kinesiology final

Shoulder Joint DOF

3 degrees of freedom

Hip Joint DOF

3 degrees of freedom

Knee Joint DOF

1 degree of freedom

Ankle and Foot DOF

3 degrees of freedom

Closed-Pack Position of the Hip

extension, slight abduction, and slight internal rotation

Position of Maximum Congruency of the Hip

Flexion, abduction, and external rotation

Stance Phase of Gait

comprises 60% of the gait cycle

comprised of:

-heel strike

-foot flat

-mid-stance (tibia perpendicular to the ground)

-heel off

-toe off

description:

-HS to FF: weight acceptance - attenuates forces

-FF to HO: mid-stance - maintains momentum; mid-stance can be viewed as a phase or an event

-HO to TO: push off - propulsion

Weight acceptance muscles (Gait)

these muscles work eccentrically to aid in absorption of force:

the quadriceps (bicpes femoris femoris, semitendinosis, semimembranosis) and the dorsiflexors (anterior tibialis)

Swing Phase of Gait

comprises of 40% of the gait cycle

comprised of:

-acceleration (rapid acceleration occurring immediately after TO)

-mid-swing (swing limb takes over stance limb)

-deceleration (swing limb decelerates preparing for HS)

Acceleration muscles (gait)

these muscles work concentrically immediately after TO:

hip flexors (iliopsoas, rectus femoris, tensor fascae latae, vastus medialis, vastus lateralis, and vastus intermedius), knee flexors (biceps femoris, semitendinosis, semimembranosis), and dorsiflexors (anterior tibialis)

Deceleration muscles (gait)

these muscles work eccentrically to bring the foot for HS:

hip extensors (gluteus maximus, hamstrings (biceps femoris, semitendinosis, semimembranosis), adductor magnus, and knee flexors (biceps femoris, semitendinosis, semimembranosis, gastrocnemius)

Knee Joint Ligaments

anterior cruciate ligament

posterior cruciate ligament

medial (tibial) collateral ligament

lateral (fibular) collateral ligament

Cruciate Ligaments

-both anterior and posterior lie in the center of the joint and are named according to their attachment sites on the tibia

-main stabilizing ligaments of the knee and restrain against anterior and posterior translations of the tibia on the femur (also restrain excessive internal and external rotation of the tibia)

Medial Collateral Ligament

-considered to be extra-articular ligaments

-the primary stabilizer of the medial side of the knee resists against valgus forces and external rotation of the tibia

Lateral Collateral Ligament

-considered to be extra-articular ligaments

-resists against varus forces

Menisci

• attaches to the tibial plateaus

• integral to normal knee function

• only the outer 25-30% of the menisci are vascularized

• medial meniscus is larger and thicker than the lateral

• lateral meniscus is smaller, thinner, and more mobile than the medial meniscus

Menisci Functions

• Load Transmission:

  • transmit 50-60% of the joint load when the knee is in extension and 85-90% when the knee is in flexion

• Shock Absorption

  • Partial menisectomy can reduce the shock-absorbing capacity of the knee by 20%

  • Loss of just 20% of this can lead to a 350% increase in contact forces

• Joint Lubrication

  • Help to compress synovial fluid into the articular cartilage

• Joint Stability

  • deepens the articulating surfaces of the tibial plateaus

• Guiding Movement

  • During flexion of the knee, it moves posteriorly

  • During extension of the knee, it moves anteriorly

Q-angle

Q= quadriceps

-the angle formed between the ASIS, center of the patella, and the tibial tuberosity

-angle measures the tendency of the patella to move laterally when the quadriceps contract

-normal considered:

• 8-14 degrees for males, 15-17 degrees for females

• >20 degrees is considered abnormal and associated with increased risk of patellar tracking problems

Angle of Torsion

between femoral neck and femoral condyles

average angle is 12-15 degrees in normal adults and is referred to as '“normal anteversion”

Angle of Inclination

created between the shaft of the femur and the femoral neck

125 degrees in a normal adult

more= coxa valga

less=coxa vara

Center Edge Angle

angle between vertical and anterolateral rim of the acetabulum

typically 30-45 degrees

Carrying Angle

-long axis of humerus and long axis of ulna (in anatomical position)

-normal degree is 10-15 (greater in females)

-excessive increased angle leads to: increased valgus stress on the elbow; increased tensile forces medially; increased compressive forces laterally

Pronation

-loose packed position of subtalar joint; unocks midfoot; allows for a flexible midfoot for weight acceptance during gait; attenuates ground reaction forces; helps foot conform to ground

-eversion; abduction; dorsiflexion

Supination

-closed packed position of subtalar joint; locks midfoot; provides a stable base during push-off of gait

-inversion; adduction; plantarflexion

Gait Cycle vs Running Cycle

-airborne/floating

-longer swing phase

-no double support

-longer stride length

-higher cadence (increased stride frequency)

-lower COG when running (lean forward more when running which results in COG being lower and closer to the lead foot)

Tension

three primary forces:

force transmitted along an object that would elongate if it were derformable

-said to be an axial force

Kinetic chain

-the components of the musculoskeletal system involved in the production and transmission of force between the base of support and the load being moved

-longest one in the human body is done during a press

rotator cuff role

keep the glenohumeral joint stable

Gravity

-force that we are working against when we are squatting, pressing, or pulling a load from the floor

-it operates vertically so the most efficient path for moving any load against this is a straight vertical line

-any force applied in any other direction is not work done against this force

Compression

force transmitted along an object that would get shorter if it were deformable

-said to be an axial force

Moment

force that tends to cause a rotation about an axis (ex:force transmitted down a wrench handle to turn a bolt)

-it is a shear force

Shear

at one end of the segment, force is being applied in one direction, while at the other end of the segment, rotational force is being resisted by the object being turned

Balance Point

-lifter load system will be in balance when it is in a position directly over the middle of the foot

-midfoot is out balance point because it is the point in which the greatest amount of force is needed to perturb our position (also where the least amount of force is needed to maintain our position)

-normal anatomical position, our center of mass is in a straight vertical line over our mid foot

Bones (squat)

transmit compressive force

connective tissue and muscles (squat)

transmit tension forces

both connective tissue and bones (squat)

work together to transmit moment

Poor jumping, lading, and cutting mechanics

injuries: ACL tears, MCL tears, lateral ankle sprains, tibia and fibula fractures

Upward rotation of scapula

-inferior angle of scapula rotates in a superior-lateral direction such that the glenoid fossa faces upward

-integral part of raising the arm overhead

-places the glenoid fossa in a position to support and stabilize the head of the raised humerus

-combo of clavicular elevation from SC joint and scapular upward rotation at the AC joint

-TOTAL OF 60 DEGREES

-muscles involved: serratus anterior and all parts of the trapezius

Squat Posterior Chain

• consists of hamstrings, glutes, and hip adductors

• trains these muscles along a longer ROM than most other exercises

• no other movement precedes the concentric contraction ofthe posterior chain with an eccentric contraction over as long range of motion

• produces a stretch-shortening cycle (stretch reflex)

Deadlift

-trains the ability to maintain a rigid lumbar spine under a load

-basic function of the spinal erectors is to hold the spine in position so that force can be transferred through the trunk

Isometric muscles (deadlift)

abdominals, obliques, intercostals, and all of the posterior musculature of the upper and lower back

Concentric muscles (deadlift)

quadriceps, glutes, hamstrings, and to a lesser degree, the adductor magnus used during deadlift

Eccentric muscles (squat)

quadriceps, glutes, hamstrings, and adductor magnus used during squat

Forces in squat

at the top of the squat, everything under the bar is in compression

Forces in Deadlift

at the top, everything is in compression but arms and shoulders are in tension