Anatomy - elbow and forearm 2

Question 1

trochlea arc of articular cartilage, how many degrees?

Answer 1

300

Question 2

distal humerus articular surface:rotation?tilt?varus/valgus?

Answer 2

5 degrees IR30 deg anterior tiltvalgus 6-8 deg

Question 3

what is the carrying angle of the elbow? (definition and value)

Answer 3

angle between long axis of humerus and long axis of ulna.10-15 deg in males, 15-20 deg in females (valgus)

Question 4

radial head safe zone: defintion and importance

Answer 4

arc between lister’s tubercle and radial styloid - roughly 90 degree arc. safe placement of screws to avoid impingement

Question 5

radius anatomic bowing:in what plane(s) and how much? where is the apex of curvature?

Answer 5

coronal, 10 deg, apex mid-radius (radial side)saggital, 4.7 degrees, apex dorsal, proximal shaft

Question 6

anteromedial facet of coronoid: how much is unsupported by ulnar metaphysis?

Answer 6

58%

Question 7

PUDA: what is it and how much?

Answer 7

proximal ulna dorsal angulation5.7degrees apex dorsal, about 47mm from tip of olecranon

Question 8

what attaches to the coronoid tip?

Answer 8

nothing

Question 9

LCL complex of elbow: name the components, origins, insertions

Answer 9

LUCL: lat epicondyle to supinator crestLRCL: lat epicondyle to annular ligamentannular ligament - from margins of sigmoid notch of proximal ulna

Question 10

MCL complex of elbow: name the components

Answer 10

anterior bundleposterior bundletransverse bundle

Question 11

anterior bundle of the MCL of elbow: name the components. When is each component most susceptible to injury?

Answer 11

anterior, central posterior BANDSanterior: in elbow extensionposterior: in elbow flexioncentral:iosmetric, doesnt matter

Question 12

what provides elbow valgus stability? at what ROM?

Answer 12

intrinsic bony restraint: 120 degreesanterior bundle of MCL: from 20-120 degrees

Question 13

list the elbow primary stabilizers

Answer 13

bony articulationMCLLCL

Question 14

list the elbow secondary stabilizers

Answer 14

radial headjoint capsuleCEO and CFO

Question 15

name the primary and secondary stabilizers to axial loading of the forearm

Answer 15

primary: radial headsecondary: TFCC, IOM

Question 16

the forearm IOM: which part is most important?

Answer 16

central part. the middle ligamentous complex.

Question 17

name all forearm muscles innervated by the median n., its origin and insertion(excluding the ones innervated by the AIN)

Answer 17

pronator teres: from CFO to lateral radiusFCR: from CFO to base of MT2 and 3palmaris longus: from CFO to flexor retinaculumFDS: from CFO to base of middle phalanges 2-5

Question 18

name all the forearm muscles supplied by the AIN, origins and insertions

Answer 18

FDP (radial 2 digits): proximal ulna and IOM to base of distal phalanges 2-5FPL: proximal radius/IOM to base of distal phalanx of thumbPQ: medial distal ulna to lateral distal radius

Question 19

explain gantzer’s accessory FPL and clinical significance

Answer 19

accessory head of FPL sometimes foundcan cause compression of AIN

Question 20

what muscles make up the mobile wad? Origins, insertions, innervation

Answer 20

BR: lateral supracondylar ridge to radial styloid - radial nECRL: lateral supracondylar ridge to dorsal base of MC2-radial nECRB: lateral epicondyle to dorsal base of MC3 - PIN

Question 21

list the superficial extensors of the forearm: origins, insertions, innervation

Answer 21

anconeus - lCEO to olecranon. radial nEDC - CEO to extensor hood.PINEDM - CEOto extensor hood. PINECU - CEO to dorsal base of MC5.PIN

Question 22

deep extensors of the forearm. origins, insertions, innervation

Answer 22

supinator. origin=LCL, lateral epicondyle, supinator crest. insertion=radial shaft. PINAPL - from proximal ulna/radius/IOM to base of 1st prox phalanx. PINEPB - from proximal radius/IOM to base of proximal phalanx of thumbEPL - from proximal ulna/IOM to thumb distal phalanx. PINEIP - from distal ulna/IOM to extensor hood. PIN

Question 23

list the contents of each wrist extensor compartment

Answer 23

1: APL, EPB2: ECRL, ECRB3: EPL4: EDC, EIP (PIN lies outside the compartment, deep to it)5: EDM6: ECU

Question 24

describe the path of the radial artery from start to finish including all its main branches

Answer 24

brachial artery in antecubital fossa branches into radial arteryradial artery gives off recurrent branch right away, just distal to biceps tendon. This travels backwards between BR and brachialis (alongside the radial n)radial a continues at proximal forearm between BR and pronator teres. It stays under BR (between deep and superficial flexors)at wrist it gives off superficial palmar branch, which pierces the thenar eminence and enters the palmthen the rest of the radial aturns laterally and enters snuffbox, then pierces between the two heads of the first dorsal interosseusthen it goes between the two heads of the adductor pollicis anteriorly, and then becomes the DEEP palmar arch

Question 25

describe the path of the ulnar artery form start to finish

Answer 25

brachial a branches in antecubital fossa into ulnar alies deep to pronator teresulnar a gives off common interosseous artery which branches into the anterior and posterior IO artery - these pass on either side of the IOM.  the posterior IO artery passes through a hole at proximal end of IOM to get to dorsal side.  anterior IO artery travels with AIN.  posterior IO artery goes down to the wrist between superficial and deep extensors, where it runs with the PIN under the 4th compartment.ulnar a then continues between FDP and FDS.  proximally it runs alongside median n (but median n dives between heads of pronator teres)distally at wrist, travels with ulnar n between FDS and FCU tendons (along with ulnar n)enters guyons canal - artery stays medial to nbecomes superficial palmar arch 

Question 26

describe the path of the median n from the elbow to the end, including the AIN

Answer 26

lies medial to brachial artery in arm, enters antecubital fossa and passes between heads of pronator teresruns between FDP and FDS (same plane as ulnar n, ulnar a)then emerges between FDS and FPL, gives off palmar cutaneous branchthen enters the carpal tunnel, then divides to the fingersAIN branches from median n at variable point as it passes between pronator teres heads.  Lies on IOM between FDP and FPL.  travels with Anterior IO artery.  terminates at PQ

Question 27

what is AIN syndrome?  how does it present?

Answer 27

AIN compression neuropathy or neuritis presents with weakness of things supplied by AIN: FPL, FDP2 and FDP3, normal sensory function.

Question 28

explain the supracondylar process and the ligament of struthers.  clinical significance?

Answer 28

rare residiual supracondylar process on ulnar side of distal humerusvistigial fibrous band connects it to medial epicondyle=ligament of struthersmedian n passes deep to it.it can cause median n compression distinguish from pronator and AIN syndrome by also having pronator weakness 

Question 29

list the sites of median n compression including AIN

Answer 29

Median n:supracondylar process/ligament of structerslacertus fibrosispronator teressublimus bridge AIN:pronator teresFDSaberrant vesselsgantzer's accessory FPL 

Question 30

describe the path of the ulnar nerve from the upper arm to the end

Answer 30

travels along anterior aspect of medial IM septum in upper arm, piercing it to the posterior side via arcade of struthers (8-10cm prox to medial epicondyle), then travels up against medial triceps head. goes behind medial epicondyle, enters cubital tunnelexits tunnel, passing into forearm between heads of FCUpenetrates deep flexor-pronator aponeurosistravesl between FDS and FDP along with ulnar a (ulnar to it)emerges between FDS and FCU tendons at wrist, enters guyon's canalbifurcates in the hand in guyon's canal into 3 zones:zone 1: proximal to bifurcation - affects both sensory/motorzone 2: deep motor branch only (supplying intrinsics)zone 3: sensory branch - supplies ulnar side of hand  

Question 31

what is pronator syndrome?  how does it present?

Answer 31

median n compression neuropathy in the forearm, usually from between pronator heads but can also be from sublimis bridge, lacertus. presents like CTS but also involves thenar/palm - i.e. palmar cutaneous n is also involved

Question 32

name the boundaries of the cubital tunnel

Answer 32

floor:MCLcapsuleolecranon roof:osborne's ligament

Question 33

name the possible sites of ulnar n compression from proximal to distal

Answer 33

 medial IM septumarcade of struthershmedial epicondyle (osteophytes)cubital tunnel/Osborne's ligament/anconeus epitrochlearisarcuate ligament - aponeurosis of FCU headsligament of spinner (aponeurosis between FDS of D3 and humeral head of FCU)deep flexor/pronator aponeurosisguyon's canal (the 3 zones) 

Question 34

what is the anconeus epitrochlearis?

Answer 34

anomalous muscle from medial olecranon to medial epicondyle - i.e. like a medial sided anconeus roughly where osborne's ligament would be  

Question 35

what is froment's sign? cause?

Answer 35

thumb cannot adduct but compensates by IPJ flexion: ulnar n palsy 

Question 36

what is wartenberg's sign?  cause?

Answer 36

small finger abduction due to unopposed EDM (it inserts more ulnarly)from loss of palmar interosseous to counteract it from ulnar n palsy

Question 37

explained a clawed hand.  what is it?  how does it happen?

Answer 37

ulnar 2 digits will claw, sometimes long finger involved a bitMCPJ hyperextension: from unopposed long extensors (loss of lumbricals)IPJs flexed - unopposed long flexors (loss of lumbricals) only occurs with LOW ulnar n palsy - high palsy would also involve FDP which would eliminate clawing

Question 38

what common nerve anastomosis occurs in the forearm?  Explain what it is , prevalence, and clinical significance

Answer 38

Martin-Gruber anastomosis. 15-32% prevalence.motor fibres from median n proper (proximal to bifurcation) or AIN cross over to ulnar n (remember they are in the same plane, between FDS and FDP).i.e. median n supplies intrinsics normally supplied by ulnar n.with high ulnar n palsy - can still have intrinsic function but lose FDP (D4,5) and FCUwith high median n palsy - loss of intrinsics!   

Question 39

describe the path of the radial nerve from elbow to the end

Answer 39

emerges at elbow between BR and brachialisbranches into superficial branch - travels under BR and pierces deep fascia to become subcutaneous on dorsoradial wrist - about 9cm proximal to radial styloidtravels to first dorsal webspace, branches. PIN dives under supinator (proximal edge=arcade of Frohse) and travels within the muscle substance, wraps around radial neck to dorsal side and supplies all extrnsic wrist extensors except ECRL (radial n)terminates as sensory branch to wrist capsule on dorsum, deep to 4th comp

Question 40

what is PIN syndrome? etiology?

Answer 40

compression neuroapthy of PIN: benign tumours, most often lipoma/ganglia, synovitis from RA, trauma, vasculitis

Question 41

what is radial tunnel syndrome?

Answer 41

compression neuropathy of the PIN that only causes pain; no motor/sensory lossoften confused with tennis elbowpain usually 3-cm distal to lateral epicondyle cf. tennis elbow occurs with compression at any of PIN syndrome sites

Question 42

what are the possible sites of PIN compression?

Answer 42

FREAS:Fibrous bands anterior to radiocapitellar joint - between barchialis and BRRecurrent radial vessels AKA leash of HenryECRB leading edgeArcade of Frohse AKA proximal edge of supinatorSupinator, distal edge

Question 43

What is Wartenberg Syndrome?  what else is it called?

Answer 43

compression neuropathy of superficial radial nusually copreseed at posterior border of BR as nerve pierces fascia to become superficialcauses: trauma e.g. traction during wrist reduction, or outside pressure AKA cheiralgia paresthetica