Ankle Flashcards
What is the true joint of the ankle and how many degrees of freedom does it have?
Tibiotarsal joint: distal joint of the lower limb
1 degree of freedom bc its a hinge joint
Joint Structure: Bones (3)
- the tibia
- fibula
- talus
what two joints make up the ankle joint
- Talocrural Joint
* Inferior tibiofibular Joint
Tibia
- distal end of the tibia is smaller than the proximal end
- flaring only medially, extends inferior to the rest of the shaft as the medial malleolus.
- The inferior surface of the shaft and the lateral surface of the medial malleolus articulate with the talus and are covered with articular cartilage.
- The interosseous border of the tibia is sharp where it gives attachment to the interosseous membrane that unites the two leg bones
- Inferiorly, the sharp border is replaced by a groove, the fibular notch, that accommodates and provides fibrous attachment to the distal end of the fibula.
Fibula
- lies posterolateral to the tibia
- Is firmly attached to it by the tibiofibular syndesmosis, which includes the in-terosseous membrane.
- The fibers of the tibiofibular syndesmosis are arranged to resist the resulting net downward pull on the fibula.
- The fibula has no function in weight-bearing
- The distal end enlarges and is prolonged laterally and inferiorly as the lateral malleolus.
Malleoli of the fibula
*form the outer walls of a rectangular socket (mortise), which is the superior component of the ankle joint, and pro-vide attachment for the ligaments that stabilize the joint
Lateral Malleoli of the fibula
is more prominent and posterior than the medial malleolus and extends approximately 1 cm more distally
Talus
Three parts
• The head carries the articulate surface of the navicular bone
• The neck, the roughened area between the body and the head, has small vascular channels
• The body features several prominent articulate surfaces: on its superior side is the trochlea tali flanked by the articulate facets for the two malleoli.
*The ankle mortise, the fork-like structure of the malleoli, holds these three articulate surfaces in a steady grip, which guarantees the stability of the ankle joint.
Talocrural Joint
This is a hinge joint formed by the distal ends of the fibula and tibula that enclose the upper surface of the talus.
It allows for both dorsiflexion (decreasing the angle between the foot and the shin) and plantarflexion (increasing the angle).
Inferior Tibiofibular joint
- This is strong joint between the lower surfaces of the tibia and fibula.
- This is supported by the inferior tibiofibular ligament.
Ligaments of the ankle: what are the names of the groups of ligaments?
Main Group *Lateral & Medial Collateral Ligaments **on either side of the joint two powerful fan-like investments which attached above at their apices to corresponding malleolus and which radiate out distally to be inserted into the tow posterior tarsal bones Accessory Groups *Anterior & Posterior Ligaments **Localized thickening of the capsule
Lateral Collateral Ligament
3 bands
- anterior talofibular
- calcaneofibular
- posterior talofibular
anterior talofibular ligament
attached: to anterior margin of fibular malleolus
run: obliquely inferiorly & anteriorly
Inserted: into talus between lateral articular facet & mouth of the sinus tarsi
calcaneofibular Ligament
Arising: from the depression in front of the apex of the lateral malleolus,
Runs: obliquely inferiorly and posteriorly
Insertion: into the lateral surface of the calcaneus
posterior talofibular Ligament
Arising: from the medial surface of the lateral malleolus behind the articular facet
Runs horizontally and inclines medially and slightly posteriorly
Insertion into the posterolateral tubercle of the talus.
Medial Collateral Ligaments
Two sets of fibers: superficial and deep( two bands)