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DPT 702: Biomechanics > Lecture 11 and 12: Elbow and Forearm Final. NEED TO FINISH > Flashcards

Lecture 11 and 12: Elbow and Forearm Final. NEED TO FINISH Flashcards

1
Q

how many bones/joints make up the forearm

A

3 bones and 4 joints

humeri-ulnar

humeroradial

radio-ulnar

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2
Q

goal of forearm joints

A

placement of hand

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3
Q

what motions are independent of one another in the forearm/wrist

A

flexion and extension and supination and pronation are independent of one another and the GH joint

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4
Q

what would you palpate at the medial and lateral epicondyles

A

lateral = common extensor/supinator tendon

medial = common flexor/pronator tendon

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5
Q

describe the trochlea

A

like a rounded empty spool of thread

medial and lateral borders flare up to form lips

trochlear groove is between the lips and spirals towards the medial side

medial lip flares/projects further distally

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6
Q

describe the trochlear notch

A

jawlike

has a longitudinal crest

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7
Q

what attaches to the tuberosity of the ulna

A

brachialis

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8
Q

what attaches to the supinator crest

A

LCL/sup mm

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9
Q

how is the radius positioned in supination

A

parallel and lateral

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10
Q

describe the ends of the radius; which is bigger/smaller

A

proximal end is small

distal end is large = major part of wrist; styloid process

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11
Q

describe the radial head

A

disc like

articular cartilage covers at 280 degrees of the rim

contacts the radial notch on the ulna

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12
Q

what is the fovea of the radius

A

shallow cup shaped depression on radial head that articulates with capitulum

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13
Q

contributions of the humeroulnar joint

A

contributes to flexion and extension

contributes to much of the stability of the elbow

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14
Q

contributions of the humeroradial joint

A

contributes to flexion and extension

ligaments press the radial head against the capitulum

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15
Q

what type of joint is the elbow (humeroulnar)

A

originally thought to be a hinge joint but it is actually a modified hinge joint because the ulna actually has a small amount of axial rotation

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16
Q

where is the axis od the elbow for flexion and extension

A

near med-lat

lateral epicondyle through convex members

medial lip of trochlea is longer so the ulna deviates laterally

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17
Q

what is the frontal plane angle of the elbow

A

normal cubitos valgus or carrying angle

average is 13 degrees

excessive = 20-25; cubitus varus secondary to growth plate injury

18
Q

what joints does the capsule around the elbow encompass

A

humeroulnar

humeroradial

radioulnar

19
Q

what are the periarticular tissues of the elbow

A

capsule

MCL

RCL

LCL

annular ligament

20
Q

describe the anterior fibers of the MCL

A

strongest

resist valgus

run from medial epicondyle to coronoid process

provides stability in the sagittal plane; 9 separate divisions

21
Q

describe the posterior fibers of the MCL

A

fan like

thickening of posterior/med capsule

from medial epicondyle to olecranon

resist valgus

tight in extreme flexion

22
Q

describe the transverse fibers of the MCL

A

from olecranon to coronoid process

only limited articular stability

23
Q

how can a WB injury to the MCL occur

A

extended and valgus force

can cause compression fx, ulnar nerve injury, anterior capsule injury, or damage to medial musculature at the epicondyles

24
Q

how can a NWB injury to the MCL occur

A

repetitive valgus produces strain

common with overhead athletes

may require “Tommy John surgery”

25
Q

what is Tommy John surgery

A

repair of the anterior fibers through a tendon graft from palmaris longus, gracilis, or plantaris

26
Q

where does the lateral collateral ligament complex run

A

2 primary bundles that run from the lateral epicondyle

resist carbs forces

27
Q

describe the radial collateral ligament

A

merges with the annular lig, supinator, and ECRB

28
Q

describe the lateral ulnar collateral ligament

A

thicker

attaches to supinator crest of ulna

taut at full flexion

guide wire with MCL in frontal plane during full flexion/extension

sling for the radial head

29
Q

when is intracapsular pressure at the elbow lowest

A

at 80 degrees flexion

“position of comfort”

those with a swollen elbow may hold this position, but there is a possibility of a flexion contracture

30
Q

what is a terrible triad injury

A

fall outstretched and supinated

elbow joint dislocation

fx radial head

fx coronoid process

problems can occur even with surgery… like persistent instability, nerve damage, heterotypic ossification, and stiffness

31
Q

ROM for elbow flexion/extension

A

5 degrees beyond neutral (5 degrees hyperextension)

145-150 flexion

“functional arc”

32
Q

what happens fi there is a spinal cord injury above C5

A

paralysis of elbow flexors

33
Q

what can result in a flexion contracture

A

immbolixation
heterotrophic ossification
osteophyte formation
inflammation/effusion elbow
muscle spasticity
triceps paralysis
scarring of skin on anterior elbow

34
Q

describe the arthrokinematics of the humeroulnar joint

A

concave trochlear notch of ulna and convex trochlea of humerus

primarily sagittal plane

ext = olecranon process wedged into olecranon fossa; extensible anterior tissues and some fibers of MCL

flex = concave trochlear notch tolls and slides on convex trochlea; elongation of ulnar n and posterior MCL

35
Q

what does the coronoid process do with full elbow flexion

A

coronoid process fits into the coronoid fossa of the humerus

36
Q

arthrokinematics of the humeroradial joint

A

between the cuplike fovea of the radial head and the capitulum

radius rolls and slides

flexion = radial fovea is pulled firmly against the capitulum by contracting muscles

minimal stability in sagittal plane

50% lateral stability to valgus forces

changes with the radial head

37
Q

structure if the interosseous membrane

A

radius and ulna bound together

central band is directed distally and medially at 20 deg from radius

tensile strength similar to patellar tendon

oblique cord is perpendicular

38
Q

function of interosseous membrane

A

central band: attachment site, binds, provides mechanism for force transmission,

transmits muscle forces to radiohumeral joint 3-4x BW

force shunted to radio ulnar joint

membrane tears = migration of radius

39
Q

describe the force transmission of a compressive force through the hand

A

transmitted through wrist at RC jt

goes to radius

force pulls central band of interosseous membrane taut

this tranfers a significant amount of force to ulna and then across humeroulnar joint

compressive forces finally transmitted to shoiulder

40
Q

describe the force transmission of holding a load (distracting force)

A

distraction slackens central band of interosseous membrane

oblique cord, annular ligament, and brachioradialis assist to support load

DPT 702: Biomechanics (13 decks)

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