Lower Extremity--lab 1 Flashcards
Peroneus Brevis is also called?
Fibularis Brevis
Origin of Peroneus Brevis
Distal 2/3 of the lateral shaft of the fibula and adjacent inter muscular septum
Insertion of Peroneus Brevis
The tendon passes posterior to the lateral malleolus (held in place along with the fibularis longus by upper and lower retinaculae) then along the lateral foot to the lateral aspect of the tuberosity at the base of the 5th metatarsal
Innervation of Peroneus Brevis
Superficial peroneal/fibular n (L4-S1, mainly S1)
Action of Peroneus Brevis
Primarily eversion and assists plantar flexion
Key Kinesiologic Function of Peroneus Brevis
Stabilizes the ankle and resists excessive inversion along with the P. longs; counterbalances the tibialis anterior and synergistically provides ankle rigidity that protects against ankle sprain; aids in suspending the lateral longitudinal arch
Peroneus Longus is also called?
Fibularis longus
Origin of Peroneus Longus
Head and proximal 2/3 of the lateral shaft of the fibula; it often also arises from the lateral tibial condyle and tib/fib capsule
Insertion of Peroneus Longus
Medial aspect of the platar surfaces of the 1st metatarsal and 1st cuneiform; before reaching the insertion the tendon passes posterior to the lateral malleolus where it is best visualized, turns anteroinferior to cross the lateral side of the calcaneus where it turns again to pass inferior to the cuboid and obliquely medial through the deep tissues of the foot; note that it’s tendon is held in place in the lateral ankle and foot by superior and inferior perineal retinaculae
Innervation of Peroneus Longus
Superifical peroneal/fibular n. (L4-S1; mainly S1)
Action of Peroneus Longus
Plantar flexion at the ankle and eversion of the foot
Key kinesiological function of Peroneus Longus
Stabalizes the ankle and along with P. brevis resists excessive inversion; counter balances the tibilias anterior and synergistically adds to ankle rigidity; supports the lateral longitudinal and transverse arches of the foot
Peroneus Tertius is also called?
Fibularis tertius
Origin of Peroneus Tertius
Distal 1/3 of the anterior surface of the fibula and adjacent interosseous membrane
Insertion of Peroneus Tertius
Dorsal surface of the base or shaft of the 5th metatarsal; note that its tendon emerges below the inferior extensor retinaculum just lateral to the extensor digitorum tendons and diverts laterally on the dorsolateral aspect of the foot; note that the tendon is sometimes absent
Innervation of Peroneus Tertius
Deep perineal/fibular n. (L4-S1, mainly S1)
Action of Peroneus Tertius
Assist with dorsiflexion at the ankle and eversion of the foot
Key Kinesiologic function of Peroneus Tertius
Is a small variable muscle that does not have any primary kinesiologic function and does not appear to provide any significant protective function against ankle sprain; aids in suspending the lateral longitudinal arch
Origin of Tibialis Anterior
Lateral condyle and anterolateral aspect of the proximal 2/3 of the shaft of the tibia; and also adjacent interosseous membrane
Insertion of Tibialis Anterior
Medial surface of the first cuneiform and adjacent first metatarsal base; the tendon passes deep to the extensor retinaculae and is prominent along the anteromedial ankle
Innervation of Tibialis Anterior
Deep perineal/fibular n (L4-5)
Action of Tibialis Anterior
Dorsiflexes at the ankle and inverts (supinates) the foot
Key kinesiologic function of Tibialis Anterior
Supports the medial longitudinal arch as a suspensor; this muscle is important to controlling pronation of the foot and collapse of the medial longitudinal arch by way of eccentric contraction; its peak muscle contraction when walking is during the contact period but when running it contracts throughout stance to control pronation; when running it helps accelerate the body by pulling the leg anterior over the fixed leg; it also assists dorsiflexion during swing preventing “toe drag”; anterior shin splints are a sign of tibialis anterior fatigue and injury due to excessive pronation; foot slap or foot drop indicate weakness or paralysis
Origin of Extensor digitorum longus
Lateral tibial condyle, proximal tibiofibular joint capsule, proximal 2/3 of anteromedial fibular shaft, adjacent interosseous membrane
Insertion of Extensor digitorum longus
It crosses deep to the superior and inferior extensor retinaculae and divides into 4 tendons. Each tendon forms and extensor hood on the dorsum of each toe which in turn inserts on the middle and distal phalanges of toes 2-5; tendons of the extensor digitorum brevis (E.D.B) join the E.D.L. tendons of toes 2-4
Innervation of Extensor digitorum longus
Deep peroneal/fibular n (L4-S1)
Action of Extensor digitorum longus
Extends joints of toes 2-5; assists ankle dorsiflexion and assists eversion of the foot