Structure and Function of the Hand

Transcription

1 Structure and Function of the Hand Some say it takes a village to raise a child, but it takes 19 bones and 19 joints in the hand for it to function smoothly.

2 The Hand Dorsal aspect The digits are numbered 5 1

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4 Joints of Hand

5 Joints and Motion of Thumb Only three joints (CMC, MCP, and IP) CMC (trapezium/1 st metacarpal) is a Saddle joint Allows mobility and stability (unusual) Motions allowed at CMC Flexion/extension Abduction/Adduction Opposition MCP and IP Flexion and Extension only

6 Add/Abd Flex/Ext

7 Opposition

8 What joint is affected? What could be the reason?

9 Joints and Motions of Digits 2-5 CMC joints Irregular synovial joints (stability over mobility) Nonaxial MCP (knuckles) Biaxial condyloid Flex/Extension Abd/Adduct (3 rd finger is reference point) IP joints (PIP, DIP) Uniaxial hinge Flex/Extend

10 Name the Joints of the Hand

11 Intrinsic vs Extrinsic of the Hand Intrinsic- Originating within the area and inserting in the area Extrinsic- Originating outside of the area but inserting in the area

12 Intrinsic or Extrinsic

13 Myology of the Hand: Extrinsics Flexor Digitorum Superficialis Origin Insertion Common flexor tendon on the medial epicondyle of the humerus, coronoid process of the ulna and radius lateral to the raidal tuberosity By 4 tendons, each to the sides of the middle phalanges of the fingers Innervation Median n. Action MCP and PIP flexion tidbit What s in a name?

14 Myology of the Hand: Extrinsics Flexor Digitorum Profundus Origin Anterior ulna and interosseous membrane Insertion By 4 tendons, each to the base of the distal phalanx of digits 2-5 Innervation Medial half: Ulnar n. Lateral half: Median n. Action MCP, PIP and DIP flexion, wrist flexion tidbit What s in a name?

15 Myology of the Hand: Extrinsics Flexor Pollicis Longus Origin Insertion Middle anterior portion of the radius and interosseous membrane Base of the distal phalanx of the thumb Innervation Median n. Action CMC, MCP and IP flexion of the thumb tidbit What s in a name?

16 Common Flexor Pathology Trigger finger Smooth gliding of flexor tendon is disrupted due to inflammtion Nodule becomes wedged inside tendon sheath and temporarily blocks gliding

17 Extensor Digitorum Muscle Extensor Digitorum Origin Insertion Lateral epicondyle of the humerus-common extensor tendon By 4 tendons, each to the base of the extensor mechanism and base of the proximal phalanx of all 4 fingers (not thumb) Innervation Radial n. Action tidbit Extension of the fingers What s in a name?

18 Extensor Indicis Muscle Extensor Indicis Origin Insertion Posterior surface of distal ulna and interosseous membrane Blends with the index tendon of the extensor digitorum Innervation Radial n. Action Extension of the index finger ONLY tidbit What s in a name?

19 Extensor Digiti Minimi Muscle Extensor Digiti Minimi Origin Insertion Innervation Radial n. Action tidbit Ulnar side of the belly of the extensor digitorum Joins the tendon of the extensor digitorum to the little finger Extension of the 5 th finger What s in a name?

20 How would you drink tea if you didn t have a EDM?

21 Myology of the Hand: Extrinsics Extensor Pollicus Longus Origin Insertion Posterior surface of the ulna and interosseous membrane Dorsal base of the distal phalanx of the thumb Innervation Radial n. Action tidbit Extension of the IP, MCP and CMC of the thumb What s in a name?

22 Myology of the Hand: Extrinsics Extensor Pollicis Brevis Origin Insertion Innervation Radial n. Action tidbit Posterior aspect of the radius and interosseous membrane Dorsal base of the proximal phalanx of the thumb Extension of the MCP & CMC joints of the thumb What s in a name?

23 Myology of the Hand: Extrinsics ABDuctor Pollicis Longus Origin Insertion Innervation Radial n. Action Posterior surface of the radius, ulna and interosseous membrane Base of the 1 st metacarpal ABD and extension of the CMC of the thumb tidbit What s in a name?

24 Anatomic Snuff Box Extensor Pollicis Longus Extensor Pollicis Brevis ABDuctor Pollicis Longus

25 Special Structures in the Hand Thenar Eminence

26 Special Structures of the Hand Hypothenar Eminence

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29 Functional Position of the Wrist & Hand Optimal wrist extension 10 ulnar deviation 45 MCP flexion Slight flexion PIP/DIP

30 Tenodesis action

31 Prehension Definition of prehension The ability to grasp objects between any two surfaces of the hand Two types Power grip Precision grip

32 Power Grip Definition: a STATIC prehension Thumb is used as stabilizer Sequence: Open hand Position fingers Approach object Take grip and hold it statically

33 Power Grip Types Cylindrical grip Spherical grip Hook grip

34 Precision Grips Definition: grasp and manipulate objects Requires more variability in positioning and better sensation Sequence: Open hand Position fingers Approach object Grasp object and manipulate it

35 Precision Grip Types Pad to pad prehension 2 types Two jaw chuck: thumb and one finger Three jaw chuck: thumb and two fingers Tip to tip prehension Similar to pad to pad but requires more IP flexion Pad to side prehension (lateral prehension) Lumbrical grip

36 The Hand: Hand specialists study and treat the hand exclusively to be considered hand therapists. Most clinicians refer patients with diagnoses of the hand to a hand therapist. What is expected? Osteology Extrinsic myology Familiarity with the intrinsic myology by names of the muscles Familiarity with the overall function of the structures intrinsically and extrinsically Grips Common injuries and potential causes

37 Voluntary Assignment Worth up to 5 points on next exam -One page (typed) summary of why the optimal position of the wrist is splinted in slight extension -Must include length tension relationship, and either active or passive insufficiency in description Use page 157 in the Mansfield text to get you started.