Lec 11 Antebrachial extensors Flashcards by Caroline Sparks

Extensor Carpi Radialis Longus and Brevis

MA: extend the wrist (radiocarpal joint), radial deviation, ECRL activate during fist clenching

PA:
Longus: lateral **supra-epicondylar ridge of humerus
Brevis: lateral epicondyle of humerus (common extensor tendon)

DA:
Longus: base of 2nd metacarpal
Brevis: base of 3rd Metacarpal

N: Radial Nerve C6, C7 C8

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Extensor Digitorum

MA: extends medial 4 digits MCP 1 degree and IP two degrees

PA: lateral epicondyle (common extensor tendon)

DA: extensor expansions of medial four digits

N: Radial N (deep branch) *C7, C8

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Extensor Digiti Minimi

MA: Extend the 5th digit MCP 1 degree and IP 2 degrees

PA: lateral epicondyle

DA: extensor expansion of 5th digit

N: Radial (deep branch) *C7 C8

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Extensor Carpi Ulnaris

MA: Extend the wrist, ulnar deviation, active during fist clenching

PA: lateral epicondyle

DA: base of 5th metacarpal

Radial N: *C7 C8

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Extensor Indicis

MA: extend the 2nd digit (MCP joint), may assist with wrist extension

PA: posterior ulna and interosseous membrane

DA: extensor expansion of 2nd digit

N: radial PIN *C7 C8

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Outcropping muscles of deep layer

abductor policis longus
extensor policis brevis
extensor policis longus

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Abductor Pollicis Longus

MA: radially abduct and extend the thumb (CMC joint)

PA: posterior proximal ulna, radius and interosseous membrane

DA: Base of 1st metacarpal

N: Radial PIN C7 *C8

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Extensor Pollicis Brevis and Longus

MA: Extend the thumb MCP and CMC joints, (Longus does IP!)

PA:
Longus: Posterior ulna and interosseous membrane
Brevis: Posterior radius and interosseous membrane

DA:
Longus: base of distal phalanx of thumb
Brevis: base of proximal phalanx of thumb

N: Radial C7 *C8

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Wrist and Hand movements precision

shoulder and elbow get arm into position and wrist and hand give us fine motor control and purposeful dexterity to interact with external environment

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How can you tell if the radius is posterior or anterior

Listers tubercles, pulley for EPBL

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Proximal row of carpals

scaphoid, lunate, triquetrum, pisiform

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Distal row carpals

trapezium, trapezoid, capitate, hook of hamate

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How can you tell if the hand if dorsal or palmar?

Palmar = full pisiform
Dorsal = half

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Parts of a metacarpal

base, shaft, head

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Distal Radial Ulnar joint

structural: pivot

uniaxial (functional classification)

pronation and supination

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Supporting ligaments of the distal radioulnar joint

volar radioulnar ligaments

dorsal radioulnar ligaments

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Radiocarpal joint (articulations and movements)

the wrist

structural: ellipsoid
functional: biaxial

distal forearm and proximal carpal bones

radius to lunate and scaphoid

movements; flexion, extension, radial deviation, ulnar deviation

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Where is the midcarpal joint

between proximal and distal row of carpals

structural; ellipsoid

functional; biaxial

movements; flexion, extension, radial and ulnar deviation and CIRCUMDUCTION

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Main Wrist and carpal ligaments

Radial collateral ligament
Dorsal radioulnar ligament
Triangular fibrocartilage disc (TFCC)
UCL?

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TFCC

cushion between distal ulna and carpals

stability on ulnar side of wrist

fills in gap between ulna and wrist!

Radial collateral ligament at wrist

originates and radius styloid process and inserts on scaphoid and trapezium

Where is the dorsal radioulnar ligament?

connects radius and ulna (think annular ligament but distal)

Carpometacarpal joints (CMC) movements and joint type

Gliding joints

Movement: volar/dorsal gliding

Metacarpophalangeal Joints

“knuckles”

structural: ellipsoid
Functional: biaxial

movements: flexion, extension, abduction, adduction of fingers

Flexion and extension of metacarpophalanges

flexion: volar gliding extension: dorsal gliding

interphalangeal joints

structural: hinge functional: uniaxial PIP = power grip DIP thumb only has IP

What joints of the wrist and hand are uniaxial?

distal radioulnar joint IP joints

CMC Thumb joint type and movements

saddle joint biaxial flexion, extension, abduction, adduction BASILAR joint TRAPEZIUM and 1st metacarpal (thumb)

Which extensor tendon zone is most delicate and why?

Zone 2 - No mans land between PIP and DIP contains both flexor and extensor tendons, making surgical interventions more difficult

How many extensor zones are there?

8 zones

Parent structure for the common interosseous artery

ulnar artery comes off below elbow then splits

What artery does the common interosseous membrane split into?

anterior and posterior interosseous artery they will be in the middle where the interosseous membrane is

Extrinsic vs intrinsic

extrinsic - originates proximal to the wrist, generates greater force intrinsic - contained entirely within the hand, precise control

Tennis Elbow

superficial extensors - ECRL and ECRB (compartment 2) inflammation of the periosteum at the lateral epicondyle pain with gripping, opening a heavy door, lifting a glass 2 kinds of inflammation are...

Epicondylitis vs epicondylosis

epicondylitis - acute inflammation epicondylosis - old pain (degenerative), not swollen

If you hand is in a mid pronated position (thumbs up), what muscles contribute to flexing the wrist? (thumb towards you)

Flexor Carpi Radials Extensor Carpi Radialis Longus and Brevis

If you hand is in a mid pronated position (thumbs up), what muscles contribute to extending the wrist? (thumb away from you)

Flexor Carpi Ulnaris Extensor Carpi Ulnaris

Where is the anatomical snuffbox located? What runs though it?

Space between the tendons of Abductor Pollicis Longus + Extensor Pollicis Brevis and the Extensor Pollicis Longus The radial artery runs through, you can feel pulse Superficial radial nerve supplies sensation

Arm and Hand dermatomes!

C6 C7 C8 know the location, slide 54

Thumb extension dermatome vs myotome

dermatome C6 Myotome C8

Review Myotomes for arm and wrist

C5: Shoulder abduction C6: elbow flexion, wrist extension C7: elbow extension, wrist flexion C8: finger flexion, thumb extension T1: finger abduction

Extensor Retinaculum (function and location)

very thick, dorsal side of wrist keeps tendons in place and separates them into 6 compartments

List the compartments

1 - APL & EPB 2 - ECRL & ECRB 3 - EPL 4 - Extensor Digitorum and Extensor Indices 5 - Extensor Digit Minimi 6 - Extensor Carpi ulnaris

De Quervain's Tenosynovitis

"Texting Thumb" cumulative trauma disorder of tendons of 1st dorsal compartment common in new mothers, repetitive keystrokes, gamers

What is Tenodesis (think your cadaver) What level spinal cord injury would someone have to use this effect?

Passive finger flexion creates by active wrist extension functional way to grip for individuals with paralysis of finger flexors Injury at C7, so they have C6 wrist extension but not C8 which is finger flexion

What are the two distal radius fractures?

Smith fracture - volar displacement of distal bone (inward) MS SMITH IS VOLITILE Colles fracture - dorsal displacement (outward)

When healing a fractured wrist, where would the plate go - which side?

Volar side because listers tubercle on dorsal side makes uneven surface

What carpal bone is most commonly fractured?

Scaphoid from a FOOSH injury can lead to necrotic proximal fragment (proximal segment can lose blood supply from radial artery and cause tissue death)