m6: forearm, wrist, hand Flashcards by aespicy buldak

● 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 _ and _.
○ Both sturdy and mobile.
● Complex, multipurpose organ
● As a prehensile organ, it can grasp with forces exceeding _ lb (445 N or 45 kg) or manipulate a delicate thread
● Conform around objects
● Pushing and pulling

Hand
palm and fingers
100 lb

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“Pollex”

1st digit or 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.

2nd digit or Index/Pointing/Forefinger

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Longest finger of the hand

3rd digit or Middle Finger

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

4th digit or Ring Finger

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Smallest finger

5th digit or Pinky/Little finger

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●
● Although the primary forearm bone for the elbow joint is the ulna, the primary forearm bone of the _ is the .
● There are two proximal carpal bones ( + _) that interact with the radius to form the wrist joint.

Wrist

wrist; radius

Scaphoid + Lunate

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●
● Not in direct contact with the carpal bones.
● _ _ separates the ulna from the carpal bones.
● _ portion of the _ is an important part of the wrist.
● The distal ulna has three parts:
1.
2.
3.

Distal Ulna

Fibrocartilaginous disc

Distal portion of the ulna

Ulnar styloid process
Fovea
Pole

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the part of the distal ulna that has bony projection, easily palpated with the forearm pronated, on the ulnar side of the wrist

ulnar styloid process

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the part of the distal ulna that has a depression at the base of this styloid process and provides attachment for the fibrocartilaginous disc.

fovea

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the part of the distal ulna that’s a concave articular surface allowing ulnar articulation with the fibrocartilaginous disc

pole

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●
● The dorsal surface has a palpable tubercle that is known as the
○
○
○

Distal Radius

○ tubercle of the radius
○ Lister’s tubercle
○ dorsal tubercle

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●
● Lies about _/- 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 _ _ tendon on the _ side
○ extensor _ and extensor _ tendons on the _ side.

Lister’s tubercle

1/3

○ extensor pollicis longus tendon on the ulnar side
○ extensor digitorum and extensor indicis tendons on the radial side.

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

Radial Styloid Process

distal

Ulnar and radial styloid processes serve as attachment sites for the ulnar and radial carpal collateral ligaments, respectively.

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

Ulnar notch

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

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●
● The _ surface of the _ makes up the proximal joint surface of the wrist and articulates with the _ and _ carpal bones.

Distal Radius + Scaphoid + Lunate

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● Carpal bones
● PROXIMAL ROW:
1.
2.
3.
4.
● DISTAL ROW:
1.
2.
3.
4.

Proximal:
○ Scaphoid
○ Lunate
○ Triquetrum
○ Pisiform
Distal:
○ Trapezium
○ Trapezoid
○ Capitate
○ Hamate

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

Scaphoid

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● Most frequently DISLOCATED carpal bone

Lunate

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● “Triangular”

Triquetrum

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● Pea-shaped

Pisiform

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● “Greater multangular”

Trapezium

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● “Lesser multangular”

Trapezoid

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

Capitate dorsum dorsopalmar direction

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

Hamate hook

● ○ most commonly fractured carpal bone ○ MOI: _ _ _ _ _ ○ articular risk of avascular necrosis after fracture | ‘_ _ supply’

Scaphoid Fracture FOOSH retrograde blood supply

● A triangular skin depression on the _ 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 _ bone is most easily palpated here and that the _ of the radial artery can be felt here

Anatomic Snuffbox lateral side scaphoid bone pulsations of the radial artery

● These bones comprise the hand: _ and _ ● The _ make up the digits. ● The metacarpals and digits are identified numerically, laterally to medially (from the anatomical position), one through five.

Metacarpals and phalanges phalanges

● Each of the five _ has a base that articulates: ○ proximally with one or more carpal bones ○ with its adjacent metacarpals

metacarpals

● Tubercle at the _ base of _ Metacarpal = distal attachment _ _ _. (Dorsolateral aspect just distal to the hamate. ● Eminence at the base of _ metacarpal bone (dorsally) = distal attachment for _ _ _ _

● Tubercle at the medial base of 5th Metacarpal = distal attachment ECU. (Dorsolateral aspect just distal to the hamate. ● Eminence at the base of 2nd metacarpal bone (dorsally) = distal attachment for ECRL

● Head of metacarpal bone (_) ● _ joint ● Palpated in _

biconvex MCP joint flexion

● ○ fracture of the _ metacarpal neck ○ clenched fist striking a hard object

BOXER’S FRACTURE 5th

● ○ fracture of the _ metacarpal base ○ forced hyperabduction of the thumb

BENNETT’S FRACTURE 1st

● 2 phalanges of the thumb ○ ○ ● 3 phalanges of the 2nd to 5th digits ○ ○ ○

● 2 phalanges of the thumb ○ Proximal ○ Distal ● 3 phalanges of the 2nd to 5th digits ○ Proximal ○ Middle ○ Distal

_ Joint ● Wide mobility of the hand ● Great structural stability in the wrist ● Allows the hand an extensive degree of function ● _ joint ● _ DOF ● _ bones ● _ joints ● Extensive ligament system

Wrist Joint ● Ellipsoidal joint ● 2 DOF ● 15 bones ● 17 joints ● Extensive ligament system

_ Joint ● Biconcave: _ _ of radius ● Biconvex: Proximal articulating surface of the _ and _ ● _ DOF ● Motions: _, _, _ deviation, _ deviation

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

_ Joint ● Formed by the proximal and distal carpal rows. ● The scaphoid articulates with the _, _, and _. ● Lunate articulates with the _. ● Triquetrum articulates with the _. ● Wrist motions: _, _, and _ and _ deviation.

Midcarpal 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.

Hand ● Each digit has: C _ _ + M _ _ ● Each of the 4 fingers has: P _ _ + D _ _

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

CMC Joints ● _ and _ CMC joint = minimal movement ● _ CMC joint = least mobile (central pillar of the hand) ● _ CMC joint = _ to _ degrees dorsovolar movement

Carpometacarpal Joints ● 2nd and 3rd CMC joint = minimal movement ● 3rd CMC joint = least mobile (central pillar of the hand) ● 4th CMC joint = 10 to 15 degrees dorsovolar movement

● ● Trapezium + Base of First Metacarpal ● _ joint ● Motions: _, _, _, _, _, _.

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

_ Joints ● _ type ● _ DOF ● Motion: _, _, _, and _. ○ Convex: Head of _ ○ Concave: Base of _ _

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

_ Joints ● _ to _ digit = DIP and PIP ● _ = Interphalangeal joint ● _ DOF ● Motion: _ and _ ● (+)_ _ _: prevents hyperextension

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

Proximal (radiocarpal) Distal (carpometacarpal) Radial collateral Volar radiocarpal Ulnocarpal ligamentous complex Radiocarpal dorsal

Extrinsic ligaments

Short/ Intermediate/ Long Volar Dorsal Interosseous Lunate-triquetral Scaphoid-lunate Scaphoid-trapezial Volar intercarpal (deltoid, V, radiate or arcuate) Dorsal intercarpal

Intrinsic ligaments

Radio-scaphoid-capitate Radiolunate Radio-scaphoid-nate Meniscus (radiotriquetral) Triangular fibrocartilage Ulno lunate ligament Medial collateral ligament

Superficial Deep

● The hand is a compact, multipurpose organ with interdependency of structures in which injury to one may affect many others. ● The hand possesses both great mobility and great stability and can shift from one to the other in a fraction of a second.

Function

● Almost all of the muscles are multiarticular and, therefore, can have an effect on each joint crossed. ● Some cross as many as seven joints, so to prevent an undesired motion by the muscle, other muscles must contract.

Function

● The hand has many automatic, neurophysiologic synergies, which are so strongly linked that a person cannot willfully separate them.

Function

● The hand is a wonderful sensory organ that provides us with tremendous feedback about our environment. ● For example, each finger tip has about _ sensory endings and the _ and _ are among the most sensitive parts of the body.

Function 100 fingertips and hands

● (1) over which joints each muscle passes ● (2) the line of action of the muscle and its tendon ● (3) the distance of the muscle to the axis of joint motion at various positions of the joint ● (4) the relative length of the muscle.

Considerations

Wrist Extensor ● Proximal attachment: _ _ ● ECRL: _ _ _ Primary wrist extensors (3 Es): 1. 2. 3.

Wrist Extensor ● Proximal attachment: Lateral epicondyle ● ECRL: lateral supracondylar ridge Primary wrist extensors: 1. ECRL 2. ECRB 3. ECU

● ● Proximal attachment: _ _ _ ● Lies anterior to the elbow axis (not a good elbow flexor compared to wrist extensors)

Wrist Flexors Medial humeral epicondyle

Primary wrist flexors (FFPFFF) 1. 2. 3. 4. 5. 6.

● FCR ● FCU ● Palmaris longus ● FDS ● FDP ● FPL

Radial and _ Motions ● _ longus and E _ _ B = centrally located. ● Muscles located on the radial side: _ deviation ● Muscles located on the ulnar side: _ deviation

Radial and Ulnar Motions ● Palmaris longus and ECRB = centrally located. ● Muscles located on the radial side: radial deviation ● Muscles located on the ulnar side: ulnar deviation

Muscles Acting on the Digits ● _ muscles with proximal attachments in the forearm or humerus and distal attachments in the hand ● _ muscles with both proximal and distal attachments existing within the hand.

Extrinsic Intrinsic

_ Muscles ● Long finger extensors ● Long finger flexors ● Thumb muscles (FEAb):

Extrinsic Muscles ○ Flexors ○ Extensors ○ Abductors

_ Muscles ● Mid-Palm Muscles ● Thenar muscles ● Hypothenar muscles

Intrinsic

Extensor Mechanism ● Other names

Extensor Mechanism ● Other names ○ extensor hood mechanism ○ extensor expansion ○ apparatus, ○ aponeurosis ○ retinaculum ○ dorsal hood, or hood

● The purpose of the assembly is to extend the digits in different positions of finger flexion. ● To provide shortcuts for the extensor tendons across the joints and to permit the digits full flexion.

Extensor Mechanism

Extensor Mechanism ● The extensor tendons must cover a longer distance from maximum extension to full flexion. ● This distance is about _ mm and can be measured in the normal subject by placing a string over the dorsum of a finger and marking the change in length from full extension to end flexion.

25 mm

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

● 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. ○ _ pulleys ○ _ pulleys

Flexor pulleys Annular pulleys Cruciate 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 _ muscles. ● It is produced by compression of the median nerve within the tunnel

Carpal Tunnel Syndrome thenar muscles

● 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 _ _ 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 long flexor

1st and 2nd digit = ?

Fine movement

3rd, 4th, and 5 digits = ?

Gross and strength

ligaments that connect carpal bones to the radius, ulna, or metacarpal

extrinsic ligaments

ligaments that attach between the carpal bones only

intrinsic ligaments

provide support, stability, and transmission of forces through the hand

extrinsic and intrinsic ligaments

Ex or In? Dorsal musles: 5 Extensors 1 Abductor

Extrinsic ED EI EDM EPL EPB APL

Ex or In? Ventral muscles: 3 Flexor

Extrinsic FDS FDP FPL

Ex or In? 3 Mid-palm muscles: 4 Thenar muscles: 3 Hypothenar muscles :

Intrinsic 4 L, 3 PI, 4 DI OP, APB, AP, FPB ODM, ADM, FDM