Bones and Joints of the Foot

Question 1

Describe the boney anatomy of the lower leg

Answer 1

The lower leg is made up of 2 bones: tibia and fibula

• The tibia (medial) is weight bearing
• The fibula (lateral) is purely for muscle attachements and bares no force; it stabilises the ankle

Question 2

The tibia and the fibula are attached to each other in 2 positions (proximally and distally)

What is a consequence to this?

Answer 2

Because they are two bnes held together by ligaments, a fracture of one is most commonly associated with fractures of the other.

Question 3

What part of the tibia is most susceptible to fracture?

Answer 3

The junction between the medial and inferior thirds of the tibia (ie. 2/3rds of the way down the bone)

This is because it has the narrowest and more cylindrical shape and has the poorest blood supply (vessels from above and vessels from below contribute but not a lot)

Question 4

Describe the superior tibiofibular joint

Answer 4

• Is a plane synovial joint that is intracapsular.
• It has no movement.
  
  • ​Allows some gliding movement but very limited
• it is reinforced by ligaments in the front and back.

Question 5

Describe the inferior tibiofibular joint

Answer 5

• It is a fibrous joint (syndesmosis) held together by fibrous tissue
• It is important in preventing the tibia and fibula from separating during weight bearing times - also important in shock absorption
• It has an anterior, posterior and inetrosseus ligament attachment
• Separation is called diastasis

Question 6

How common is disolcation or subluxation in the tibiofibular joints?

Answer 6

Very rare. They are very stable joints

Question 7

What is the interosseus membrane in the lower limb? What are some of its functions?

Answer 7

It is also called the middle tibiofibular ligament. It extends between the interosseous crests of the tibia and fibula, helps stabilize their relationship

• It also separates the muscles on the front from those on the back of the leg (compartments)
• Is a site of attachment for muscles

Question 8

What are the bones of the foot?

Answer 8

1. Tarsal bones (5 types)
2. Metatarsals
3. Phalanges

Question 9

What is important about the first two (distal most) tarsal bones?

Answer 9

They are vertically orientated (while the remaining are horizontal)

Question 10

Describe the first tarsal bone

Answer 10

Talus

This bone articulates with with tibula and fibular above forming the ankle.

It also articulates with the calcaneus below and the other tarsal bones (navicular) in front

Question 11

Describe the Calcaneus bone

Answer 11

It is the important weight bearer on the ground of the leg.

It articulates with the talus bone on top

Question 12

What are the other tarsal bones that make up the foot?

Answer 12

• Navicular (medially, attached to the talus)
• Cuboid (laterally, attached to the calcaneus)
• Medial, intermediate and lateral cuneiforms

Question 13

How many metatarsal bones are there? What is special about the 2nd?

Answer 13

There are 5: one each coming off the cuneiforms, and two coming off the cuboid

The 2nd metatarsal is slender in contrast to the others and hence is susceptible to fractures “root marching fracture”

Question 14

Describe the phalanges (14 of them)

Answer 14

There are 2 phalanges in the hallux (the big toe) and then there are three in each of the other digits..

They are the same as in the hand.

Question 15

Describe the trabeculae of the foot

Answer 15

They are arrange in weight bearing forces

Question 16

There are numerous accessory and sesamoid bones in the foot (with tendons)

What are their importance?

Answer 16

There are 2 under the first metatarsal that create a tunnel

Common cause of avulsion fractures: particularly the Os trigonum

Question 17

The talus is the key bone of the foot

What are the [3] main joints in relation to the talus?

Answer 17

• The ankle joint above it (with the tibia and fibula)
• The subtalar joint below it (with the calcaneus)
• The midtarsal joint in front of it (talocalcaneonavicular joint and the calcaneocuboid joint)

Question 18

What type of joint is the ankle joint?

What are the movements?

Answer 18

A hinge joint

Thus there is flexion and extension (plnatr and dorsiflexion)

There is very little lateral movement

Question 19

The body of the talus bone fits into a “mortice” between the malleloli of the bones of the leg.

Describe what is meant by this

Answer 19

The tibia forms the medial malleolus that extends down

The fibula forms the lateral malleolus extending downwards.

The tarlis bone fits in between these two extensions of bone (this space is referred to as the mortice). This gap is deepened posteriorly by the inferior transverse ligament

Question 20

Describe the joint axis of the ankle in relation to the movements of the ankle

Answer 20

The lateral mallelous extends further down distally than does the medial. This means that the axis of movement of the ankle is not horizontal (it is at an oblique angle)

• Plantar flexion causes the sole of the foot to move medially
• Dorsiflexion causes the sole of the foot to sway out laterally

Question 21

Describe the capsule of the ankle joint

Answer 21

It extends anteriorly into the neck of the talus

Question 22

What are the supports of the ankle joint?

Answer 22

Being a Hinge joint, it has collateral ligaments passing from the malleoli to the nearest bones of the foot

There is also the ligaments form the distal tibiofibular syndesmosis (omplex fibrous joint composed of multiple ligaments and a broad fibrous membrane that spans between the tibia and fibula throughout the length of both bones)

Question 23

Describe the medial (deltoid) collateral ligament of the ankle

Answer 23

They are not very strong ligaments that is rarely injured

Question 24

Describe the lateral collateral ligament of the ankle

Answer 24

It is not as strong as the medial collateral

It is made up of 3 distinct bands:

1. Anterior talofibular ligament: fibula to tarlis
2. Posterior talofibular ligament: fibula to tarlis
3. Calcaneofibular ligament: fibula to calcaneus

Question 25

What are most ankle injuries?

Answer 25

**Inversion sprains during flexion** causing damage to the lateral collateral ligament (especially the **anterior talofibular band**) This leads sto infusion (swelling into the joint) and bleeding that projects into the neck of the talus up.

Question 26

What is a possible consequence of the inversion (and flexion) injury to the ankle?

Answer 26

It may lead to a fracture of the lateral malleoli

Question 27

What are the important joints of the foot?

Answer 27

* Subtalar (tarlis to the calcaneous) * Talocalcaneonavicular (TCN) connecting the tarlus to the calcaneus and navicular bone * Calcaneocuboid (conecting the calcaneus to the cuboid) * Tarsometatarsal joints * Metatarsal-pharyngeal joints * Interpharyngeal joints

Question 28

Describe the sub-talar joint

Answer 28

It connects the tarlus one to the calcaneus below It is subdivided into two joints by a groove/canal between the bones called the **sinus tarsi.** This canal contains an **interosseous talo-calcaneal ligament** that is very strong and resists both inversion and eversion of the ankle (limits side to side movement)

Question 29

What are the movements of the subtalar joint?

Answer 29

Eversion (pronation) and inversion (supination) of the ankle.

Question 30

How are the movements of the sub-talar joint used in the gait cycle?

Answer 30

We strike the ground with an inverted (supinated) foot and then the weight rolls across the foot until it is everted (prontination) just before it leaves the ground for the next stride

Question 31

Describe the effect of the subtalar joint position on the arch of the foot

Answer 31

Question 32

What are the two mid tarsal joints? What are their actions?

Answer 32

1. Talocalcaneo-navicular (TCN) joint (like a ball and socket joint) 2. Calcaenocuboid joint

Question 33

What are the main movements of the midtarsal joints?

Answer 33

Eversion + abduction of the ankle = protonation Inversion + adduction of the ankle = supination

Question 34

What are the joints of the toes?

Answer 34

Metatarso-phalyngel and the interphalangeal joints They are condyloid joints and hinge joints that enable flexion and extension movements, adduction and abduction but no side-side movement. The articular surfaces are expanded by plantar and dorsal plates of cartilage

Question 35

What is the plantar aponeurosis?

Answer 35

It is a thick band of connective tissue between the calcaneus and the metatarsal heads. It binds the skin of the foot for grip and protection and mainatins longitudial arges of the foot.

Question 36

What is the clinical significance of the plantar aponeurosis?

Answer 36

It can have plantar fasciitis (inflammation of the aponeurosis) with or without a boney spur. This occurs when traction at the calcaneual attachment by running up hills, wearing the wrong shows and other stresses causes an inflammatory response to produce boney changes at the site. This is very painful

Question 37

Describe the [3] weight bearing points of the arches of the foot What is the purpose of the arch?

Answer 37

1. Calcaneal tuberosity 2. Head of the Metatarsal 1 3. Head of the medatasal 5 It provides a stable base for standing and a dynamic spring action in locomotion (2 longitudinal arches medial and lateral and 1 transverse arch - hemi arch)

Question 38

What is the difference in support for static vs. dynamic activity in the arch of the foot?

Answer 38

Ligamentous support for static vs. muscular support for dynamic