Flashcards in Anterior and Lateral Compartments of Leg Deck (26)
What are the compartments of the leg and how are they formed?
Anterior, lateral and posterior
These are formed by the tibia, fibula, interosseous membrane and the ant/posterior intermuscular septae
Which leg compartment is most at risk for compartment syndrome and why?
The anterior compartment, as there is little space, and it is bound rigidly by deep fascia, interosseous membrane and the tibia/fibula bones.
What are the muscles of the anterior leg compartment
Extensor Digitorum Longus
Extensor Hallicus longus
What is the interosseous membrane?
Thick sheet of tissue, like deep fascia. Strongly binds tibia and fibula and divides leg into ant/post compartments.
What is the function of the anterior compartment?
What is the origin and insertion of the Tibialis ant.?
Origin: Superior lateral tibia and interosseous membrane
Insertion: Medial cuneiform and base of the 1st metatarsal
Dorsiflexion and inversion at subtalar joint
What is the origin and insertion of the extensor digitorum Longus? Actions?
Origin: Superior fibula and interosseous membrane
Insertion: Lateral four digits
Dorsiflexion and extension of digits
What is the origin and insertion of the extensor hallicus longus? Action?
Origin: middle ant fibula and interosseous membrane
Insertion: Great toe
What is the peroneus tertius
Random little muscle that originates on the inferior fibula and inserts onto the base of the 5th metatarsal. As it crosses the ankle joint it dorsiflexes and also slightly everts foot.
What muscles are within the lateral compartment?
Where does the peroneus Longus originate and insert? And what does this mean for movement?
Origin: Superior lateral fibula
Insertion: Medial cuneiform and base of 1st metatarsal
This muscle inserts in the same area as tibialis anterior, and therefore does the opposing action to EVERT the foot, as well as weakly plantaflex
Where does the peroneus brevis originate and insert?
Origin: inferior fibula
Insertion: Base of 5th metatarsal
Weak dorsiflexor and slightly everts foot (with peroneus tertius)
Name the four retinaculums of the foot
Superior extensor retinaculum
Inferior extensor retinaculum
These pin down the tendons of the anterior (extensor) muscles.
Superior Peroneal Retinaculum
Inferior Peroneal Retinaculum
These pin down the tendons of the peroneal (lateral) muscles
What is the clinical purpose of Retinaculum?
Holds down tendons to prevent bowstringing of muscles and tendons. If not held in place tendons could rub on bone (eg peroneal tendons on distal fibula) and snap.
Where would you find a pulse for foot?
Dorsalis Pedis pulse: just lateral to EHL tendon on dorsal surface of 2nd metatarsal
Posterior Tibial Artery pulse: arch of foot
What are the three main arteries that trifurcate off the popliteal artery to supply the leg?
Peroneal Artery: supplies lat. compartment
Anterior Tibial Artery: supplies anterior compartment
Posterior Tibial artery: supplies posterior compartment
What is interesting clinically about the anterior tibial artery?
It passes anteriorly through the interosseous membrane to supply ant. comp. At the ankle joint it crosses deep to the EHL tendon (midway through malleoli) to become Dorsalis Pedis. DP can be used to find a pulse ( that isn't always around boob)
What does the sciatic nerve bifurcate into at the popliteal fossa?
Common peroneal (runs laterally around femur) and tibial nerve (stays post)
What are the two lateral compartment muscles
Dorsal Foot Muscles are? And what is their common origin?
Extensor Digitorum Brevis
Extensor Hallucis Brevis
They originate at the inferior extensor retinaculum and calcaneous
Extensor digitorum brevis
Extensor hallicus brevis
insertion and action
-Base of big toe (extension of great toe)
-phalanges of lateral four toes (extension of toes)
What are the five p's of compartment syndrome?
4) Paresthesia (nerve cut off)
Why would you get paresthesia in C S?
When the pressure builds to a certain level and cuts off the nerve supply to the limb
What would be the appearance of a lower extremity if suffering long term from CS?
Grey and dusky. Pallor due to arterial supply being cut off.
Where could you check for Compartment syndrome
In the 2nd meta tarsal of the foot, as there is no arterial supply you will not find a dorsalis pedis pulse.