Master Muscular Movements Kinesiology Quiz

Knee extension occurs when the leg straightens at the knee joint. The quadriceps muscle group is responsible for this movement. It includes the rectus femoris, vastus medialis, vastus intermedius, and vastus lateralis. These muscles contract together to pull the tibia forward, extending the knee. Other muscles like the hamstrings or gluteus maximus perform opposite or different actions and are not prime movers here.

Knee flexion refers to bending the knee and bringing the heel toward the body. The primary muscles responsible are the hamstrings, including semimembranosus, semitendinosus, and biceps femoris. The popliteus assists by unlocking the knee, while the gastrocnemius also contributes due to crossing the knee joint. Quadriceps extend the knee, making them antagonists rather than prime movers during knee flexion movements.

Hip flexion is the movement of lifting the thigh toward the torso. The iliopsoas is the strongest hip flexor, assisted by rectus femoris and pectineus. These muscles work together to bring the femur forward during walking, running, and sitting movements. Muscles such as gluteus maximus and hamstrings perform the opposite action of hip extension and therefore are not primary hip flexors.

Hip extension occurs when the thigh moves backward from a flexed position. The gluteus maximus is the primary muscle responsible, especially during powerful movements like climbing or rising from sitting. The hamstrings, including semitendinosus, semimembranosus, and the long head of biceps femoris, assist in this action. Muscles involved in hip flexion or abduction do not contribute significantly to hip extension.

Hip abduction is the movement of the leg away from the midline of the body. The gluteus medius and gluteus minimus are the primary muscles responsible. They play a crucial role in stabilizing the pelvis during walking and single-leg stance. Weakness in these muscles can cause abnormal gait patterns. Other muscles like adductors or hip flexors assist in different movements, not abduction.

Hip internal, or medial, rotation occurs when the femur rotates inward toward the midline. The gluteus minimus is a primary contributor to this motion due to its anatomical position and fiber direction. It works alongside smaller assisting muscles to stabilize the hip during movement. Larger muscles like rectus femoris or psoas major are primarily flexors and do not primarily create internal rotation of the hip.

Hip external, or lateral, rotation turns the thigh outward away from the midline. The gluteus maximus is the most powerful external rotator of the hip. It works with a group of deep rotator muscles, including piriformis and obturator muscles. These muscles are especially active during walking and stability tasks. Muscles involved in hip flexion or abduction do not primarily perform external rotation.

Ankle plantar flexion refers to pointing the toes downward, such as when standing on tiptoes. The gastrocnemius and soleus muscles are the primary movers for this action. Together, they form the calf muscle group and attach to the calcaneus through the Achilles tendon. These muscles generate powerful force during walking, running, and jumping. Muscles in the thigh or upper body do not contribute to this movement.

Ankle dorsiflexion is the action of lifting the foot upward toward the shin. The tibialis anterior is the prime mover for this movement and is located on the front of the lower leg. It plays an essential role during walking by preventing the foot from dragging on the ground. Muscles such as gastrocnemius and soleus perform plantar flexion, making them antagonists during dorsiflexion.

Ankle inversion occurs when the sole of the foot turns inward. The primary muscles responsible are the tibialis anterior and tibialis posterior. These muscles help stabilize the foot and maintain proper arch support during standing and walking. While other muscles assist with foot movement, they do not primarily create inversion. Excessive inversion without control can lead to common ankle injuries such as lateral ankle sprains.

Ankle eversion involves turning the sole of the foot outward. The peroneus longus and peroneus brevis muscles are the prime movers for this action. Located on the lateral side of the lower leg, they help stabilize the ankle and prevent excessive inversion. These muscles are especially important during uneven surface walking. Muscles like tibialis posterior act in opposition and are responsible for inversion, not eversion.

Flexion of toes two through five involves bending the smaller toes downward. The flexor digitorum longus is the primary muscle responsible for this movement. It runs along the posterior lower leg and inserts into the distal phalanges of toes two through five. This muscle assists with push-off during walking and balance control. Other toe flexors either act on the big toe or serve as assisting muscles.

Big toe flexion refers to bending the hallux downward toward the ground. The flexor hallucis longus is the prime mover responsible for this action. It plays a major role in walking, running, and jumping by contributing to push-off force. The muscle runs along the posterior leg and inserts at the distal phalanx of the big toe. Other muscles either extend the toe or flex the smaller toes.

Extension of toes two through five means straightening these toes upward. The extensor digitorum longus is the prime mover for this action. Located in the anterior compartment of the leg, it helps lift the toes during the swing phase of gait. This prevents tripping and allows smooth walking. Flexor muscles perform the opposite action, while other anterior muscles focus on ankle movement rather than toe extension.

Extension of the big toe involves lifting the hallux upward. The extensor hallucis longus is the primary muscle responsible. It assists with foot clearance during walking and contributes to balance control. This muscle originates on the fibula and inserts on the distal phalanx of the big toe. Other muscles listed either flex the toe or assist with foot stabilization but do not produce extension of the big toe.

Genu varus is a lower limb alignment condition commonly referred to as bowlegs. In this condition, the knees angle outward while the ankles move closer together. This alignment places increased stress on the medial knee compartment. Genu varus can be normal in early childhood but may persist or worsen due to injury or arthritis. It differs from genu valgus, where the knees angle inward instead.

Genu valgus, commonly called knock knees, occurs when the knees angle inward toward each other while standing. This alignment causes the ankles to separate. It is frequently observed in children during growth and may correct naturally. Persistent genu valgus can increase stress on the lateral knee structures. This condition is different from genu varus, which involves outward knee angulation, and from foot or spinal deformities.

Calcaneo valgus is a foot alignment condition where the calcaneus, or heel bone, angles outward. This causes the foot to tilt laterally during standing. It is often seen in infants and may resolve with development. Persistent calcaneo valgus can affect gait mechanics and ankle stability. This condition differs from calcaneo varus, where the heel angles inward, and from rotational deformities that do not involve heel positioning.

Calcaneo varus is a foot deformity in which the calcaneus angles inward toward the midline. This inward heel position causes the foot to supinate excessively. It may be congenital or develop due to muscle imbalance or neurological conditions. Calcaneo varus alters weight distribution during walking and increases lateral foot stress. It contrasts with calcaneo valgus, where the heel angles outward, and requires different corrective approaches.

Hallux valgus is a common foot deformity where the big toe angles inward toward the other toes. This misalignment often leads to the formation of a bunion at the first metatarsophalangeal joint. It can cause pain, inflammation, and difficulty wearing shoes. Hallux valgus differs from conditions affecting the smaller toes or the heel. The deformity progresses over time and is influenced by footwear and biomechanics.

The anterior cruciate ligament, or ACL, is a key stabilizing ligament of the knee. It prevents the tibia from sliding forward relative to the femur and limits excessive rotation. The ACL runs from the anterior tibia to the posterior femur inside the knee joint. Injury to the ACL commonly occurs during sudden stops or direction changes and can significantly impair knee stability during athletic activities.

The posterior cruciate ligament, or PCL, stabilizes the knee by preventing the tibia from sliding backward relative to the femur. It runs from the posterior tibia to the anterior femur and is thicker and stronger than the ACL. PCL injuries are less common and usually result from direct trauma, such as a dashboard injury. The PCL works with other ligaments to maintain knee stability during movement.

The medial collateral ligament, or MCL, provides stability to the inner side of the knee. It resists valgus forces that push the knee inward. The MCL runs from the medial femur to the medial tibia and is attached to the medial meniscus. Injury often occurs from lateral impact to the knee. Its role is critical for frontal plane stability and protecting the knee during side-to-side movements.

The lateral collateral ligament, or LCL, stabilizes the outer side of the knee by resisting varus forces. It runs from the lateral femur to the fibula and helps maintain proper alignment during movement. Unlike the MCL, it is not attached to a meniscus. LCL injuries typically result from medial forces applied to the knee. Together with other ligaments, it contributes to overall knee stability.

The iliotibial band, or IT band, is a thick band of fascia located on the lateral side of the thigh. It connects muscles such as the tensor fascia latae and gluteus maximus to the tibia. The IT band provides lateral stability to the hip and knee during walking and running. Tightness or irritation of this structure can cause lateral knee pain, commonly known as IT band syndrome.

The medial meniscus is a C-shaped cartilage structure located between the femur and tibia on the medial side of the knee. It functions as a shock absorber, helps distribute load, and deepens the tibial joint surface. The medial meniscus is attached to the MCL, making it more prone to injury. Damage often occurs with twisting motions and can lead to pain, swelling, and joint instability.

The lateral meniscus is a cartilage structure located between the femur and tibia on the lateral side of the knee. It acts as a shock absorber and helps stabilize the joint by increasing surface contact. Unlike the medial meniscus, it is more mobile and less frequently injured. The lateral meniscus plays an essential role in load distribution, joint lubrication, and smooth knee movement during dynamic activities.

The deltoid ligament is a strong ligament complex located on the medial side of the ankle. It connects the medial malleolus of the tibia to the talus, calcaneus, and navicular bones. This ligament stabilizes the ankle and prevents excessive eversion. It also helps support the medial longitudinal arch of the foot. Injury to the deltoid ligament is less common but can significantly affect ankle stability.

The lateral ankle ligament complex consists of three ligaments: anterior talofibular, calcaneofibular, and posterior talofibular ligaments. These structures are located on the lateral side of the ankle and connect the fibula to the talus and calcaneus. They stabilize the ankle during inversion movements. Injury to these ligaments is common in ankle sprains, particularly involving the anterior talofibular ligament.