hand Flashcards
explain the joints of the hand
CMC: carpal metacarpal
MCP: metacarpal phalange joint
PIP: proximal interphalange joint
DIP: distal interphalange joint
describe which is concave/convex in each joint of the thumb
CMC: carpal= Concave in the sagittal plane and convex in the transverse
metacarpal base = convex in the sagittal plane and concave in the transverse
MCP: metacarpal head = convex and base of proximal phalange = concave
PIP: proximal phalange head = convex and base of middle phalange = concave
DIP: middle phalange head = convex and base of distal phalange = concave
What is in the third ray of the hand
-capitate
-3rd metacarpal
-3rd proximal phalanx
-3rd middle phalanx
-3rd distal phalanx
what is the most stable part of the hand
the 3rd ray - everything moves around it
describe the thumbs orientation to the palm
rotated anterior about 90* for a functional grasp
What are the arches of the hand
- longitudinal: 3rd metacarpal to 3rd disal phalange (keystone arch)
- proximal transverse: distal row of carpals
- distal transverse: around the MCP joints of all digits
2&3 accommodate BV and nerves that enter the hand
Which fingers have the most mobility at the CMC joints
1st, 4th, and 5th
Joint support at the CMC joint on the dorsal side
-dorsal inter metacarpal ligaments and dorsal carpometacarpal ligaments reinforce joint capsule externally
-carpometacarpal joint: more reinforcement of the thumb CMC joint
~posterior oblique ligament
~radial collateral ligament
Joint support of the CMC joint on the palmar side
-palmar intermetacarpal ligaments and palmar carpometacarpal ligaments reinforce joint capsule
anterior oblique ligament adds support to the thumb side
Arch that forms when you close your fist
-based around movement of 4th and 5th metacarpal on 3rd ray and movement on the 2nd ray on the 3rd ray
CMC joint surfaces
saddle joint
-concave in one direction and convex in the other
Osteokinematics of he CMC joint ROM
-flexion: 0-45-50*
-extension: 0-10-15*
-abduction: 0-45*
-adduction: return back to neutral
Arthrokinematics thumb CMC–abduction
roll and slide happen in opposite directions: (convex moving on concave)
Arthrokinematics thumb CMC–flexion/extension
roll and slide in the same direction: concave moving on convex
what produces opposition
flexion and some medial rotation
What are palmar plates
cartilaginous extensions off the distal end of metacarpals, proximal phalanx, middle phalanx, and distal phalanx
-protect joint surfaces and keep flexor tendons from getting trapped in joint surface
what are the MCP, IP joints reinforced by?
palmar plate, joint capsule, and collateral ligaments
and fibrous sheaths that holds tendons in place so they do not get caught in the join surfaces
osteokinematics of MCP of the four digits
-flexion: 0-90-110-115* (motion increases as you move to ulnar side)
-extension: 0-30-45*
-abduction: 0-20*
-adduction: back to neutral
arthrokinematics of MPC flexion/extension
flexion: anterior/palamar roll and slide (Same direction)
extensions: posterior/dorsal roll and slide
arthrokinematics of MPC– abduction/adduction
-roll and slide in same direction
~laterally/radially if it goes towards thumb
~ulnarlly if it goes towards 5th digit
Thumb osteokinematics of IP
flexion: 0-70*
extension: 0-20*
osteokinematics of digit IP
-flexion: more motion in more lateral digits (2nd/5th)
~PIP: 0-10-120*
~DIP: 0-70-90*
Extension (hyperextension): 0-30*
Thenar muscles
-flexor pollicis brevis
-abdutor pollicis brevis
-opponens pollicis
Hypothenar muscles
-opponens digit minimi
-flexor digit minimi
-abductor digit minimi
What makes up the the carpal tunnel
scaphoid, lunate, triquatruim, pisiform, transverse carpal ligament
What runs though the carpal tunnel
Flexor digitorum superficialis tendons
flexor digitorum profundus tendons
-flexor pollicis longus tendon
-mediaan nerve
What happens to the fingers when they are relaxed and the wrist is flexed
fingers extend due to passive length tension (created by the non contractile components such as CT and fibrous tissue such as tendons)
What happens to the fingers when they are relaxed and the wrist is extended
fingers flex due to passive length tension (created by the non contractile competes such as CT and fibrous tissue like tendons)
Tenodesis
can use passive tension to grasp lightweight objects by changing the wrist position
What’s muscles of the hand are responsible to fine motor skills and what do the other group of muscles do?
intrinsic does the finer motor control where as the extrinsic positions fingers, wrist and hand
describe the toque differences between different muscles of the hand and their relation to the axis of rotation
- further from the center axis means more torque that can be generated (larger internal moment arm)
- adductor pollicis gives a powerful grip
- the flexors generate more torque because there not many times where the extensors work against resistance
intrinsic positive meanse
lumbricals and interossei are working
-position is flexion of the MCP and extension of the IP joints
Extrinsic positive
FDS, FDP
-extension of the MCP and flexion of the IP joints
Describe the phases of opening the hand and muscles that work
- early phase: most of the force is produced by Extensor digitorum, and FCR
- middle phase: extensor digitorum and FCR are still producing more of the face but the lumbricals and interossei are starting to produce force
- late phase: Extensor digitoum and FRC as well as the lumbricals and interossei are producing the force to fully extend the phalanges
What happens when a patient with an ulnar nerve injury extends the fingers?
-it is difficult to fully extend finger 4 and 5 IP joints
-the ulnar nerve injury will also affect the lumbricals and interossei
-get the claw hand deformity
-would need to be stabilized to extend the IP joint
describe the extensor hood mechanism
extensor hood on the dorsal side with fibrous insertions
-lateral band is above the PIP and DIP joints but below th joint axis on the MCP joint
Muscle activity during closing of the hand
- early phase: FDP and FDS produce a majority of the force as well as ECRB and ECRL producing some force at the CMC joint
- Late phase: the lumbricals and interossei will increase the contribution of finger flexion
Review each type of grip
see powerpoint
Key pinch grip
other fingers provide the index finger with support
extrinsic and intrinsic muscles will provide power
common injuries of the hand
-tendonitis
-fractures
-dislocations
-other
Joint deformities: Zig-zag deformity of the thumb
-taut flexor pollicis longus
-overstretched palmar plate at MCP joint
-ruptured ligaments/dislocation at CMC joint
-happens when you over stretch palmar plate/ligaments
-can happen when you fall on an outstretched hand or pull on it
-makes the thumb very unstable
Swan-neck deformity
lateral band shifts below DIP and causes flexion and the lateral band shifts above the PIP giving hyperextension
-lax joints and muscles will over pull on some joint
Boutonniere deformity
DIP hyperextension and PIP flexion
the lateral band shift more dorsal causing hyperextension
ulnar drift
musculature on ulnar side over power and pulls the joints that way
-common in people with arthritis
Bowstring deformity
-palmar dislocation of MCP joint can cause the tendons to bowstring
-due to a ruptured collateral ligament and the loss of the anatomical bully that keeps the tendons close to the bones
The development of ulnar drift
A ruptured RCL can cause a bowstringing force
-can happen when there is disruption of the dorsal hood mechanism
-there is an overpowering ulnar force that results in the distal end being pulled ulnarly
-there is a rotation that occurs at the MCP joint and then a shift of the carps towards the ulnar side
radial nerve injury
-nerve injuries can happen at different levels
-wrist drop means that there is an issue with the wrist extensors which can mean the innervation is disrupted in the forearm
ulnar nerve injury
-claw hand
-cannot extend finger IP joints
-intrinsic problem – presentation when you cannot extend the fingers
Median nerve injury
-impact thumb and the thenar emeniace
-cannot oppose, flex or abduct the thumb
