Hands, Forearm, Wrist Flashcards by Fell into the rabbithole

● Positions the hand.
● Provides a stable platform from which the hand
functions.
● Finely tuned hand positioning.
● Global positioning of the hand.

Wrist

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● Predominant part of the body serving many purpose.
● Contains the palm and fingers.
○ Both sturdy and mobile.
● Complex, multipurpose organ
● As a prehensile organ, it can grasp with forces
exceeding 100 lb (445 N or 45 kg) or manipulate a
delicate thread
● Conform around objects
● Pushing and pulling

Hand

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“Pollex”

Thumb

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Often used to point, and pointing is a
method of making things clearer and it is
the purpose of an index

Index/Pointing/Forefinger

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Longest finger of the hand

Middle Finger

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It was believed that this finger contained a
“vein of love” that flowed directly to the
heart

Ring finger

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Smallest finger

Pinky/Little finger

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primary forearm bone
of the wrist

radius.

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interact with the radius to form the
wrist joint.

(Scaphoid +
Lunate

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● Not in direct contact with the
carpal bones.
● Fibrocartilaginous disc
separates the ulna from the
carpal bones.
● Distal portion of the ulna is an
important part of the wrist.

Distal Ulna

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is a bony
projection, easily palpated with
the forearm pronated, on the
ulnar side of the wrist

Ulnar styloid process

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a depression at the base
of this styloid process and
provides attachment for the
fibrocartilaginous disc.

Fovea

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a concave articular
surface allowing ulnar
articulation with the
fibrocartilaginous disc

Pole

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● Lies about 1/3 of the wrist’s width
from the radial styloid process.
● Has grooves on either side of it
that serve as a pulley for the:
○ extensor pollicis longus
tendon on the ulnar side
○ extensor digitorum and
extensor indicis tendons on
the radial side

Lister’s Tubercle

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● Distal projection on the
radial surface of the radius.
● More distal than ulnar
styloid process.
● Ulnar and radial styloid
processes serve as
attachment sites for the
ulnar and radial carpal
collateral ligaments,
respectively

Radial Styloid Process

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p● Sigmoid notch
● On the ulnar (lateral)
aspect of the distal radius
is the articulating surface
for the distal radioulnar
joint

Ulnar notch

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PROXIMAL ROW

○ Scaphoid
○ Lunate
○ Triquetrum
○ Pisiform

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DISTAL ROW

○ Trapezium
○ Trapezoid
○ Capitate
○ Hamate

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● Navicular
● Most frequently
fractured carpal bone
● Floor of the anatomic
snuffbox

Scaphoid

Most frequently
dislocated carpal bone

Lunate

“Triangular”

Triquetrum

Pea-shaped

Pisiform

“Greater multangular”

Trapezium

“Lesser multangular”

Trapezoid

● Occupying a central position at the wrist (in line with the middle finger) ● Os magnum ● Best approached from the dorsum, where a slight depression indicates its location ● The axis of motion for ulnar and radial deviation goes through this bone in a dorsopalmar direction

Capitate

It has a hooked process on its palmar side, called the hook of the hamate

Hamate

● A triangular skin depression on the lateral side of the wrist that is bounded medially by the tendon of the extensor pollicis longus and laterally by the tendons of the abductor pollicis longus and extensor pollicis brevis ● Its clinical importance lies in the fact that the scaphoid bone is most easily palpated here and that the pulsations of the radial artery can be felt here

Anatomic Snuffbox

○ fracture of the 5th metacarpal neck ○ clenched fist striking a hard object

BOXER’S FRACTURE

○ fracture of the 1st metacarpal base ○ forced hyperabduction of the thumb

BENNETT’S FRACTURE

2 phalanges of the thumb

○ Proximal ○ Distal

.3 phalanges of the 2nd to 5th digits

○ Proximal ○ Middle ○ Dista

● Wide mobility of the hand ● Great structural stability in the wrist ● Allows the hand an extensive degree of function ● Ellipsoidal joint ● 2 DOF ● 15 bones ● 17 joints ● Extensive

Wrist Joint

● Biconcave: Distal end of radius ● Biconvex: Proximal articulating surface of the scaphoid and lunate ● 2 DOF ● Motions: flexion, extension, radial deviation, ulnar deviation

Radiocarpal Joint

● Formed by the proximal and distal carpal rows. ● The scaphoid articulates with the trapezium, trapezoid, and capitate. ● Lunate articulates with the capitate. ● Triquetrum articulates with the hamate. ● Wrist motions: flexion, extension, and radial and ulnar deviation

Midcarpal Joint

● Each digit has: CMC + MCP ● Each of the 4 fingers has: PIP + DIP

feel ko important

minimal movement

2nd and 3rd CMC joint

least mobile (central pillar of the hand)

3rd CMC joint

10 to 15 degrees dorsovolar movement

4th CMC joint

● Trapezium + Base of First Metacarpal ● Saddle joint ● Motions: flexion, extension, abduction, adduction, opposition, reposition.

Carpometacarpal Joint of Thumb

● Condyloid type ● 2 DOF ● Flexion, extension, abduction, and adduction. ○ Convex: Head of metacarpals ○ Concave: Base of proximal phalanges

Metacarpophalangeal Joints

● 2nd to 5th digit = DIP and PIP ● Thumb = Interphalangeal joint ● 1 DOF ● Motion: flexion and extension ● (+) volar plate mechanism: prevents hyperextension

Interphalangeal Joints

6 Extensor Tunnels ● Tunnel 1: ● Tunnel 2: ● Tunnel 3: ● Tunnel 4: ● Tunnel 5: ● Tunnel 6:

6 Extensor Tunnels ● Tunnel 1: APL + EPB ● Tunnel 2: ECRL + ECRB ● Tunnel 3: EPL ● Tunnel 4: ED + EI ● Tunnel 5: EDM ● Tunnel 6: ECU

a fibrous band connecting the proximal phalanx and distal sheath that covers the proximal and distal interphalangeal joints and middle phalanx

Extensor hood

the flexor digitorum superficialis and profundus tendons are enclosed in synovial-lined tunnels, which are maintained against the palmar surfaces of the phalanges by pulleys. ○ Annular pulleys ○ Cruciate pulleys

Flexor pulleys

● Consists of a burning pain or “pins and needles” along the distribution of the median nerve to the lateral three and a half fingers and weakness of the thenar muscles. ● It is produced by compression of the median nerve within the tunnel

Carpal Tunnel Syndrome

● There is a palpable and even audible snapping when a patient is asked to flex and extend the fingers. ● It is caused by the presence of a localized swelling of one of the long flexor tendons that catches on a narrowing of the fibrous flexor sheath anterior to the metacarpophalangeal joint. It may take place either in flexion or in extension.

Trigger Finger