Biomechanics Exam 1 Study Guide

Biomechanics

the study of action and forces; application of mechanical principles in the study of living organisms

includes both the internal forces produced by muscles and the external forces that act on the body

Mechanics

branch of physics that analyzes the actions of forces on particles and mechanical systems; used to study the anatomical and functional aspects of living organisms

Statics

branch of mechanics dealing w/systems in a constant state of motion; either at rest or moving w/a constant velocity

Dynamics

branch of mechanics dealing w/systems subject to acceleration

Kinesiology

study of human movement

Kinematics

study of the description of motion, including considerations of space and time

what we are able to observe visually when watching a body in motion; study of size, sequencing, and timing of a movement - form or technique of a movement in a sport

Kinetics

study of the action of forces; force of a pull or push acting on the body

Anatomical reference position

erect standing position w/all body parts, including the palms of the hands, facing forward; considered the starting position for body segment movements

Superior

closer to the head

Inferior

farther away from the head

Anterior

toward the front of the body

Posterior

toward the back of the body

Medial

toward the midline of the body

Lateral

away from the midline of the body

Proximal

closer in proximity to the trunk

Distal

at a distance from the trunk

Superficial

toward the surface of the body

Deep

inside the body and away from the body surface

Cardinal planes

3 imaginary perpendicular reference planes that divide the body in half by mass

Sagittal plane

(left and right halves) divides body vertically; plane in which forward and backward movements of the body and body segments occur

Frontal plane

(coronal plane; front and back halves) splits body vertically; plane in which lateral movements of the body and body segments occur

Transverse plane

(horizontal; top and bottom halves) plane in which horizontal body and body segment movements occur when body is anatomical position

Mediolateral axis

(front-horizontal axis) perpendicular to the sagittal plane

Anteroposterior axis

(sagittal-horizontal axis) rotation in the frontal plane

Longitudinal axis

(vertical axis) rotation in the transverse plane

Sagittal plane movements

flexion/extension, hyperextension, dorsiflexion, plantarflexion

Frontal plane movements

abduction/adduction, right/left lateral flexion, elevation/depression, deviation, inversion/eversion

Transverse plane movements

rotation, pronation/supination, horizontal abduction/adduction

Flexion

anteriorly directed sagittal plane rotations of the head, trunk, upper arm, forearm, hand and hip

posteriorly directed sagittal plane rotation of lower leg

Extension

movement that returns a body segment to anatomical position from a position of flexion

Hyperextension

rotation beyond anatomical position in the direction opposite the direction of flexion

Dorsiflexion

bringing the top of the foot toward the lower leg

Plantarflexion

"planting" the ball of the foot

Abduction

moves a body segment away from the midline of the body

Adduction

moves a body segment closer to the midline of the body

Lateral flexion

sideways rotation of the trunk

Elevation

superior movement of the shoulder girdle

Depression

inferior movement of the shoulder girdle

Radial deviation

rotation of the hand at the wrist in the frontal plane toward the radius (thumb side)

Ulnar deviation

hand rotation toward the ulna (pinky side)

Eversion

outward rotation of the sole of the foot

Inversion

inward rotation of the sole of the foot

Pronation

combination of eversion, abduction and dorsiflexion at the subtalar joint

Supination

inversion, adduction, and plantar flexion at the subtalar joint

Horizontal abduction

(horizontal extension) movement of segments in the transverse plane from an anterior position to a lateral position

Horizontal adduction

(horizontal flexion) movement of segments in the transverse plane from a lateral to an anterior position

Long bones

skeletal structures consisting of a long shaft w/bulbous ends aka condyles, tubercles or tuberosities (e.g., femur, humerus, finger bones)

form the framework of the appendicular skeleton

Short bones

small, cubical skeletal structures, including the carpals and tarsals

provide limited gliding motions and serve as shock absorbers

Flat bones

skeletal structures that are largely flat in shape (e.g., scapula, sternum, ribs, patellae, some bones of skull)

protect underlying organs and soft tissues and provide large areas for muscle and ligament attachments

Irregular bones

skeletal structures of irregular shape (e.g., sacrum, vertebrae, coccyx, maxilla)

fulfill special fxs in the human body

Sesamoid bones

bones that are found on joints of the body (e.g., pat

Synarthroses

(immovable) fibrous joints that can attenuate force (shock absorbers), but permit little or no movement of the articulating bones

a) sutures of the skull - irregularly grooved articulating bone sheets that mate closely and tightly connected by fibers that are continuous w/the periosteum; eventually completely replaced by bone

b) syndesmoses - dense fibrous tissue binds the bones together, permitting extremely limited movement (e.g., coracoacromial, mid-radioulnar, mid-tibiofibular, inferior tibiofibular joints)s

Amphiarthroses

(slightly movable) cartilaginous joints that attenuate applied forces and permit more motion of the adjacent bones than synarthrodial joints

a) synchondroses - the articulating bones are held together by a thin layer of hyaline cartilage (e.g., sternocostal joints and the epiphyseal plates before ossification)

b) symphyses - thin plates of hyaline cartilage separate a disc of fibrocartilage from the bones (e.g., vertebral joints and pubic symphysis).

Diarthroses

(freely movable) "synovial" ; indicating only slight limitations to movement capability

at these joints, the articulating bone surfaces are covered w/articular cartilage, an articular capsule surrounds the joint, and a synovial membrane lining the interior of the joint capsule secretes a lubricant "synovial fluid"

Gliding joint

(plane; arthrodial) the articulating bone surfaces nearly flat, only movement permitted is nonaxial gliding (e.g., the intermetatarsal, intercarpal and intertarsal joints, and facet joints of the vertebrae)

Hinge joint

(ginglymus) one articulating bone surface is convex and the other is concave; strong collateral ligaments restrict movement to a planar, hinge-like motion (e.g., ulnohumeral and interphalangeal joints)

Pivot joint

(screw; trochoid) rotation is permitted around one axis (e.g., atlantoaxial joint and the proximal and distal radioulnar joints)

Condyloid

(ovoid; ellipsoidal) one articulating bone surface is an ovular convex shape, and the other is a reciprocally shaped concave surface; flexion, extension, abduction, adduction and circumduction are permitted (e.g., the second through fifth metacarpophalangeal joints and the radiocarpal joints)

Saddle

(sellar) the articulating bone surfaces are both shaped like the seat of a riding saddle; movement capability is the same as that of the condyloid joint, but greater ROM is allowed (e.g., carpometacarpal joint of the thumb)

Ball and socket joint

(spheroidal) the surfaces of the articulating bones are reciprocally convex and concave; rotation in all 3 planes of movement is permitted (e.g., the hip and shoulder joints)

Whole muscle

composed of muscle fibers in fascicles

covered in CT (epimysium, perimysium, endomysium)

Muscle fibers

"muscle cells" - several nuclei and mitochondria p/fiber

Myosin and Actin filament (proteins)

Organized into sarcomeres - connected end to end forming a myofibril (takes several to form one muscle fiber)

Parallel muscle fiber

greater ROM

Pennate muscle fiber

greater force production for a given cross-sectional area

Excitability

muscle tissue can be stimulated and activated

Ability to generate tension

muscle can pull (does not always shorten) - contract

Extensibility

muscle tissue can be stretched (lengthened)

Elasticity

if stretched within reasonable limits, the muscle tissue will return to its original length

Isometric

generation of tension w/no change in muscle length

-static; not changing (e.g., wall sit, planks; isolated movements)

Isotonic

generation of tension w/a change in muscle length

Concentric

muscle shortening (a true muscle contraction)

*moving a weight away from pull of gravity

*part of exercise when targeted muscle is working to perform action

Eccentric

tension generation w/muscle lengthening (e.g., gradual decrease in muscle tension to control the lengthening of a muscle)

*controlling weight against gravity's pull

*the "return"

Line of Pull

fundamental concept to understanding action of muscle; a muscle can only pull - its joint action is determined by its relation (physical orientation) to the joint it crosses

Agonist

prime mover or synergist; muscle doing the work (concentric/eccentric work) at a given time

Antagonist

acts to slow or stop a movement (opposite); (e.g., bicep and tricep)

Stabilizers

no acceleration; static and no changes in length

Neutralizers

negating an action you do not want to happen (e.g., pronators prevent supinators)

All-or-None Principle

a neural stimulus that achieves activation threshold will cause the specific muscle fiber(s) to contract w/100% force; applies to individual muscle fibers that are activated

*length tension = greater force production

Motor unit recruitment

a motor neuron and all of the muscle fibers it innervates

*more motor units recruited = greater force production (more pulling force generated)

Length-Tension Relationship

a muscle will generate max. force concentrically if it is pre-stretched slightly (eccentric)

Force-Velocity Relationship

muscle force production is inversely related to the velocity of concentric action (shortening)

*max. force production at zero velocity (isometric)

*max. shortening velocity decreases as the "load" increases

Muscle strength

the amount of force that can be generated by a muscle or muscle group

*determined by force (tension) development of muscle

Moment arm length

perpendicular distance from joint (rotational) axis to line of pull of the muscle (most effective at 90 degree angle)

Angle of pull

angle of pull of muscle on bone - influences the the moment arm length

Rotary component

the portion of total muscle "pull" or force directed 90 degrees to the bone; force that will cause joint motion

Muscle power

product of force and velocity

max. power output has an optimal combination of force and velocity

muscular force can be developed; velocity can be to an extent