Elbow Flashcards
ELBOW:
capsule - what, distal (2) medlat (1) pos (1), weak where, fat pad where (between + 3), triangular synovial fold what
capitulum - med/lat, cave/vex, groove, where to shaft
trochlea -shape, med vs. lat length & therefore, where to shaft, groove, ridge
ulna vs. radius - surface area, function
fovea - where, cave/vex, fits into
capsule
- shared by all joints
- distal (coronoid process & annular ligament), medlat (collateral ligaments), pos (olecranon fossa)
- weak antpos
- fat pad: between synovial membrane & capsule; adjacent to olecranon trochlea coronoid fossa
- triangular synovial fold: divides elbow joint
- capitulum: lateral/with radius, convex, capitulotrochlear groove, ant to humeral shaft
- trochlea: hourglass, medial/with ulna, medial longer = carrying elbpw, ant to humeral shaft, trochlear groove (divides trochlea), trochlear ridge (divides notch in ulna)
ulna - more surface area & function
fovea
- at radial head, concave
- fits into capitulotrochlear groove
ELBOW: Joints
HRJ - contact + motion (2G), congruency + why, type
HUJ - contact + motion (2G), congruency + why, type
HUMERORADIAL JOINT
- modified hinge, incongruent since humerus smaller than radius
- in flexion = radial head x radial fossa of humerus
- in extension = capitulum of humerus x radial head (no real contact d/t capitulotrochlear groove)
HUMEROULNAR JOINT
- modified hinge, congruent since trochlea does not make full contact unless weighted
- in flexion = trochlear ridge of ulna & trochlear groove of humerus slide on each other til coronoid process of ulna fits into coronoid fossa
- in extension = olecranon process x olecranon fossa
ELBOW: Joints
PRUJ - type, ulnar radial notch (where + cont with)
DRUJ - type, ulna x carpals, pole vs. seat
carrying angle - normal, if forearm bones shorter + dominant arm, when change, humerus x ulna axis, disappear in (2), function in weight + anatomical position
PROXIMAL RADIOULNAR JOINT
- pivot
- ulnar radial notch: below trochlear notch, cont with annular ligament
DISTAL RADIOULNAR JOINT
- pivot
- no ulna x carpal
ulnar surface area
- pole: with articlar disc
- seat: ulnar notch of radius
CARRYING ANGLE
- N: 10-15 (F) >5 (M), change at 14-15y
- inc if shorter forearm bone & dominant arm
- humerus & ulna axis not aligned
- disappear in PRO EXT & SUP FLEX
- anatomical position: shoulder ER, elbow EXT, SUP
- leads hand away from center of mass
ELBOW:
interosseous membrane - purpose (2)
axis - pass (2), ulna shift in PRO/SUP, flexion more in PRO/SUP
varus resistance (3), valgus resistance (1)
interosseous membrane
- stability, transfer weight from radius to ulna
axis
- pass capitulum & trochlea
- in pronation = ulna shift VARUS/LAT
- flexion in SUP>PRO
- valgus resistance: MCL>
- varus resistance: bony (50%), LCL (25%), ant joint capsule (25%)
ELBOW: Ligaments - MCL
shape, attach, receptors
proximal enthesis - fused with, where (2)
distal enthesis - where
anterior bundle - from to, restrain + ROM, muscles (3)
transverse band - purpose, from to
posterior bundle - blend, from to, limit
- MCL: triangular, no attachments, has mechanoreceptors
- proximal enthesis: fused with common flexor tendons, at humeral & trochlear articular cartilage
- distal enthesis: at coronoid process of ulna
anterior bundle
- from med epi to coronoid process
- against valgus (primary at 30 60 90; secondary til 120)
- overlay by FCU, teres, flexor digitorum
transverse band
- from olecranon process to coronoid process
- for joint approximation
posterior bundle
- blends with joint capsule
- from med epi to olecranon & coronoid process
- limits elbow EXT
ELBOW: Ligaments - LCL
RCL - reinforce, shape, from to, medical, against (2)
LUCL - from to, muscle (2), reinforce
annular - against (3)
quadrate - from to, purpose/limit
oblique cord - from to, purpose, fiber angle
RADIAL COLLATERAL LIG
- reinforce humeroradial articulation
- fan-shaped, from lat epi to annular
- always in elbow dislocations
- against varus & longitudinal distraction
LATERAL ULNAR COLLATERAL LIG
- from lat epi to ulna & annular
- overlay by supinators & extensors
- reinforce humeroulnar articulation
ANNULAR LIG
- against varus, supination, forceful valgus
QUADRATE LIG
- from radial notch to radial neck
- keep radial head from moving too much in PRO/SUP
OBLIQUE CORD
- ulna to radial tuberosity; fiber at right angle to interosseous membrane
ELBOW: Muscles
biceps - PCSA, peak degree of SUP & FLEX (+why), resistance, capsule
brachialis - PCSA, type of contraction, resistance, peak degree
brachioradialis - PCSA, peak degree, resistance
which for mob vs. stability & why
BICEPS
- medium PCSA, peak SUP at 40-50 PRO & FLEX at 80-100
- active in resisted (all positions), unresisted (not fully pronated)
- keeps capsule away during flexion
BRACHIALIS
- biggest PCSA, any contraction & resistance
- peak at 100 FLEX
BRACHIORADIALIS
- smallest PCSA, active in resisted
- peak at 100-120 FLEX
brachialis for mob since close to axis; brachiorads for stability since far
ELBOW: Muscles
triceps - capsule, which head workforce, resistance
anconeus - when in EXT, PRO/SUP
pronator teres - peak in resistance + position
pronator quadratus - resistance, fiber of superficial vs. deep (pass x across x)
supinator vs. biceps in resistance of SUP
TRICEPS
- keep capsule away during extension
- medial head: workforce since single-jointed; active in unresisted
- both heads active in resisted
ANCONEUS
- early EXT, help stabilize in PRO/SUP
PRONATOR TERES
- peak in resisted & rapid, weak in extended elbow
PRONATOR QUADRATUS
- both resisted & unresisted
- fiber of superficial head: pass transverse to interosseous membrane
- fiber of deep head: pass obliquely
SUPINATION
- supinator for unresisted, biceps for resisted
