Dynamic Anatomy of Wrist & Hand

1. Articulations and
movements of the wrist
Articulations and
movements of fingers

2. Introduction
 The hand is primarily used for manipulation
activities requiring very fine movements
incorporating a wide variety of hand and finger
postures.
 Consequently, there is much interplay between
the wrist joint positions and efficiency of finger
actions.
 The hand region has many stable yet very
mobile segments, with complex muscle and joint
actions.

3. Anatomical and Functional Characteristics of
the Joints of the Wrist and Hand
 The wrist consists of 8 small carpal bones but
can be functionally divided into
1. The radiocarpal and
2. The mid-carpal joints.
 The radiocarpal joint is the articulation where
movement of the whole hand occurs.

4.  The radiocarpal
joint involves
1. the distal end of
the radius,
2. the scaphoid and
3. the lunate.
 Movements
possible at this
joint: flexion-
extension and
radial-ulnar
flexion. DIP = distal interphalangeal, PIP = proximal
interphalangeal,
MCP = metacarpophalangeal

5. Midcarpal and Intercarpal Joints
 There are two rows of
carpals: proximal and
distal.
 The articulation
between the two rows
of carpals is called the
midcarpal joint, and
the articulation
between a pair of
carpal bones is
referred to as an
intercarpal joint.

6.  The scaphoid is
the most important
carpals because
1. it supports the
weight of the arm,
2. transmits forces
received from the
hand to the bones
of the forearm, and
3. is a key participant
in wrist joint
actions.

7. Carpometacarpal Joints
 The carpometacarpal (CMC)
joint connects the carpals with
each of the five fingers via the
metacarpals.
 They are numbered from the
thumb to the little finger, with
the thumb being the first ray and
the little finger the fifth.
 The CMC articulation provides
the most movement for the
thumb and the least movement
for the other fingers.

8. Metacarpophalangeal Joints
 The metacarpophalangeal
joints (MCP) connect the
metacarpals connect with the
phalanges.
 The MCP joints of the four
fingers (not the thumb) allow
movements in two planes:
flexion-extension and
abduction-adduction.
 The MCP of the thumb allow
only flexion-extension

9.  The fingers can be abducted when extended and
then cannot be abducted or adducted when flexed
around an object. Why?
 The collateral ligaments restrict this movement.

10. Interphalangeal Joints
 The most distal joints in the
upper extremity link are the
interphalangeal articulations
(IP).
 Each finger has two IP
joints, the proximal
interphalangeal (PIP) and
the distal interphalangeal
joint (DIP).
 The thumb has one IP joint.

11.  The IP joints allow movement in one plane
only: flexion and extension.
 The collateral ligaments restrict movements other
than flexion and extension.

12. Summary of movements
 Wrist
 Flexion & extension
 Abduction & adduction
 Fingers
 Flex & extend
 MCP joints also abduct & adduct

13. Movements of the wrist

14. Movements of the wrist

15. Movements of the wrist

16. Movements of the hand
Abduction/adduction

17. Movements of the hand
Opposition/reposition
 Opposition: movement of thumb across palmar
aspect to oppose any or all of the phalanges.
 Reposition: movement of thumb as it returns to
anatomical position from opposition with hand and/or
fingers.

18. Combined Movements of the Wrist and Hand
 The wrist position influences the position of the
metacarpal joints, and the metacarpal joints influence
the position of the interphalangeal joints.
 This requires a balance between muscle groups.
 Most of the muscles that act at the wrist and finger
joints originate outside the hand in the region of the
elbow joint. They are called extrinsic muscles.
 The intrinsic muscles originating within the hand
create movement at the MCP and IP joints.

20. Functional groups of muscles
 The wrist flexors: flexor carpi ulnaris, flexor carpi
radialis, palmaris longus.
 The wrist extensors: extensor carpi ulnaris, extensor
carpi radialis longus, extensor carpi radialis brevis.
 The wrist flexors and extensors pair up to produce ulnar
and radial flexion.
 Radial flexion joint movement is important in many sports
such as baseball because it creates the close-packed position
of the wrist, thus stabilizing the hand.

21. Flexors of the wrist Extensors of the wrist

22.  Finger flexion is performed primarily by the flexor
digitorum profundus and flexor digitorum
superficialis.
 The flexor digitorum profundus cannot independently flex
each finger. Thus, flexion at the middle, ring, and little
fingers usually occurs together because the flexor tendons
all arise from a common tendon and muscle.
 The flexor digitorum superficialis is capable of flexing each
finger independently.

24.  Extension of the fingers is created primarily by the
extensor digitorum muscle.

25.  Abduction of fingers 2, 3, and 4 is performed by
the dorsal interossei muscles (intrinsic muscles).
 Abduction of finger 5 is performed by the
abductor digiti minimi brevis.

26. Nerves
 Flexors are innervated by the ulnar and median
nerves.
 Extensors are innervated by the radial nerve.
 All intrinsic muscles are innervated by the ulnar
nerve.

27. Strength of the Hand and Fingers
 How to grasp or grip an object?
 A firm grip requiring maximum output uses the
extrinsic muscles.
 Fine movements, such as a pinch, use more of the
intrinsic muscles to fine-tune the movements.
 If power is needed in a grip, the fingers flex at all three
joints to form a fist. If the thumb adducts, the grip is
more powerful. A precision grip usually involves slight
flexion at a small number of finger joints with the
thumb perpendicular to the hand.

29. Injury Potential of the Hand and Fingers
 Many injuries can occur to the hand as a result of
absorbing a blunt force, as in impact with a ball, the
ground, or another object.
 Extreme hyperextension is the most common injury.
This can result in a sprain of the wrist ligaments, a
strain of the wrist muscles, a fracture of the scaphoid or
other carpals, a fracture of the distal radius, or a
dislocation between the carpals and the wrist or other
carpals.
 The distal end of the radius is one of the most
frequently fractured areas of the body because the bone
is not dense and the force of the fall is absorbed by the
radius.

30.  Carpal tunnel syndrome
 One of the most frequent work injuries
 The carpal tunnel is formed by the carpals and by the
transverse carpal ligament. Traveling through this tunnel
are the wrist flexor tendons and the median nerve.
 Caused by repetitive actions at the wrist, usually repeated
wrist flexion. This leads to the inflammation of the
tendons and the compression of the median nerve.

31. The floor and sides of the carpal tunnel are formed by the carpals, and the top of the
tunnel is covered by ligaments. Within the tunnel are wrist flexor tendons and the
median nerve. Overuse of the wrist flexors can impinge the median nerve, causing
carpal tunnel syndrome.