Anatomy - elbow and forearm 2 Flashcards
trochlea arc of articular cartilage, how many degrees?
300
distal humerus articular surface:rotation?tilt?varus/valgus?
5 degrees IR30 deg anterior tiltvalgus 6-8 deg
what is the carrying angle of the elbow? (definition and value)
angle between long axis of humerus and long axis of ulna.10-15 deg in males, 15-20 deg in females (valgus)
radial head safe zone: defintion and importance
arc between lister’s tubercle and radial styloid - roughly 90 degree arc. safe placement of screws to avoid impingement
radius anatomic bowing:in what plane(s) and how much? where is the apex of curvature?
coronal, 10 deg, apex mid-radius (radial side)saggital, 4.7 degrees, apex dorsal, proximal shaft
anteromedial facet of coronoid: how much is unsupported by ulnar metaphysis?
58%
PUDA: what is it and how much?
proximal ulna dorsal angulation5.7degrees apex dorsal, about 47mm from tip of olecranon
what attaches to the coronoid tip?
nothing
LCL complex of elbow: name the components, origins, insertions
LUCL: lat epicondyle to supinator crestLRCL: lat epicondyle to annular ligamentannular ligament - from margins of sigmoid notch of proximal ulna
MCL complex of elbow: name the components
anterior bundleposterior bundletransverse bundle
anterior bundle of the MCL of elbow: name the components. When is each component most susceptible to injury?
anterior, central posterior BANDSanterior: in elbow extensionposterior: in elbow flexioncentral:iosmetric, doesnt matter
what provides elbow valgus stability? at what ROM?
intrinsic bony restraint: 120 degreesanterior bundle of MCL: from 20-120 degrees
list the elbow primary stabilizers
bony articulationMCLLCL
list the elbow secondary stabilizers
radial headjoint capsuleCEO and CFO
name the primary and secondary stabilizers to axial loading of the forearm
primary: radial headsecondary: TFCC, IOM
the forearm IOM: which part is most important?
central part. the middle ligamentous complex.
name all forearm muscles innervated by the median n., its origin and insertion(excluding the ones innervated by the AIN)
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
name all the forearm muscles supplied by the AIN, origins and insertions
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
explain gantzer’s accessory FPL and clinical significance
accessory head of FPL sometimes foundcan cause compression of AIN
what muscles make up the mobile wad? Origins, insertions, innervation
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
list the superficial extensors of the forearm: origins, insertions, innervation
anconeus - lCEO to olecranon. radial nEDC - CEO to extensor hood.PINEDM - CEOto extensor hood. PINECU - CEO to dorsal base of MC5.PIN
deep extensors of the forearm. origins, insertions, innervation
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
list the contents of each wrist extensor compartment
1: APL, EPB2: ECRL, ECRB3: EPL4: EDC, EIP (PIN lies outside the compartment, deep to it)5: EDM6: ECU
describe the path of the radial artery from start to finish including all its main branches
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
describe the path of the ulnar artery form start to finish
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 thencontinues 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
describe the path of the median n from the elbow to the end, including the AIN
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
what is AIN syndrome? how does it present?
AIN compression neuropathy or neuritispresents with weakness of things supplied by AIN: FPL, FDP2 and FDP3, normal sensory function.
explain the supracondylar process and the ligament of struthers. clinical significance?
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 compressiondistinguish from pronator and AIN syndrome by also having pronator weakness
list the sites of median n compression including AIN
Median n:supracondylar process/ligament of structerslacertus fibrosispronator teressublimus bridgeAIN:pronator teresFDSaberrant vesselsgantzer’s accessory FPL
describe the path of the ulnar nerve from the upper arm to the end
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
what is pronator syndrome? how does it present?
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
name the boundaries of the cubital tunnel
floor:MCLcapsuleolecranonroof:osborne’s ligament
name the possible sites of ulnar n compression from proximal to distal
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)
what is the anconeus epitrochlearis?
anomalous muscle from medial olecranon to medial epicondyle - i.e. like a medial sided anconeus roughly where osborne’s ligament would be
what is froment’s sign? cause?
thumb cannot adduct but compensates by IPJ flexion: ulnar n palsy
what is wartenberg’s sign? cause?
small finger abduction due to unopposed EDM (it inserts more ulnarly)from loss of palmar interosseous to counteract itfrom ulnar n palsy
explained a clawed hand. what is it? how does it happen?
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
what common nerve anastomosis occurs in the forearm? Explain what it is , prevalence, and clinical significance
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!
describe the path of the radial nerve from elbow to the end
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 sideand supplies all extrnsic wrist extensors except ECRL (radial n)terminates as sensory branch to wrist capsule on dorsum, deep to 4th comp
what is PIN syndrome? etiology?
compression neuroapthy of PIN: benign tumours, most often lipoma/ganglia, synovitis from RA, trauma, vasculitis
what is radial tunnel syndrome?
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 elbowoccurs with compression at any of PIN syndrome sites
what are the possible sites of PIN compression?
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
What is Wartenberg Syndrome? what else is it called?
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 pressureAKA cheiralgia paresthetica
