1. CHAPTER 7 Wrist and Hand

2. Introduction
The wrist and hand are composed of multiple joints.
The wrist fine-tunes hand position.
The hand contains palm and fingers.

3. Fingers are referred to as digits, of which there are five per hand.
Introduction
Fingers are referred to as digits, of which there are five per hand.
The hand is a complex multipurpose organ.
Prehension
Sense organ
Expression and nonverbal communication

4. Bones—Wrist Distal ulna
Not in direct contact with carpal bones (triangular fibrocartilage complex; TFCC)
Three parts:
Ulnar styloid process
Fovea
Pole

5. Bones—Wrist Distal radius Primary forearm bone of wrist Features
Dorsal surface tubercle—redirect pull of extensor pollicis longus (EPL)
Radial styloid process
Ulnar notch

6. Bones—Wrist Carpal bones Categorized into proximal and distal rows
Capitate—occupies central position
Scaphoid—most commonly fractured carpal
Lunate—most frequently dislocated carpal
Pisiform—serves as attachment for flexor carpi ulnaris (FCU)
Hamate—unique hook feature

7. Bones—Hand Metacarpals
Base articulates with carpal bones and adjacent metacarpals.
The shaft is slightly curved with a palmar concavity.
The head articulates with the base of proximal phalanx.

8. Bones—Hand Phalanges Thumb—two: proximal and distal
Digits 2–5—three: proximal, middle, and distal
Base—biconcave
Distal heads—bicondylar

9. Joints—Wrist Radiocarpal joint
Biconcave distal radius and convex proximal row
TFCC
Attaches to distal radius and ulna
Apex attached to triquetrum
Part of flexion/extension; radial and ulnar deviation occur at this joint
Recommend inserting Figure 7-5

10. Joints—Wrist Midcarpal joint Formed by proximal and distal rows
Additional amounts of flexion/extension; radial/ulnar deviation
Recommend inserting
7-4

11. Carpometacarpal joints (2–5)
Joints—Hand
Carpometacarpal joints (2–5)
Metacarpal bases 2–5 articulate with one another.
There is minimal motion of the second and third.
Fourth and fifth have significant motion.
Third acts as a stable pillar about which hand rotates.

12. Carpometacarpal joints—first
Joints—Hand
Carpometacarpal joints—first
Saddle
Thick but loose capsule
Motions include:
Flexion/extension
Abduction/adduction
Opposition/reposition
Recommend inserting Figures 7-8A, B, C

13. Metacarpophalangeal joints
Joints—Fingers
Metacarpophalangeal joints
Condyloid with two degrees of freedom
Flexion/extension; abduction/adduction
Convex heads of metacarpals—3/4 covered with articular cartilage
Concave bases of phalanges—volar plates

14. Interphalangeal joints
Joints—Fingers
Interphalangeal joints
Digits 2–5—proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints
Thumb—one interphalangeal joint
Hinges—one degree of freedom
Flexion/extension

15. Joints—Soft Tissue Supporting Structures
Ligaments of the wrist
Complex ligaments—cover all aspects of wrist
Extrinsic—radius, ulna, or metacarpals to carpals
Flexor and extensor retinacula—Carpal Tunnel Syndrome on flexor side
Intrinsic—between carpal bones only
V-shaped ligament
No ligaments between capitate and lunate

16. Joints—Soft Tissue Supporting Structures
Ligaments of the hand and fingers
Medial and lateral collaterals
Taut in flexion—assist with ability to grip
Loose in extension—allow abduction/adduction
Deep transverse carpal ligament
Attaches to heads of metacarpals 2–5

17. Joints—Soft Tissue Supporting Structures
Ligaments of the hand and fingers
Thumb
Two sesamoids attached to volar plate
Several ligaments attached
Sesamoid mechanism facilitates pinch precision

18. Muscles Wrist extensors Common origin—lateral epicondyle
With elbow >15°— anterior to elbow axis
Primary wrist extensors:
Extensor carpi radialis brevis (ECRB)—extensor carpi radialis longus (ECRL)—extensor carpi ulnaris (ECU)
Extensor digitorum
Wrist extension when fingers extended

19. Muscles Wrist flexors Common origin—medial epicondyle
With elbow flexed, may aid in elbow flexion
Primary muscles
Flexor carpi radialis (FCR)—FCU—flexor digitorum superficialis (FDS)—flexor digitorum profundus (FDP)—Palmaris Longus (PL)—FPL—APL

20. Radial/ulnar deviation
Muscles
Radial/ulnar deviation
Deviation occurs in frontal plane about an A-P axis.
Muscles (either flexors or extensors) that are further from axis will assist with respective deviation.
Wrist extensors and flexors work synergistically.

21. Muscles—Extensor Mechanism
Tendinous system
Three bands—central (one); lateral (two)
Retinacular system
Extensor hood
Flexor pulleys

22. Motions—Wrist Osteokinematics Radial deviation—bony end feel
Midcarpal and radiocarpal each responsible for 1/2
A-P axis through capitate
Ulnar deviation—firm end feel
Midcarpal responsible for 1/3
Radiocarpal responsible for 2/3

23. Motions—Wrist Osteokinematics Flexion Extension
50° at radiocarpal joint; 35° at midcarpal
Extension
50° at midcarpal joint; 35° at radiocarpal
Axis for flexion/extension also passes through capitate

24. Motions—Wrist Arthrokinematics Convex proximal row on concave ulna
Roll and glide in opposite directions
Wrist extension—posterior roll; anterior glide
Arthrokinematics similar at midcarpal joint
Close-packed position—full wrist extension

25. Osteokinematics—metacarpophalangeal (MCP) joints (2–5)
Motions—Fingers
Osteokinematics—metacarpophalangeal (MCP) joints (2–5)
~90° of flexion; extension is variable depending on individual and whether motion is active or passive.
End feels are typically firm for both flexion and extension.
Close-packed position = full flexion.

26. Osteokinematics—MCP joints (digits 2–5)
Motions—Fingers
Osteokinematics—MCP joints (digits 2–5)
~20° of abduction/adduction can occur when MCP joints are extended.
Little or no abduction/adduction with MCP joints in flexion due to Closed Packed Position.

27. Osteokinematics—MCP joints (thumb)
Motions—Fingers
Osteokinematics—MCP joints (thumb)
Hinge joint
Flexion = 45–60°
Extension = 0–20°
Small amount of side-to-side motion with thumb in slight flexion
Allows for fine-tuning grasp

28. Motions—Fingers
Osteokinematics—proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints
Hinge joints
Flexion = 120°
Extension = 0° (unless hyperlax)
Resting position (for both MCP and IP joints)
20° of flexion
Close-packed position
Full extension (thumb); full flexion (2–5)

29. Arthrokinematics—MCP and IP joints
Motions—Fingers
Arthrokinematics—MCP and IP joints
Roll and glide in the same direction
True for both flexion/extension and abduction/adduction motions
In loose-packed position (20°)—large joint play motions are possible

30. Functional Movements of Wrist and Hand
Types of grasp
Power grip
Incorporates entire hand
Is used for gross grasping activities
Is involved in holding an object between partially flexed fingers and palm while thumb provides counterpressure
Different types of power grips—see Table 7–4

31. Functional Movements of Wrist and Hand
Types of grasp
Precision grip
Is used for accuracy and refinement; object manipulation
Thumb abducted—ready to oppose
Different types of precision grips—see Table 7–5

32. Functional Movements of Wrist and Hand
Strength of grip
Males grip strength (100#) on average 2× greater than females of similar age.
Studies vary, but overall, ~6% stronger grip on dominant side.

33. Functional Movements of Wrist and Hand
Grasping
Finger flexion occurs with the wrist stabilized in extension.
Grip is significantly weakened if wrist flexion occurs.
Influenced by passive insufficiency of wrist extensors and active insufficiency of wrist flexors
Optimal wrist position during grasp = 20–35° extension with slight ulnar deviation.

34. Functional Movements of Wrist and Hand
Abduction/adduction digits 2–5
Away from midline = abduction; toward = adduction
Midline—through middle finger
Occurs at MCP joints when extended
Abduction coupled with extension; adduction with flexion

35. Balanced Forces Thumb Mobility
Carpometacarpal (CMC) joint = a saddle joint that enhances mobility
Motions: flexion/extension; abduction/adduction; opposition and reposition

36. Summary Wrist and hand as a complex organ with many responsibilities
Balance of extrinsic and intrinsic muscle activity
Functional position of wrist (20–35° of extension); ability of injury to affect optimal wrist position