Anatomy Review: Ankle, Knee, and Hip

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

Heart Rate Respons to Exercise

The primary purpose of the cardiorespiratory system is to deliver adequate amounts of oxygen and remove waste from body tissues .  The purpose of cardiovascular regulation is maintaining adequate blood flow to all body tissues.  In addition, the circulatory system transports nutrients and aids in temperature regulation.  During exercise, the demand for oxygen to the muscles is 15 to 25 times greater than at rest.  The heart cannot accomplish this by itself, and does not work in isolation.  The respiratory system and the circulatory system function together as a “coupled unit” delivering the body’s oxygen and nutrients and taking away carbon dioxide and wastes to maintain homeostasis.

     During exercise, there is an increase in oxygen demand on body tissues and many things happen in the body such as an increase in blood pressure, heart rate, and respiratory rate.  To meet the demand for oxygen, two major adjustments of blood flow are made, and increase in the amount of blood being pumped per minute by the heart or the cardiac output, and a redistribution of blood flow from inactive organs to the active skeletal muscle.

     The heart has an electrical conduction system makes of two nodes (special conduction cells) and a series of conduction pathways.  The heart begins beating with an electrical impulse from the sinoatrial (SA) node.  The SA node is the pacemaker of the heart, responsible for setting rate and rhythm and is located in the wall of the right atrium.  The impulse spreads through the walls of the atria, causing them to contract.  Then, the impulse moves through the atrioventricular (AV) node (a relay station) located at the junction between the atria and ventricles.  As the impulse travels down the bundles, the ventricles contract and the cycles repeats itself, this cycle of atrial and ventricular contractions pumps blood of the heart to the rest of the body.

     Resting and exercise heart rate are controlled by the sympathetic and parasympathetic nervous system.  The sympathetic division of the autonomic nervous system prepares the body for physical activity by increasing heart rate, blood pressure and respiration.  The sympathetic division also stimulates the release of glucose from the liver for energy.  Once exercise begins, the sympathetic nervous system is activated and the heart rate rises quickly.  Heart rate also rises by simply thinking about exercise, which is referred to as anticipatory heart rate response.

The parasympathetic division helps to slow down heart rate and respiration.  At rest, the heart is controlled by the parasympathetic division, which is why the average resting heart rate is 60 beats per minute or less.  One of the explanations of why endurance athletes have such a low resting heart rate following training is due to increased parasympathetic response.  During exercise, the release of epinephrine and norepinephrine stimulate receptors in the heart which causes heart rate to increase. 

Written By: WST trainer Melissa Robinson