Biomechanics Exam 1

what are the three parts of the pelvis?

ilium, ischium, and pubis

what is an innominate?

one side of the pelvis

what is the angle of inclination of the femur?

angle formed by the femoral neck and the femoral shaft in the frontal plane

what is the normal angle of inclination for the femur?

125 degrees

what is coxa varus angle?

<125 degrees

what is coxa valgus angle?

>125 degrees

changes in joint angle can result in…?

decreased muscle strength, joint degeneration, decreased ROM

What is the normal name for coxa valgus? What is this increased risk for?

hip dysplasia

risk of femoral subluxation and dislocation

what causes coxa varus?

trauma, infection, underlying bone disease (rickets, OI, etc)

what is femoral torsion?

the rotational relationship between the neck of the femur and the femoral shaft

what is normal femoral torsion?

15 degrees

what is femoral anteversion?

angle is > 15 degrees

what is femoral retroversion?

angle is < 15 degrees

what is the acetabular labrum?

serves to deepen the acetabulum (by 30%) to diminish the load from the femoral head

what part of the acetabular labrum is vascular?

outer 1/3

what part of the acetabular labrum is avascular?

inner 2/3

how does the acetabular labrum create a suction like force?

creates negative pressure, keeping synovial fluid in the joint

normal value of flexion, osteokinematics at the hip - femur on the pelvis

0-120 degrees

normal value of extension, osteokinematics at the hip - femur on the pelvis

0-30 degrees

normal value of abduction, osteokinematics at the hip - femur on the pelvis

0-45 degrees

normal value of adduction, osteokinematics at the hip - femur on the pelvis

0-30 degrees

normal value of internal (medial) rotation, osteokinematics at the hip - femur on the pelvis

0-45 degrees

normal value of external (lateral) rotation, osteokinematics at the hip - femur on the pelvis

0-45 degrees

What is the hip flexion ROM needed for ascending stairs?

47-66 degrees

What is the hip flexion ROM needed for descending stairs?

26-45 degrees

What is the hip flexion ROM needed for walking on level surfaces?

30-44 degrees

What is the hip flexion ROM needed for sitting with knees flexed?

90-112 degrees

What is the hip flexion ROM needed for putting on socks?

120 degrees

What is the hip flexion ROM needed for squatting?

115 degrees

what is lumbopelvic rhythm?

movement of the lumbar spine in relation to the pelvis

What is ipsidirectional lumbopelvic rhythm?

combined movement of pelvis and hip

What is contradictional lumbopelvic rhythm?

pelvis and spine rotate in opposite directions

what is trendelenburg sign?

weak hip abductors opposite the lower hip causing Lspine to bend toward the weak side to compensate.

in the femur and hip joint, what is the convex surface and what is the concave surface? In which direction does roll and slide happen?

convex - femur

concave - acetabulum

roll and slide - opposite

in hip flexion and internal (medial) rotation, in which direction does the femoral head slide?

posterior

in hip extension and external (lateral) rotation, which direction does the femoral head glide?

anterior

in hip abduction, which direction does the femoral head glide?

inferior

lumbar lordosis shortens which muscle?

psoas major muscle

in end range flexion, adductors act as…

extensors

in end range extension, adductors act as….

flexors

glut med anterior fibers abduct during…

flexion

glut med posterior fibers abduct during…

extension

when the hip is in neutral, glut med posterior fibers all…

externally rotate

when the hip in in flexion, all fibers of glut med…

internally rotate

what are the actions of glut min?

abduct, hip flexion, internal rotation

when is the greatest force generated at hip flexion for the glut max?

70 degrees

what is the up phase of squatting? What are the primary movers?

concentric hip and knee extension

hamstrings and gluts extend the hip

what is the down phase of squatting? What are the primary movers?

eccentric control of hip and knee flexion

hamstrings and gluts control hip flexion

what are the hip lateral rotators?

PGOGOQ

piriformis

gemellus superior

obturator internus

gemellus inferior

obturator externus

quadratus femoris

when hip flexion is >90 piriformis…

becomes a medial rotator

when stretching a muscle, what position should you put it in"?

the most lengthened position (opposite the action)

What are three functions of the skeletal system?

stores vitamins and minerals, support frame, and protects organs

what are the two fibrous proteins?

collagen and elastin

what is ground substance?

gel-like substance made of proteoglycans and glycosaminoglycans causes tissue to swell. With fibrous proteins, creates semifluid structure that resists compression

what are the three different cell types fibroblasts can differentiate to?

chondroblasts (cartilage), osteoblasts (bone), tenoblasts (tendon)

what are the 6 structural components that make up a joint composition?

joint capsule, ligaments, tendons, articular cartilage, bursae, fibrocartilage

what are the two layers in a joint capsule?

stratum fibrosum (outer) - external support, contains type I afferent receptors

stratum synovium (inner) - manufactures synovial fluid, contains type II receptors

What does synovial fluid do?

shock absorption, nutrition, lubrication, and delivers oxygen and nutrients to chondrocytes

ligaments are structures that do what?

resist motion

intra-articular

within the joint capsule (ACL, PCL)

extra-articular

outside the joint capsule (MCL, PCL)

Ligaments contain afferent sensory nerve fibers that carry feedback to the CNS about what?

movement, force, and injury

Ligaments connect….

bone to bone

tendons connect….

muscle to bone

tendon collagen fibers are oriented in a _____ direction to generate _____ forces

parallel, tensile

tenosynovium

synovium filles sheath that protects tendons from friction

what are the three types of cartilage?

hyaline (articular), fibrocartilage, and elastic

what does hyaline (articular) cartilage do?

protects ends of bones, reduces friction and dissipates load

what does fibrocartilage do?

in joins with discs, stabilizes and disperses force

where can you find elastic cartilage?

ears, epiglottis, and nose

what are osteoblasts

build and deposit new bone

what are osteoclasts

absorb/break down old or injured bone

what is an organic matrix?

collagen and proteoglycans

what is an inorganic matrix?

mineral component of bone

where is spongy bone?

epiphysis of long bone and center of shaft

where is compact bone?

shafts of long bone

What are fibrous joints?

syndesmosis, sutures, gomphosis…point is provide stability

what are cartilaginous joints?

symphysis and synchondrosis

what are synovia joints?

hinge, pivot, ellipsoid, condyloid, saddle, ball and socket, and plane

what is arthrokinematics?

interaction between two joint surfaces during osteokinematic movement (accessory movement)

hypomobile

decreased arthrokinematics motion

hypermobile

increased arthrokinematics motion

closed-packed position

maximum, congruence/contact in joint surfaces

loose(open)-packed position (resting position)

joint ligaments and capsule are slack

Arthrokinematics Roll

the points of contact of each surface change

Arthrokinematics Slide (glide)

points of contact remain the same throughout slide, motion of moving joint is parallel to stable joint surface

Arthrokinematics Spin

points of contact on each articulating surface are the same, one surface turns on or around another in a rotary motion

Convex surface moving on concave =

roll and slide in OPPOSITE directions

Concave surface moving on convex =

roll and slide in SAME direction

What are the three types of muscle connective tissue?

endomysium, perimysium, and epimysium

what is a group/bundle of muscle fibers called?

fascicle

What is fascia?

epi, peri, and endomysium woven together

where muscle fiber and tendon connective tissue meet is called…?

myotendinous junction

superficial fascia

under the dermis, skin mobility

what does deep fascia do?

binds muscle groups to other structures/each other

agonist

muscle that is contracting to initiate a specific movement

antagonist

muscle with the opposite action of the agonist

synergist

one of the several muscles acting together to produce a movement

co-contraction (stabilization)

the agonist and antagonist contract at the same time

concentric

muscle shortens with contraction