The ankle and foot The ankle and foot Foot and ankle combine flexibility ( propulsion) with stability(support) structure because consist of a complex of joints, bony structure, ligamentous attachments, and muscle contraction. The flexible/rigid characteristics of the ankle/foot complex provide multiple functions, including: 1. Ankle joint forces up to 4.5 times body weight to occur while walking. 2. It provides a base of support. 3. It acts as a lever during push-off period of stance. 4. It provides adequate flexibility for absorption of the shock of the body weight and for accommodation to uneven terrain. 5. Prehensile. Structure of the ankle and foot (see figure 1). Bony Parts: It contains a total of 26 bones
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The ankle and foot
The ankle and foot
Foot and ankle combine flexibility ( propulsion) with stability(support)
structure because consist of a complex of joints, bony structure,
ligamentous attachments, and muscle contraction. The flexible/rigid
characteristics of the ankle/foot complex provide multiple functions,
including:
1. Ankle joint forces up to 4.5 times body weight to occur while walking.
2. It provides a base of support.
3. It acts as a lever during push-off period of stance.
4. It provides adequate flexibility for absorption of the shock of the body
weight and for accommodation to uneven terrain.
5. Prehensile.
Structure of the ankle and foot (see figure 1).
Bony Parts: It contains a total of 26 bones
1. Leg
Tibia and fibula
2. Hindfoot
Talus and calcaneus
3. Midfoot
Navicular, cuboid, and three cuneiforms
4. Forefoot
Five metatarsals and 14 phalanges, which make up the 5 toes (3
phalanges for each toe except the large toe, which has 2 phalanges)
Figure 1: Structure of the ankle and foot
Arches of the Foot (see figure 2).
They are formed by the structure and arrangement of the bones (tarsus
and metatarsus) and maintained by ligaments and tendons the arches are
not rigid; they “give” when weight is placed on the foot, and they spring
back as the weight is lifted.
There are 2 types of arches:
Longitudinal arch: divided into medial and lateral parts
The medial part originates at the calcaneus, rises at the talus, and
descends to the first three metatarsal bones and receives weight of
the body. The medial arch is supported by the spring ligament.
Lateral part consists of the calcaneus, cuboid, and fourth and fifth
metatarsal bones and acting essentially as a space through which
tendons canpass. It is supported by the long and short
plantarligaments.
Transverse Arch – side to side concavity from anterior tarsal bones
(calcaneus, navicular, and cuboid) to all fivemetatarsal bones.
Figure 2: Arches of the Foot
The factors maintaining the arches of the foot (see figur3).
Figur3: The factors maintaining the arches of the foot.
Functions of the arches:
1. Support the weight of the body in standing.
2. Act as a lever to propel the body in walking and running.
3. During weight bearing, mechanical energy is stored released to assist
with push-off of the foot from the surface.
Transmission of body weight:
The structures of the foot are anatomically linked such that the load is
evenly distributed over the foot during weight bearing.
Approximately 50% of body weight is distributed through the subtalar
joint to the calcaneus, with the remaining 50% transmitted across the
metatarsal heads. The head of the first metatarsal sustains twice the load
borne by each of the other metatarsal heads. Tibia is the only true weight-
bearing bone in the body.
Muscle Function in the Ankle and Foot (see figuer4):
Both the extrinsic muscles (11) and the intrinsic (22) muscles of the foot
play a vital role in the mechanics of the foot. (See appendix 1).
Figure 4: Muscles
Muscle control of the ankle during gait
1. The muscles of the anterior compartment (dorsiflexors)
actprimarily during swing and early stance phase. This action
enables the foot to clear the ground during swing phase and then
allows it to be placed gently on the ground after heel strike.
2. The posterior, or calf, group acts from midstance to toe-off.
3. In normal standing, the gravitational line falls anteriorly to the
axis of the ankle joint, creating a dorsiflexion moment. The soleus
muscle contracts to counter the gravitational moment through its
pull on the tibia.
4. The intrinsic muscles of the foot activity in the last half of the
stance phase.
Joints
The joints of the foot are divided into three sections—hindfoot
(rearfoot), midfoot, and forefoot (see figure 5-6).