Lec 11 Antebrachial extensors Flashcards
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
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
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
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
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
Outcropping muscles of deep layer
abductor policis longus
extensor policis brevis
extensor policis longus
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
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
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
How can you tell if the radius is posterior or anterior
Listers tubercles, pulley for EPBL
Proximal row of carpals
scaphoid, lunate, triquetrum, pisiform
Distal row carpals
trapezium, trapezoid, capitate, hook of hamate
How can you tell if the hand if dorsal or palmar?
Palmar = full pisiform
Dorsal = half
Parts of a metacarpal
base, shaft, head
Distal Radial Ulnar joint
structural: pivot
uniaxial (functional classification)
pronation and supination
Supporting ligaments of the distal radioulnar joint
volar radioulnar ligaments
dorsal radioulnar ligaments
Radiocarpal joint (articulations and movements)
the wrist
structural: ellipsoid
functional: biaxial
distal forearm and proximal carpal bones
or
radius to lunate and scaphoid
movements; flexion, extension, radial deviation, ulnar deviation
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
Main Wrist and carpal ligaments
Radial collateral ligament
Dorsal radioulnar ligament
Triangular fibrocartilage disc (TFCC)
UCL?
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)
