Week 13 Anatomy - Knee and Lower Limb Myo/Dermatomes Flashcards
What type of joint is the knee?
Synovial hinge joint
What are the roles of ligaments in knee stability?
Lateral and medial collateral ligaments prevent lateral movement of femur on tibia
Anterior cruciate prevents tibia sliding anterior relative to the femur.
Posterior cruciate prevents tibia sliding posteriorly in relation to the femur
Describe blood supply to the knee?
Genicular anastomosis from genicular branches of the femoral, popliteal, anterior and posterior recurrent branches of the anterior tabla recurrent and circumflex fibular arteries
What is the broad sensory innervation of the knee?
Anterior = femoral nerve
Posterior = tibial nerve
Lateral = common fibular
Medial/articular surface = obturator and saphenous nerve
What is the cruciate anastomosis, and what is its function?
Four way meeting of medial and lateral circumflex femoral arteries with inferior gluteal artery superiorly and first perforating artery inferiorly, anatomically situated around the proximal femur.
Allows blood to flow from internal iliac/inferior gluteal artery into the leg if there is a blockage of the femoral artery
What are the GASP bursae of the knee, which communicate with the synovial cavity of the knee?
Gastrocnemius
Anserine
Suprapatella
Popliteus
What are the borders of the popliteal fossa?
Supero-lateral = biceps femoris
Supero-medial = Semimembranosus
Infero-lateral = lateral head gastrocnemius
Inferomedial = medial head gastrocnemius
Floor = synovial membrane of knee joint
Roof = skin + fascia
What two nerves form from the the sciatic nerve?
Tibial nerve
Common fibular nerve
(Formed when the sciatic nerve divides in posterior compartment of the thigh)
Describe contents of the popliteal fossa: (Medial to lateral)
**Serve and volley next ball
Termination of small saphenous vein
Popliteal artery and vein
Tibial nerve
Posterior cutaneous nerve of thigh and sural cutaneous nerves
Popliteal lymph nodes and lymphatic vessels
What are the muscles that make up the quadriceps group, and what are their actions?
What nerve innervates them?
Rectus femoris: AIIS to patella
Vastus lateralis: Greater trochanter to patella
Vastus intermedius: Anterior femur to patella
Vastus medius: Intertrochanteric line to patella
Act to extend knee, innervated by femoral nerve (anterior compartment of thigh)
What are the muscles of the posterior thigh, their common origin, actions, and innervation?
Semitendinosus: “T for Top”
Semimembranosus:
Biceps Femoris:
Common origin = ischial tuberosity (all except short head biceps, which originate from linea aspera femur)
Innervation = sciatic nerve (tibial division L5-S2)
Action is extension of hip, flexion of knee.
What are the muscles of the anterior compartment of the leg, and their actions?
Tibialis anterior: From lateral condyle and IOM to medial and inferior surface of medial cuneiform and base of 1st metatarsal –> dorsiflexion and inversion
Extensor digitorum longus: Lateral condyle and IOM to middles and distal phalanges of lateral 4 digits –> dorsiflexion and extension of toes
Extensor hallicus longus: middle part of anterior fibula and IOM to dorsal aspect of great toe –> dorsiflexion, extension great toe
Fibula’s tertius: Inferior third of anterior tibia and IOM to dorsum of 5th metatarsal –> dorsiflexion and eversion
What is the nerve that supplies the anterior compartment of the leg?
Deep fibular nerve
What are the muscles of the lateral compartment, actions?
Fibularis longus: Head of fibula to base of 1st metatarsal (running behind lateral malleolus) –> eversion, weak plantarflexion
Fibula’s brevis: Inferior fibular to dorsal aspect of tuberosity of 5th metatarsal –> eversion and weakness plantarflexion
What nerve innervates lateral compartment?
Superficial fibular nerve
What are the muscles of the superficial compartment of the posterior leg, actions?
Gastrocnemius: 2 heads: lateral from lateral femoral condyle, medial from popliteal aspect of femur, superior to medial epicondyle, both attaching onto calcaneal/achilles tendon –> posterior surface of calcaneus
Soleus: Posterior aspect of head of fibula, onto calcaneal/achilles tendon posterior surface of calcaneus
Plantaris: inferior end of lateral supracondylar line of femur, onto calcaneal/achilles tendon posterior surface of calcaneus
What is the major difference in function between gastrocnemius and soleus?
Gastrocnemius also functions to flex the knee as it crosses the knee joint as well
What nerve is responsible for innervation of both superficial and deep compartments of the posterior leg?
Tibial nerve
What are the muscles of the deep compartment of the posterior leg, actions?
Popliteus: lateral surface of lateral condyle of femur to posterior surface of tibia –> Unlocks knee by rotating femur on tibia + weak flexion
Flexor hallucis longus: originates on contralateral side (lateral) to hallux, from inferior posterior surface of fibula and IOM to base of distal phalanx of great toe –> flexion of great toe, weak plantarflexion
Flexor digitorum longus: from medial posterior tibia, to bases of distal phalanges of lateral 4 digits –> flexes lateral 4 digits, plantarflexion
Tibialis posterior: from IOM and posterior tibia to tuberosity of navicular, cuneiform, cuboid, calcaneus, and base of 2,3,4th metatarsal –> plantarflexion
What nerve supplies anterior compartment of leg? What can a lesion clinically cause?
Deep fibular nerve, lesion can cause a foot drop/inability to dorsiflex
What nerve supplies the lateral compartment?
Superficial fibular nerve
What nerve supplies the posterior compartments?
Tibial nerve
What is the blood supply to the leg compartments?
Anterior compartment = anterior tibial artery
Lateral compartment = perforating branches of anterior tibial artery and fibular artery
Posterior compartment = posterior tibial artery and fibular artery
What is the dermatomal region for L1?
Inguinal region
What is the dermatomal region for L2?
Upper, lateral thigh
What is the dermatomal region for L3?
Inner lower thigh
What is the dermatomal region for L4?
Medial lower leg, medial malleolus
What is the dermatomal region for L5?
Lateral lower leg +3 medial toes (including great toe)
What is the dermatomal region for S1?
Lateral foot
What is the dermatomal region for S2?
Posterior thigh
What is the dermatomal region for S3?
Gluteal region
Myotome for hip flexion?
L2/L3 - “Lift to the C(eiling)
Myotome for hip extension?
L4/5 - “Take a stride”
Myotome for lateral hip rotation?
L5/S1 - “Open wide for fun”
Myotome for medial hip rotation?
L1/L2/L3 - “Touch together your knees”
Myotome for hip adduction?
L1/L2/L3/L4 - “Close the door”
Myotome for hip abduction?
L5/S1 - “Open wide for fun”
Myotome for knee flexion?
L5/S1 - “Kick your bum”
Myotome for knee extension?
L3/L4 - “Kick the door”
Myotome for dorsiflexion?
L4/L5 - Point your toes high
Myotome for plantar flexion?
S1/S2 - “Put on your shoe”
Myotome for inversion?
L4/L5 - “Roll to the right”
Myotome for eversion?
L5/S1 - “Pinky is number 1”
