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sciatic nerve - Coggle Diagram

- - - - common fibular nerve
        
        superficial fibular nerve
        
        is a terminal branch of the
        common fibular nerve
        
        course
        
        arises at the neck of fibula
        -descending between fibularis muscle
        & the lateral side of extensor digitorum longus
        -here it gives rise to motor branches
        which supply the:
        fibularis longus & brevis
        
        the nerve continues it;s descent
        with a purely cutaneous function:
        to the anterolateral aspect of the lower leg
        
        when it reaches the lower 3rd of the leg,
        -it pierces the deep crural fascia &
        -terminates by dividing into:
        
        the medial
        
        & intermedial dorsal cutaneous nerves
        -these nerves enter the foot to
        innervate the majority of it's dorsal surface.
        
        motor functions
        
        supplies
        
        fibularis longus
        
        & the fibularis brevis
        (lateral compartment of the lower leg)
        
        they act to avert the foot
        -& thus act at the subtalar joint
        
        weakly contribute to plantarflexion
        (mainly carried out by gastrocnemius & soleus)
        
        sensory functions
        
        innervates:
        
        skin over anterolateral leg
        
        skin of dorsum of foot
        (except the webbed space between
        the hallux & the 2nd digit via the medial & intermedial dorsal cutaneous nerves)
        
        dermatomes to which these areas correspond are
        L5 & S1
        
        course
        
        begins @ the apex of the popliteal fossa
        where the sciatic nerve bifurcates into the
        tibial & common fibular nerves
        
        the common fibular nerve follows the
        -*medial border of the biceps femoris
        -running in a lateral & inferior direction
        -over the lateral head of gastrocnemius.*
        
        at this point the nerve gives rise to
        -2 cutaneous branches
        -which contribute to the innervation of the
        skin of the leg
        
        to enter the lateral compartment of the leg,
        -the nerve wraps around the neck of fibula,
        -passing between the attachments of the
        fibularis longus muscle.
        
        here the common fibular nerve terminates
        -by dividing into the
        
        superficial fibular nerve &
        
        the deep fibular nerve
        
        motor functions
        
        innervates
        
        short head of biceps femoris
        (part of hamstring muscles which flex the knee)
        
        Also supplies (via branches) the
        muscles in the lateral and anterior
        compartments of the leg
        
        if common fib nerve is damaged
        
        the patient may lose the ability to
        
        dorsiflex
        
        & evert the foot
        
        & extend the digits
        
        sensory functions
        
        -2 cutaneous branches arise frm the common fib nerve as it moves over the lat head of gastrocnemius
        
        1.sural communicating nerve
        
        this nerve combines with a branch of
        the tibial nerve to form the
        sural nerve
        
        innervates
        
        the skin over the lower posterolateral leg
        
        2.lateral sural cutaneous nerve
        
        innervates
        
        the skin over the upper lateral leg
        
        deep fibular nerve
        
        is a terminal division of the
        common fibular nerve
        
        course
        
        arises within the lateral compartment of the leg,
        betw the fibularis longus & neck of fibula
        
        with the anterior tibial artery
        -it descends in a plane initially between
        the tibialis anterior & extensor digitorum longus
        -& then distally betw the tibialis anterior &
        -finally medial to the anterior tibial artery
      - tibial nerve
        
        course
        
        Here, the tibial nerve also gives rise to
        branches that contribute towards
        -the sural nerve,
        which innervates the
        posterolateral aspect of the leg.
        
        it its course down the leg,
        posterior to the tibia.
        
        During its descent,
        it supplies the deep muscles of
        the posterior leg.
        
        is a branch of the sciatic nerve
        
        arises at the apex of the popliteal fossa.
        
        It travels through the popliteal fossa
        giving off branches to
        -muscles in the superficial
        posterior compartment of the leg.
        
        At the foot, the nerve passes
        posteriorly and inferiorly to the medial malleolus, through a structure known as the tarsal tunnel.
        
        This tunnel is covered superiorly
        by the flexor retinaculum.
        
        Within this tunnel, branches arise
        from the tibial nerve
        to supply cutaneous innervation to
        the heel.
        
        Immediately distal to the tarsal tunnel,
        the tibial nerve terminates
        by dividing into sensory branches,
        which innervate the sole of the foot.
        
        Motor Functions
        
        innervates all the muscles in the
        posterior compartment of the leg.
        
        superficial posterior compartment
        
        Plantaris – Plantar flexes the ankle.
        
        Soleus – Plantar flexes the ankle.
        
        Gastrocnemius – Plantar flexes the ankle and
        flexes the knee.
        
        deep posterior compartment
        
        Popliteus – Laterally rotates the femur on the
        tibia to unlock the knee.
        
        Flexor hallucis longus – Flexes the big toe and
        plantar flexes the ankle.
        
        Flexor digitorum Longus – Flexes the other
        digits and plantar flexes the ankle.
        
        Tibialis posterior – Inverts the foot and plantar
        flexes the ankle.
        
        Sensory Functions
        
        In the popliteal fossa,
        -the tibial nerve gives off cutaneous branches.
        -These combine with branches
        from the common fibular nerve to form
        the sural nerve.
        
        sural nerve
        
        innervates the
        skin of the
        
        posterolateral side of the leg
        
        and the lateral side of the foot.
        
        also supplies all the sole of the foot
        via 3 branches:
        
        • Medial calcaneal branches
        
        arise within the tarsal tunnel
        
        innervate the skin over the heel.
        
        • Medial plantar nerve
        
        Innervates the plantar surface of
        
        the medial three n a half digits,
        
        and the associated sole area.
        
        • Lateral plantar nerve
        
        Innervates the plantar surface of
        
        the lateral one n a half digits,
        
        and the associated sole area.