Biomechanics & Pathomechanics of Hand
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Transcript of Biomechanics & Pathomechanics of Hand
MECHANICS & PATHOMECHANICS OF HAND
By : Amrita TomarGuided By: Dr.Manisha Rathi
Hand consist of :
•4 fingers
•1 thumb
Creases of hand:
Joints of hand :
Total 19 bones&19 articulationsby29 muscles
sL
TP
HCpTm Tz
CMC JOINT OF FINGERS
2nd to 4th CMC joints
•Plain synovial joint•Articular surfaces: 1) distal carpal row 2) proximal surface
of base of 2nd to 4th metacarpal row
•Ligaments
1) deep transverse metacarpal ligament - It tethers the metacarpal heads together and provides CMC joint stability.
2) volar & dorsal longitudinal ligaments
5th CMC joint•saddle joint
•2 degrees of freedom -flexion -extension -abduction -adduction
•CMC Joints of 2nd 3rd 4th digits–plane
uniaxial joints.
•CMC Joint of 5th digit-biaxial joint.
•Flex of CMC and additional adduction of
the 5th MC improves the ability of the
hand to grasp the objects of various sizes.
where as extn of MC helps to release
those objects.
Palmar arches : 1) Proximal transverse
arch2) Distal transverse arch3) Longitudinal arch
• Proximal transverse
arch is formed by
trapezium, trapezoid,
capitate and hamate.
• Curve shape of the arch
is still maintained when
the hand is open by the
lig.; i.e. transverse
carpal lig. and
intercarpal lig.
• Distal transverse arch is present transversely across
the arch.
The adjustable position of 1st 4th and 5th MC heads
around the relatively fixed 2nd and 43rd MC forms a
mobile distal transverse arch at the level of MC heads
that augments the fixed proximal transverse arch of
the distal carpal rows.
• Longitudinal arch extends the length of digits from
proximal to distal.
Functions of palmar arches :-
• It allow the palm and the digits to
confirm optimally to the shape of the
object being held.
•It maximizes amount of surface contact,
enhancing stability as well as sensory
feedback
MCP JOINT OF FINGERS• Articular surfaces:
Proximally-
convex metacarpal head
Distally-
concave base of
the 1st phalanx
• Joint is incongruent due to inappropriate articular surface
• Type of joint: synovial joint of condylar variety
• 2 degrees of freedom-
flex/ext
abd/add
• Flexion and extension increases from radially to
ulnarly
• ROM: 1) index flexion- 90 degree
2) little finger flexion- 110 degree
• Ligaments :
1) Radial Collateral ligament
2) Ulnar Collateral ligament
• Each composed of two parts –
collateral ligament proper &
accessory collateral ligament
•They provide stability through out the
MCP jt ROM with part of fibres taut at
various points in the range
• Volar plate : It is an accessory joint
structure to enhance the joint stability
by increasing the joint congruency.
INTERPHALANGEAL JOINTS OF FINGERS•True synovial hinge joint
•Articular surfaces: Proximally- pulley shaped head of
phalanx (large) Distally- base of phalanx having 2 shallow
concave facets with a central ridge.(small)
• Ligaments- radial collateral ligament
- ulnar collateral ligament
• Lig. Remains taut and Provide stability and support to PIP and DIP Joint throughout.
• Volar plates- reinforce each joint capsule and enhance stability and limit hyperextention.
• ROM- 1 degree freedom (flexion- extention)
ROM for PIP and DIP flexion increases from radially to ulnarly.
• index PIP joint flexion - 100 degree
index DIP joint flexion - 80 degree
• 5th PIP joint flexion – 135 degree
5th DIP joint flexion – 90 degree
Muscles:
extrinsic- the finger muscles having proximal attachment above the wrist (radiocarpal jt)
intrinsic- the finger muscles having attachment distal to the wrist (radiocarpal jt).
MCP & IP joints of thumb are structurally and functionally
identical to the MCP & IP joint of the finger
MCP joint of thumb differs in that it is reinforced by the 2
sesamoid bones which improve the leverage of
flexor pollucis brevis
CMC JOINT-THUMB
• Articulation between trapezium and the base of 1st metacarpal
• Articular surfaces - Trapezium - saddle shaped portion
spherical portion
Saddle shaped portion is concave in sagittal plane and convex in frontal plane
Spherical portion-convex in all direction Base of 1st metacarpal has a reciprocal
shape to that of trapezium
Flexion /extension and abduction/adduction are proposed to occur on saddle shape surfaces whereas axial rotation of the metacarpal that accompanies opposition is proposed to occur in the spherical surface
•TYPE OF JOINT -biaxial , saddle •Two degrees of freedom Flexion/ extension-around AP axis- 53 d Abd /add-around coronal axis- 42 d Rotation 17 d
•Flexion /extension and
abduction/adduction are proposed to
occur on saddle shape surfaces whereas
axial rotation of the metacarpal that
accompanies opposition is proposed to
occur in the spherical surface
•Type of joint:
-biaxial , saddle
•Two degrees of freedom:
Flexion/ extension-around AP axis- 53 d
Abd /add-around coronal axis- 42 d
Rotation 17 d
•Capsule: Relatively lax, but it is
reinforced by following ligaments.
• These ligaments are important stabilizers of the CMC
joint. As a group they resist the tendency of CMC to
dislocate
• The large functional demands placed on the CMC joint
of thumb results in a painful condition called BASILAR
JOINT ARTHRITIS
• When the ligaments are weakened by arthritis, the
joint often dislocates laterally relative to the
trapezium.
Functions of the CMC joint
•It has a unique range & direction of
motion that produces opposition (abd+
flex+add+ simultaneous rot.) of thumb
•This opposition occurs in all forms of
prehensions
EXTRINSIC MUSCLES
FLEXORS OF THE DIGITS..
FLEXOR DIGITORUM SUPERFICIALIS..• O
▫ Medial epicondyle of humerus
▫ Coronoid process▫ Middle ½ anterior radius
• I▫ Four tendons separating
into two parts that insert into sides of bases of middle 2-5 phalanx
• N▫ Median
• A▫ MCP flexion digits 2-5▫ PIP flexion digits 2-5
FLEXOR DIGITORUM PROFUNDUS..• O
▫ Antero-medial surface of ulna
▫ Interosseus membrane• I
▫ Four tendons inserting into distal phalanxes of digits
2-5• N
▫ Median 2-3 digits▫ Ulna 4-5 digits
• A▫ DIP flexion of 2-5 digits
FLEXOR POLLICIS LONGUS..• O
▫ Anterior middle ½ of radius
▫ Interosseus membrane• I
▫ Palmar surface of base of distal 1st phalanx
• N▫ Median
• A▫ IP Flexion of thumb
EXTENSORS OF THE FINGERS..
EXTENSOR DIGITORUM COMMUNIS..• O: Common extensor tendon from lat.epicondyle of humerus, and
deep antebrachial fascia.• I: By 4 tendons, each penetrating a membranous expansion of the
dorsum of the 2-5 digits and dividing over the proximal phalanx into a medial and 2 lateral bands. The medial band inserts into the base of the middle phalanx while the lateral bands reunite over the middle phalanx and insert into the base of the distal phalanx.
• N: Radial, C6, 7, 8• A: Extends the MCP joints and, in conjunction with the lumbricals
and interossei, extends the IP joints of the 2-5digits. Assists in abd of the index, ring, and little fingers; and assists in ext and abd of the wrist.
EXTENSOR INDICIS..
• O▫ Dorsal surface lower
½ body of ulna▫ Interosseus
membrane• I
▫ Ulnar side of index finger’s EDC tendon
• N▫ Radial (posterior
interosseus)• A
▫ MCP and IP Ext of 2nd digit
EXTENSOR DIGITI MINIMI..
• O▫ Lateral epicondyle of
humerus• I
▫ Extensor expansion of 5th digit
• N▫ Radial (posteior
interosseus)• F
▫ MCP and IP extension of 5th digit
EXTENSORS OF THUMB..
EXTENSOR POLLICIS LONGUS..
• O▫ Posterior 1/3 ulna▫ Interosseus
membrane• I
▫ Posterior surface of base of thumb distal phalanx
• N ▫ Radial (posterior
interosseus)• A
▫ CMC, MCP and IP Ext of 1st digit
EXTENSOR POLLICIS BREVIS..
• O▫ Dorsal 2/3 of radius
• I▫ Dorsal surface of base
of proximal 1st phalanx• N
▫ Radial (posterior interosseus)
• A▫ CMC & MCP Ext of
thumb▫ CMC ABD of thumb
ABDUCTOR POLLICIS LONGUS..• O
▫ Posterior distal 2/3 of ulna▫ Posterior middle 1/3 of radius▫ Interosseus membrane
• I▫ Radial side of base of 1st
metacarpal• N
▫ Radial (posterior interosseus)• A
▫ CMC ABD & Ext of thumb
INTRINSIC MUSCLES
THENAR EMINENCE..
ABDUCTOR POLLICIS BREVIS..
• O▫ Scaphoid tuberosity▫ Trapezium ridge▫ Transverse carpal
ligament• I
▫ Lateral base f proximal 1st phalanx
• N▫ Median
• A▫ CMC & MCP ABD of
thumb
FLEXOR POLLICIS BREVIS..
• O▫ Superficial head –
trapezium▫ Deep head – trapezoid,
capitate and palmar ligaments of distal carpal bones
• I▫ Base of prximal 1st
phalanx on radial side▫ Extensor expansion
• N▫ Superficial – median▫ Deep – Ulnar
• A▫ CMC & MCP Flexion of
thumb
OPPONENS POLLICIS..
• O▫ Trapezium▫ Transverse Carpal
Ligament• I
▫ Radial side of 1st metacarpal shaft
• N▫ Median
• F▫ Opposition
HYPOTHENAR EMINENCE..
Abductor Digiti Minimi..
•O▫Pisiform
•I▫Ulnar side base of 5th
proximal phalanx•N
▫Ulnar•A
▫MCP ABD of 5th digit
Flexor Digiti Minimi..
•O▫Hamate bone▫Transverse carpal
ligament•I
▫Ulnar side of proximal 5th phalanx
•N▫Ulnar
•A▫MCP Flexion of 5th
digit
Opponence Digiti Minimi..
• O▫ Hook of hamate▫ Transverse carpal
ligament
• I▫ Ulnar border of entire
5th metacarpal bone
• N▫ Ulnar
• A▫ MCP flexion & rotation
of 5th digit
Palmaris Brevis..
•O▫Flexor retinaculum
•I▫Palmar surface skin
on ulnar side of hand
•N▫Ulnar
•A▫Wrinkles skin of
hand on ulnar side
Adductor Pollicis..• O
▫ 1.Oblique Head Capitate bone Bases of 2-3
metacarpals▫ 2.Transverse Head
Proximal 2/3 of palmar surface of 3rd metacarpal
• I▫ Ulnar side of base of 1st
proximal phalanx• N
▫ Ulnar• A
▫ CMC ADD of thumb
Lumbricals..
• O▫ Tendons of FDP
• I▫ Extensor expansion on
dorsal aspect of each digits radial side
• N▫ 1 and 2 – median▫ 3 and 4 – ulnar
• A▫ MCP flexion 2-5 digits▫ DIP & PIP ext 2-5
digits
Palmar Interossei..
• O▫ 1st – ulnar side base of 1st
metacarpal bone▫ 2nd – ulnar side of 2nd MC
bone▫ 3rd – radial side of 4th MC
bone▫ 4th – radial side of 5th MC
bone• I
▫ Extensor expansion of 2,4 and 5th digits
• N▫ Ulnar
• A▫ ADD of 1st, 2nd, 4th and 5th
digits towards midline of hand
Dorsal Interossei..• O
▫ 1st lateral head – ulnar side of 1st metacarpal bone
▫ 1st medial head – radial side of 2nd metacarpal bone
▫ 2nd, 3rd, 4th space between metacarpal bones
• I▫ 1st – radial side 2nd
proximal phalanx▫ 2nd – radial side of 3rd
▫ 3rd – Ulnar side of 3rd
▫ 4th – ulnar side of 4th
• N▫ Ulnar
• A▫ ABD of 2nd, 3rd, and 5th
finger from midline
To learn..
PULLEYS
5 ANNULAR & 3 CRUCIATE
•A1 -MINOR C1•A2 -MAJOR C2•A3 -MINOR C3•A4 -MAJOR•A5 -MINOR
ZONES OF THE HAND
Dorsum of the hand, wrist, and forearm are divided into 8 anatomic zones to facilitate classification and treatment of extensor tendon injuries
•Zone 1 (distal interphalangeal [DIP] joint)•Zone 2 (middle phalanx)•Zone 3 (proximal interphalangeal [PIP] joint)•Zone 4 (proximal phalanx)•Zone 5 (metacarpophalangeal [MCP] joint)•Zone 6 (dorsum of hand)•Zone 7 (wrist)•Zone 8 (dorsal forearm)
Extensor tendon zones; dorsal aspect of the hand and wrist
flexor tendon zones; volar aspect of the hand and wrist.
TENODESIS
As the wrist is extended , the thumb & fingers automatically flex due to the stretch placed on the extrinsic digital flexors. The flexion occurs passively, without effort from the subject..
A person with c6 level qudriplegia using tenodysis action to grasp a cup of water.
SWAN NECK DEFORMITY• Commonly seen in Rheumatoid arthritis• It causes PIP joint hyperextension and DIP joint flexion• It can be a result of musculotendinous imbalance or joint laxity• It can originate from abnormalities at the DIP jt, PIP jt.
MALLET FINGERAt DIP jointRupture of the terminal
extensor tendon attachment causes flexion at the DIP joint
Because of which there is inadequate extensor force at DIP jt, causing flexion at the joint.
The extensor force concentrates more proximally causing PIP joint hyperextension
• It has got three components
flexion of PIP jt
and
hyperextension of DIP jt
Boutonniere’s deformity
• This is because of Syonovial proliferation within the PIP jtContracture of the oblique retinacular ligament
The central band ruptures and the lateral band slips into the palmar direction.. To the PIP joint ,thus proximal
interphalangel joint looses its only means of extension.. Any tension in lateral bands produces flexion at the PIP…and
hyperextention at DIP
• It is caused by rupture of the ulnar collateral
ligament
• It is characterised by radial deviation deformity
of the MCP joint with secondary adduction of the
thumb at the metacarpal
GAMEKEEPER’S THUMB
ZIG-ZAG DEFORMITY OF THUMB
Commonly seen in RA.The thumb metacarpal
dislocates laterally at the CMC jt. Causing
hyperextention at MCP jt. The IP jt. Remains
partially flexed owing to the passive tension in the stretched and taut flexor
pollicis longus.The bow string of the
tendon of the EPL across the MCP jt creates a large
extensor moment arm,thereby magnifying
the mechanics of the deformity.
• It leads to ulnar deviation of the digits at the metacarpo-phalangeal joint.
•Mainly due to weakning of the capsuloligamentous structures as seen in RA.
Ulnar Drift
• caused due to injury to ulnar nerve.
• It causes MCP joint hyperextension and PIP jt and DIP jt flexion
• Ulnar nerve injury can be at the wrist or
elbow levelAt the wrist level the muscles
that may be affected are hypothenar muscles,
dorsal and palmar interrosei, ulnar two
lumbricals, adductor pollicis, deep head of flexor pollicis brevis
ULNAR CLAW HAND
If these muscles are paralysed the ulnar two fingers have no intrinsic support
And the extrisic muscle pull predominates. The extensor digitorum has a larger moment arm at MCP
joint and consequently pulls the joint in hyperextension. As a result FDP is stretched and results in PIP and DIP jt
flexion.
At the elbow level injury The muscles affected are flexor carpi ulnaris, flexor
digitorum profundus to ring and little finger This causes slight alteration in the claw hand deformity,
where DIP joint remains in extension due to paralysis of flexor digitorum profundus.
Due to injury to the median nerve CMC jt of the thumb goes in to ext. and
add. And MCP jts and IP jts in to flex. Injury at the wrist causes paralysis of the
thenar muscles and lumbricals of the index and ring fingers.
Hence there is insufficient balance to the extrisic muscles of the thumb
And the EPL has a large adductor moment arm at the CMC joint causing adduction and extension.
Consequently the FPL is stretched , causing MCP & IP joint flexion.
APE THUMB
PALMAR DISLOCATION OF MCP JOINT
Advanced stages of osteoarthritis in the hands of an 86-yearoldpianist. Note the carpometacarpal joint subluxation at the base of
eachthumb. Atrophy of the first dorsal interossei as well as nodules and
jointenlargements are apparent, but the individual is still functional.
Click below to know what your hands can do…
REFERENCES..
•CAROL OATIS•ELIZABETH KENDALL•DONALD NEUMANN•CYNTHIA NORKIN•CALLIET•www.googleimages.com
THANK YOU