Hand Osteology, Arthrology and Muscle/Joint Interaction Lecture 15 Flashcards
What is made up of the 1st metacarpal and trapezium?
CMC thumb joint
What shape is the CMC thumb joint?
Saddle
What do we need to know about the capsule of the CMC thumb joint?
naturally loose, strengthened by tension in embedded ligaments (3-7)
When are ligaments tight in the CMC thumb joint?
Tight in opposition, flexion and abduction
Does the CMC thumb joint have sensory receptors?
YES many!
What is common at the CMC thumb joint?
Osteoarthritis
What can osteoarthritis at the CMC thumb joint cause?
Radial dislocation and ‘hump’
What is a classic saddle joint?
Each articular surface convex in one direction and concave in the other
How many degrees of freedom does the CMC thumb joint have? where?
2 - add/add in sagittal plane; flexion/extension in frontal plane
_________ and _______ from 2 planes with the CMC thumb joint
Opposition/reposition
What amount of abduction is full with the CMC thumb joint?
45 degrees anterior to plane of palm
What happens with the arthrokinematics of the thumb during CMC thumb abduction and adduction?
Convex articular surface of thumb metacarpal moving on fixed concave trapezium
What roll and slide is there with abduction of the CMC thumb joint?
rolls palmar and slides dorsally
What does abd/add of the CMC thumb joint do to the musculature & ligaments?
Elongates adductor pollicis and most ligaments
What roll and slide is there with adduction of the CMC thumb joint?
rolls dorsally and slides palmar
What is flexion and extension of the CMC thumb joint associated with?
Varying amount of axial rotation; flexion medial rotation and prontation
Why is flexion / extension of the CMC thumb not a 3rd degree of motion?
Cannot be done independently
How much more can the CMC thumb joint be extended from anatomical position?
10-15 degrees
How much does the CMC thumb joint flex from full extension?
45-50 degrees
What os the arthrokinematics of CMC thumb flexion ?
Concave metacarpal on convex trapezium
What is the roll and slide with CMC thumb flexion?
Metacarpal rolls and slides in ulnar direction
What guides medial rotation with CMC thumb flexion?
Shallow groove in trapezium
What is the slide and glide with CMC thumb extension?
Slide/glide in lateral direction
What are the osteokinematics of thumb abduction and adduction?
sagittal plane movement around a medial-lateral axis of rotation through the metacarpal
What is the joint geometry of thumb abduction and adduction?
Convex diameter of metacarpal moving on concave surface of trapezium
What are the arthrokinematics of thumb abduction?
palmar roll and dorsal slide
What are the arthrokinematics of thumb adduction?
Dorsal roll and palmar slide
What are the osteokinematics of flexion and extension of the thumb?
Frontal plane movement around an anterior-posterior axis of rotation through the trapezium
What is the joint geometry of flexion and extension of the thumb?
Concave diameter of the metacarpal moving on a convex surface of the trapezium
What are the arthrokinematics of thumb flexion?
Medial roll and slide
What are the arthrokinematics of thumb extension?
Lateral roll and slide
What does effectiveness of pinching and gripping motions depend on?
Opposition
What is thumb opposition a combination of?
- Thumb MC abduction
- flexion and medial rotation towards small finger, trapezium also spins slightly; small and ring finger cup to help
Is full thumb opposition closed or open packed?
Closed
What are the general features of the MCP joints?
Ovoid, convex head of metacarpal and shallow concave proximal phalanges
What is critical to the stability of the hand?
Mechanical stability
What is each MCP joint capsule made up of?
pair of radial and ulnar collateral ligaments and one palmar plate
What kind of connective tissues are part of the MCP joints?
elaborate and interconnecting
Where do collateral ligaments attach proximally?
Proximal attachment at tubercle
What are the different parts of the collateral ligaments?
Cord part (thick and strong) & accessory part
What are volar (palmar) plates?
Dense, thick fibrocartilage; runs base of proximal phalanx thinner elastic portion to MC
What do fibrous digital sheaths form?
Form tunnels or pulleys for extrensic finger flexors
Where are fibrous digital sheaths anchored?
Plates
What is the MCP joint formed by?
Concave proximal phalanx; collateral ligaments and dorsal surface of the plate
What accepts the large MC head?
A 3-sided recepticle
What does the 3 sided recepticle do in the MCP joint?
Increases articular area and stability
How many deep transverse metacarpal ligaments are there in the MCP joints?
3
What are the ostrokinematics of MCP joint flexion/extension?
Sagittal plant around medial-lateral axis
How does MCP flexion/extension increase?
Increases from 2nd to 5th MCP (90-115)
How much extension past neutral do the MCP joints get?
up to 30-45 degrees
What are the osteokinematics of abduction/adduction?
Frontal plane around anterior-posterior axis
How far each way do MCP joints go from midline during abduction/Adduction?
20 degrees
What are the accessory motions of the MCP joints?
distracted/compressed; translation A-P / side-side; axial rotation
What do the accessory motions of the MCP joints allow for?
Conforming to objects in grasp
What are the arthrokinematics of MCP joints?
Head of MC rounded at apex/ flat palmar surface
What are MCP joints covered in?
Articular cartilage
What moves on what with MCP joints?
Concave phalanx moving on convex MC head
What is the roll/slide of the MCP joints?
Roll and slide the same way
What is the difference in flexion and neutral with abduction?
Less motion in flexion than neutral
When are ligaments taut with abduction? also does what?
Taut in full flexion, also compresses joint
What is in contact with the phalanx?
The flatter potion of head
Why does flexion at the MCP joint increase distance between the attachment points of most of the cord part of the collateral ligaents?
Cam -shaped metacarpal head
What happens to the distance between the proximal and distal attachments of the collateral ligaments with the PIP joint?
Remain essentially constant throughout flexion
What are the ostrokinematics of the MCP joint of the thumb?
Convex head of 1st metacarpal and concave proximal phalanx of thumb
How many degrees of freedom are there of the MCP joint? What?
1 - flexion/ext in frontal plane
What are considered accessory motions of the MCP joint of the thumb?
Abduction/Adduction
What injury is due to large forces and not motion of the thumb?
“skiier’s injury”
When is the thumb vulnerable especially?
30 degrees
Where are the two kinds of IP joints?
Proximal and distal IP joints
How many degrees of freedom at the IP joints? What are they?
1 - flexion / extension
What are the head of proximal phalanx shaped by? What are the separated by?
Head of proximal phalanx 2 rounded condyles separated by central groove
What does the central groove of the IP joint help with?
guiding flexion/extension, limits rotation
What does the palmar plate limit with IP joints?
Hyperextension
What do the check-rein ligaments do in the IP joints?
Reinforce palmar plates and assists in limiting hyperextension
What has no check-rein ligaments?
DIP joints
What are part of the IP joints? (ligaments / plates)
Radial and ulnar colateral ligaments and palmar plates
What are the kinematics of the PIP joint?
100-120 degrees flexion, minimal hyperextension
What are the kinematics of the DIP joint?
70-90 degrees of flexion, 30 degrees of hyperextension
What is the roll and slide of the IP joints?
Concave base rolls and slide in palmar direction
What helps stabilize the IP joints?
The dorsal capsule tension
When is the IP joint closed packed?
Full extension
How many degrees of freedom of the thumb IPs? What degrees?
1 degree of freedom, flexion 70 degrees, extension to 20 degrees
What is unique about the innervation of the hand?
Small fiber-per-axon ratio typical of most intrinsic hand muscles, single axon may innervate as few as 100 muscle fibers
What does the radial nerve innervate?
Extensive extensor muscles (ED, EDM, EI, EPL, EPB, APL)
What does the median nerve innervate?
Most of the extrinsic flexors (FDS, FDP, FPL; ABP, OP, FPB - thenar eminence and lateral 2 lumbricals)
What does the ulnar nerve innervate?
Medial half of FDP, hypothenar muscles (FDM, ADM, PB) and 2 medial lumbricals; all interossei and add pollcis
Where are the extrinsic attachments?
In forearm and epicondyles
Where are the intrinsic attachments?
Hand
Where is the proximal attachments of the extrinsic flexors of digits?
Humerus and forearm
What do all the extrinsic flexors of digits do?
All flex digits (grasp) and subtle opposition
What does the flexor digitorum superficialis do? where is it located?
Flexes PIP joints, independently
Deep to 3 wrist flexors, pronator teres; 4 tendons cross wrist and split at proximal phalanx - attached middle phalanges
Where is the FDP? What does the flexor digitorum profundus do?
Deepest of forearm, attaches base of distal phalanx
Sole flexor of DIP, index indep
What does the flexor pollicis longus do? Where does it run?
Flexes and radially deviates wrist if unopposed
Lateral to FDP, sole flexor of IP
What are the tendons surrounded by?
Synovial sheaths
What does the synovial sheath around tendons do?
Reduces friction between structrues
What can cause fibrotic changes tot he connective tissue in the wrist?
Overcrowding, small tunnel, water retension, inflammation, swelling of tendons, repeated or excessive stress to wrist
Where is the fibrous digital sheath anchored?
To plates and phalanges
What is embedded in the fibrous digital sheath?
Bands of tissue called flexor pulleys A1-A5 and C1-C3
What does the digital synovial sheath serve as?
Nutritional and lubrication
What can be developed post laceration/surgery?
Adhesions
What exercises do we do with adhesions?
Tendon gliding exercises
What are flexor pulleys?
5 annular pulleys for each finger (A1-A5) embedded within fibrous digital sheath
Where do flexor pulley attach to shafts?
Major at A2 and A4 (mid and prox)
Where do flexor pulley attach to palmar plates?
Minor at A1, A3, and A5
What are cruciate pulleys?
C1-3 thin, crisscross over tendons where digital sheaths bend during flexion
What ligaments of thumb are pulleys for FPL?
Annular and oblique ligaments
What happens without the flexor pulleys?
Get “bowstring”; A2 & A4 reduce torque significantly if injured
What is tenosynovitis?
Tendons/synovial lining inflammed
What can be developed with tenosynovitis?
Nodule which gets “stuck” in sheath and can snap through it
What is another name for tenosynovitis?
Trigger finger
What percentage of climbers have pulley injuries?
20%
Which pulley is the most frequently injured?
A2
What do the proximal stabilizer muscles do during active finger extension?
Greater force at PIPs and greater force stabilizer at extensor digitorum
What is tenodesis action of a healthy person?
As the wrist is extended, the thumb and fibers automatically flex because of the stretch placed on the extrinsic digital flexors; flexion occurs passively
What are the extrinsic extensors of fingers?
- Extensor digitorum (wrist and finger extensor)
- Extensor indicis
- Extensor digiti minimi (often connected to ED)
- Cross wrist under retinaculum
** within synovial lined compartments
What are tendons connected by?
Juncturae tendinae
