Sievert: Posterior Leg and Foot Flashcards
What will the main difference between damaging the median nerve at the wrist vs the elbow?
At the wrist: primarily affects thenar compartment muscles, leading to thumb derotation, but a normal hand. This is called ape hand. At the elbow: you lose deep compartment muscles due to the deep branch of the median nerve. So, you will get papal blessing (thumb derotated, but also get straightening of 2 fingers)
What are the lateral and medial malleolus? What is significant about these structures? On which bone is the lateral ma
bumps on the tibia and fibula at the ankle; these structures are important, because muscles that pass anterior are dorsiflexors and muscles that pass posterior are plantarflexors.
Together the two bones of the leg make a nice articular surface for the (blank) bone of the foot. This surface is wider anteriorly and narrow posteriorly. The articular surface is held together by the anterior and posterior (blank) ligaments.
talus; tibiofibular
How is the interosseous membrane different in the leg than in the forearm?
In the leg, the interosseous membrane does not have predominant fibers oriented in a certain direction. In the forearm, the interosseous membrane is designed to transmit force from the radiocarpal joint up to the elbow.
What is the main supporting bone of the leg?
tibia
What is the fibula primarily used for?
helps hold the ankle joint together; serves as an attachment site for muscles
How many compartments are there in the leg? What are they? What surrounds each compartment?
four compartments; anterior compartment, lateral compartment, deep posterior, and superficial posterior compartment; each compartment is surrounded by a crural fascia (deep fascia of the leg)
What is contained in the anterior compartment?
extensor muscles: tibialis anterior, extensor hallucis longus, extensor digitorum longus
anterior tibial artery and veins
deep fibular nerve
What is contained in the lateral compartment?
fibularis longus
fibularis brevis
superficial fibial nerve
What is contained in the deep posterior compartment?
deep flexor muscles: flexor digitorum longus, tibialis posterior, flexor hallucis longis, popliteus
posterior tibial artery and veins
tibial nerve
fibular artery and veins
What is contained in the superficial posterior compartment?
superficial flexor muscles: soleus, gastrocnemius, plantaris (tendon)
Why are there two neurovascular bundles in the deep posterior compartment? Where do both of the bundles come from?
the fibular vascular bundle is making its way over to the lateral compartment; both are derived from the tibfib trunk
What is notable about the plantaris tendon?
it tears easily and may lead to spontaneous contraction
The gastrocnemius and soleus are both powerful (blank). They have a mechanical advantage due to their attachment to the (blank), which is as far away from the axis of rotation as possible!
plantarflexors; Calcaneal tendon
Does the gastrocnemius cross the knee joint? Does the soleus?
Yes, so the gastroc has action at the knee joint; no, the soleus only works at the ankle
If you plantarflex from an extended knee, what muscles are you using? If you plantarflex from a sitting position, what muscle are you using?
gastroc and soleus; soleus only (gastroc taken out of the picture - when flexing the knee, can’t use gastroc to plantarflex)
What is the action of the muscles of the deep posterior compartment?
plantar flexors and inverters in addition to their obvious named action because they pass posterior to the medial malleolus
Which compartment is the popliteus located in? What action does it serve?
proximal deep compartment; serves to unlock the knee joint
What is the action of the muscles in the anterior compartment? Which of these muscles is a good invertor?
dorsiflexion in addition to their namesake functions; tibialis anterior is a good invertor
What two functions does the extensor hallucis longus perform?
dorsiflexion, extension of big toe
What two functions does the extensor digitorum longus perform?
dorsiflexion, extension of all other toes (besides big toe)
What does the tibialis anterior muscle do?
in addition to being a powerful dorsiflexor, it is also a good invertor **crosses to the medial side of the foot
The ankle itself only flexes and extends, but there are joints that allow you to rotate the plantar surface of the foot inward or outward. What is this motion called? What are most sprains caused by?
rolling the ankle inward is eversion!!! the other direction is inversion; most sprains caused by inversion (rolling ankle)
What muscle of the anterior compartment is a powerful invertor due to its attachment to the medial foot?
tibialis anterior
What is a tiny muscle that comes off of the extensor digitorum longus that is kind of reminiscent of a lumbrical. It attaches to the 5th metatarsal. What is significant about this muscle?
fibularis tertius; this muscle has a clinical involvement in inversion sprains, because lots of tension is placed on this muscle when you roll your ankle, and this could cause the muscle to be torn off of the 5th metatarsal.
2 muscles of the lateral compartment? What is there action?
fibularis longus and brevis; they are posterior to the malleolus, so they are plantar flexors. They both attach to the lateral side of the foot, so they are evertors.
Which tendon/muscle of the lateral compartment wraps under the plantar aspect of the foot and forms a supportive sling with the tibialis anterior at the base of the 1st metatarsal?
fibularis longus
What supplies nerve innervation to the leg?
entirely sciatic nerve