Upper Extremity: Hand (Part 1) Flashcards
A digit (ray) contains
- Metacarpal
- Proximal phalanx
- Intermediate (Middle) phalanx
- Distal phalanx
- Thumb (pollex) does not have a middle phalanx
Joints of the Hand
- Carpometacarpal joints
- Metacarpophalangeal (MCP) joints (“knuckles”)
- Interphalangeal (IP) joints
Carpometacarpal Joints
- Between proximal end of metacarpal and distal row of carpals
- 1st carpometacarpal joint is a saddle joint
Metacarpophalangeal (MCP) Joints (“Knuckles”)
- Between distal end of metacarpal and proximal phalanges
Interphalangeal (IP) Joints
- Proximal (PIP)
- Distal (DIP)
- Thumb only has an interphalangeal joint
Middle Finger
- Used as a reference point with finger abduction/adduction
Types of Grips
- Power
- Precision
Power Grip
- Different types
- Significant force produced
Power Grip Relies on
- Finger flexion
- Wrist extension
- Thumb adduction, flexion, opposition
Precision Grips
- Different types
- Less force
Fascia of the Palm
- Continuous with antebrachial fascia (forearm deep fascia)
- Fascia is thin over thenar and hypothenar regions
- Palmar aponeurosis
Palmar Aponeurosis
- Thick, covers central compartment and flexor tendons
- Made up of longitudinal and transverse bands
Palmar Aponeurosis Attaches to
- Flexor retinaculum and palmaris longus
- Fibrous sheaths
Compartments of the Palm
- Compartments created by bone, deep fascia, and septa extensions
Compartments of the Palm Containing Muscle
- Thenar
- Hypothenar
- Central
- Adductor
- Interosseous
Spaces of the Compartments of the Arm
- Thenar
- Midpalmar
Midpalmar Compartment of the Arm
- Communicates through carpal tunnel into the forearm
Fibrous Digital Sheath (Tendon Sheath of the Hand)
- Osseofibrous tunnel
- Surrounds digital synovial sheaths
- Vincula
Fibrous Digital Sheath Structure
- Surrounds digital synovial sheaths
- Formed by annular and cruciform ligaments
- Prevents bowstringing
Vincula of Fibrous Digital Sheath
- Attaches tendons to bones and neighboring tendons
- Allow for the passage of blood vessels
Tendon Sheaths of the Hand
- Fibrous digital sheath
- Ulnar bursa
- Radial bursa
Ulnar Bursa
- Communicate with the synovial sheath of the 5th digit
Radial Bursa
- Communicates with 1st digital synovial sheath
Spread of Infection (Hand to Forearm)
- Midpalmar space > forearm
- 1st digit > wrist/distal forearm
- 5th digit > wrist/distal forearm
Clinical Importance of Tendon Sheaths/Infection
- Infection in the synovial sheaths of the hand/digits can spread into the forearm (Space of Parona)
Dupuytren’s Contracture
- Thickening and shortening of palmar aponeurosis
- Most common in ring and little finger
- Nodule thickenings progresses to contracture of longitudinal bands
Dupuytren’s Contracture Cause
- Unknown
- Hereditary predisposition
- Possible risk factors: smoking, diabetes, manual labor
- Microvascular ischemia
Dupuytren’s Contracture Treatment
- Fasciotomy
- Fasciectomy
- Collagenase injections (break down collagen)
Trigger Finger
- Thickening of a flexor tendon in the distal palm
- Restriction of tendon gliding under the fibrous sheath
- Palpable nodule that gets “stuck”
- Locking of finger into flexion (most common)
- “Snaps” into place
Trigger Finger Cause
- Unknown
- Other disease conditions (diabetes, inflammatory arthritis)
- Repetitive, forceful digital flexion
Intrinsic Muscles of the Hand
- Thenar muscles
- Adductor pollicis
- Hypothenar muscles
- Lumbricals
- Interossei
Thenar Muscles
- Abductor pollicis brevis
- Flexor pollicis brevis
- Opponens pollicis
Hypothenar Muscles
- Abductor digiti minimi
- Flexor digiti minimi
- Opponens digiti minimi
Interossei Muscles
- Dorsal
- Palmar
Thenar Muscles Proximal Attachments
- Flexor retinaculum
- Carpal bones (trapezium, scaphoid)
Thenar Muscles Distal Attachments
- 1st metacarpal (OP)
- Base of thumb proximal phalanx
- Sesamoid bone ( for APB, FPB)
Thenar Muscles Innervation
- Recurrent branch of median nerve
- Deep portion of FPB can be innervated by deep branch of ulnar nerve
Thenar Muscles Function
- Name tells you function
- APB: abduction of the thumb
- FPB flexes CMC and MCP
- Opposition involves flexion, abduction and medial rotation at thumb CMC
Adductor Pollicis
- 2 heads
- Oblique
- Transverse
Oblique Adductor Pollicis Proximal Attachment
- Capitate
- Base of 2nd and 3rd mets
Transverse Adductor Pollicis Proximal Attachment
- Palmar surface of 3rd met
Adductor Pollicis (Both Obliqe and Transverse) Distal Attachments
- Medial aspect of proximal phalanx, sesamoid bone
Adductor Pollicis (Both) Innervation
- Deep branch of ulnar nerve
Adductor Pollicis (Both) Function
- Moves thumb toward hand
