Wrist

What is the concave and convex portion of the Radiocarpal Joint?

-Concave: Distal radius and articular disc -Convex: Proximal scaphoid, lunate, triquetrum

What is the Concave & Convex of the Medial Compartment of the Midcarpal Joint?

-Concave: Distal surface of scaphoid, lunate, triquetrum -Convex: Capitate & Hamate ****Arthrokinematic analysis focuses on medial

What is the Concave & Convex portion of the Lateral Compartment of the Midcarpal Joint?

-Concave: Proximal surface of trapezium and trapezoid -Convex: Distal pole of scaphoid

Carpal Tunnel

-Concavity palmar aspect of carpals -Transverse carpal ligament -Tunnel formed

What is the function of the Palmar Radiocarpal Ligaments?

-Deep & Seperate from palmar capsule of wrist -Stronger/thicker than dorsal radiocarpal -Taut in: Full Extension

Special Considerations of FCR?

-Does not cross carpal tunnel -Passes in separate tunnel formed by groove of trapezium and fascia from transverse carpal ligament

What are the examples of the extrinsic ligaments of the wrist?

-Dorsal Radiocarpal Ligaments -Radial Collateral Ligament -Palmar Radiocarpal Ligaments -Ulnocarpal Complex(triangular fibrocartilage complex/TFCC)

What muscles radially deviate the wrist?

-ECRL -ECRB -EPL -EPB -FCR -APL -FPL *These muscles are lateral to AP axis of rotation *ECR & FCR are synergists here to stabilize wrist

What muscles ulnarly deviate the wrist?

-ECU -FCU *FCU & ECU are synergists and stabilize. Injury to one of the muscles you are incapacitate kinetics of UD. If no ECU, FCU unopposed, flexed posture, poor grip.

What are the secondary wrist extensors?

-EDU(Extensor Digitorum Communis) -EI -EDM -EPL

Purpose of the wrist ligaments

-Essential to maintain alignment and transfer forces, otherwise leads to deformation/instability

What does the Ulnocarpal Complex(Triangular Fibrocartilage Complex/TFCC) compose of?

-Fills: ulnocarpal space allowing pronation/supination -Articular Disc -Ulnar Collateral Ligament -Palmar Ulnocarpal ligament

What are the tendons and nerves that pass through the carpal tunnel?

-Flexor Digitorum Superficial Tendon( 4 tendons) -Flexor Digitorum Profundus Tendons (4 tendons) -Flexor Pollicis Longus -Median Nerve

Wrist Flexors: Functional Considerations

-Internal moment arm & cross sectional area: FCU produces greatest flexor torque of primary flexors -ECU acts eccentrically during wrist flexion: stabilize ulnar side of wrist (fragile, lack of bony reinforcement) -FCR & FCU Synergistic: Wrist Flexion *Opposition with: Radial Deviation & Ulnar Deviation *Varying degrees UD/RN with wrist flexion -Flexors 2x cross sectional area wrist extensors, similar strength disparity -Lifting: Large isometric flexion torques *Co-activation: wrist extensors for favorable flexor length

What is the Capitate carpal bone associated with?

-It is the wrist axis of rotation. Provides longitudinal stability of the wrist -Articulation with 3rd MC=longitudinal Stability

What are the Intermediate Intrinsic Ligaments?

-Lunotriquetral Ligaments -Scapholunate Ligaments -Scaphotrapezial Ligaments

What is the function of the Radial Collateral Ligament?

-More developed palmarly -Taut with: Ulnar Deviation and combined extension

What is the Scaphoid bone prone to?

-Most frequently fractured carpal because it's on the radial side and when we exert pressure on a fall 80% of the pressure on the radius and 20% on ulna -Minimal Blood Supply**

Dorsal Intercalated segment instability (DISI) or Ventral Intercalated Segment Instability (VISI)

-Named by location of distal lunate -Disrupts natural arthrokinematics, high stress, joint destruction, unstable -Altered length-tension relationships *Ulnar Translocation of the Carpus 1. Ulnar tilt of radius creates tendency for ulnar translation 2. Normally resisted by extrinsic ligaments (palmar radiocarpal) 3. RA weaken ligaments

What are the Long Intrinsic Ligaments?

-Palmar Intercarpal Ligament (Inverted V) -Dorsal Intercarpal Ligament

Flexion Central Column Arthrokinematic

-Palmar roll & dorsal slide *Not stable *Poorly suited for WB

What classifies ligaments to be Intrinsic Ligaments?

-Proximal and Distal attachments on carpals

What classifies ligaments to be Extrinsic Ligaments?

-Proximal attachment outside carpal; attached distally to carpals

What occurs in rotational collapse of wrist?

-Proximal row prone to create the zigzag deformity -Zigzag deformity when compressed both ends -Prevented by ligaments, tendons, intercarpal articulations -Lunate most frequently dislocated; no muscles attach *Scaphoid for stability; tear scapholunate ligament

What is the function of Scapholunate ligament?

-Scaphoid rolls on radius at different speed than the lunate ***Damage to ligament may predispose to joint instability and disrupt natural kinematics

What are the Intrinsic Ligaments of the wrist?

-Short -Intermediate -Long

Additional Arthrokinematics Proximal Carpals

-Slight "rocking" into flexion or extension -Position of scaphoid and lunate changes with RD and UD

What type of motions are associated with Intercarpal Joints?

-Small Gliding Motions -IMPORTANT TO COMPLETION OF FULL ROM

Wrist UD and RD (Frontal Plane Kinematics)

-Synchronous convex on concave rotations -UD: *Ulnar (medial) roll and radial slide *Hamate presses proximal carpals against radial styloid process *Stability to wrist for gripping -RD: *Radial (lateral) roll and ulnar slide

What is the function of the Dorsal Radiocarpal Ligaments?

-Thickening of fibrous capsule -Reinforce posteriorly -Taut in: Full flexion

How do we achieve Maximal Grip Effort

1. Finger flexion with wrist flexion: Decreased force 2. Greater extension nearly triples force 3. Extrinsic finger flexors elongated enough length to put in mid range=more conductive to higher force production

Arthrokinematic driven by?

Actively driven by Muscles, but passively controlled by ligaments (Double V System)

Functions of muscles at the wrist

All muscles have moment arms producing torques: in both sagittal and frontal planes EX: ECRB -Dorsal to Medial-Lateral Axis -lateral to AP axis -Moment arm: Wrist extension & radial deviation

What is the CMC joint composed of?

Rigid articulation capitate & base third MC

What does the Trapezium articulate with?

Saddle-shaped articulates with 1st MC

What are the proximal row carpal bones that are relatively mobile?

Scaphoid Lunate Triquetrum Pisiform

What is the function of Lister's Tubercle of the Dorsal Surface Radius?

Separates ECRB and EPL

What does the distal forearm affect?

The ROM at wrist

Central column does not..?

-Account for all the carpal bones that participate in the motion

Wrist Closed and Resting Positions for Midcarpal Joint

-Closed Packed: Extension with UD -Resting Position: Neutral or Slight Flexion with UD

What carries most of the weight bearing force in the Radiocarpal Joint?

-80% of WB force scaphoid/lunate to radius, 20% articular disc

What is the "Average" position of function?

-10-15 degree of extension -10 degrees of Ulnar Deviation

Functional position of motion for frontal plane motion?

-30 degree UD -10 Degree RD

Making a Fist

1. Main Function: Position and Stabilize wrist for activities involving the hand 2. Finger flexion generates torque at wrist *Counterbalanced by: Wrist Extensors 3. Strong grip applied, extensors hold wrist -35 degrees extension/5 degrees UD -Optimizes: Length-tension relationship of extrinsic finger flexors -Repetitive grasping may lead to lateral epicondylopathy (tennis elbow) because we use our extensors even when we are flexing

Function of Extensor Retinaculum?

1. Tunnels 2. Prevents Bowstringing 3. Stabilize

Palmar Tilt allows what?

10 degree posterior to horizontal plane. Palmar tilt allows flexion > extension

How many degrees of freedom in the wrist?

2 degrees of freedom -Flex/Ext (Sagittal Plane) -UD/RD (Frontal Plane)

Ulnar Tilt allows what?

25 degrees of the radius towards ulna. Ulna tilt allows ulnar deviation > radial deviation

Capitate has a firm articulation with?

3rd Metacarpal and directs osteokinematics of hand

Functional position of motion for sagittal plane motion?

40 degrees flexion and extension

In what column does the Wrist Extension and Flexion occur in?

Central Column

Wrist Closed and Resting Positions for Intercarpal Joint

Closed Packed: Extension Resting Position: Neutral or slight flexion

Wrist Closed and Resting Positions for Radiocarpal Joint

Closed Packed: Extension Resting Position: Neutral with slight UD

What is the function of the Short Intrinsic Ligaments?

Connect distal row of carpals(single mechanical unit)

Radial Nerve innervates

Dorsal Side

Extension of Central Column Arthrokinematics

Dorsal roll & palmar slide -Elongates palmar radiocarpal ligament and wrist and finger flexors -Adds stability to wrist -Useful with WB through UE

What are the primary Wrist Extensors?

ECRL ECRB ECU

What are the primary wrist flexors?

FCR FCU PL(10 % are missing this)

What are the secondary wrist flexors?

FDP FDS FPL

When does the Ulnar Collateral Ligament become taut in?

Full Radial Deviation

What is considered to to be the axis of wrist motion?

Head of capitate(proximal)

During the wrist double joint system the motion is simultaneous where?

Radiocarpal and midcarpal joints

What is the lunate bone associated with?

Kienbock's Disease: Avascular necrosis (lack of blood supply causing the bone cells to die)

What is the function of the Palmar Intercarpal Ligament?

Lateral Leg: Connects capitate to scaphoid Medial Leg: Connect capitate to triquetrum

What is the Mid Carpal Joint composed of?

Lunate & Capitate

What compartment of the Midcarpal Joint has more motion?

Medial Compartment: Larger/more motion

Consider Cross Sections Areas with..?

Moment Arm

Median and Ulnar innervates

Palmar Side

What is the function of Palmar Carpal Ligament?

Prevents bowstringing

What has greater torque radial deviation or ulnar deviation?

Radial Deviation has 15% greater torque than Ulnar Deviation

What is the Radiocarpal Joint Composed of?

Radius & Lunate

Why isn't there a 3rd degree of freedom for wrist?

The lack of 3rd degree allows pronator/supinator muscles to transfer torques to hand(hand moves with radius)

What are the distal row carpal bones that are relatively mobile?

Trapezium Trapezoid Capitate Hamate