascular supply of the foot and give the regions supplied by each.
  5. 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.
  6. Identify the structure of the ankle and foot joints and describe how the joints and ligaments provide firm footing but flexibility of movement.
  7. Describe the arches of the foot and how the bony structure and ligaments form and support them.

Learning Objectives and Explanations:

1. 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. (W&B 644-652, TG3-40A, TG3-40B, TG3-41A, TG3-41B, TG3-61B)

Bones:

http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/images/dorsal_foot_bones.gif

http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/images/plantar_foot_bones.gif

Images from "Anatomy of the Human Body" by Henry Gray are provided by: http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/images/bartleby.gif

There are 7 tarsal bones, 5 metatarsal bones (the big toe is number 1, the little toe is number 5), and 14 phalanges. The big toe has only 2 phalanges, proximal and distal, while toes 2-5 each have 3, distal, middle, and proximal.

The tarsals have specific names, which you need to learn. The pictures above will help, but working with the bones in your bone box will help much more
. Starting posteriorly, the bone you feel at the very back of your foot is the calcaneus, and on the top of it you find the talus. The talus articulates with the calcaneus below, the tibia and fibula above and on the sides, and the navicular bone in front. Anterior to the navicular, you find the three cuneiforms, medial, intermediate, and lateral. Finally, the cuboid bone is lateral to the cuneiforms, articulating with the 4th and 5th metatarsals anteriorly, and the calcaneus bone posteriorly. (Latin, cuneiform = wedge-shaped, calcaneum = heel, navicula = boat)

Arches:


There are two longitudinal arches
, medial and lateral. The higher medial arch passes from the calcaneus to the talus to the navicular to the cuneiforms to the metatarsals. They are supported by the plantar calcaneonavicular ligament (spring ligament), and also by the tendons of the tibialis anterior and tibialis posterior muscles. The transverse arch results from the shape of the distal row of tarsal bones and the bases of the metatarsal bones. Imagine an arch that goes over the top of the cunieforms and cuboid, and is supported by the shape of the bones, various ligaments, and the tendons of the fibularis longus, tibialis anterior, and tibialis posterior muscles.

Joints:


The subtalar joint
is formed between the large concave facet on the under surface of the body of the talus and the convex posterior articular surface on the superior aspect of the calcaneus. A loose, thin walled articular capsule unites the two bones by attaching to the margins of the articular surfaces. The transverse tarsal joint is the designation for the irregular plane which extends from side to side across the foot and is composed of the talonavicular articulation medially and the calcaneocuboid joint laterally. This joint allows inversion and eversion of the foot.

Ligaments:


The plantar ligaments of the joints of the foot are very strong. They they are supplemented by robust interosseous ligaments which keep the bones from spreading apart. Notable on the sole of the foot are the long plantar ligament
and the plantar calcaneoucuboid and plantar calcaneonavicular ligaments. The elasticity of the latter and its support of the head of the talus have led to it being called the "spring ligament." The plantar aponeurosis may be likened to a "tie rod" for the longitudinal arch, firmly connecting its ends and preventing their spread.

2. Describe the arrangement, specializations, and compartments of the foot. (W&B 626-629, TG3-48A, TG3-49, TG3-50, TG3-51)

The dorsum of the foot is a single compartment, while the plantar foot is divided into four compartments, the medial, lateral, central, and adductor-interosseous compartments.

3. Identify the muscles of the foot and give their functional significance in locomotion. (W&B 623-632, TG3-49, TG3-50, TG3-51, TG3-52A, TG3-52B)

The muscles are best considered in their different compartments. Dorsum of the foot:

Muscle

Origin

Insertion

Action

Innervation

extensor digitorum brevis

superolateral surface of calcaneus

extensor expansion of toes 2-4 (tendon to hallux is called extensor hallucis brevis)

extends toes 2-4

deep fibular (peroneal) nerve

extensor hallucis brevis

superolateral surface of calcaneus

dorsum of base of proximal phalanx of hallux

extends great toe

deep fibular (peroneal) nerve


We must also consider the extensor expansions. The three tendons of the extensor digitorum brevis join the lateral sides of the tendons of the extensor digitorum longus muscle to the second, third and fourth toes. These form the extensor expansion on these digits.

Blood supply to these muscles is via the
dorsalis pedis artery, which comes from the anterior tibial artery.

Plantar Foot:

Medial Compartment:

Muscle

Origin

Insertion

Action

Innervation

abductor hallucis

medial side of tuberosity of calcaneus

medial side of base of proximal phalanx of hallux

abducts hallux; flexes metatarsophalangeal joint

medial plantar nerve

flexor hallucis brevis

cuboid, lateral cuneiform, medial side of first metatarsal

medial belly: medial side of proximal phalanx of hallux; lateral belly: lateral side of proximal phalanx

flexes metatarsophalangeal joint of hallux

medial plantar nerve (lateral belly occasionally receives innervation from lateral plantar nerve)


Blood supply to these muscles is via the
medial plantar artery, which is from posterior tibial artery.

Lateral compartment:

Muscle

Origin

Insertion

Action

Innervation

flexor digiti minimi brevis, of foot

base of 5th metatarsal bone

lateral side of base of proximal phalanx of 5th digit

flexes metatarsophalangeal joint of 5th digit

lateral plantar nerve

abductor digiti minimi, in foot

tuberosity of calcaneus

lateral side of base of proximal phalanx of 5th digit

abducts 5th toe; flexes metatarsophalangeal joint

lateral plantar nerve

Blood supply here is from the lateral plantar artery, a branch of the posterior tibial artery.

Central compartment:

Muscle

Origin

Insertion

Action

Innervation

flexor digitorum brevis

tuberosity of calcaneus, plantar aponeurosis, intermuscular septae

base of middle phalanx of digits 2-5 after splitting to allow passage of flexor digitorum longus tendons

flexes metatarsophalangeal & proximal interphalangeal joints of digits 2-5

medial plantar nerve

quadratus plantae

anterior portion of calcaneus & long plantar ligament

tendons of flexor digitorum longus m.

assists flexor digitorum longus in flexing toes

lateral plantar nerve

The central compartment also technically contains the tendons of the flexor digitorum longus muscle. Also, note the split innervation of this compartment. Blood supply to the flexor digitorum brevis muscle is from both the medial and lateral plantar arteries, while the quadratus plantae muscle only receives the lateral plantar artery. Adductor-interosseous compartment:

Muscle

Origin

Insertion

Action

Innervation

adductor hallucis

oblique head: bases of metatarsals 2-4; transverse head: heads of metatarsals 3-5

lateral side of base of proximal phalanx of hallux

adducts great toe (moves it toward midline of foot; i.e. 2nd digit)

deep branch of lateral plantar nerve

dorsal interosseous, of foot

four muscles, from shafts of adjacent metatarsal bones

bases of proximal phalanges for digit 2 (both sides) & digits 3,4 (lateral side)

abduct digits 2-4 (move these digits away from midline as defined by a line passing through 2nd digit), flex metatarsophalangeal joints and extend interphalangeal joints of those digits

deep branch of lateral plantar nerve

plantar interosseous, of foot

base and medial side of metatarsals 3-5

bases of proximal phalanges and extensor expansions of digits 3-5

adduct digits 3-5 (move these digits toward the midline of the foot as defined by the second digit),flex metacarpophalangeal and extend interphalangeal joints of digits 3-5

deep branch of lateral plantar nerve

The adductor hallucis muscle receives blood from the plantar arterial arch, the plantar interosseous muscles get plantar metatarsal arteries, and the dorsal interosseous muscles get dorsal metatarsal arteries.
In summary, think about what you see as you take off the layers of the foot. First, you are confronted with the plantar aponeurosis. As soon as you peel it off, you see the flexor digitorum brevis muscle which runs from the calcaneus to mid-sole, and then has 4 tendons that go to toes 2-5. If you reflect it, you then see the flexor digitorum longus tendon and lateral to it is quadratus plantae muscle. (The latter muscle helps longus flex the toes in a straight line. Look at the tendon running from the medial malleous obliquely across the sole. By itself it would flex the toes medially.) Reflect this layer, and you see the adductor hallucis muscle. It is the one with both a transverse and an oblique head. You will also see the interosseous muscles between the metatarsal bones. The dorsal interosseous muscles abduct
(DAB) the 2nd, 3rd, and 4th toe. (Since the midline is the 2nd toe, one can abduct this toe in two directions. Hence, it gets 2 muscles, one on either side, for abduction. The 3rd and 4th toes each get one of these muscles, and because one wants to abduct the toes, the muscles must be on the lateral side of the metatarsals. The big toe and the little toe have their own abductors.) The plantar interosseous muscles adduct (PAD) the 3rd, 4th, and 5th toes, i.e. pull them towards the second toe. (Therefore, these muscles must be on medial side of the bone. The second toe's adduction occurs simply by relaxing the abductors. The big toe has its own adductor muscle.)

4. Identify the vascular supply of the foot and give the regions supplied by each. (W&B 623-632, TG3-49, TG3-50, TG3-51)

The dorsalis pedis, the continuation of the anterior tibial artery, has many branches, and eventually becomes the deep plantar artery. This artery dives to the sole of the foot (between the 2 heads of the 1st dorsal interosseous muscle, between the 1st and 2nd toes). It unites with the lateral plantar artery to form the plantar arterial arch.

The
posterior tibial artery divides into the medial and lateral plantar arteries. The medial plantar artery runs in the groove between the medial and central compartments. It supplies the medial compartment, including the muscles of the great toe. It also gives off most of the plantar digital branches. The lateral plantar artery supplies the lateral compartment, including the muscles of the little toe. Both the lateral and medial plantar arteries supply the central compartment.

5. 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. (W&B 581, 621-622, TG3-49, TG3-50, TG3-51)

As for the innervation of muscles, the dorsum of the foot gets the deep fibular nerve. The lateral plantar compartment gets the lateral plantar nerve, the medial plantar compartment gets the medial plantar nerve, and the central compartment gets both. These plantar nerves result from the forking of the tibial nerve in the sole of the foot.

Cutaneous nerve distribution in the leg and foot: see Objective 3 above.

Cultural enrichment: Check out these sections from the 1918 version of Gray's Anatomy of the Human Body! Some of the terms are (of course) out-of-date, but the illustrations are timeless.

The Muscles and Fasciae of the Leg - The Fasciae Around the Ankle - The Veins of the Lower Extremity, Abdomen, and Pelvis - Nerves - Surface Anatomy of the Lower Extremity - Surface Markings of the Lower Extremity

 

 

1. List and describe the various types of moveable joints and give examples of each type. (W&B 46-51)

The three major types of joints, along with subtypes and examples, are listed here:

·       Fibrous joints: the most simple joints. They are only connected by fibrous ligaments. A suture is a fibrous joint that eventually fuses, forming one bone from two (a synostosis), like in the skull of a growing infant. A gomphosis is the joint between a tooth and the jaw. A syndesmosis is a fibrous membrane or ligament that joins two bones. The tibia and fibula have an interosseous ligament or membrane, as do the radius and ulna.

·       Cartilaginous joints: joined by cartilage only. These joints are avascular or anervous, except at their margins. Synchondroses are temporary joints present in growing bones. The epiphyseal plate (growth plate) will later ossify into solid bone. The epiphysis has hyaline cartilage and the extension of ossification from the diaphysis side converts it to bone. A symphysis is a permanent cartilaginous union. They always have hyaline cartilage on the bony surfaces concerned, and these cartilaginous surfaces are joined by fibrous tissue or fibrocartilage.

·       Synovial joints: "diarthroses" (freely moveable joints). These joints are joined by a fluid-filled capsule and accessory ligaments. Examples include the knee, ankle, and hip.

2. List the characteristics of and identify the parts of a typical synovial joint. (W&B 47-49)

Synovial joints consist of:

·       Hyaline cartilage: covers the full weight-bearing surface, providing a smooth yet resilient surface

·       Joint capsule: a cavity, made of accessory ligaments, with synovial fluid inside. This reinforces the synovial membrane.

·       Synovial membrane lining: secretes synovial fluid and covers the synovial cavity. It reaches to the edges of the hyaline cartilage.

·       Accessory structures: accessory ligaments ("intracapsular" and "extracapsular"); articular discs or menisci, which are pads of fibrous cartilage; muscles and tendons; and subsynovial fat.

Types of synovial joints

·       Plane: involves flat surfaces. Movements consist of sliding of one surface on the other, and may be multidirectional in one plane. Examples: facet joints, joints of the tarsal bones of foot.

·       Hinge (ginglymus): movement around a single axis at right angles to the bone. Permits flexion and extension only. These usually have strong collateral ligaments on each side reinforcing the joint. Examples: elbow, knee.

·       Pivot (trochoid): rotary movement around a longitudinal axis. Rounded process of bone rotates within a sleeve or ring composed of a bony fossa and a strong ligamentous band. Examples: atlas-axis, radioulnar joint.

·       Condyloid: oval surfaces allowing movements in two planes at right angles to each other. Example: radiocarpal joint

·       Saddle (sellar): movement in two basic axes, with circumduction. Example: carpal-metacarpal joint of the thumb.

·       Ball and socket: allows movement in any axis. Examples: hip, shoulder.

3. Recall the movement characteristics of the various types of synovial joints. (W&B 47-49)

See #2 above.

  4-7??

http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/images/ankle_joint_lateral.jpg

http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/images/ankle_joint_medial.jpg

Images from "Anatomy of the Human Body" by Henry Gray are provided by: http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/images/bartleby.gif

Ankle Joint: (TG3-60A, TG3-60B) The ankle joint is a hinge type of synovial joint. It is located between the distal ends of the tibia and fibula and the superior part of the talus. The distal ends of the tibia and fibula form a deep socket into which the trochlea of the talus fits. (Latin, trochlea = block of pulleys, from Greek, trochos = wheel) The tibia itself articulates with the talus in two places: the inferior surface and medial malleolus of the tibia. The medial malleolus grips the talus tightly during movements of the joint. This grip is strongest during dorsiflexion because the anterior part of the talus is wider than the posterior, and that wide section is forced into the joint. Plantar flexion is relatively unstable and most injuries occur then. The lateral malleolus of the fibula also articulates with the talus. The ankle joint has less range of movement than the knee or the hip, so there are fewer supporting structures needed. The fibrous capsule is supported on each side by strong collateral ligaments The lateral ligament is composed of three parts:

·       anterior talofibular ligament: a flat, weak band

·       posterior talofibular ligament: a thick, fairly strong band

·       calcaneofibular ligament: a round cord

The medial ligament has four parts, but you only need to know it as the deltoid ligament. It stabilizes the ankle during eversion and prevents subluxation (partial dislocation) of the joint. (deltoid = shaped like a delta... the Greek letter)

8. Describe the blood and nerve supply of the joints  

·       Ankle:

o      Blood Supply: derived from malleolar branches of the fibular artery and the anterior and posterior tibial arteries

o      Nerve supply: derived from the tibial nerve and the deep fibular nerve

 

 9. Examine the articulation between the talus and calcaneus (the subtalar joint) and study the transverse tarsal joint, which is a complex joint that consists of the talonavicular joint and the calcaneocuboid joint. What are their functions?

The transverse tarsal joint refers to an irregular articular plane which extends from side to side across the foot and is made of the talonavicular articulation medially and the calcaneocuboid joints laterally. At this plane primarily, and at other tarsal joints to a lesser degree, are produced the movements of inversion and eversion of the foot. With inversion is the combined adduction and plantar flexion; with eversion, abduction and dorsiflexion. The contribution of the subtalar and talocalcaneonavicular joints is that of movement around the axis that passes through the tarsal sinus. These movements allow the foot to be placed firmly on slanting and irregular surfaces and still serve as a firm basis of support for the body. (TG3-61)

10. Identify the structure of the ankle and foot joints and describe how the joints and ligaments provide firm footing but flexibility of movement. (W&B 642-652, TG3-60A, TG3-60B)

The structure of the ankle joints have been described in #4 above. The following are the structures of the foot joints, as described in the session on the foot:

Joints:


The subtalar joint
is formed between the large concave facet on the under surface of the body of the talus and the convex posterior articular surface on the superior aspect of the calcaneus. A loose, thin walled articular capsule unites the two bones by attaching to the margins of the articular surfaces. This joint allows the foot to be placed firmly on slanting and irregular surfaces.The transverse tarsal joint is the designation for the irregular plane which extends from side to side across the foot and is composed of the talonavicular articulation medially and the calcaneocuboid joint laterally. This joint allows inversion and eversion of the foot.

Ligaments:


The plantar ligaments of the joints of the foot are very strong. They are supplemented by robust interosseous ligaments which keep the bones from spreading apart. Notable on the sole of the foot are the long plantar ligament
and the plantar calcaneocuboid and plantar calcaneonavicular ligaments. The elasticity of the latter and its support of the head of the talus have led to it being called the "spring ligament." The plantar aponeurosis may be likened to a "tie rod" for the longitudinal arch, firmly connecting its ends and preventing their spread.

11. Describe the arches of the foot and how the bony structure and ligaments form and support them. (TG3-40A, TG3-40B, TG3-41A, TG3-41B, TG3-61A, TG3-61C)

There are two longitudinal arches, medial and lateral. They pass from the calcaneus to the talus to the navicular to the cuneiforms to the metatarsals. They are supported by the plantar calcaneonavicular ligament (spring ligament), and also by the tendons of the tibialis anterior and tibialis posterior muscles. The transverse arch results from the shape of the distal row of tarsal bones and the bases of the metatarsal bones. Imagine an arch that goes over the top of the cuneiforms and cuboid, and is supported by the shape of the bones, various ligaments, and the tendons of the fibularis longus, tibialis anterior, and tibialis posterior muscles.

Cultural enrichment: Check out these sections from the 1918 version of Gray's Anatomy of the Human Body! Some of the terms are (of course) out-of-date, but the illustrations are timeless.

Classification of Joints - The Kind of Movement Admitted in Joints - Shoulder Joint - Elbow Joint - Radioulnar Joint - Wrist Joint - Intercarpal Articulations - Carpometacarpal Articulations - Intermetacarpal Articulations - MP Joints - IP Joints - The Muscles and Fascia of the Forearm - The Muscles and Fascia of the Hand - Surface Anatomy of the Upper Extremity - Surface Markings of the Upper Extremity - Hip Joint - Knee Joint - Ankle Joint - Arches of Foot - Surface Anatomy of the Lower Extremity - Surface Markings of the Lower Extremity

 

Questions and Answers:

10. Does the anterior lateral malleolar artery communicate with the perforating artery?

Yes. The anterior lateral malleolar artery comes off the anterior tibial artery around the ankle; it goes to the lateral malleolus. The fibular (peroneal) artery, off the posterior tibial artery, gives off a perforating branch that passes forward at the distal border of the interosseous membrane and anastomoses with the anterior lateral malleolar artery. (TG3-38)

11. Trace the deep fibular (peroneal) nerve into the anterior compartment of the leg 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?

The deep fibular nerve serves the tibialis anterior muscle, the extensor digitorum longus muscle, the extensor hallucis longus muscle, and the fibularis (peroneus) tertius muscle. It also provides articular branches to the tibiofibular syndesmosis and the ankle joint. After crossing the ankle, the deep fibular nerve divides into medial and lateral branches, which supply the dorsum of the foot, and supplies the extensor digitorum brevis and extensor hallucis brevis muscles. The medial branch divides into two dorsal digit branches which supply adjacent sides of the first and second digits. Twigs also go to the metatarsophalangeal and interphalangeal articulations of the great toe and one to the first dorsal interosseous muscle. The lateral branch passes laterally, deep to the extensor digitorum brevis muscle. It ends in an enlargement from which branches distribute to this muscle, the tarsal joints, and the three lateral intermetatarsal spaces for the supply of the periosteum and the joints. The cutaneous innervation supplied by this nerve is on the dorsum of the foot, between the second and big toe. (TG3-37)

12. Which nerve supplies the muscles of the lateral compartment?

The lateral compartment has two muscles: fibularis (peroneus) longus and fibularis (peroneus) brevis. Innervation is via the superficial fibular (peroneal) nerve. (TG3-36)

13. What innervates the flexor digitorum brevis muscle?

The medial plantar nerve, from the tibial nerve, innervates the flexor digitorum brevis muscle. (TG3-49)

14. 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.

The axis of abduction or adduction of digits of the foot is a line through the second toe. (Note that, in the hand, the axis runs through the third finger.)

See #7 above.

15. What is the plantar arterial arch?

The lateral plantar artery, off of the posterior tibial artery, crosses the sole of the foot diagonally from the medial to the lateral side. At the medial side of the base of the 5th metatarsal bone, the artery turns medially around the margin of the quadratus plantae muscle and sinks between the adductor hallucis and interosseous muscles. It perforates the plantar interosseous fascia and passes medially across the proximal ends of the second, third, and fourth metatarsal bones and the corresponding interosseous muscles. Here it forms the plantar arterial arch, anastamosing in the first interosseous space with the deep plantar branch of the dorsalis pedis artery. (TG3-51)

 

21. What contacts the articular (medial) surface of the lateral malleolus?

The medial side of the lateral malleolus, which is part of the fibula, articulates with the lateral surface of the talus.

22. Note the iliopectineal bursa beneath the iliopsoas. Does it communicate with the hip joint?

The iliopectineal bursa lies between the iliopsoas muscle and the capsule. When the capsule is perforated here, the bursa is open to the joint cavity.

 

30. What does the transverse tibiofibular ligament do?

This ligament helps to hold tibia and fibula together. It also forms a portion of the articulation with talus.

31. Relate the arrangements of the malleoli and ligaments to the prevalence of ankle sprains.

Most ankle sprains are caused by inversion of the foot, which causes tearing of the lateral ligaments: the calcaneofibular and posterior talofibular ligaments. Slight sprains might involve just partial tears, such as in the anterior talofibular ligament. Sometimes the lateral malleolus can be avulsed off the fibula or the fibula fractured if the ligaments are particularly strong. In effect, the ligaments are stronger than the bone, and the bone often "gives" first. The medial ligament is more rarely strained, but when it is it is due to eversion of the foot.

32. How is the stability of the ankle joint provided?

See #7 and #10 above.

33. Which position is most stable? Why this position?

Dorsiflexion is more stable than plantarflexion. The talus is stabilized due to the wider anterior side of the trochlea being immobilized by the tibial articulation. In plantarflexion, the skinnier posterior side is articulating more and so more movement is possible since it does not completely fill the space allowed the anterior side.

34. What muscles provide action of the ankle joint?

Dorsiflexion: muscles of anterior compartment of leg. These include the tibialis anterior muscle, the extensor hallucis longus muscle, the extensor digitorum longus muscle, and the fibularis tertius muscle. When the foot is fully everted, it is also fully dorsiflexed. (But remember, inversion and eversion are actions of the foot itself.

Plantarflexion: muscles of posterior compartment of leg. These include the tibialis posterior muscle, the flexor hallucis longus muscle, the flexor digitorum longus muscle and the plantaris muscle. The lateral compartment also participates in plantar flexion. (In fact, all
muscles which enter the foot behind the malleoli plantarflex the foot. When the foot is fully inverted, it is also fully plantarflexed.

35. What muscles provide stability of the ankle joint?

All of the muscles mentioned above that cross the ankle lend stability to the ankle. The ligaments provide the stability as well. See also #4 and #7 above.

36. What is the function of the plantar ligaments dissected?

long plantar ligament: maintains the arches of the foot and forms a tunnel for the tendon of the fibularis longus by extending some of its fibers to the bases of the metatarsals.

short plantar ligament: deep and medial to the long plantar ligament. It also provides support of the longitudinal arch.

plantar calcaneonavicular (spring) ligament: highly elastic. It completes the socket for the head of the talus bone on the medial side and provides springy cushion for the foot. It also helps maintain the longitudinal arch of the foot. (
TG3-61A)

37. What are the actions of the subtalar articulation?

This joint is pretty stiff, though it allows some inversion and eversion.

38. What is the tarsal sinus?

It is a cavity lying between the talus and the calcaneus. (TG3-41B)

39. What is the interosseous talocalcaneal ligament?

This ligament is located inside the tarsal sinus. It is a strong band which connects the adjacent surfaces of the talus and the calcaneus along the oblique tarsal grooves. It provides support for the subtalar joint. (TG3-60B)

40. What are the two parts and the action of the transverse tarsal joint?

It is formed by the combined talonavicular and calcaneocuboid joints. The two separate joints align transversely. (Transection across the transverse tarsal joint is a standard method for surgical amputation of the foot.)

Inversion and eversion take place primarily through the transverse tarsal joint
. (TG3-61B).

41. What are the actions of the foot?

Dorsiflexion, plantar flexion, inversion and eversion of the foot are the main actions of the foot.

 

Updated: 14 November 2011