1213 Week 15 P

1213 Week 15 P

Course of the Tibial Nerve
1. Movement Terms
  1. inversion - the foot is rolled onto its lateral edge, big toe rises
  2. they all start with the foot flat on the floor
  3. eversion - the foot is rolled onto its medial edge, the little toe rises
  4. dorsiflexion - the toes rise towards the shin
  5. plantarflexion - the toes point downwards and the heel rises
2. the sciatic nerve splits to form the tibial and common fibular nerves which innervate 4 of the 6 muscle compartments in the lower leg and foot
3. the tibial branch provides motor supply to the posterior compartments of the lower limb and carries sensory information from the touch receptors on the lateral side of the lower leg and plantar surface of the foot
4. the sciatic nerve exits the pelvis through the greater sciatic foramen
  1. it then runs posterior to the femur deep to the lateral hamstring (biceps femoris) to the popliteal fossa
    1. the nerve enters the popliteal fossa on the posterior aspect of the knee joint
      1. as it descends the posterior thigh the tibial branch innervates the hamstrings
        at the most proximal aspect of the popliteal fossa the sciatic nerve divides into the common fibular and tibial nerve.
        the common fibular nerve descends laterally, obliquely and superficially to wrap around the fibular head
        it then divides into superficial and deep branches which innervate the lateral and anterior compartment muscles of the lower leg - ankle everters and dorsiflexors
        the tibial nerve decends the popliteal fossa in the midline medial to the common fibular and enters the lower leg
        it descends the midline and then courses medially to enter the ankle and foot around the medial aspect of the ankle joint
        as it descends it gives off innervating branches to the posterior compartment - plantarflexors and knee flexors
5. Damaging the Tibial Nerve
  1. if the tibial nerve is damaged at the popliteal fossa plantarflexion will not occur at the ankle joint because the tibial nerve provides innervation to the posterior compartment muscles where plantarflexion arises from
  2. if the lateral compartment muscles lose their innervation eversion would not happen at the ankle joint because they are in the lateral compartment which controls eversion
  3. if the muscles in the anterior compartment lose their innervation from the deep fibular dorsiflexion would not happen at the ankle joint because the anterior compartment muscles control dorsiflexion
  4. all muscles of the posterior compartment plantarflex the foot at the ankle joint
Monosynaptic Stretch Reflex
1. the varying strength of tendon tap doesn't effect the latency as the distance between the stimuli and receptor doesn't change
2. the harder the tap the greater the amplitude as there is a bigger degree of stretch of the muscle spindle which increases AP firing rate which increases the number of muscle units recruited to oppose the stretch
3. the effect of contracting the muscle before tapping doesn't affect latency but does decrease amplitude because the muscle spindle is slack and so isn't sensitive to stimuli which decreases AP firing rate
4. Enter text here

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	Created by 06watkinse over 10 years ago