elbow/forearm (brian) Flashcards
trochlea arc of articular cartilage, how many degrees?
300
distal humerus articular surface: rotation? tilt? varus/valgus?
5 degrees IR 30 deg anterior tilt valgus 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 angulation 5.7degrees 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 crest
LRCL: lat epicondyle to annular ligament
annular ligament - from margins of sigmoid notch of proximal ulna
MCL complex of elbow: name the components
anterior bundle
posterior bundle
transverse bundle
anterior bundle of the MCL of elbow: name the components. When is each component most susceptible to injury?
anterior, central posterior BANDS
anterior: in elbow extension
posterior: in elbow flexion
central: iosmetric, doesnt matter
what provides elbow valgus stability? at what ROM?
intrinsic bony restraint: <20 or >120 degrees
anterior bundle of MCL: from 20-120 degrees
list the elbow primary stabilizers
bony articulation
MCL
LCL
list the elbow secondary stabilizers
radial head
joint capsule
CEO and CFO
name the primary and secondary stabilizers to axial loading of the forearm
primary: radial head
secondary: 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 radius
FCR: from CFO to base of MT2 and 3
palmaris longus: from CFO to flexor retinaculum
FDS: 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 2-5
FPL: proximal radius/IOM to base of distal phalanx of thumb
PQ: medial distal ulna to lateral distal radius
explain gantzer’s accessory FPL and clinical significance
accessory head of FPL sometimes found
can cause compression of AIN
what muscles make up the mobile wad? Origins, insertions, innervation
BR: lateral supracondylar ridge to radial styloid - radial n
ECRL: lateral supracondylar ridge to dorsal base of MC2-radial n
ECRB: lateral epicondyle to dorsal base of MC3 - PIN
list the superficial extensors of the forearm: origins, insertions, innervation
anconeus - lCEO to olecranon. radial n
EDC - CEO to extensor hood. PIN
EDM - CEO to extensor hood. PIN
ECU - 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. PIN
APL - from proximal ulna/radius/IOM to base of 1st prox phalanx. PIN
EPB - from proximal radius/IOM to base of proximal phalanx of thumb
EPL - from proximal ulna/IOM to thumb distal phalanx. PIN
EIP - from distal ulna/IOM to extensor hood. PIN
list the contents of each wrist extensor compartment
1: APL, EPB
2: ECRL, ECRB
3: EPL
4: EDC, EIP (PIN lies outside the compartment, deep to it)
5: EDM
6: 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 artery
radial 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 palm
then the rest of the radial a turns laterally and enters snuffbox, then pierces between the two heads of the first dorsal interosseus
then 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 a
lies deep to pronator teres
ulnar 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 n
becomes 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 teres
runs between FDP and FDS (same plane as ulnar n, ulnar a)
then emerges between FDS and FPL, gives off palmar cutaneous branch
then enters the carpal tunnel, then divides to the fingers
AIN 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 neuritis
presents 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 humerus
vistigial fibrous band connects it to medial epicondyle=ligament of struthers
median n passes deep to it.
it can cause median n compression
distinguish 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 structers
lacertus fibrosis
pronator teres
sublimus bridge
AIN:
pronator teres
FDS
aberrant vessels
gantzer’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 tunnel
exits tunnel, passing into forearm between heads of FCU
penetrates deep flexor-pronator aponeurosis
travesl between FDS and FDP along with ulnar a (ulnar to it)
emerges between FDS and FCU tendons at wrist, enters guyon’s canal
bifurcates in the hand in guyon’s canal into 3 zones:
zone 1: proximal to bifurcation - affects both sensory/motor
zone 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:
MCL
capsule
olecranon
roof:
osborne’s ligament
name the possible sites of ulnar n compression from proximal to distal
medial IM septum
arcade of struthers
hmedial epicondyle (osteophytes)
cubital tunnel/Osborne’s ligament/anconeus epitrochlearis
arcuate ligament - aponeurosis of FCU heads
ligament of spinner (aponeurosis between FDS of D3 and humeral head of FCU)
deep flexor/pronator aponeurosis
guyon’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 it
from ulnar n palsy
explained a clawed hand. what is it? how does it happen?
ulnar 2 digits will claw, sometimes long finger involved a bit
MCPJ 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 FCU
with 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 brachialis
branches into superficial branch - travels under BR and pierces deep fascia to become subcutaneous on dorsoradial wrist - about 9cm proximal to radial styloid
travels 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
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 loss
often confused with tennis elbow
pain usually 3-cm distal to lateral epicondyle cf. tennis elbow
occurs 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 BR
Recurrent radial vessels AKA leash of Henry
ECRB leading edge
Arcade of Frohse AKA proximal edge of supinator
Supinator, distal edge
What is Wartenberg Syndrome? what else is it called?
compression neuropathy of superficial radial n
usually copreseed at posterior border of BR as nerve pierces fascia to become superficial
causes: trauma e.g. traction during wrist reduction, or outside pressure
AKA cheiralgia paresthetica
