Biomechanics - Body Movements - Assignment Example

?Biomechanics-Body Movements In no more than 250 words explain how a group of muscles work together to perform a bicep curl. Skeletal or striated muscles usually work in groups to achieve a specific movement in the body. A bicep curl is the net effect of 2 muscles located in the upper portion of the arm. The bicep curl is a movement that takes place in conjunction with the bones to which the biceps brachii and the triceps muscles are attached respectively (McKinley & O’Loughlin, 2008). The two muscles are antagonistic to each other. The biceps brings about flexion while the triceps is responsible for extension of the upper arm. The upper end of the biceps has its origin from the scapula and its lower end is inserted on the radius bone lying on the medial aspect of the forearm. The muscle is located in the front portion of the forearm. Contraction of biceps brachii in response to nervous stimulation causes flexion i.e. the forearm is raised in an upward movement. The muscle is therefore categorized as a flexor muscle. In response to the flexion, i.e. when the biceps contracts, the antagonistic triceps muscle relaxes simultaneously. The triceps is located in the posterior portion of the upper arm with its origin from the scapula as well as the humerus bones. The point of insertion of triceps is at the olecranon process of the ulna, the long bone in the forearm located on the lateral side. Contraction of the triceps straightens or extends the arm and this is the reason for its classification as an extensor muscle. The movement follows the pattern of a lever of the third order, wherein the load is located at the hand, and the fulcrum at the elbow (Peterson & Bronzino, 2008). 2) In no more than 250 words describe the function of the skeleton and its importance in movement. The human skeleton is an integrated framework of 206 bones which supports the soft tissue and protects the vital organs (McKinley & O’Loughlin, 2008). The skeletal system has been classified as the axial skeleton, comprising of the bones lying along the central axis of the body, which includes the skull, the vertebral column and the rib cage; and the appendicular skeleton, comprising the bones of the arms and legs, as well as the pelvic and the pectoral girdles (McKinley & O’Loughlin, 2008). The appendicular skeleton is more pertinent as far as the body movements are concerned although the axial skeleton is by no means non-contributory, as it provides the central axis or the pivot around which the body movements occur. The mandible is the mobile portion in the skull and the vertebrae too glide to a certain extent to impart flexibility to the vertebral column. The appendicular skeleton however shows a great degree of motility and is responsible for locomotion. The upper and the lower limbs emanate from the pectoral and the pelvic girdle respectively while the ribs form a bony cage to protect the vital organs. The skeleton provides the hard, bony framework for the origin as well as insertion of the skeletal muscles, the contraction and relaxation of which is actually responsible for locomotion. The skeletal muscles are highly specialized and often occur in pairs to produce movement antagonistic to each other. The movement of the joints can vary from simple gliding, rotation, adduction, abduction, flexion and extension. The muscles are firmly attached to the bones through specialized structures called ligaments and tendons and movements occur in the form of levers of the 1st, 2nd and the 3rd order. 3) In no more than 250 words describe and provide examples of each synovial joint. Synovial joints are freely mobile articulations in which the participating bones are separated by a space called joint cavity (McKinley & O’Loughlin, 2008). These joints are freely mobile and are functionally classified as diarthrosis. There are four synovial joints in the human skeleton viz. the glenohumeral (shoulder) joint; the temporomandibular joint; the elbow, and the knee joint (McKinley & O’Loughlin, 2008). The cavity of each synovial joint is filled with a specialized synovial fluid which circulates into and out of the cartilage matrix under the effects of combined compression and re-expansion of the articular cartilage. The articular cartilage, which lacks the perichondrium, is a thin hyaline cartilage which reduces friction during the joint movement. It acts as a spongy cushion and prevents damage to the articulating ends of the bones participating in the joint. The repeated compression and relaxation at a synovial joint during exercise is essential for the health of the articular cartilage as the synovial fluid is replenished with nutrients, at the same time the waste material is removed from the joint. The synovial fluid lubricates as well as nourishes the articular cartilage as well as the articulating bones. The articular capsule is composed of an outer, fibrous layer composed of dense connective tissue and an inner, synovial membrane composed of areolar connective tissue. All synovial joints are highly innervated by sensory nerves which assist in detection of movement and pain stimuli, as well as high vascularisation to bring in nutrients and take away metabolic waste products. Bursae, fat pads and tendons are the other specialized structures present in synovial joints meant for protection, cushioning and strength respectively. 4) In no more than 250 words discuss the 3 main planes of movement and in each instance provide an example of muscle involvement. The three main planes of movement are the sagital, frontal and transverse planes. The sagital plane divides the body into the right and left parts and is therefore a vertical plane. The frontal plane is also vertical but divides the body into the anterior and posterior parts. The transverse plane is horizontal and divides the body into the superior and inferior parts with respect to the area where the transverse plane is applied. Human body movements are therefore described in a three dimensional format according to these three planes as well as on the basis of the axis, the latter being a straight line around which an object rotates. Although body movements in human beings cannot be simplified into strictly occurring in one plane as some movements juxtapose into one form from the other, still certain movements can be attributed to be occurring in specific planes. Most flexion and extension movements occur in the sagital plane such as walking, squatting, raising the arms alternatively or thrusting the legs forward sequentially during walking. Movements occurring in the frontal plane are exemplified by abduction (away from body midline)/adduction (movement towards the bodyline), side flexion, inversion (movement of sole towards medial side) and eversion (movement of sole towards lateral side), such as the movements occurring while jumping and bending towards one side (McKinley & O’Loughlin, 2008). Movements attributable to the transverse plane include rotation, horizontal flexion/extension as well as supination (lateral rotation of forearm)/pronation (medial rotation of forearm), such as the movements occurring during throwing, flinging or twisting of the hips. References McKinley, M. & O'Loghlin, V.D. 2008. Human Anatomy, Third Edition, McGraw Hill, NY, USA, 174-270 Peterson, D.R. & Bronzino, J.D. 2008. Muscular Movement, Biomechanics, Principles and Applications, CRC Press, FL, USA, 20-2-20-4 Read More