Biomechanics II - Quiz 1

Kinesiology definition

Study of human movements

Biomechanics definition

Mechanical principles that relate directy to the human body

3 ways movement can be analyzed

• Anatomical contributions to movement (functional anatomy)

• Describing motion characteristics (kinematics)

• Determining the cause of motion (kinetics)

Functional anatomy definition

Study of the body components needed to perform a human movement or function

Prime focus of functional anatomy

The movement produced by the muscle or muscle group

Sagittal plane

• Separates the body into right and left halves

• Motion around the frontal axis

• Movement around joint: flex/ext

Frontal plane

• Separates the body into front and back halves

• Motion occurs around the sagittal axis

• Movement around joint: add/abd

Transverse plane

• Separates the body into upper and lower halves

• Motion occurs around the vertical axis

• Motion at the joint: rotation, supination/pronation

Bones that make up the pelvic girdle

• Sacrum

• Coccyx

  • Two hip bones (ilium, ischium, and pubis)

Sacroiliac joints

• Posterior laterally

• Sacrum and Iliac

Pubic symphysis joint

• Anteriorly

• 2 sides of the pubis connect in the front

Lumbosacral joint

• Superiorly

• L5 and S1, vertebraeW

Which joint has the most movement in the pelvic girdle

Lumbosacral

Functions of the pelvis

• Supports the weight of the body

• Recieves ground forces and transmits them up the vertebral column

• Supports and protects the pelvic viscera

• Provides attachment for muscles

• Makes up bony portion of birth canal

Why do women have a wider pelvis

It makes up the bony portion of the birth canal

Posterior sacroiliac ligament attachment point

PSIS

Sacrotuberious ligament attachment point

PIIS

Where does the sciatic nerve pass through

Greater sciatic foramen

Innervates the hamstring

Scatic nerve

Hold together the anterior part of the SI joint

Anterior sacroiliac ligament

Strongest and deepest ligament in SI joint

Interosseus sacroiliac ligament

Prevents forward movement of sacrum

Short posterior sacroiliac ligament

Prevents downward movement of sacrum

Long posterior sacroiliac ligament

Attachment of the glute max and prevents forward rotation of the sacrum

Sacrotuberous ligament

Nutation definition

Sacral flexion-base of sacrum moves anteriorly and inferiorly thus inferior portion of sacrum and coccyx move posteriorly

Counternutation definition

Opposite of nutation, occurs with trunk extension or hip flexion

Pubic symphysis function

• Low mobility

• High stability

Limits the rotation of L5 nd S1 and assists in preventing L5 from moving anterior on S1

Iliolumbar ligament

Ideal spinal tilt

30 degrees

Increased lumbar lordosis

• More hollowed out lumbar area

• Greater angle than 30 degrees

Decreased lumbar lordosis

• Straightened out lumbar area

• Angle smaller than 30 degrees

Neutral position for pelvic girdle

When ASIS and PSIS are level

Anterior pelvic tilt

• Occurs in the sagittal plane

• ASIS moves anteriorly to the pubic symphysis

• Lumbar vertebrae go into increased lordosis

• Hip flexion

Posterior pelvic tilt

• Occurs in the sagittal plane

• ASIS moves posterior to the pubic symphysis

• Decreased lordosis

• Hip extensionL

Lateral pelvic tilt

• Occurs in the frontal plane

• Right or left

• Iliac crest height is not level

Motions when the left leg is off the ground

• L iliac crest drops (L lateral tilt)

• L hip abducts

• R hip adducts

• Trunk laterally bends to the R

Hip hiking

• The pelvis is raised on the unsupported side

• Occurs when walking with the leg forced straight

• Allows the foot to clear the ground during swing phase

Acetabulum movement during pelvic rotation

• Right leg forward —> left acetabulum rotates medially

• Right leg backward —> left acetabulum rotates laterally

Primary muscles in roation

• Obliques

• Adductors (opp. side)

• Lats (opp. side)

• Medial and lateral rotators @ the hip

Point of reference in hip movement

NWB leg

Anterior pelvic tilt force couple

Hip flexors and trunk extensors

Shortened and lengthened muscle in APT

• Shortened: hip flex and trunk ext

• Lengthened: hip ext and trunk flex

Posterior pelvic tilt force couple

Hip extensors and trunk flexors

Shortened and lengthened muscles in PPT

• Shortened: hip ext and trunk flex

• Lengthened: hip flex and trunk ext

Lateral flexion force couple

WB hip abductors and NWB quadratus lumborum

Hip drop (Trendelenburg)

• NWB leg dips below the other

• The trunk still laterally bends to the WB side

• Caused by weak WB hip abductors