A&p Chapter 11 - The Muscular System

The buccinator muscle is responsible for forming the major portion of the cheek. This muscle is located in the wall of the cheek and helps to compress the cheeks during actions such as blowing or sucking. It also plays a role in keeping food in the mouth while chewing.

Longer fibers in a muscle allow for a greater range of motion because they provide more flexibility and elasticity. When the fibers are longer, they can stretch and contract over a larger distance, allowing for a wider range of movement in the muscle. This increased range of motion can be beneficial in activities that require extensive movement, such as dancing or gymnastics. Therefore, the statement that longer fibers in a muscle result in a greater range of motion is true.

The biceps brachii is responsible for flexing the forearm, making it the prime mover in this action. On the other hand, the triceps brachii is responsible for extending the forearm, making it the antagonist to the biceps. This means that when the biceps contracts to flex the forearm, the triceps relaxes to allow this movement. Therefore, the statement is true as it correctly identifies the roles of the biceps brachii and triceps brachii in forearm flexion.

The three superficial posterior plantar flexors of the leg are the gastrocnemius, soleus, plantaris, and calcaneus. These muscles work together to flex the foot and point the toes downwards. They all insert on the calcaneus, or heel bone, via the Achilles tendon. The gastrocnemius is the largest and most visible muscle of the calf, while the soleus is located deeper and helps provide stability during movements. The plantaris is a smaller muscle that assists in plantar flexion, and the calcaneus is the bone that forms the heel of the foot.

Movement occurs when muscles contract and pull on the origin, which is generally located across a joint. Muscles exert force on tendons that are attached to bones, causing them to move. Additionally, muscles that move a body part cannot cover the moving part. Therefore, the correct answer is 1, 2, and 4.

When you leave the classroom pouting, you are using the mentalis muscle. The mentalis muscle is located in the chin area and is responsible for controlling the movement of the lower lip and chin. When you pout, the mentalis muscle contracts, causing the chin to protrude and the lower lip to push forward.

The iliotibial tract is composed of the tendon of the gluteus maximus muscle, the deep fascia that encircles the thigh, and the tendon of the tensor fascia latae muscle. The tensor fascia latae muscle is located on the outer side of the hip and thigh and plays a role in stabilizing the knee joint. Its tendon contributes to the formation of the iliotibial tract, which is important for the stability and movement of the hip and knee joints.

The rectus femoris has fascicles arranged on both sides of a centrally positioned tendon, which is a characteristic of a bipennate muscle. In a bipennate muscle, the fascicles are arranged in a feather-like pattern on both sides of the tendon, allowing for a greater force production and range of motion compared to other muscle types.

The gracilis muscle is not involved in flexing the thigh. The rectus femoris, sartorius, iliacus, and tensor fascia latae muscles all contribute to flexion of the thigh. However, the gracilis muscle primarily functions to adduct the thigh, meaning it brings the leg towards the midline of the body.

The answer is correct because the serratus anterior muscle is not comblike in shape. It is actually a flat, triangular muscle located on the lateral surface of the rib cage. It helps to stabilize the scapula and is not located on the body's anterior surface.