BiologicalStructural Bases Anatomical Description and Its Limitations Key

Biological/Structural Bases Anatomical Description and Its Limitations

Key Anatomical Concepts ● Anatomical Position ● Planes- particular spatial direction or dimension of motion ○ ○ ○ Frontal Sagittal Transverse ● Axes- imaginary line about which a body rotates ○ ○ ○ Anterio-posterior Medio-lateral Longitudinal

Directional Terms ● ● ● ● Superior- head Inferior- feet Anterior- front Posterior- back Medial- midline Lateral- sides Distal- farther from the torso Proximal- closer to the torso

Joint Motions ● Sagittal Plane ○ ○ Flexion- decrease in joint angle Extension- increase in joint angle Flexion- forward movement Extension- backward movement ● Frontal Plane ○ ○ Abduction- away from the midline Adduction- toward the midline ● Transverse Plane ○ ○ Inward rotation- medial Outward rotation- lateral

Special Joint Motions ● ● ● ● Pronation- internal rotation of forearm and foot Supination- external rotation of forearm and foot Horizontal adduction- shoulder towards midline Horizontal abduction- shoulder away from midline Elevation- superior direction (shoulders and jaw) Depression- inferior direction (shoulders and jaw) Circumduction- conical movement (shoulder)

Joint Motion Activity ● Find a partner and a space in the room ● Take 1 major sports movement and describe the body movements with correct directional and joint movement terminology ● 3 step process for each movement ○ ○ ○ 1: Pre-movement- what the athlete looks like to start the movement 2: During Movement- what is happening to the body during the movement 3: Post-movement- how does the athlete look at the end ● Do not tell the name of the movement. Only the description. ● Pass paper to another group and they will perform the action and try to guess the movement.

Muscle Structures ● Epimysium- connective tissue around the whole muscle ● Perimysium- connective tissue around each fascicle ● Fascicles- many distinct bundles of muscle fibers ○ Hundreds of muscle fibers within each fascicle ● Endomysium- connective tissue around each muscle fiber ● Connective tissue blends together to form a tendon or fuse with the calcified connective tissue, periosteum

Muscle Arrangement ● Parallel ○ ○ Muscle fascicles are aligned parallel to the long axis or line of pull Rectus abdominis, sartorius, biceps brachii ● Pennate ○ ○ ○ Muscle fascicle are aligned at a small angle to a tendon or aponeurosis Aponeurosis- a distinct connective tissue band within a muscle Feathered appearance Unipennate ■ Tibialis posterior and semimembranosus Bipennate ■ Rectus femoris and gastrocnemius Multipennate ■ Deltoid

Muscle Structure ● Each muscle fiber consists of hundreds to thousands of smaller filaments called myofibrils ● Myofibrils have small sections called sarcomeres ○ ○ ○ Contractile structures of muscles Actin Myosin ● Hypertrophy ○ ○ Stretching increases sarcomeres in series within muscles to increase range of motion Number of sarcomeres are muscle fiber length are related to muscle performance

Muscle Actions ● Muscle forces are the main internal motors and brakes for human movement ● Torques created by skeletal muscles coordinate with torques from external forces to obtain motion ● Neuromuscular activation of muscles that contributes to movement or stabilization ● Eccentric ● Isometric ● Concentric ● Based on the balance of the forces and torques present at any given instant

Muscle actions ● If the torque the activated muscle creates is equal to the torque of the resistance ○ Isometric- same length ● Torque of the muscle group makes is larger than the torque of the resistance ○ Concentric- muscle shortening ● Torque of the muscle group makes is less than the torque of the resistance ○ Eccentric- muscle lengthens

Muscle Tension ● Activated muscles create forces by pulling about equally on all their attachments ● Active ○ ○ Forces created between actin and myosin fibers (contractile proteins) Uses energy stored in ATP ● Passive ○ ○ Force that comes from an elongation of the muscletendon unit Passive insufficiency- increase in passive tension limits range of motion in multiarticular muscles

The effect of passive tension on joint motions can be felt easily in multijoint muscles when the muscles are stretched across multiple joints. This phenomenon is called passive insufficiency. Lie down in a supine (face upwards) position and note the difference in hip flexion range of motion when the knee is flexed and extended. The hamstring muscle group limits hip flexion when the knee is extended because these muscles cross both the hip and the knee joints. Clinical tests like the straight-leg raise (Eksstrand, Wiktorsson, Oberg, & Gillquist, 1982), active knee extension (Gajdosik & Lusin, 1983), and the sit-and-reach (Wells & Dillon, 1952) all use passive insufficiency to evaluate hamstring static flexibility. Careful body positioning is required in flexibility tests because of passive insufficiency and other mechanical factors across several joints. Some aspects of this issue are explored in Lab Activity 3.

Review What is biomechanics? Why study it? Biomechanical knowledge is useful for solving what kinds of problems? Qualitative vs Quantitative. Compare and Contrast.

Review What are the nine principles of Biomechanics? Explain each one. Anatomical terms to describe position and motion in the body. Name and define three kinds of muscle actions.