elbow Flashcards
what (basic) account for the eblows stability
bony articulation and soft-tissue stabilizers
what kind of joint is the elbow
Hinge joint
what are the 2 component of the elbow joint
Humero-radial
Humero-ulnar
what bones make up the basic elbow joint
the distal humerus, proximal radius and proximal ulna
what make up the Humeroulnar articulation
between the trochlea and the trochlear notch
what is the movement seen at the Humeroulnar articulation
flexion and extension
what makes up the Humeroradial articulation
between the capitulum and the head of the radius
what action is seen at the Humeroradial articulation
pronation/supination, flex/ext
what makes up the Proximal radioulnar joint
between the head of the radius and the radial notch of the ulna
what movement is seen at the Proximal radioulnar joint
pron/sup
what movement do we see at the distal radial ulnar joint
pron/sup
what makes up the distal RU joint
Articulation between the lateral side of head of ulna with ulnar notch of distal radius
what separates joint cavity of distal RU joint from wrist joint
an Articular disc
how much joint stability is provided by the bony architecture
50%
how Congruous is the elbow joint
One of the most congruous joints
how much joint stability is provided by the soft tissues of the elbow joint
50%
how many degrees of freedom in a hindge joint
2 DF
what movement is allowed at the elbow joint - high joint
flexion and extension
Proximal and distal RU are what kind of joint
pivot joints (trochoid) and allow axial rotation or pivoting.
how many joints are in the elbow
Anatomically there is 1 joint, the cubital complex (elbow), and 1 capsule
what kind of movement is allowed at all of the elbow structures - all together now
Physiologically, the elbow movements are flexion/extension & pronation/supination
Fibrous capsule
Completely encloses joints and blends with annular ligament and collateral ligament on each side
Annular ligament
holds the radial head in place in radial notch
what are the static soft tissue stabilizers of the elbow
Anterior capsule and collateral ligaments
Synovial capsule of the elbow jt
inner layer
Lines the deep surface of the annular ligament
synovial capsule and the proximal radio-ulnar joint
the SC Continuous with the synovial membrane of the proximal radio-ulnar joint
radius in the synovial membrane
Radius is able to rotate in here without tearing
role of the Medial and lateral ligament complexes
primary elbow stabilizers, and are thickenings of the fibrous capsule
Restrict – varus and valgus stress
valgus stresses cause the
Most instability
which is stronger the medial or lateral collateral ligament complex
medial
how many fat pads does the elbow have
3 fats pads - between the fibrous capsule and synovial membrane
3 elbow fat pads locations
Olecranon fossa – post
Coronoid fossa – ant
Radial fossa – ant
what is the bursa role in the elbow
Bursa role is to reduce friction of surface that are moving in each other
Subcutaneous olecranon bursa
between skin and olecranon process
Subtendinous olecranon bursa
between tendon of triceps and olecranon process
Bicipitoradial bursa
between biceps tendon and radial tuberosity
Radioulnar bursa:
between extensor digitorum, radiohumeral joint, and supinator
Olecranon bursitis
Inflammation of the subcutaneous olecranon bursa – olecranon bursitis or “student’s elbow”.
what causes Olecranon bursitis
Caused by repeated friction and pressure of the bursa.
Distal RU fibrous capsule- weakness.
encloses the joint – It has weak anterior and posterior bands
Distal RU synovial capsule
capsule lines the fibrous capsule and the proximal surface of the disc.
Sacciform recess is the proximal extension of the synovial capsule and it accommodates twisting during pron/sup
what makes up the medial complex
Formed by the Medial Collateral Ligament (MCL) or ulnar collateral ligament (UCL)
role of the medial complex
resist valgus stress
where is the medial complex coming from
Originates on the central part of anteroinferior medial epicondyle, just posterior to the axis of rotation for flexion/ext
3 bundles of the medial complex
anterior, posterior, and transverse
Anterior bundle of the medial complex characteristics
strongest and stiffest - most important component of ligamentous complex,
when does the ant bundle of the medial complex stabilize the elbow
primarily stabilizes elbow from 30° to 120°
portions of the anterior bundle of the medial complex
anterior band
posterior band
deep middle portion
anterior band of the ant bundle of the medial complex is taut when
taut close to extension
(stabilizes from ± 30 to 60°)
Deep middle portion of the anterior bundle of the medial complex
isometric during movement - positioned along the ulnohumeral joint axis
Posterior band of the anterior bundle of the medial complex
taut in flexion (stabilizes from 60° to 120° flexion)
Posterior bundle - the medial bundle
less defined thickening of capsule – functions as a corestraint with anterior bundle, taut at terminal elbow flexion
Transverse bundle runs from
from the tip of the olecranon to just distal to the coronoid (variably present, little role in elbow stability)
- not seen in everyone
Radial head role in support
Radial head is a secondary ulnohumeral joint stabilizer to valgus loads
Flexor and pronator muscles - as support
originate at the medial epicondyle and provide additional support on the medial side of the elbow
most common Medial complex injuries
Chronic attenuation and Posttraumatic
what type of people is chronic attenuation often seen in
throwing players
what is chrontic attenuation
combination of valgus and external rotation force, stretching over time
what is Posttraumatic
usually after a fall onto an outstretched hand (FOOSH) - associated injuries include fractures of radial head, olecranon, or medial epicondyle
the Lateral Collateral Ligament (LCL) is composed of which ligamnets
composed of radial collateral ligament, lateral ulnar collateral ligament, annular ligament, and accessory lateral collateral ligament
y shaped
lateral ulnar collateral ligament is a key stablizer for what
is key stabilizer for varus stress and posterolateral stability
where does the radial collateral ligament run
lateral humerus at the elbow axis of rotation and courses distally inserting into annular ligament
where does the lateral ulnar collateral ligament run too
lateral epicondyle to ulna (proximal)
what muscle does the RCl give rise too
origin for the supinator muscle
LCL is the primary restraint to
maintain ulnohumeral and radiocapitellar joints in a reduced position when elbow is loaded in supination
what is is called when there is an insuffiency in the LCL
posterolateral rotatory instability (PLRI),
what is posterolateral rotatory instability (PLRI),
commonly posttraumatic and is a combination of axial compression, external rotation, and valgus force
what are the 2ndary restraints of the elbow
the extensor muscles
posterolateral elbow rotatory instability requires insufficiency of
ligaments and muscular origins about the lateral elbow
Annular ligament runs from
from anterior margin of radial notch of ulna around the radial head to the posterior margin of radial notch (covered with hyaline cartilage)
Quadrate ligament runs from
from neck of radius to the inferior surface of radial notch of ulna
when does the qaurate ligament get taut
Anterior fibers = forearm supination
posterior fibers= during pronation
Shafts of radius and ulna are connected by
interosseous membrane (IM) (syndesmosis) and oblique cord (OC)
what muscles interest into the IO
FDP, FPL, APL, EPB, EPL, EI
what joint does the IO provide support too
RUJ
IM resists what kind of displacement
IM resists proximal displacement of radius on ulna during pushing movements
what kind of displacement does the oblique cord resist
OC resists distal displacement of radius during pulling movements
Distal RU joint - ligaments
Anterior radioulnar ligament
Posterior radioulnar ligament
triangular fibrocartilage complex (TFCC),
Anterior and posterior radioulnar ligament properties
both are weak - therefore we need support for other areas (triangluar)
triangular fibrocartilage complex (TFCC) is made up of what
extensor carpi ulnaris, interosseous ligament, pronator quadratus, and associated forearm muscles
Blood for Cubital Complex
elbow anastomosis via collateral branches from brachial artery and recurrent branches from radial and ulnar arteries
Blood for DRUJ
anterior and posterior interosseous arteries
Nerve Supply for Cubital Complex
articular branches primarily from musculocutaneous, median, and radial nerves
Nerve Supply for DRUJ
articular branches of anterior and posterior interosseous nerves
Elbow movement
flexion and extension
sup and pro
what joints do pronation and supination
in radio-capitellar and proximal and distal RU joints.
what jts do Flexion/extension
ulnohumeral and radio-capitellar joint.
Flexion/extension axis
Axis of rotation passes through the capitellum in line with the bottom of the trochlear sulcus (red line)
Supination/pronation axis
Axis passes through the center of the radial head and extends through the radial border of the distal ulna
Extension degress
0
5-10 hyperextension
what limits extension
Limited by bony contact and tension of anterior muscles and ligaments
how much active flexion can we get
145
how much passive flexion can we get
160
what is passive flexion limited by
limited by bony contact and posterior soft tissue tension
what is active tension lmited by
limited by apposition of contracting anterior muscles
is the distal humerous concave or convex
convex
trochlea & capitulum
Proximal ulna has concave feature
trochlear notch
Proximal radius has concave feature
radial head
flexion artho
anterior (volar) roll and glide of ulna and radius on humerus
- look at the fist
extension artho
posterior (dorsal) roll and glide of ulna and radius on humerus
Movements of proximal RUJ
pronation and supination
movement seen in the cubital complex during pronation and supination
Rotation (spin) of the head of radius about its axis in the osseofibrous ring (i.e., on the capitulum)
what does volar mean
anterior
range of supination and pronation
90-degrees
supination is restricted by
Limited by tension in interosseous membrane and volar capsule of the distal RU joint
what do the radius and ulna look like in supination
parallel
in pronation what do the radius and ulna look like
the cross each other
what restricts pronation
bony contact of the radius and the ulna ring(capitulm) and tension in dorsal band of distal RU joint
what is moving in pronation and supination at the proximal RUJ
convex radial head on the concave radial notch of the ulna
pronation at proximal RUJ
anterior roll and posterior glide of radial head on proximal ulna
supination at the proximal RUJ
posterior roll and anterior glide of radial head on proximal ulna
Distal RUJ cave and vex
Medial aspect of radius is concave AP (ulnar notch); radial aspect of distal ulna is convex AP
Distal RUJ pronation
anterior roll and glide of distal radius on ulnar head
Distal RUJ supination
posterior roll and glide of distal radius on ulnar head
do we do joint mobilzation and play in open or closed packed ppositions
open
Open-packed position Humeroulnar joint
70° of elbow flexion, 10° supination
Open-packed position Humeroradial joint
full extension and supination
Open-packed position Radioulnar joints
proximal- 35° of supination, 70° elbow flexion
distal - 10° supination
Close-packed position Humeroulnar joint
full elbow extension
Close-packed position Humeroradial joint
90° of flexion, 5° of supination
Close-packed position Radioulnar joints
5° of supination
during extension what do the olecranon and epis form
a stright line
during flexion what do the olecranon and epis form
isosceles triangle
Elbow flexion contractures develop when
rapidly when elbow is immobilized for extended period of time (6 weeks)
traumatic compressive forces what is most likely to fracture
Radial head and coronoid process are liable to fracture
is the elbow often dislocated
2nd most common joint dislocated
Dislocations may be simple (not fracture) or complex (with fractures)
what is more common Posterior or anterior dislocation
post
Posterior dislocation what direction does the ulna and humerus move
posterior - ulna
anterior - humerous
what normally causes a Posterior dislocation
due to fracture of coronoid process or humeral condyles (compressive force with extended elbow)
Associated fractures with elbow dislocations are more common in what population
children (bone fusion occurs ~ 14 to 17)
elderly due to fragile bones
In children where do we see associated fractures
fracture-separation of proximal radial epiphysis, or fracture dislocation of the humeral condyles
carrying angle - created by what
formed by the orientation of the trochlear groove
the distal projection of the medial edge of the trochlear compared to the lateral edge
the lateral orentation of the ulnar shaft
what is the average carrying angle
14
larger in females
is carrying angle present in fleexion and extension
not flexion just extesnion
where is the supinator crest
distal to the trochlear groove
what attaches at the supinator creast
laterasl portion of the UCL and supinator muscle
is the radial head concave or convex
concave
how many joints does the triceps cross
2
what are stronger elbow flexors or extensors
Elbow extensors are weaker than the elbow flexors by around 30%, and the dominant side is around 5-10% stronger than the non-dominant side.
Common Extensor Tendon comes from what side of the humerous
lateral epicondyle
what is in the common extensor tendon
Extensor carpi radialis brevis (Deep radial n.)
Extensor digitorum (PIN)
Extensor digiti minimi (PIN)
Extensor carpi ulnaris (PIN)
Lateral epicondylitis
Principally ECRB
May involve radioulnar bursa
Radial Nerve Entrapments
Posterior interosseous n. (comes off deep branch of radial n.) runs between 2 heads of supinator muscle through the Arcade of Frohse (present in 30% of population), which is a possible site of entrapment
Intermediate layer of the forearm
Flexor digitorum superficialis
Common Flexor Tendon comes from what part of the humerous
medial epicondyle
Common Flexor Tendon- muscles
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Flexor digitorum superficialis
Medial Epicondylitis
Inflammation of medial epicondyle and common wrist flexor tendon
Median Nerve Entrapment
Median and anterior interosseous nerves pass through the 2 heads of pronator teres
The 2 heads are joined by the tendinous arch of the FDS, and nerve can be entrapped there
Ulnar Nerve Entrapment
In tunnel entrance - space formed by medial intermuscular septum and covering layer of fascia (arcade of Struthers), pink
In tunnel exit: between two origins of flexor carpi ulnaris (Osborne’s lig), blue
