Intrinsic Hand

Question 1

Importance of Thumb in ADLs

Answer 1

Performs 50% of movement of hand!

Question 2

% of Motor Cortex of Brain Devoted to Hand Muscles

Answer 2

About 25%!

Question 3

Numbering of Fingers

Answer 3

Thumb considered Digit #1, then index finger is #2…. pinky is #5.

Question 4

5th Carpometacarpal (CMC) Joint

Answer 4

Considered the most mobile metacarpal joint, as it allows pinky to oppose thumb.

Question 5

CMC Joints of Digits 2-5

Answer 5

Index Finger (#2): Trapezoid articulates with 2nd metacarpal (MC)
Middle Finger (#3): Capitate articulates with 3rd MC
Ring Finger (#4) and Pinky (#5): Hamate articulates with 4th/5th MCs

Question 6

Functional Groups of Intrinsic Hand Muscles

Answer 6

1) Thenar Group
2) Hypothenar Group
3) Interossei Group
4) Lumbrical Group

Question 7

Thenar Group of Intrinsic Hand Muscles

Answer 7

Thumb muscles that originate at Thenar Eminence (fat part of base of thumb).

1) Abductor Pollicis Brevis* (CMC abduction)
2) Flexor Pollicis Brevis* (CMC flexion)
3) Opponens Pollicis* (CMC opposition)
4) Adductor Pollicis** (CMC adduction)
* Innervated by Median Nerve (C6-7)
* *Innerv. by Ulnar Nerve (C8, T1)

Question 8

Hypothenar Group of Intrinsic Hand Muscles

Answer 8

Pinky muscles that originate in Hypothenar Eminence (fat part on ulnar side of palm). All innervated by Ulnar Nerve (C8, T1).

1) Opponens Digiti Minimi (pinky opposition)
2) Abductor Digiti Minimi (MCP abduction)
3) Flexor DIgiti Minimi Brevis (MCP/PIP/DIP flexion)

Question 9

Interossei Group of Intrinsic Hand Muscles

Answer 9

Abductors/Adductors of MCP joint of fingers. Innervated by Ulnar Nerve (C8, T1).

1) Palmar Interossei (“PAD”=Palmar adduct)
2) Dorsal Interossei (“DAB”=Dorsal abduct)

Question 10

Lumbrical Group of Intrinsic Hand Muscles

Answer 10

Unique to body, no bony attachments; proximal attachment to tendons of flexor digitorum profundus; distal attachment to extensor digitorum communis.
• There are 4 total lumbricals.
• Flex MCP and Extend DIP/PIP
• Causes “Intrinsic Plus” position of hand when activated.

Question 11

Radial Nerve

Answer 11

• Terminal branch of brachial plexus.
• Innervates posterior muscles—most extensors.
• Injury/palsy causes wrist drop

Question 12

Median Nerve

Answer 12

• Terminal branch of brachial plexus.
• Innervates palmar side of thumb, digits 2-3, and radial half of digit 4. (Intrinsic anterior muscles)
• Considered “nerve of function” due to palmar innervation.
• Injury causes “ape hand” (thumb kept in plane of hand)

Question 13

Ulnar Nerve

Answer 13

• Terminal branch of brachial plexus
• Innervates ½ of 4th digit, and digit #5; intrinsic anterior muscles
• Injury causes “claw” hand of 4th-5th digits (loss of lumbricals; or “intrinsic minus” position)

Question 14

“Intrinsic Plus” vs. “Intrinsic Minus”

Answer 14

Positions of hand.

Plus: When lumbricals are activated. Extended wrist, flexed MCP (knuckles). Ideal position for healing injuries. Like holding a book by its binding.

Minus: When ulnar nerve compromised and lumbricals not working. “Claw hand” of 4th and 5th digits. Affects other fingers due to shared ligaments.

Question 15

Functional Hand Position

Answer 15

Ideal position for strength and precision.
• Wrist extended 20˚
• Fingers slightly flexed at all joints
• Thumb in opposition with MCP and IP flexed

Question 16

Tenodesis

Answer 16

Flexion of fingers due to passive insufficiency of extrinsic finger flexor muscles.
• Wrist extension naturally causes fingers to close/flex
• Used as functional grip for quadriplegics due to SCI below C6 (C7 injuries)

Question 17

Wrinkles in Hands

Answer 17

Caused as function of nerves. If nerve is cut, skin stops wrinkling/is unable to sweat.

Wrinkles on backs of finger knuckles are “dimples” where skin attaches to tendons.

Question 18

Dynamometer

Answer 18

Device used for grip testing.
• Client must sit with shoulder adducted, neutrally rotated, elbow flexed 90˚, forearm neutral, wrist betw 0-30˚ extension, and betw 0-15˚ ulnar deviation.
• 3 trials are taken of each hand
• Examiner must hold/support dynamometer (or rest on something) to prevent dropping. Very heavy!
• Uninvolved hand used as comparison for dominant/non-dominant.
• Normative data used, with variables considered such as age

Question 19

Pinch Gauge

Answer 19

Used to test pinch strength.
• Use same seating position as dynamometer.
• 3 trials obtained, bilaterally
• 3 types of pinches evaluated:
1) 2-point pinch (thumb/index)
2) lateral pinch
3) 3-point pinch (thumb tip to tips of index/middle)

Question 20

Swan Neck Deformity

Answer 20

Finger with hyperextended PIP joint and flexed DIP joint. Conditions that loosen PIP and allow it to hyperextend can produce this, such as RA.

Question 21

Boutonniere Deformity

Answer 21

Occurs when disease/injury causes PIP joint to become flexed and DIP joint is pulled up into too much extension (hyperextension).
• Can be caused by a ligament tear.

Question 22

Mallet Finger

Answer 22

AKA: Baseball Finger; Dropped Finger; Extensor Tendon Injury
• Injury to extensor digitorum tendon at DIP joint. Causes DIP to be flexed.
• Usually occurs when a ball, while being caught, hits outstretched finger and jams it, creating ruptured/stretched extensor digitorum tendon.

Question 23

Trigger Finger

Answer 23

AKA: Stenosing Tenosynovitis
• A finger or thumb gets stuck in bent position, and snaps when straightened. If it’s severe, finger may become locked in bent position and requires surgical release.

Question 24

Dupuytren’s Contracture

Answer 24

Thickening of fibrous tissue layer under skin of palm/fingers. Painless, but tightening (contracture) can cause fingers to flex. Creates a “cord” in the palm at base of finger.

Question 25

Kapandji Scoring Tool

Answer 25

Measures end stage of opposition; to assess opposition of thumb. Based on where client can touch tip of thumb. Scores 1-10 based on how far reach goes. 1=radial side of index proximal phalanx 10=distal palmar crease

Question 26

Rheumatoid Arthritis (RA) of Hand and Thumb

Answer 26

Autoimmune arthritis. Cause unknown. Women 20-50. Hands, wrists, elbows, shoulders, hips, ankles. Fatigue, joint pain, inflammation, edema, warmth, redness. Causes progressive joint destruction, deformity, disability. Hand: Ulnar deviation of MCP joints; swan neck or boutonniere deformities, or zigzag pattern of hand. May require “MCP joint implant arthroplasty” (silicone spacers replace MCP joint). OT: Conservative mgmt. or postop after joint replacement; prevention of further deformity; energy conservation; joint protection; assistive devices; pain control; strength maintenance

Question 27

Osteoarthritis (OA) of Hand and Thumb

Answer 27

Caused by wear and tear on joints. Overuse or trauma. Pain and stiffness. More prevalent in females 50+. Common in PIP/DIP, CMC of thumb, cervical/lumbar spine, shoulders, knees, and hips. Similar treatment to RA. • CMC of thumb most common site for surgical reconstruction. Removal of trapezium and a tendon used as arthroplasty (joint replacement).

Question 28

Synovitis

Answer 28

Thickening and inflammation of synovial lining of joints. Can accompany RA. Can cause ligament and tendon destruction, leading to laxity and possible rupture.

Question 29

Repetitive Stress Injuries (RSIs) of Hand and Thumb

Answer 29

``` AKA: Cumulative Trauma Disorders (CTDs) • Affect wrist, hand, thumb more often than anywhere else in body HAND: • Carpal Tunnel Syndrome (CTS) • Tendinitis • Trigger Finger ```

Question 30

Tendinitis

Answer 30

Irritation or inflammation of tendon. Prevalent in hand/wrist; can be precursor to other RSIs (ie: could lead to CTS). • Microscopic tears in tendons can occur, especially at musculotendinous junction (where tendon and muscle join). • Pain, swelling. • Most common in: Flexor and extensor tendons of wrist; Extensor tendons of thumb

Question 31

Carpometacarpal Protocol

Answer 31

CMC joint protocol to follow after CMC arthroplasty for OA. Protection of joint; edema/pain/scar mgmt.; exercises.

Question 32

Palmar Aponeurosis

Answer 32

Thickened, central portion of deep palmar fascia. Protects flexor tendons of palm; gives firm attachment to skin of palm to help with grip. When this has contracture, it causes Dupuytren’s Disease.

Question 33

Skier’s Thumb

Answer 33

Acute injury to ulnar collateral ligament (UCL) of thumb. Often seen among skiers who fall with ski pole still in hand. Hyperextension of proximal phalanx, tearing UCL. Categorized I-III, and treatment depends on level. Rest/splint up to surgical repair.

Question 34

Fasciotomy

Answer 34

Removing thickened fascia to release contracture (such as in Dupuytren’s disease).

Question 35

Stener Lesion

Answer 35

Occurs when aponeurosis of adductor pollicis muscle goes between MCP and torn UCL, ie: in Skier’s Thumb. Prevents adequate healing of ligament, and requires surgery. Surgery = suturing ligament to itself or adjacent bone.

Question 36

Avulsion Fracture

Answer 36

Injury to bone at an attachment when ligament/tendon tear and pull off a piece of the bone. Can occur with Skier’s Thumb, grade III.

Question 37

Volar Arch

Answer 37

Cupping of the hand, created by opposing the small finger.

Question 38

Volar Plate

Answer 38

Fibrous connective tissue and fibrocartilage located under each joint of the fingers and thumb; limits hyperextension.

Question 39

Dorsal vs. Palmar Fascia

Answer 39

Dorsal: Loose, thin, mobile; prone to avulsion injury or accumulation of edema. Palmar: (AKA Palmar Aponeuroses.) Deep, thick, fibrous; oriented in many directions; stabilizes skin to underlying structures for protection (ie: during resistive grasping)

Question 40

Functional Arches of Hand and Wrist

Answer 40

1) Proximal Transverse Arch (base of meta- and carpal bones; maintained by flexor retinaculum) 2) Distal Transverse Arch (formed by metacarpal heads) 3) Longitudinal Arch (runs from wrist to length of fingers)

Question 41

Functional Position of Hand

Answer 41

When wrist is extended to about 20˚.