Antebrachial Extensors Flashcards
Posterior compartment (extensors) are all innervated by:
Radial nerve or its branches
3 functional groups of the extensors muscles
1- muscles that extend and abduct or Adduct the hand at the wrist
2- muscles that extend the medial four digits
3- muscles that extend or abduct the thumb
Muscles that extend and abduct or adduct the hand at the wrist (3)
Extensor carpi radialis longus
Extensor carpi radialis breves
Extension carpi ulnaris
Muscles that extend the medial four digits (3)
Extensor digitorum
Extensor Indicis
Extensor digiti minimi
Muscles that extend or abduct the thumb (3)
Abductor pollicis longus
Extensor pollicis breves
Extensor pollicis longus
Superficial extensor muscles (6)
Brachioradialis Extensor carpi radialis longus Extensor carpi radialis breves Extensor carpi ulnaris Extensor digitorum Extensor digiti minimi
Extensor carpi radialis longus and brachioradialis muscles attach to the:
To the lateral super epicondyle right ridge of the humerus and adjacent intermuscular septum
All superficial extensor muscles have attachments to:
To the common extensor tendon to the lateral epicondyle
Deep extensor muscles (5)
Abductor pollicis longus Extensor pollicis breves Extensor pollicis longus Extensor indicis Supinator
Deep extensor muscles are also known as
Outcropping muscles
Extensor muscles (10)
Brachioradialis Extensor carpi radialis, longus AND brevis Extensor digitorum Extensor digit minimi Extensor carpi ulnaris Aconeus Supinator Abductor pollicis longus Extensor pollicis longus and brevis Extensor indicis
OINA for extensor carpi radialis longus
OR: Lateral supracondylar ridge of humerus
INS: Base of 2nd metacarpal bone
NS: Radial
Action: extends hand at wrist
Abducts hand at wrist
Extensor carpi radialis longus’ has a synergistic function with ______ ___ because:
With finger flexors
Because it keeps the wrist extended to allow increased grip strength
OINA for extensor carpi radialis brevis
OR: Lateral epicondyle of humerus
INS: base of the 3rd metacarpal bone
NS: Deep branch of radial (sometimes radial PRIOR to bifurcation)
AC: Extends hand at wrist
Abducts hand at wrist
Extensor carpi radialis brevis occasionally arises from:
From a common belly with its longer partner
OINA of extensor carpi ulnaris
OR: Lateral epicondyle of humerus
Posterior border of the ulna
INS: Medial side of the base of the 5th metacarpal Bone
NS: posterior interosseous branch
AC: extends hand at wrist
Adducts hand at wrist
Extensor carpi ulnaris is synergistic with:
With finger flexors because keeps the wrist extended to allow increased grip strength
OINA for extensor digitorum
OR: Lateral epicondyle of humerus
INS: Extensor expansions of the medial 4 digits
NS: Posterior interosseous branch
AC: Extension at the DIP, PIP, MCP
Wrist extension when fingers are extended
OINA for extensor digiti minimi
OR: Lateral epicondyle of humerus
INS: Extensor expansions of the 5th digit
NS: Posterior interosseous branch.
AC: Extends digit 5
Where do the 4 extensor tendons pass
Deep to the extensor retinaculum to the medial four digits
As the tendons pass over the dorsum of the wrist the are covered with:
Synovial sheaths
The extensor indicis joins the _______ ______ as it passes through the _______
Extensor digitorum
Extensor retinaculum
What extensor has its own sheath
Extensor digiti minimi
Oblique intertendinous connection at the MCP joints restricts:
Independent extension of the digits, except index and 5th
The tendons of the 2-5 extensor tendons form the:
Extensor expansions on the distal metacarpals
The distal tendons form”
Complex mechanical structures
The 4 tendons of the extensor digitorum join:
The fascia expansion called the extensor expansion
The extensor expansion spilts into how many parts? Where?
3 parts near the PIP
3 parts of the extensor expansion after splitting
1 central part
2 lateral parts
Where does the central part of the extensor digitorum insert?
Into the base of the middle phalanx
2 lateral parts of the extensor expansion converse to be inserted:
Into the base of the distal phalanx
The tendon to the index finger is joined on its medial side by:
The tendon of the extensor indicis
The tendon to the little fingers is joined:
On its medial side by the 2 tendons of the extensor digiti minimi
OINA for Abductor pollicis longus
OR: Posterior aspect of ulna, radius, and posterior interosseous membrane
INS: Base of 1st metacarpal
NS: Posterior interosseous branch
AC: Abducts digit 1
Extends digit 1
OINA for extensor pollicis brevis
OR: posterior aspect of ulna, radius and interosseous membrane
INS: base of the proximal phalanx of the thumb
NS: posterior interosseous branch
AC: Extends proximal phalanx at MCP joint
Can extend 1st metacarpal at the carpometacarpal joint
Forms lateral boundary of the snuff box
OINA for Extensor pollicis longus
OR: Post. Surface of middle 1/3 of ulna and interosseous membrane
IN: Base of distal phalanx of thumb
NS: Posterior interosseous branch
AC: Extends distal phalanx at MCP and PIP
Contributes to thumb abduction
Forms medial boundary of the snuff box
OINA for Extensor indicis
OR: Posterior surface of the ulna and interosseous membrane
IN: extensor expansion of 2nd digit
NS: Posterior interosseous branch
AC: Extends all the joints of the index finger
Assists in wrist extension
Allows independent index finger action
Medial border of the snuffbox
The tendon of the extensor pollicis longus
Lateral border of the snuffbox
Pair of parallel tendons: The extensor pollicis brevis and abductor pollicis longus
Distal border of the snuffbox
Approximate apex of the snuffbox isosceles triangle
Floor of the snuffbox
Varies depending on position of wrist-
But both the trapezium and primarily the scaphoid can be palpated
Artery that passes through the snuffbox on its course to the proximal space in between the 1st and 2nd metacarpals to contribute to the superficial and deep palmar arches
Radial artery
Vein that arises within the anatomical snuffbox
Cephalic vein
Radial nerve can be palpated by:
By stroking along the extensor pollicis longus with the dorsal aspect of a fingernail
OINA for Supinator
OR: Lateral epicondyle of humerus
Supinator fossa and crest of ulna
INS: Radius
IN: Deep branch of radial nerve
AC: Rortates the radius to supinate the forearm and hand ***Supinates regardless of flexion/extension position (versus biceps brachii)
Why is it difficult to secure a screw with the left hand?
The strongest Supinator is the biceps, which is much more powerful that pronation
