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EXSC3505 Unit 1

Structural Kinesiology

Introduction

Kinesiology is the study of the human anatomy, physiology, and mechanics that allow for movement. Specifically, we will be examining the bones and joints, the attaching muscles, and the movement that occurs due to this anatomy. Having an understanding of these concepts will not only reinforce the human anatomy, but also give better analysis of movement that is created. Although we will be breaking the body down into individual segments, it is important to understand that the body moves as a whole and everything is interconnected. Not only will the textbook be a useful source but it is encouraged that you use "Anatomy and Physiology Revealed" through the Kean Library. Once the program is launched, select the appropriate "module," such as skeletal for this unit, and then select a study area to review. There are dissections, animated videos, quizzes, and more. This will help with visualizing the structures within our own bodies.

Reference terminology

To better describe the anatomy, reference position is necessary. The most commonly used reference positioning in known as anatomical position. The is when the person is standing upright, facing forward, with their feet parallel to one another and palms facing forward. All anatomical directional terms describe the body while it is in this position. Fundamental position is very similar except the palms are facing towards the body, as if someone was standing naturally. To reference one body part in relation to another, reference lines can be used, such as vertebral line that runs the length of your spine. More examples can be found on pages 2-3 in the textbook.

Directional terminology is used like giving an individual directions to a location. Just like saying "take the turnpike north," on the body we could say "superior to the patella." It is also important when using directional terminology to use a body part as context so the information is more specific. A complete list of terms can be found on pages 4-5 in the textbook.

Planes and Axes

When analyzing movement, it is often characterized by the plane of motion or an imaginary two-dimensional surface through which movement occurs. The three cardinal planes divide the body in two halves. The sagittal plane bisects the body from front to back and splits us into a right and left half. Primarily, movements of flexion and extension take place in this plane. Stand with your side up against a wall and bend over to touch your toes. You will notice your side never leaves the wall. This is an example of flexion of the spine and movement in the sagittal plane. The frontal plane bisects you from side to side, dividing you into front and back. Since abduction and adduction occur in this plane it is easy to demonstrate. Stand with your back against a wall and perform a jumping jack. Again you will see your back stays in contact with the wall. The final plane is the transverse plane with divides the body into a top and bottom half. Any rotational movement, such as twisting your waist, occurs in this plane. Although some basic movements occur in the cardinal planes, most of our dynamic movements occur in diagonal planes, either upper-extremity high, upper-extremity low, or lower-extremity low. These are a combination of multiple planes of movement.

As the movement occurs within a plane, the joint moves in a 90-degree relationship to that plane. Therefore, since the sagittal plane bisects the body from front to back, the axis runs side to side. Therefore, the frontal axis moves in the sagittal plane. Consequently, the sagittal axis, that runs anterior to posterior, moves in the frontal plane. The vertical axis moves in the transverse plane. For example, when you shake your head no, that in the transverse plane. Imagine your spinal column as a rod, mimicking the vertebral axis. As that rod spins back and forth, it produces the "no" rotational movement, that occurs in the transverse plane.

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Skeletal system

There are 206 bones that make up the skeletal system. Functions include support and protection, attachment site for muscles, mineral storage, and hemopoiesis or blood cell formation. The axial skeleton consists of the skull and trunk region while the upper and lower extremities make up the appendicular skeleton. Bones are classified into five categories based on their shape and function, long bones, short bones, flat bones, irregular bones, and sesamoid bones. Most bones have similar features to them, easily seen by examining a long bone such as the femur. The shaft, or diaphysis, has an outer wall of hard, dense, compact bone (cortex) and surrounded by a periosteum. The inner lining of the cortex is known as the endosteum and the inner portion of the diaphysis is the marrow cavity. The long ends of the bone are known as the epiphysis, shaped to articulate with the neighboring bone. Early in development there is a plate of cartilage that separates the epiphysis from the diaphysis known as the epiphyseal growth plate. This eventually solidifies when maturity is reached. The edge of the epiphysis is covered by an articular cartilage to allow for smooth joint movement.

The solidification of cartilage that occurs at the growth plate is not the only occurrence in the body. The continual repair, breakdown and new bone formation occurs based on the stresses placed on the bone particularly by the forces produced by the muscles attached. When a bone is fractured, the healing process progresses from cartilage formation to hard bone. Bones also have distinctive markings to enhance their function. It can either be processes (some elevation) that primarily serve as an attachment site for tendons or ligaments or cavities (some indentation) that allow spaces for other structures.

Joints and movement

Bone structure plays a role in the type and movement allowed at a joint. Some joints, such as sutures, allow for no movement. These can be found between the bones that comprise your skull. Other joints are classified as amphiarthrodial, or slightly movable. An example of a symphysis amphiarthrodial, one held together by a fibrocartilage pad, is the intervertebral disks of the spine. Diarthrodial, or synovial joints, are most commonly found in the body and allow for free movement. Synovial joints are surrounded by a membrane known as a joint capsule that helps to produce and contain synovial fluid. This fluid acts as a lubricant to the joint and when a joint is injured, the reason it can swell up like a water balloon. Synovial joints are held together with ligaments that connect one bone to another and vary in length, shape, and strength. Some ligaments are intra-articular, or located within the joint capsule, while others are extra-articular, or located outside the joint capsule. Hyaline and articular cartilage provides additional lubrication and cushioning between the two bony surfaces.

Diarthrodial joints are further classified by the type of movement allowed and the surfaces of the joint. Gliding joints, such as the carpal joints of the wrist, provide limited movement but ball-and-socket joints (enarthrodial), such as the shoulder, allow movements in all directions. Descriptions of all the joints can be found in Table 1.6 of the textbook. A general rule-of-thumb is that the more movement a joint has, it sacrifices some stability.

Therefore, a joint like the shoulder that has movement in all directions is likely to dislocate, or the joint comes out of alignment, due to the lack of stability. Stability and mobility can be altered by muscle tension, proprioception, and motor control. The amount of movement, or range of motion, that takes place can be measured by healthcare professions using a goniometer. However, it is important to note that the range of motion for a particular joint varies between individuals.

Osteokinematic motion is movement that occurs in relation to the three cardinal planes of motions around an axis of rotation at the joint. Common motions include flexion, extension, abduction, adduction, and rotation. A further breakdown of motions at individual joints can be found in Table 1.7. In order for these motions to occur, athrokinematic motion must also take place. These accessory motions occur at the joint surface and can either be a spin, roll, glide, or combination of the three. This motion is minimal and therefore not easily measured. However, if the arthrokinematic motion does not occur or is limited, it can significantly impact the osteokinematic motion.

(CSLO 1, CSLO 2, CSLO 4)

References

Floyd, R.T., & Thompson, C.W. (2018). Manual of structural kinesiology (20th ed). New York, NY: McGraw Hill. ISBN10: 125987043X ISBN13: 9781259870439

Skeletal Module. (n.d.). Retrieved from http://anatomy.mheducation.com/html/apr.html?animal=human& login=1562016601139