Given the idea that muscles pulling on bones causes movement of the body. Explain the actions that occur as a person takes two steps. (Describe muscle contractions and relaxations in both the leg leaving the ground and the one remaining on the ground.)
When a person takes two steps, there are a series of muscle contractions and relaxations involved to facilitate the movement. Let's break down the actions that occur in both legs during this process:
Leg leaving the ground:
1. As the person begins to take a step, the muscles in the leg leaving the ground undergo a series of contractions to prepare for the movement. The quadriceps muscles in the front of the thigh contract to extend the knee joint.
2. Simultaneously, the muscles in the calf region, including the gastrocnemius and soleus, contract to plantarflex the ankle joint, pushing the foot off the ground.
3. As the leg leaves the ground, the hip flexor muscles, such as the iliopsoas, contract to lift the leg and swing it forward.
Leg remaining on the ground:
1. In the leg that remains on the ground, the hip extensor muscles, including the gluteus maximus and hamstrings, contract to stabilize the pelvis and allow forward movement.
2. The quadriceps muscles in the front of the thigh of the grounded leg contract to provide support and stability during each stride.
3. Additionally, the muscles in the calf region, particularly the tibialis anterior, contract to provide dorsiflexion of the ankle, ensuring a smooth transition of weight from the grounded leg to the swinging leg.
As the leg that was initially on the ground completes one step and pushes off, the roles of the two legs switch, and the process repeats.
It's important to note that the coordination of muscle contractions and relaxations involved in walking is a complex process, controlled by signals from the brain and spinal cord. This simplified explanation highlights the key muscles involved in each leg, but there is a network of interconnected muscles working together to achieve smooth and coordinated movement during walking.