Unit 9

Primary radial and Ulnar Deviators

- The axis is the capitate with internal moment arms shown for the FCU and the ECU. The ECU has longer MA than FCU -The axis is the capitate with the internal moment arms for the ECRB and the FCR. The FCRB & ECRL similar MA with FCR.

functional activities of the hand

- The hand has an extraordinary ability to manipulate objects. To control the complex ability of the hand to manipulate objects, the motor and sensory cortex of the brain are very well represented compared with other body parts requiring less motor coordination. - Manipulation may involve functions that require fine (writing, precision gripping) as well as gross motor control (power grip, power key pinch). See Neumann p. 287 for more details.

wrist joint 2

- during compression of the wrist, the radiocarpal joint transfers 80% and the TFCC 20% of compressive load. the radius contacts the lunate (40%) and scaphoid (60%) - the radiocarpal joint has 2 degrees of freedom: flex/ext., ulnar/radial deviation - the radius is concave in both sagital and frontal planes. the scaphoid and lunate are convex in both sagital and frontal planes.

thumb joints

-2 degrees of freedom ( flex/ext, add/abd) and has rotation too. - flex/ext: 53 degrees, add/abd 42 and rotation 17 degrees -it is a saddle joint and similar to the SC joint - thumb opposition seperates human from monkeys. -most complex of the CMC joints, enabling extensive and essential movements of the hands.

thumb OA 2

-83% of Australian PTs who practice manual therapy complained of thumb pain. Most common joints were thumb MCP & CMC. -Thumb pain is common among physical therapists. Particularly PTs who use their thumbs regularly in manual therapy techniques. -Protect your thumb, avoid MT techniques that involve utilization of the thumb. -PT management involves splinting, rest, and gentle exercise to relieve pain.

Hand arches

-Arches help hand joints to adapt to objects shape for gripping. -Resting position for hand joints are in the relaxed arched position of the hand shown here -Intercarpal joints of distal row contributes to the proximal transverse arch of the palm. There is less motion near the keystones of these arches than on the sides of the arches.

key points 9D

-Arthrokinematics: in general, the bones of the first and second carpal rows, glide in opposite direction of their respective osteokinematic movements -Wrist compression add linear forces on the first carpal row from lateral to medial direction -The wrist flexors and extensors work in synergy to grip objects with the hand -Gripping forces are strongest in slight wrist extension -Imbalance on wrist muscle strength may lead to injury

key points 9a2

-Arthrokinematics: the bones of the first and second carpal rows, glide in opposite direction of their respective osteokinematic movements - ¡ Wrist compression add linear forces on the first carpal row from lateral to medial direction -¡ The wrist flexors and extensors work in synergy to grip objects with the hand -¡ Gripping forces are strongest in slight wrist extension -¡ Anatomical position of tendons crossing the wrist helps to determine muscle function -¡ Imbalance on wrist muscle strength may lead to injury

arhtrokinematics of the wrist 2

-Based on the concave/convex rule, during radial deviation, the scaphoid and lunate glide in the opposite direction of radial deviation. And vice- versa for wrist ulnar deviation. -The triquetrum does not touch the capitate and hence does not slide on the capitate during these deviations -Similar to the motion of the lunate, the capitate slide in the opposite direction of radial deviation and vice-versa -The axis for ulnar/radial deviation is the capitate. The scaphoid and the hamate rolls around this axis and glides for these carpal bones are negligible during these osteokinematic movements.

arthrokinematics of the wrist

-Based on the concave/convex rule, during wrist flexion, the first carpal row glide in the opposite direction of wrist flexion. And vice-versa for wrist extension -Note that, even though not on the illustration from your book, the scaphoid bone also glide in the same direction of the lunate. -Following the concave/convex rule, during wrist flexion, there is also a posterior glide of the convex capitate and hamate (medial compartment) on the concave scaphoid, lunate, and triquetrum. -For our purposes, we will ignore the glides occurring in the lateral compartment between the scaphoid and the trapezium/trapezoid.

muscle function on the wrist during gripping

-Both wrist flexors and extensors act synergistically on the wrist during gripping or when we make a fist -For gripping, the synergistic action of these muscles are strongest in the slight extension, then neutral, than flexion. -For functional activities, it is best to have patients function with the wrist in slight extension

MCP Stability

-Collateral ligaments assist with lateral stability for the joints, they are taut in flexion (90 degrees, closed packed position for the MCPs) and loose with extension (0 degrees allowing movement into Abd and Add). -The capsule here is not thick anteriorly. -Palmar plates (meniscus like structure) made of fibrocartilage assist with joint congruence (help to distribute stress on the MCP surfaces). They help prevent OA in these joints, they are larger here those than in the PIPs and DIPs. This helps explain the absence of OA in these joints. -Range of flexion increase from 5th to 2nd MCP joint (make a fist and see).

opening the hand

-Early phase: The ED extend the MCPs. -Middle phase: The intrinsic muscles (lumbricals and interossei) assist the ED with extension of the PIP and DIP. They also prevent the ED from hyperextending the MCPs. -Late phase: finger extension continues, this action occurs with the wrist flexors (the carpi radialis and others) pulling the wrist in slight flexion.

closing of hand

-Early phase: The FDP, FDS, and interosseous flex the DIP and PIP. -Late phase: Finger flexion continues, the wrist extensors (carpi radialis brevis and others) extend the wrist slightly. The ED decelerates flexion of the MCPs. The intensity of the red indicates the relative intensity of muscle activity.

wrist joints 3

-Midcarpal joints: the first row of carpal bones with the second row of carpal bones. Two degrees of freedom with: flexion, extension, ulnar and radial deviations. Less contribution to the angular movements of the wrist than radiocarpal joint -The midcarpal joint is divided into medial and lateral compartments. The former is comprised of the convex capitate and hamate fitting into the concave scaphoid, lunate, and triquetrum. The lateral compartment comprises of the convex scaphoid with the concave trapezium and trapezoid. There is little motion, if any, on the lateral compartment when compared with the medial compartment

reduce stress to prevent Median N lesion

-Operate tools with a straight neutral wrist position. -Hand tools should be wellbalanced and easy to hold. -Tools should not have sharp edges or ridges that might impair circulation or exert pressure on the nerves. - Hand tools should keep vibration to a minimum

action of thenar & hypothenar muscles

-Opposition of the thumb and small finger. (The axes of rotation for all flexion and extension movements are in green. The axes of rotation for abduction and adduction at the MCP joint of the small finger and the CMC joint of the thumb are in purple.

key points C2

-PIP and DIP extension occurs with synergic a pull of the extensor hood and slight flexion of the wrist. -PIP and DIP flexion occurs with synergic stabilization of the MCPs (intrinsics) and extension of the wrist. -The inability of the hand intrinsics to stabilize the MCPs in neutral allow the ED to pull the MCPs into hyperextension in the claw hand deformity. -The complex motor control of the hand muscles is evident in the motor cortex in the brain -The mobile area of transition between the metacarpal joint and radius is vulnerable to fractures, dislocations, instability, and sprains.

extrinsic & intrinsic PLUS positions

-Several hand functions will involve a combination of intrinsic and extrinsic plus. -Ulnar nerve damage and inability of the hand intrinsics to prevent MCP hyperextension during finger extension will lead to the contractures observed in the deformity shown in B.

hand joints 2

-The CMC joints of the fingers are surrounded by articular capsules and strengthened by multiple dorsal and palmar carpometacarpal and intermetacarpal ligaments. The dorsal ligaments are particularly well developed -These ligaments prevent flexion and extension in the CMCs and provide stability. -The articular surfaces, coupled with strong ligaments, permit very little movement. The inherent stability of these central metacarpals also provides a firm attachment for several key muscles. -The arthrokinematic movements here are negligible and when present may indicate ligament tear and instability, particularly on the 2nd and 3rd joints.

hand intrinsics function

-The adductor pollicis is a two-headed muscle (oblique & transverse) deep in the web space of the thumb. It produces large flexion and adduction torques. -Both heads of the Add Pollicis act on flexion and adduction of the CMC. The transverse head of the uses a very long moment arm to generate both flexion and adduction. -Both heads of the adductor pollicis also act in flexion of the MCP joint.

wrist instability

-The cause of carpal instability is lesion of specific ligaments, the lesion is often a result of compression forces. ¡ The stable distal row is less likely to be affected compared with the proximal carpal row. -Carpal instability may be static (demonstrated at rest) or dynamic (demonstrated only during free or resisted movement), or both. -The most common instabilities are Dorsal Intercalated Segment Instability (DISI), Volar Intercalated Segment Instability, and Ulnar translocation of the carpus. -It is beyond the scope of this lecture to their clinical presentation

IP osteo/arthro

-The concave- convex rule is useful here. -During flexion of the DIP and PID, the distal moving phalange glide occurs in the same direction of bone motion and vice versa with extension.

MCP Osteo/arthro

-The concave-convex rule here is used to guide joint mobilization. During flexion of the phalange, the glide occur in the same direction of bone motion and vice versa. -In abduction, the glide also goes in the same direction of bone motion and vice versa.

thumb extrinsic muscle function

-The dorsal extrinsics are the EPL, EPB, and APL. -The EPL extends the IP, MCP, and CMC joints of the thumb. The EPL may also adduct the CMC when this joint is positioned in abduction and the tendon is medial to the axis of motion. -The EPB is an extensor of the MCP and CMC joints of the thumb. -The APL extends and abducts the CMC joint. -The palmar extrinsic FPL is the sole flexor of theIP joint.

wrist ligaments

-The dorsal ligaments are weaker and thinner than the palmar ones. They may be intrinsic or extrinsic. Intrinsic only join carpal bones. Extrinsic joins forearm with carpal bones or fingers. -Palmar ligament are "v" shaped to assist with radial and ulnar deviation. -The Ulnocarpal ligament complex: TFCC (including disc and meniscus homolog), ulnolunate ligament, and ulnar collateral ligament, assists with compression absorption. The TFC refers only to the disc

hand muscle 3

-The extrinsic extensors of the fingers are the ED, the EDI, and the EDM. These tendons lack a defined digital sheath or pulley system. -The extensor tendons merge with an aponeurosis to form the extensor hood for the fingers. The ED tendon splits into: central tendon (base of mid phalanx), lateral bands and terminal tendon (distal phalanx). -The ED extends mainly the MCP: -Hand intrinsics attach to the extensor hood and play a major role to extend the DIP and PIP

Finger inter-phalangeal joints

-The fingers have 2 IP joints: DIP and PIP. -The IP joint surfaces are convex proximately and concave distally. -They have palmar plates (less developed than MCP). -Flexion range increase from ulnar side to radial side. The PIP joints flex to about 100 to 120 degrees. The DIP joints allow less flexion, to about 70 to 90 degrees -These joints allow swing mainly into flexion and extension. But, external rotation occur during flexion and internally during extension.

arthrokinematics of wrist compression

-The first carpal row may slide from lateral to medial direction when the wrist is compressed. The greater the compression forcers, the greater the potential to slide. Excessive compression may cause instability and injury

hand intrinsic muscle function

-The hand has 20 intrinsic muscles divided in 4 sets: thenar eminence, hypothenar eminence, adductor pollicis, and lumbricals-interossei. -The primary responsibility of the thenar muscles (Abd PB, FPB, & Opp Pollicis) is to position the thumb in varying amounts of opposition to facilitate grasping. The FPB also flexes the MCP and CMC of the thumb. -The the hypothenar muscles (Flex DM, Abd DM, Opp DM, Palmaris Brevis) cup the ulnar border of the hand. This action deepens the distal transverse arch, and enhances digital contact to hold objects.

key points 9c

-The hand has 4 sets of intrinsic muscles (thenar, hypothenar, adductor pollicis, lumbricals & interossei). -The finger and thumb has pulley systems to improve the torque efficiency of the flexors -Full finger extension requires passive assistance of the extensor hood -Thenar and hypothenar muscles of the hand are responsible for thumb opposition. -The interossei muscles adduct and abduct the finger as well as assist with finger MCP flexion with PIP and DIP extension

intrinsics & extrinsic interaction

-The interaction between the extrinsic and intrinsic muscles can produce an infinite number of functions. All these functions involve to some degree opening and closing of the digits. -The muscle action to open the fingers involve a complex interaction between wrist extensors, and finger flexors. -As you learned in your AA1 class, resistance to hand movement comes more from tissue viscoelasticity than from gravity.

hand intrinsic function 3

-The interossei act at the MCP joints to spread the digits apart (ABD) or bring them together (ADD). -The palmar interossei adduct the second, fourth, and fifth MCP joints. The 1st palmar interosseous muscle of the thumb flexes the thumb MCP and brings this joint to the midline of the hand. They play a role on MCP flexion and extension of the PIP and DIP. -The 4 dorsal interossei have distal attachments to the oblique fibers of the dorsal hood as well as to the sides of the proximal phalanges. Similar to the lumbricals they also flex the MCP and extend the DIP and PIP. They abduct the index, middle, and ring fingers. The 5th finger has its own abductor.

hand joints

-The joints of the hand include, thecarpometacarpal (CMC), the metacarpal phalangeal (MCP), and the interphalangeal joints of the fingers (PIP & DIP) and thumb (IP). -Carpometacarpal joints. The 2nd to 5th metacarpals articulate with the distal carpal row. The 2nd and 3rd CMCs are plane joints with one degree of freedom (flex/ext, but motion here is negligible). The 4th CMC is plane and has observable flex/ext. The 5th CMC is saddle like and has two degrees of freedom (flex/ext & add/abd). -Motion on 4th and 5th CMCs assist with hand closure and thumb opposition. -Illustration of the mobility at the CMC joints. The second and third digits are rigid. -In contrast, the more peripheral CMC joints form mobile radial and ulnar borders, which are capable of "folding" around the hand's central pillar. The function of the CMC joints allows the concavity of the palm to fit around many objects.

hand intrinsics function 2

-The lumbricals are 4 slender muscles that have origin off the tendons of the FDP. All four lumbricals show marked variation in both size and attachments. -Their contraction flexes the MCP joints and extend the PIP and DIP joints. The extension results from the pull on the lateral band of the extensor hood.

wrist joints 4

-The medial compartment has more motion to wrap around objects in the center of the palm of the hand. The lateral compartment serves as an imaginary axis for thump opposition where the medial border of the hand meets the thumb in the center of the hand (lateral compartment) -The intercarpal joints has 13 articulations. These joints have very small gliding and rotary motions. We will not focus on these movements. -Ulnar anatomical variance will affect load distribution on the wrist. There will be more compression on the lunate with negative variance and more compression on the TFCC with positive variance.

combined movements of the wrist

-The more natural path of motion combines elements of both planes: extension naturally occurs with radial deviation, and flexion with ulnar deviation. -During radial deviation, there is combined extension; while in ulnar deviation, there is combined flexion.

scaphoid and lunate lesions

-The scaphoid is located in the direct path of force transmission through the wrist. 2nd only to fractures of the distal radius. Mechanism for is a fall on a fully supinated forearm with the wrist extended and radially deviated. -Kienböck's disease, is a painful disorder of unknown cause, characterized by AVN of the lunate. Possible mechanism is trauma (dislocation or fracture) or to repetitive or near-constant lower-magnitude compression forces.

key points 9a

-The the radiocarpal and the midcarpal joints (medial compartment) are the most movable wrist joints -Abnormal anatomical ulnar variance may lead to injuries -The dorsal ligaments of the wrist are weaker than the palmar ones -The V shaped palmar ligaments passively guide radial/ulnar deviations -Wrist Osteokinematics: flexion combines with ulnar deviation and extension with radial deviation.

muscles of the wrist

-The wrist is controlled by a primary and a secondary set of muscles. The primary muscles do not reach the digits and attach on the carpal bones only, while the secondary muscles cross the carpal bones to act on the fingers and thumb. -The function of these muscles are based on their anatomic positions when crossing the axis of motion of the wrist -Muscles anterior to the axis act as flexors and vice versa. Muscles lateral to the axis act as radial deviators and vice versa.

PIP & DIP stability

-They have collateral ligaments and accessory ligaments, both taut in extension (closed packed position). -Minimal hyperextension is usually allowed at the IP joints. -The close-packed position of the PIP and DIP joints is considered to be full extension, most likely because of the stretch placed on the collateral ligaments in extension. -Sprained fingers are often taped or braced near full extension to prevent contractures and enhance joint stability during the protected healing phase of rehabilitation.

hand joints 3

-Traditionally, the MCP joints of the 2nd-5th fingers have two degrees of freedom allowing Flex/Ext and Add/Abd. -The MCP joints of the fingers are ovoid articulations formed between the convex heads of the metacarpals and the shallow concave proximal surfaces of the phalanges. -In addition to traditional movements, the joint can be distracted-compressed, translated in anterior-to-posterior and side-to-side directions, and axially rotated. The extent of passive axial rotation is particularly remarkable. -Joint mobilization is commonly performed here by manual therapists.

wrist muscle torque

-When comparing muscle group ability to generate torque, the flexors are the strongest group, followed by the radial deviators, then ulnar deviators, and last the extensors. The wrist flexors may be 70% stronger than the extensor muscles.

osteokinematics of the wrist

-Wrist flexion/extension are swings that take place in two different joint axis. Flexion on the wrist comes with ulnar deviation and extension comes with radial deviation. Next slide. These combined movements also occur in wrist radial and ulnar deviation. -The movement of flexion and extension occurs at different joints from full flexion to full extension. From 90 of flexion to the neutral position, the movement occurs mostly in the mid-carpal joint. From the neutral position to 30 degrees of extension, the motion occurs mostly between the scaphoid and lunate/triquetrum. And from 30 to 70 degrees of extension, between the radius/TFCC and scaphoid.

wrist joints

-composed of the radiocarpal joint, midcarpal, and the intercarpal joint. the wrist tranfers forces of the UE to the hand and vice versa - the radiocarpal joint is the MOST IMPORTANT joint of the wrist. the angular movements of the wrist on the sagital and frontal planes occur mostly here - the radius articulates with the scaphoid and lunate bones. the TFCC on the medial side of the distal, it helps to transfer weight from the radius to the wrist. the distal ulna DOES NOT contact the first carpal row of bones

osteo/arthro thumb

-follows the concave-convex rule. -Metacarpal adbuction comes with trapezium glide in the opposite dircetion of bone motion and vice-versa for adduction -while in extension comes with trapezium glide in the same direction of bone motion and vice versa.

motor homunculus

-is larger than the lower extremities. -its HUGE (so she said and that i know)

TFCC vs TFC

-tfcc: UCL, PUCL,PRUL, disc tfc: just the articular disc

cmc thumb joints

-the saddle shape allows to fully oppose other digits. - the thumb is able to encircle objets held within the palm. -opposition greatly enhances the dexterity of human prehension.

cmc thumb opposition

A) Two phases of opposition are shown: (1) abduction and (2) flexion with medial rotation. (B) The detailed kinematics of the two phases of opposition: the posterior oblique ligament is shown taut; the opponens pollicis is shown contracting in red

thumb CMC OA

Biomechanical Considerations: -The thumb CMC is very mobile, repetitive motion increases joint laxity allowing gap between articulating surfaces. Reduced joint congruence leads to cartilage degeneration and initiates the arthritic process. Good joint congruency is important to maintain cartilage nutrition and health. - Excessive range of CMC abduction and repetitive thumb opposition may be the main mechanical causes.

zig-zag carpal instability

Instability may be prevented or managed with taping and bracing. Because of the lack of muscle attachments connecting the first carpal row with the radius, Exercise often will not help to improve stability in this area.

Carpal Tunnel Syndrom

Median N lession can cause: - over crowed tunnel with several tendons - repetitive motion: excessive stress - chronic inflammation leads to scar in tunnel

wrist flexors

Primary ( act on wrist only) -FCR, FCU, PL Secondary ( acts on wrist and hand) -FDF, FDS, FPL, AbPL, EPB The flexor carpi ulnaris has the greatest wrist flexion torque potential of the primary flexors. An overly spastic flexor carpi ulnaris muscle frequently contributes to a wrist flexion (and ulnar deviation) deformity in persons with cerebral palsy

wrist extensors

Primary muscles ( acts on the wrist only) -ECRL,ECRB, ECU Secondary ( acts on wrist and hand) -ED, EI, EDM,EPL -The main function of the extensors is to position and stabilize the wrist during activities involving active flexion of the digits. - the extensor retinaculum prevents the underlying tendons from "bowstringing" up and away from the radio-capral joint during active movements of the wrist

extensor hood mechanism

The transfer of passive force in the stretched oblique retinacular ligament during active extension of the finger. The numbered sequence (1 to 4) indicates the chronologic order of events

cmc stability

¡ CMC of the thumb (trapezium/metacarpal) l It has a capsule reinforced by radial, ulnar, palmar, and dorsal ligaments. l It has an intermediate ligament to prevent separation of 1st from 2nd CMC. l Closed-packed in extreme of opposition. Resting position in neutral. l Function: opposition and prehension. l Prone to and Notorious for developing OA (next presentation). l Medial/ulnar collateral ligament sprains are common.

hand muscle function

¡ Muscles that control the digits are classified as either extrinsic or intrinsic to the hand ¡ The extrinsic flexor muscles of the digits are the FDS, FDP, and FPL. ¡ The FDS main function is to flex the PIP joints. With the exception of 5th finger, each tendon can be controlled relatively independently of the other. ¡ The FDP main function is to flex the DIP joints. The FDP of the index finger can be controlled independently. However, the remaining 3 tendons are interconnected, which usually prohibit isolated DIP joint flexion of a single finger. The FDP helps the FDS flex the PIPs.

hand muscle function 2

¡ The FPL is the sole flexor of the thumb IP. It also flexes the MCP and CMC joints. If not opposed, the FPL also flexes and radially deviates the wrist. ¡ The extrinsic tendons have protective fibro-osseous tunnels known as fibrous digital sheaths. The sheaths are anchored to the phalanges and the palmar plates and embedded in flexor pulleys. ¡ The flexors pass through 5 annular (A1-A5) and 3 cruciate ligaments before they reach the PIP. They make muscle contraction more efficient. ¡ The thumb has only two pulleys (A1 and A2) and one oblique ligament

joint stability 1

¡ The MCP of the thumb may have 30 to 60 degrees of flexion. It may have 0 to 15 degrees of extension Add/Abd here are minimum or negligible in the majority of the population. Some rotation occur here as well but it is negligible. l Significant less motion than finger MCPs. Main function is to provide further flexion during thumb opposition. l The capsule (1) is reinforced palmarly by sesamoid bones (2) and intersesamoid ligaments (3).

key points hands B

¡ The concave-convex rule may be useful to guide manual therapy for most hand joints. ¡ The CMC of the thumb is the most movable and most prone to instability among the CMC joints. ¡ The MCP of the fingers have much more motion than the MCP of the thumb. ¡ The ligaments of the IP joints of the fingers are taut in extension and those of the MCP are taut in flexion ¡ The MCP of the fingers and the CMC of the thumb have two degrees of freedom. ¡ The PIP and DIP of the fingers as well as the MCP and IP of the thumb have one degree of freedom.

joint stability 2

¡ The thumb only has one IP. These joints have one degree of freedom allowing flex/ext. They are similar to the IPs of the fingers. Rotation here is negligible. ¡ Concave-convex rule is the same for the fingers. Bone motion and glides occur in same direction for flexion and extension for both MCP and IP. ¡ Note same direction of glide and roll for the MCP and IP joints of the thumb.