The lower body is well suited for weight baring activity and movement. The musculature of the lower extremities is bigger and the joints are more stable than the upper extremity joints. The three joints of the lower extremity that are used in walking mechanics are the hip, knee, and ankle (Hall).
The hip is a ball and socket joint where the head of the femur sits in the acetabulum of the ilium. The ligaments that cross over the joint are the Iliofemoral, Pubofemoral and Ischiofemor ligaments which aid in the strength and stability of the joint (Hall).
The hip flexors are a group of skeletal muscles that act to flex the femur onto the lumbo-pelvic complex. The hip flexors pull the knee upward in the direction of the chest. The Iliopsoas consists of two muscles, the Iliacuse and the Psoas Major. The Iliacus origionates on the pelvic crest and attaches on the femur. The Psoas Major, the longer of the two muscles originates on the lumbar vertebrae and attaches to the femur. The hip flexors work to move the legs and keep the hips stable (Martini.) The knee is a synovial joint that is also built to handle heavy weight bearing loads. Like the hip many ligaments cross the knee joint to enhance its stability. The ligaments of the knee are the medial and lateral collateral ligaments (prevent lateral motion) and then anterior and posterior cruciate ligaments, which limit the forward and backwards movement of the femur (Hall.) The muscles that are responsible for knee extension are the quadriceps, which consist of the Vastus Intermedius, Vastus Lateralis, Vastus Medialis, and Rectus femoris. The origin of the Vastus Intermedius is the Anterior and lateral shaft of femur and the insertion is the tubercle of tibia. The Vastus Lateralis origin is at the outer surface of the greater trochanter of the femur, the insertion is at the patella via the quadriceps tendon. The Vastus Medialis originates at the lower intertrochanteric line and its insertion is the medial part of the patella. The Rectus Femoris originates at the anterior inferior iliac spine and its insertion is at the patella (Martini.).
The muscle group that is responsible for knee flexion is the hamstrings or the Biceps femoris which originates at the Ischial tuberosity and Linea aspera of the femur and inserts at the head of the fibula. The semimembranosus originates at the Ischial tuberosity and inserts on the posterior surface of the medial condyle of the tibia. The Semitendinosus has the same origin as the Semimembranosus and inserts at the proximal, medial surface of the tibia (Martini.).
The ankle is a hinge joint that is supported by the anterior and posterior tibiofibular ligaments and the crural interosseous tibiofibular ligament (Hall.). The muscles responsible for dorsi flexion are the Tibialis anterior, Extensor digitorum and Hallicus longus. The muscles responsible for plantar flexion are the Gastrocnemius and the soleus (Martini.).
The Tibialis Anterior originates at the upper half of lateral shaft of tibia, and inserts at the base of first metatarsal. The Extensor Digitorum longus originates at the lateral condyle of the tibia and inserts at the distal phalanges two through five. The Extensor Hallicus longus originates at the anterior surface of the fibula and originates on the superior surface of phalanges two through five. The Gastrocnemius’ origin is the femoral condyles and its insertion is the calcaneus. The Soleus inserts at the head and proximal shaft of the fibula and inserts at the calcaneus (Martini.).
Written By: WST Trainer Vicky Ziolkowski