Lecture Joints of Elbow, Forearm, Wrist, and Hand

IP joints have

1 degree of motion: flexion/extension due to tongue in groove articulation between head of proximal phalanx and base of distal phalanx.

elbow complex stabilized by

1. bony articulation b/t olecranon process with olecranon fossa of ulna 2. firbous jnt capsule 3. collateral ligaments : medial and lateral collateral ligaments.

annular ligament functions to

1. hold radial head in place to guide and control the spin 2. Limit distraction and dislocation of radius

articular surfaces of posterior distal humerus

1. olecranon fossa - for articulation w/ olecranon process of ulna 2. Olecranon process and olecranon fossa fully articulated (locked out) when humeroulnar joint in full extension

3 radioulnar joints

1. proximal radioulnar joint - 2. Middle radioulnar joint 3. Distal radioulnar joint

Articular components of proximal radius

1. radial fovea 2. radial head/rim

articular components of proximal ulna

1. trochlear nothc 2. coronoid process 3. olecranon process 4. radial notch

MCP joints have

2 degrees of freedom flexion/extension abduction/adduction

The wrist is ellipsoid in shaped and has

2 degrees of freedom flexion/extension radial and ulnar deviation (wrist abduction/adduction)

CMC joint of thumb has

2 degrees of freedom - highly movile, saddle shaped, synovial joint formed form trapezium and base of MC1

3 radioulnar joints

2 synovial and 1 fibrous joint

CMC joint of thumb surrounded by ____ ligaments

5 ligaments 5 collateral ligaments

joints at elbow

Humeroulnar joint humeroradial joint

ligaments for MCP joint limit

Limits medially (varus) and laterally (valgus) directed forces at joints.

when you push away, push up, or off of something you are

Load is driven up radius NOT ulna using interosseous membrane is used to distribute some of the load from the radius to the ulna.

only the ____ articulates with the wrist

Radius

3. Distal radioulnar joint

Synovial joint b/t ulnar head and ulnar notch of radius

pronation

The radius rotates and pivots about the fixed ulna such that the radius and ulna are no longer parallel to each other

MCL tenses if you increase

Valgus it limits valgus

elbow has an ____ axis of rotation

a oblique medial lateral axis of rotation thorugh capitulum and trochlea of distal humerus.

the elbow and ofrearm joints function

adjust and increase the functional range of the upper limb allow for pronation/supination of forearm independent of shoulder movement for greater functional flexibility and manipulation.

The radial notch of ulna and annular ligament are both lined with

articular cartilage

radila head/rim

articulates with radial notch of ulna and annular ligament

Middle radioulnar joint

assist in stabilizing the proximal and distal radioulnar joints during forearm pronation and supination

palmar radiocarpal and ulnocarpal ligaments

attach from palm of distal radius and ulna to palmar aspect of carpals and limit WRIST EXTENSION

valgus

away from midline

excessive cubital valgus

away from midline producing excessive increase in the angle

collateral circulation at elbow

branch off brahcial a. -> profunda brachii a. runs along the distal humerus crosses the lateral elbow and anastomses with branch of radial artery (radial recurrent a. ) superior ulnar collateral a.

dislocation of radial head is more common in

children and juvenilles before epihysis has osefied

The radial notch of ulna and annular ligament

complete articular surfaces for radial head

Middle radioulnar joint is important in transmitting

compression forces form load bearing radiocarpal joint to the ulna so that compression forces are distributed between both forearm bones

distal radioulnar joint

convex ulnar head concave ulnar notch of radius articular disc

coranoid process articulation with

coranoid fossa of distal humerus

Coronoid fossa articulates with

coronoid process of ulna

ulnar head

distal

Interosseous membrane is not good for this type of load

distraction on forearm Distracting radius distally, moving radius closer to ulna and interosseous membrane gets laxity. Annular ligament and muscle forces take up the support of the laod.

dorsal radiocarpal ligaments run from

dorsal distal radius to dorsal aspect of carpals (Scaphoid, lunate, triquetrum) LIMITS WRIST FLEXION

Ligaments for MCP joint come off

dorsum of metacarpal head. Dorsal cord like portion Palmar fan shape from dorsal to palamar

joints of forearm are designed to

facilitated pronation and supination provide rotation of wrist and hand independent of roatation of ulna humerus

radiocarpal joint

favor flexion and ulnar deviation

Middle radioulnar joint

fibrous joint formed by union of crests of radius and ulna via interosseous membrane

2. Middle radioulnar joint

fibrous joint w/ interosseous membrane attached to crest of radius and ulna

distal radioulnar joint reinforced by

firbous joint capsule capsular ligaments : palmar and dorsal Articular disc: attaches form ulnar notch of radius to ulnar styloid process. The articular disc is interpose dbetween the ulna and distal radius - thus the distal ulna DOES not articulate iwth carpal bones

CMC I provides 2 degrees of motions

flexion/extension (coronal plane/AP axis) Abduction/Adduction (saggital plane/coronal axis) Opposition requires Axial rotation coupled w/other motions

radial collateral lig

from radial styloid prcess to scaphoid and trapezium limits ulnar deviation

The _______ joint is not necessary for elbow flexion

humeroradial joint

Pronation and supination is rotation that is indendent of the ____ and ______

humerus and ulna

laxity in RCL and UCL leads to

hyper mobility at wrist and over time degeratvive dease

palmar volar plate limits

hyperextension Most important limit to MCP hyperextension Reinforces anterior joint capsule Increases contact area between MC heads and base of phalanges improvidng MCP joint stability

forearm pronation and supination is

independent of the shoulder

Humeroulnar joint

limited to 1 degree of motion. Flexion/Extension Due to inerlocking of trochlear notch w/ trochlea and olecranon process and olecranon fossa.

the long digital flexors and extensor tendons cross

many joints. Each joint uses up some of the force and ROM that can be produced by the muscle-tendon unti.

collaeral ligaments reinforce the

medial and lateral elbow joint complex

MCL

medial collateral ligament - runs medial edpicondyl of humerus to coronoid process of olecranon process of ulna - Collectively provides most important limit to valgus force Also limits flexion/extension

CMC joints

most stable allows a good cupping motion most mobile is thumb

trochlear

moves in trochlear groove

when the elbow is fullly extended there is

no contact between radial head and capitulum of humerus.

the onlique angle of elbow forms a

normal carrying angle at elbow aka normal cubitus valgus = 18 degrees

olecranon process articulation with

olecranon fossa of humerus

radiocarpal joint

palmar tild distal radial articular surface is tilted 10 degrees in palmar direction. greater flexion ROM than extension ROM.

supination

parallel ulna and radius

the radiocarpal joint does not include the

pisiform

LCL

provides primary limit to varus directed force

radial head

proximal

Radiocarpal joint

proximal row of carpal bones Scaphoid lunate triquetrum distal radius articular disc attaches form ulnar notch of radius to ulnar styloid process

Ligamentous support of radiocarpal joint

radial collateral lig ulnar collageral lig

capitulum articulates with

radial fovea

radial fovea is concave depression in

radial head for articulation w/convex capituluum.

during elbow flexion , muscle-tendon forces will drive the

radial head in contact with capitulum.

radial notch articulation with

radial head/rim of radius

During pronation and supination, the radial head spins in the

radial notch of the ulna to allow the shaft of the radius to pivot about the ulna

wrist is composite joint comprising

radiocarpal and midcarpal Most of motion occurs at radiocarpal joint but full wrist ROM requries both joints to move normally. Both joints are synovial joints reinforced by ligaments

interosseous membrane takes load off

radius and puts it onto ulna

supination

radius and ulna positioned in parallel to each other

radial head spins and pivotes the

radius over the ulna

Primary function of wrist joints is to

regulated the amount of muslce-tendon force and ROM of extrinsic muscles that control the hand movements.

clinical implications of lax MCL

repetitive tension on MCL Compression at Lateral joint b/t radial head and capitulum of humerus Instability at medial joint Excessive cubitus valgus

MC heads are

round, base of proximal phalanges are shallow short not good stable fit so needs lots of ligaments for support

ulnar collateral ligament

runs from ulnar styloid process to pisiform, triquetrum, hamate, base of 5th metacarpal and limits radial deviation is limited

extended

space b/t humeroradial jnt

the radiocarpal joint is enclosed by

strong fibrouse joint capsule and reinforced by extrinsic ligaments that limit both radial and ulnar deviation and wrist flexion and extension

IP joints

synovial IP forme dbetween middle and proximal phalanges of fingers and thumb and middle and distal phalagnes of DIP

1. proximal radioulnar joint -

synovial int b/t radial head, annular ligament, and radial notch of the ulna

Proximal radioulnar joint

synovial jnt comprised of: radial notch of ulna - articular cart Radial head/rim - synovial membrane Annular ligament - attaches form anterior to posterior aspect of radial notch of ulna and is lined with articular cartilage encircling the radial head/rim

MCP joints

synovial joints formed between MC heads and base of phalanges

the elbow joint is a compound (more than 2 bones)

syovial joint includes: distal humerus, proximal ulna, proximal radius - all surrounded by firbous joint capsule

Deep transverse metacarpal ligaments

thick bands of firbous CT run between palmar plate to to palmar plate at MCp joints limit spread of fingers at MCP joint

Palmar volar plates

thick fribocart plates attach from palmar head of MC heads to palmar base of proximal phalanges

excessive cubital varus

toward midline producing excessive decrease in angle

varus

towards mideline

trochlea articulates with

trochlear notch of ulnar

radiocarpal joint

ulnar tilt - distal radius angled at 25 in ulnar direction provides for greater ulnar deviation ROM than radial ROM

LCL

weaker than MCL two parts 1. lateral epicondyl of humerus to annular ligament of radius 2. lateral epiondyl to supinator crest of ulna

radiocarpal joint ligaments limit

wrist motion in saggital plane = extension and flexion