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

Question 1

how many bones/joints make up the forearm

Answer 1

3 bones and 4 joints

humeri-ulnar

humeroradial

radio-ulnar

Question 2

goal of forearm joints

Answer 2

placement of hand

Question 3

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

Answer 3

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

Question 4

what would you palpate at the medial and lateral epicondyles

Answer 4

lateral = common extensor/supinator tendon

medial = common flexor/pronator tendon

Question 5

describe the trochlea

Answer 5

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

Question 6

describe the trochlear notch

Answer 6

jawlike

has a longitudinal crest

Question 7

what attaches to the tuberosity of the ulna

Answer 7

brachialis

Question 8

what attaches to the supinator crest

Answer 8

LCL/sup mm

Question 9

how is the radius positioned in supination

Answer 9

parallel and lateral

Question 10

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

Answer 10

proximal end is small

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

Question 11

describe the radial head

Answer 11

disc like

articular cartilage covers at 280 degrees of the rim

contacts the radial notch on the ulna

Question 12

what is the fovea of the radius

Answer 12

shallow cup shaped depression on radial head that articulates with capitulum

Question 13

contributions of the humeroulnar joint

Answer 13

contributes to flexion and extension

contributes to much of the stability of the elbow

Question 14

contributions of the humeroradial joint

Answer 14

contributes to flexion and extension

ligaments press the radial head against the capitulum

Question 15

what type of joint is the elbow (humeroulnar)

Answer 15

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

Question 16

where is the axis od the elbow for flexion and extension

Answer 16

near med-lat

lateral epicondyle through convex members

medial lip of trochlea is longer so the ulna deviates laterally

Question 17

what is the frontal plane angle of the elbow

Answer 17

normal cubitos valgus or carrying angle

average is 13 degrees

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

Question 18

what joints does the capsule around the elbow encompass

Answer 18

humeroulnar

humeroradial

radioulnar

Question 19

what are the periarticular tissues of the elbow

Answer 19

capsule

MCL

RCL

LCL

annular ligament

Question 20

describe the anterior fibers of the MCL

Answer 20

strongest

resist valgus

run from medial epicondyle to coronoid process

provides stability in the sagittal plane; 9 separate divisions

Question 21

describe the posterior fibers of the MCL

Answer 21

fan like

thickening of posterior/med capsule

from medial epicondyle to olecranon

resist valgus

tight in extreme flexion

Question 22

describe the transverse fibers of the MCL

Answer 22

from olecranon to coronoid process

only limited articular stability

Question 23

how can a WB injury to the MCL occur

Answer 23

extended and valgus force

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

Question 24

how can a NWB injury to the MCL occur

Answer 24

repetitive valgus produces strain

common with overhead athletes

may require “Tommy John surgery”

Question 25

what is Tommy John surgery

Answer 25

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

Question 26

where does the lateral collateral ligament complex run

Answer 26

2 primary bundles that run from the lateral epicondyle resist carbs forces

Question 27

describe the radial collateral ligament

Answer 27

merges with the annular lig, supinator, and ECRB

Question 28

describe the lateral ulnar collateral ligament

Answer 28

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

Question 29

when is intracapsular pressure at the elbow lowest

Answer 29

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

Question 30

what is a terrible triad injury

Answer 30

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

Question 31

ROM for elbow flexion/extension

Answer 31

5 degrees beyond neutral (5 degrees hyperextension) 145-150 flexion "functional arc"

Question 32

what happens fi there is a spinal cord injury above C5

Answer 32

paralysis of elbow flexors

Question 33

what can result in a flexion contracture

Answer 33

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

Question 34

describe the arthrokinematics of the humeroulnar joint

Answer 34

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

Question 35

what does the coronoid process do with full elbow flexion

Answer 35

coronoid process fits into the coronoid fossa of the humerus

Question 36

arthrokinematics of the humeroradial joint

Answer 36

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

Question 37

structure if the interosseous membrane

Answer 37

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

Question 38

function of interosseous membrane

Answer 38

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

Question 39

describe the force transmission of a compressive force through the hand

Answer 39

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

Question 40

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

Answer 40

distraction slackens central band of interosseous membrane oblique cord, annular ligament, and brachioradialis assist to support load