A&P Chapter 9

flexion
Explanation: The motion of raising your hand and placing it on the shoulder of a person standing in front of you requires extension of the shoulder. To perform this motion, the shoulder joint must move through a range of motion that includes extension. The muscles that move the shoulder joint through this range of motion are the deltoid muscle and the rotator cuff muscles.

Elastic
Explanation: The major joint categories are the ball-and-socket joints, the hinge joints, the gliding joints, and the pivot joints. The saddle joints are not a major joint category.

These are all fibrous joints.
Explanation: All three of these types of joints are classified as immovable, or fibrous, joints. This means that they do not allow for any movement between the bones that they are connecting. Sutures are found in the skulls of infants, and are made up of very thin layers of connective tissue. Gomphoses are found in the teeth, where the root of the tooth is connected to the jawbone. Syndesmoses are found between the long bones in the legs, and are made up of a thicker band of connective tissue.

synostosis
Explanation: The least movable joints are the joints between the bones of the skull. These joints are held together by ligaments and muscles, and they allow for very little movement.

synovial
Explanation: The most movable joints are synovial joints. Synovial joints are the most common type of joint in the body. They are formed where the ends of two bones meet, and are surrounded by a capsule of connective tissue. The capsule is lined with a membrane that secretes a fluid, which lubricates the joint and helps to reduce friction.

The interosseous membrane
Explanation: Articular cartilage is not an anatomical component of a synovial joint. The articular cartilage is a type of cartilage that covers the surfaces of the bones where they come into contact with each other. The joint cavity is a space within the joint that is filled with fluid. The interosseous membrane is a type of connective tissue that connects the bones of the skeleton. The fibrous capsule is a type of connective tissue that surrounds the joint. The synovial membrane is a type of connective tissue that lines the joint cavity.

articular cartilage
Explanation: The smooth, connective tissue lining that covers the opposing bony surfaces of a synovial joint is called the synovial membrane.

The length of the bone
Explanation: There are several factors that determine the range of motion of a joint, but the shape of the bone surfaces is not one of them. The length of the bone, the stiffness of the ligaments, the strength of the ligaments, and the action of the muscles associated with the joint all play a role in determining the range of motion of a joint.

extend
Explanation: When you walk up the stairs, your hip and knee joints work together to lift your body weight. The muscles in your legs contract to help lift your body up the stairs. The hip and knee joints work together to allow your legs to move in a coordinated fashion.

abduction
Explanation: The action of raising an arm to one side of the body to stop a taxi is an example of abduction of the shoulder. The shoulder is a ball-and-socket joint that is able to move in many directions. Abduction is the movement of a limb away from the midline of the body.

elevation; depression
Explanation:The action of raising an arm to one side of the body to stop a taxi is an example of abduction of the shoulder. The shoulder is a ball-and-socket joint that is able to move in many directions. Abduction is the movement of a limb away from the midline of the body.

hyperextension of the neck
Explanation: While standing, looking up at the stars requires a lot of patience. You have to be patient in order to see the stars.

synovial
Explanation: The temporomandibular joint (TMJ) is a hinge joint that connects the lower jaw (mandible) to the skull. The TMJ allows the mandible to move up and down and side to side, and it is responsible for chewing and talking. The TMJ is a synovial joint, which means it is surrounded by a thin layer of fluid that lubricates the joint and prevents the bones from rubbing against each other.

inferiorly
Explanation: The rotator cuff tendons enclose the shoulder joint on all sides except the front, which partly explains the nature of most shoulder dislocations. The rotator cuff is a group of four muscles and their tendons that surround the shoulder joint. The tendons attach the muscles to the bones of the shoulder. The rotator cuff muscles and tendons help lift the arm and stabilize the shoulder joint. Most shoulder dislocations occur when the arm is forced out of the socket from the front. This happens because the front of the shoulder joint is not surrounded by the rotator cuff tendons.

Coxal joint
Explanation: There is no definitive answer to this question as stability is relative and depends on the individual. However, in general, the coxal joint is considered to be the most stable joint because it is a ball-and-socket joint that is surrounded by strong ligaments. The glenohumeral joint is also a ball-and-socket joint, but it is less stable because it is not surrounded by as many ligaments. The tibiofemoral joint is a hinge joint, which means that it is less stable than a ball-and-socket joint. The humeroulnar and humeroradial joints are both pivot joints, which means that they are even less stable than a hinge joint.

The anterior cruciate ligament (ACL)
Explanation: The ACL is a major ligament in the knee that helps to prevent hyperextension. The PCL is another major ligament in the knee that also helps to prevent hyperextension. The fibular collateral ligament is a ligament that helps to stabilize the knee joint. The medial meniscus is a C-shaped piece of cartilage that helps to cushion the knee joint. The lateral meniscus is also a C-shaped piece of cartilage that helps to cushion the knee joint.