Wrist and Hand
How many degrees of freedom does the MP joint of the thumb have?
Hinge joint with 1 degree of freedom - only has flexion and extension
What movements occur at the interphalengeal joints?
Just flexion and extension - they are hinge joints with 1 degree of freedom
What muscle doesn't attach to bone?
Lumbricals - primarily MP flexors - Origin is on FDP tendon (the one that goes out to the finger) - Inserts on extensor mechanism - on the back of fingers (from volar surface to the back
The ______ has a split in it so that the _____ can pass and insert on the distal phalanx. This is called ______ chiasm
The flexor digitorum superficialis has a split in it so that the flexor digitorum produndus can insert onto the distal phalanx. This is called campers chiasm. -- the FDP bends the DIP joint --- the FDS inserts on the middle phalanx
What side of the hand has the most ligaments? Why is this?
The volar (palmar) side - it prevents major dislocations from occurring and protects the hand with more "squishy" or "shock absorbing" structures
Is the collateral ligament loose or tight when MP's are in flexion?
Tight! -- it is stretched out - two components are the cord and fan - located above the axis of rotation
Which carpal bone articles with the first metacarpal and is the source of the thumbs unique movements?
Trapezium
What is tenodesis?
Wrist extension or hand grasp is when your knuckles are higher than your wrist. When your wrist is extended, your fingers naturally curl or grip. When the wrist is extended, the tendons along the fingers shorten and pull the finger joints into flexion. - strongest in extension
What bone does the lunate articulate with?
capitate - center of location for flexion and extension and radial/ulnar deviation
Is the extensor carpi ulnaris stronger in flexion or extension?
flexion
What movements occur at the midcarpal joint?
flexion/extension and radial and ulnar deviation
what pinch is used for key turning?
lateral (key) - twist and rip
Ulnar deviation mostly occurs at what joint?
radiocarpal joint
Is there greater radial deviation or ulnar deviation at the wrist?
ulnar deviation - occurs in the frontal plane and its axis of rotation is anterior to posterior
Tendons in the first compartment of extensor retinaculum
· Abductor pollicis longus (APL) · EPB (extensor pollicis brevis)
What does the pulley system in the extrinsic flexors do?
- Flexor tendons - volar surface ---->Pulleys are holding tendon close to the bone o Prevents bowstringing ---->A2 is the biggest and most important - Annular and cruciate ---->Describes how they look ---->Cruciate - cross
What are the five zones of the hand?
- Zone 1 is tip of finger - Zone 5 is wrist - Zone 2s are the worst - no man's land for flexor tendon injuries · FDS and FDP run in sheath together o Cut one, cut the other o Forms a lot of scar tissue as it heals o Tendons are stuck and cannot move - T2 is the thumb
What is the cascade sign?
- fingers in full flexion, tips all point towards scaphoid - index and middle stay close to the thumb (important for prehension) - prehension from radial side - grip strength comes from ulnar side
What does the transverse carpal ligament do to support the hand?
- forms the roof of the carpal tunnel - prevents bowstringing of the flexor tendons
What does the extensor retinaculum do?
- forms the roof over 6 dorsal compartments for extensor tendons
What brakes in a boxer's fracture?
- fracture of the 5th metacarpal - comes from punching someone - problems with strength but prehension might be okay
What are and where are the check rein ligaments located?
- only at PIP and DIP joints - continuation or fold into part of volar plate -between P1 and P2 - adds extra support to volar plate
What does the palmar aponeurosis do?
- protects underlying neurovascular structures and tendons - soft tissue fascial complex in palm of hand
How does the Triangular fibrocartilage complex support joint stability and what is it comprised of?
- shock absorber between the wrist and ulna - Triangular fibrocarticlage which is a disc between the radius and ulna - Ulnocarpal ligament - Dorsal and volar raidal ligaments - Extensor carpi ulnaris sheath - ulnolunate and ulnotriquetral ligaments
What structures protect the hand and provide stability?
- transverse carpal ligament - palmar aponeurosis - extensor retinaculum
What type of pinch is important for picking up coins or pens?
2 point pinch (tip to tip) - thumb and pointer
What type of pinch is used for playing cards?
3 point (tripod) - thumb, pointer, middle finger
How many metacarpals are there?
5 in flat palm of hand
What muscle is located between the pisiform and the base of the fifth finger?
Abductor digiti minimi
What are the hypothenar muscles? *ball of little finger
Abductor digiti minimi Flexor digiti minimi Opponens digiti minimi
The distal tendons of which three muscles form the "anatomical snuffbox"
Abductor pollicis Extensor pollicis brevis Extensor pollicis longus
What muscles are responsible for thumb carpometacarpal abduction?
Abductor pollicis longus Abductor pollicis brevis
Which muscle is stronger - extensor carpi radialis breivs or extensor carpi radialis longus?
Brevis - inserts into base of 3rd metacarpal, base of wrist, centrally located
The radial and ulnar artery form what two structures?
Deep and superficial palmar arches
What muscles are involved in wrist radial deviation?
Extensor carpi radialis longus Extensor carpi radialis brevis Flexor carpi radialis Abductor pollicis longus
True or False - there is movement between the distal row and metacarpals
False - no movement here
What is Dupuytren's disease?
Fascia tightens, familial disease Treatment: - inject fascia with collagenase and breaks up the fascia
What are the extrinsic muscles? *bellies in forearm
Finger flexors - flexor digitorum superficialis - flexor digitorum profundus - flexor pollicis longus Finger extensors - extensor digitorum comunis - extensor indicis - extensor digiti minimi
What are the intrinsic muscles? *bellies in hand
Hypothenar muscles (muscles for 5th finger) Thenar muscles (thumb muscles) Adductor pollicis Interossei (4 dorsal abduct, 3 volar adduct) Lumbricals (no attachment to bone)
The actions of the intrinsic muscles are influenced by the different positions of what?
MCP, DIP, and DIP joints
Proper name of the "knuckle" joint
Metacarpalphalengeal joint
There is 1.5x more extension at the ________joint than at the ________ joint
Midcarpal joint - distal carpal glides on proximal row
What muscle is responsible for thumb carpometacarpal oppostition?
Opponens pollicis
Which muscle creates opposition of the thumb?
Opponens pollicis
Which four carpals serve as attachment sites for the flexor retinaculum?
Pisiform Hook Hamate Trapezium tubercle Scaphoid tubercle
What are the four types of grip?
Power Hook Spherical Cylindrical
What grip is most commonly tested and measured in adults?
Power grip
Mnemonic for carpal bones
Proximal Row She (scaphoid) Likes (lunate) To (triquetrum) Play (pisiform) --------------- Distal Row Try (trapezium) To (trapezoid) Catch (capitate) Her (hamate)
where is the CMC joint of the thumb?
between carpals and base of metacarpal
The supeficial palmar arch forms what structure?
common palmar digital arteries
P3 of finger is called what
distal phalanx
Are the extensor carpi radialis longus and brevis stronger in flexion or extension?
extension
The common extensor tendon in made up of what muscles?
extensor carpi radialis brevis (ECRB) and longus, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris come together to form the common extensor tendon.
What bone does the triquetrum articulate with?
hamate
Radial deviation mostly occurs at what joint?
midcarpal joint
P2 of finger is called what
middle phalanx
What row moves ulnarly on the radius and radioulnar disc during radial deviation?
proximal
P1 of the finger is called what
proximal phalanx
Tendons in the second compartment of extensor retinaculum
· Extensor carpi radialis brevis and longus (wrist extensors)
Tendons in the fifth compartment of extensor retinaculum
· Extensor digiti minimi (little finger extensor)
Midcarpal joint mobility occurs between the scaphoid and what 3 bones?
trapezium, trapezoid, capitate
What is the extensor retinaculum?
- A thickening of the deep fascia on the extensor aspect of the wrist - holds tendons down and in place - 6 tunnels (compartments) the extensor tendons travel through
What structures provide stability to the wrist?
- articulations (8 bones interconnected) - ligaments (more on palmar surface) ---->Extrinsic ligaments (RCL, UCL, dorsal and palmar radiocarpal, TFCC) ---->Intrinsic ligaments - muscles (PQ, ECU, FCU)
What does the extensor digitorum do?
- extensor of the MP joints - crosses wrist on way to the fingers (belly in forearm) - helps wrist ONLY if something goes wrong with wrist extensors
What is the purpose of the palmar ligament and volar plate?
- stops hyperextension and dislocation on palmar side
What are the bones of the wrist?
-Ulna (40% load) - Radius (60% load)
What muscles are responsible for flexion at the wrist?
Flexor carpi radialis Fexor carpi ulnaris Palmaris longus
What muscle is the primary wrist flexor?
Flexor carpi radialis (60% of work) - FCU comes in only if person needs additional support
What muscle is responsible for thumb carpometacarpal flexion?
Flexor pollicis brevis
What muscle is responsible for thumb metacarpophalengeal flexion?
Flexor pollicis brevis
How many muscles act on the thumb? How many of those are located at the thenar eminence?
- Eight - Four of the eight
What movements occur at the carpometacarpal joint of the thumb?
Flexion/extension Abduction/adduction Opposition/repositon
What band of tissue forms the "roof" of the carpal tunnel?
Flexor Retinaculum
The _____ eminence is located at the thumbs base, while the ______ eminence is located along the ulnar side of the palm
- Thenar (fleshy mass) - Hypothenar
How many phalanges are there?
14 phalanges - each finger except thumb has 3
How many planes of motion does the Radiocarpal joint have?
2 - flex/ext and rd/ud
What are the three types of pinch patterns?
2 point (tip to tip) 3 point (tripod - playing cards) Lateral (key or spoon)
What are the thenar muscles? *ball of thumb
Abductor pollicis brevis Flexor pollicis brevis Opponens pollicis
What muscle is responsible for thumb carpometacarpal adduction?
Adductor pollicis
What is the acronyum for remembering the intrinsic muscles? *not discussed in lecture but good to reference*
All For One, And One For All A- abductor pollicis brevis f- flexor pollicis brevis o- opponens pollicis A- adductor pollicis o- opponens digiti minimi f- flexor digiti minimi brevis A- adductor digiti minimi
What joint of the hand is typically fractured, irritated, etc?
CMC
If the extensor pollicis brevis gets irritated what syndrome can occur?
De Quervain's Syndrome
What is De Quervain's tenosynovitis
De Quervain's tenosynovitis involves the tendons of the extensor pollicis brevis and abductor pollicis longus. - inflammation of the tendons within the first extensor compartment of the wrist, resulting in wrist pain and swelling. - It is most common in women between the ages of 30-50, especially in those with occupations or hobbies involving repetitive movements of the wrist
What muscles are responsible for extension at the wrist?
Extensor carpi radialis longus Extensor carpi radialis brevis Extensor carpi ulnaris
What muscles are involved in wrist ulnar devation?
Extensor carpi ulnaris Flexor carpi ulnaris
What muscles are responsible for extension of the fingers?
Extensor digitorum communis Extensor digiti minimi (extends little finger) Extensor indicis (extends index)
What muscle is responsible for thumb carpometacarpal extension?
Extensor pollicis brevis
What muscle is responsible for thumb metacarpophalengeal extension?
Extensor pollicis brevis
What muscle is responsible for thumb interphalangeal extension?
Extensor pollicis longus
What muscle extends the distal tip of the thumb? *hint* the tendon wraps around listers tubercle as it goes out to the thumb
Extensor pollicus longus (ELP)
The pisiform acts as an attachment site for what muscle?
Flexor carpi ulnaris
The lumbricals sprout from the sides of the tendons of which muscle?
Flexor digitorum profundus
What muscle bends the tips of the fingers (DIP joints)?
Flexor digitorum profundus
This muscle flexes the PIP joints and has tendons that pass through the carpal tunnel to attach to the phalanges
Flexor digitorum superficialis
What muscles are responsible for flexion at the fingers?
Flexor digitorum superficialis (PIP flexion) Flexor digitorum profundus (DIP flexion) Flexor digiti minimi brevis
What muscle is responsible for thumb interphalangeal flexion?
Flexor pollicis longus
What is the name of a common type of injury that occurs on the volar side of an outstretched hand?
Foosh injury
What movements occur at the metacarpophalangel joint "knuckle"
It is a condyloid joint - flexion/extension -abduction/adduction
What movements occur at the distal interphalangeal joint "DIP"
It is a hinge joint - flexion/extension (lumbricals/interossei)
What movements occur at the proximal interphalangeal joint "PIP"
It is a hinge joint - flexion/extension (lumbricals/interossei)
Extensors of the wrist originate on what side?
Lateral
Flexors of the wrist originate on what side?
Medial
What types of joints are CMC joints 2-5
Plane joints with very little movement if any at all
What main arteries supply blood to the hand?
Radial artery Ulnar artery
There is 1.5x more flexion at the ________joint than at the ________ joint
Radiocarpal joint - proximal row of carpal slides dorsally onto the radius and disc
True or False - there is movement between the proximal and distal rows of the carpals
True - this is where the midcarpal joint is located
What ruptures when skiers thumb occurs?
Ulnar collateral ligament
Which two structures pass through the Tunnel of Guyon?
Ulnar nerve Ulnar artery
The common palmar digital arteries turn into what structure that supplies blood to the flexor tendons?
Vinculars
Is there a lot of mobility at the CMC joint?
Yes - fibrous joint capsule
Where is the midcarpal joint located?
between proximal and distal rows of carpal bones
What two bones have the most mobility at the midcarpal joint?
scaphoid and triquetrum
The actions of the extrinsic muscles are influenced by the position of what?
the wrist
Tendons in the third compartment of extensor retinaculum
· EPL - goes around listers tubercule on the way out to the distal thumb
Tendons in the sixth compartment of extensor retinaculum
· Extensor carpi ulnarus
Tendons in the fourth compartment of extensor retinaculum
· Extensor digitorum (NP extensors) · Extensor indicis (index finger extension)
What is ulna variance?
· Ulna positive - tip creates problems at the wrist for clients (styloid process is more distal - we do not want this) o Ulna shortened to bring styloid process more proximal · Ulna negative o Styloid process of ulna more proximal, lower o most people have this · Ulna neutral o Everything is where it should be o Axis for pivot joint is in line
Which carpal forms the floor of the "anatomical snuffbox"?
Scaphoid
