Anatomical Structure

Anatomical structure affects movement ability in the hip by the single non jointed structure of the pelvis. The pelvis rotates all three planes of movement. One movement is the rotating of the femur so that the acetabulum is positioned toward the direction of approaching femoral movement. Another is the posterior pelvic tilt, when the anterior superior iliac spine is tilted backward, it position the head of the femur in front of the hipbone to enable flexion. Lastly, anterior pelvic tilt enables femoral extension, and lateral pelvic tilt toward the opposite side facilitates lateral movements of the femur. Movement of the pelvic girdle also coordinates with certain movements of the spine. There are six muscles which are responsible for flexion
at the hip: iliacus, psoas major, pectineus, rectus femoris, sartorius, and tensor fascia latae. The three hamstrings: bicep femoris, semitendinosus, and semimebranosus are responsible for the hip extensors. An abductor of the hip is the gluteus medius with the fluteus minimus assisting. These muscles stabilize the pelvis during the phase of walking and running and when an individual stands on one leg. The hip adductors are those muscles that cross the joint medially and include the adductor longus, adductor brevis, adductor magnus, and gracilis. The hip adductors are regularly active during the swing phase of the gait cycle to bring the foot beneath the body’s center of gravity for placement during the support phase. (Hall,228) There are six muscles function exclusively as lateral rotators. These are the piriformis, gemellus superior, gemellus inferior, obturator internus, obturator externus, and quadratus femoris. The major medial rotator of the femur is the gluteus minimus, with assistance from the tensor fascia latae, semitendinosus, semimembranosus, and gluteus medius. Medial and lateral rotators are able to apply more tension when the hip is in 90° of flexion than when it is fully or moderately extended. Anatomical structure of the knee that affects movement is flexion and extension.
They are mainly movements permitted at the tibia femoral joint. The three hamstring muscles play a role as the primary flexors. Muscles that assist with knee flexion are the gracilis, sartorius, popliteus, and gastrocnemius. (Hall,236)The quadriceps muscles affect the movement by consisting of the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius, they are the extensors of the knee. Tension development in the semimembranosus, semitendinosus, and popliteus produces medial rotation of the tibia, with the gracilis and sartorius assisting. The biceps femoris is solely responsible for lateral rotation of the tibia. Abduction and adduction moments at the knee can also be actively generated by contracting of the muscles crossing the medial and lateral aspects of the knee to resist externally applied adduction and abduction
moments.
The ankle has an axis of rotation, which is essentially frontal, although it is slightly oblique and its orientation changes somewhat as rotation occurs at the joint. The ankle’s motion occurs mostly in the sagittal plane, with the ankle functioning as a hinge joint with a moving axis of rotation during the stance phase of walking. The medial and lateral malleoli serve as pulleys to channel the tendons of muscles crossing the ankle either posterior or anterior to the axis of rotation, thereby enabling their contributions to either dorsiflexion or plantar flexion. (Hall, 245)The tibialis anterior, extensor digitorum longus, and peroneus tertius are the prime dorsiflexors of the foot. (Hall, 245) Inversion and eversion are the movements that occur largely at the subtalar joint, although gliding actions among the intertarsal and tarsometatarsal joints also contribute. Inversion occurs in the sole of the foot turning inward toward the midline of the body. As the heel hits the ground, the rear portion of the foot typically inverts to some extent. When the foot rolls forward and the forefoot contacts the ground, plantar flexion occurs.
The knee is adapted to its weight bearing function because the knee is positioned between the body’s two longest bony levers (the femur and the tibia) the potential for torque development at the joint is large. The knee is also a major weight-bearing joint. The muscles contributing to the knees weight bearing and tension contribute to forces with compression dominating when the knee is fully extended. During gait the compressive force at the tibiofemoral joint is a little greater compared to three times the body weight. It increases up to approximately four times body weight. The hip is evenly distributed across both legs during upright standing motion, the weight supported at each hip is 1.5 the weight of the body segments above the hip, or about one-third of total body weight. However, the total load on each hip in this situation is greater than the weight supported, because tension in the large, strong hip muscles further adds to compression at the joint. An example is, as gait speed increases, the load on the hip increases during both swing and support phases. The weight is supported through the skeleton of the foot, and muscle tension all help to load off some weight from the hip. The ankle supports a force applied to the foot during running/walking with an early impact peak followed almost immediately by a peak, as the foot pushes off against the ground. The structures of the foot are anatomically linked such that the load is evenly distributed over the foot during weight bearing. Approximately 50% of body weight is distributed through the subtalar joint to the calcaneus, with the remaining 50% transmitted across the metatarsal heads. (Hall,251)
Some muscle that are active during the hip is the gluteus medius. It is the major abductor acting at the hip, with the gluteus minimus assisting . During the adductors, muscles cross the joint medially and include adductor longus, adductor brevis, adductor magnus, and gracilis. (Hall, 226)The three hamstrings such as the biceps femoris, semitendinosus, and semimembranosus. Six muscles primarily responsible for flexion at the hip are those crossing the joint anteriorly: the iliacus, psoas major, pectineus, rectus femoris, sartorius, and tensor fascia latae.(Hall,226) “Rectus femoris Iliopsoas (Iliacus) (Psoas) Sartorius Pectineus Tensor fascia latae Gluteus maximus Gluteus medius Gluteus minimus Gracilis Adductor magnus Adductor longus Adductor brevis Semitendinosus Semimembranosus Biceps femoris (long head) The six outward rotators.”(Hall 226)
Muscles acting on the knee are the popliteus, which acts to medially rotate the tibia with respect to the femur, enabling flexion to occur. Muscles that assist with knee flexion are the gracilis, sartorius, popliteus, and gastrocnemius. “ Vastus lateralis Vastus intermedius Vastus medialis Semitendinosus Semimembranosus Biceps femoris (Long head) (Short head) Sartorius Gracilis Popliteus Gastrocnemius Plantaris” Muscles acting on the ankle are “tibialis anterior Extensor digitorum longus Peroneus tertius Extensor hallucis longus Gastrocnemius Plantaris Soleus Peroneus longus Peroneus brevis Flexor digitorum longus Flexor hallucis longus Tibialis posterior”(Hall,236)
Some common injuries for the hip are fractures, contusions, and strains.
Fractures occur although the pelvis and the femur are large and one of the strongest bones, the hip is high for repetitive loads ranging from four to seven times body weight during locomotion. Fractures occur frequently in elderly with osteoporosis which occurs during the support phase of walking. A contusion happens when the muscles on the anterior aspect of the thigh are in a prime location for supporting blows during participation in contact sports. Strains occur because most daily activities do not require every day hip flexion and knee extension; the hamstrings are not commonly stretched unless exercises are performed for that specific purpose. The knee common injuries are anterior cruciate ligament, posterior cruciate ligament, medial collateral ligament injuries blows, meniscus injuries, and iliotibial band friction syndrome, patellofemoral pain syndrome, and shin splits. Injuries to the ACL are common in sports because it involves pivoting and cutting. Most of these occur when the femur is rotated on the planted leg with the knee close to full extension during cutting, landing, or stopping. These kinds of activities such as accelerating and decelerating involving sudden changes in direction which produce large rotational moments of sudden forces at the knee, particularly when such movements are not planned. Posterior cruciate ligament (PCL) injuries most commonly occur from sport
participation or motor vehicle accidents. Medial collateral ligament injuries occur to the lateral side of the knee. When the foot is planted and a lateral blow of sufficient force is sobtained, in return a sprain or rupture occurs. Meniscus injuries is medial collateral ligament attaches to the medial meniscus, stretching or tearing of the ligament can also result in damage to the meniscus. Iliotibial band friction syndrome is the tensor fascia lata which develops tension to assist with stabilization of the pelvis when the knee is in flexion during weight bearing. Patellofemoral pain syndrome occurs during or after physical activity which is a joint motion that involves anterior knee pain during. Shin splints cause pain along the anterolateral or posteromedial aspect of the lower leg. This is a loosely defined overuse injury, often associated with active activity such as running or dancing that may involve microdamage to muscle attachments on the tibia and/or inflammation of the periosteum. Ankle injuries are sprains, overuse injuries achilles,alignment anomalies of the foot, and injuries related to high and low arch structures. Ankle sprains are the most common of all sport because the joint capsule and ligaments are stronger on the medial side of the ankle, inversion sprains involving stretching or rupturing of the lateral ligaments are much more common than eversion sprains of the medial ligaments. Overuse Injuries Achilles tendinitis involves inflammation and sometimes microrupturing of tissues in the Achilles tendon, typically accompanied by swelling. Two possible mechanisms for tendinitis have been proposed. The first is that repeated tension development results in fatigue and decreased flexibility in the muscle, increasing tensile load on the tendon even during relaxation of the muscle. The second theory is that repeated loading actually leads to failure or rupturing of the collagen threads in the tendon. Achilles tendinitis is usually associated with running and jumping activities and is extremely common among theatrical dancers. Alignment anomalies of the foot are varus and valgus which can occur in all of the major links of the lower extremity. These may be congenital or may arise from an imbalance in muscular strength. Lastly, injuries related to high and low arch structures, arches that are higher or lower than the normal range have been found to influence lower-extremity kinematics and kinetics, with implications for injury. Specifically, as compared to those with normal arches, high-arched runners have been found to exhibit increased vertical loading rate, with related higher incidences of ankle sprains, plantar fasciitis, iliotibial band friction syndrome, and fifth metatarsal stress fractures.