Transcript Antebrachium Extensors

Antebrachium Extensors
Extensor retinaculum
• thick fibrous fascia band at wrist -holds
forearm tendons in place
• from lateral radius to medial ulna (styloid
process), triquetrum & pisiform bones
Extensor Canals
• six osteofibrous canals: post side of bones
• extensor tendons pass through to dorsal
hand
Extensor Canals
• a. abductor pollicis longus, \
extensor pollicis brevis / in #1: most lateral
• b. extensor carpi radialis longus \
extensor carpi radialis brevis / in #2
• c. extensor pollicis longus - in #3
• d. extensor digitorum \
extensor indicis / in #4
• e. extensor digiti minimi - in #5
• f. extensor carpi ulnaris - in #6
Anatomical snuff box
• depression on dorsolateral wrist bounded
by tendons of:
• abductor pollicis longus, extensor pollicis
brevis & extensor pollicis longus (where
the scaphoid bone lies in the floor here,
most likely be fractured, local tenderness,
death & absorption of the bone later)
Muscles
• Muscles 3 Functional groups +
brachioradialis & supinator
– i) extend hand at wrist = the 3 extensor carpi's
- radialis longus & brevis; & ulnaris
– ii) extend medial 4 digits (fingers) = extensors
digitorum; indicis; digiti minimi
– iii) extend thumb (1st digit) = abductor pollicis
longus; extensor pollicis longus & brevis
Muscles
• Extensor are arranged in three anatomical
layers
• Superficial layer
– brachioradialis
– extensor carpi radialis longus
– extensor carpi radialis brevis
– extensor digitorum
– extensor digiti minimi
– extensor carpi ulnaris
BRACHIORADIALIS
• ORIGIN
proximal two thirds of lateral supracondylar
ridge of humerus, and lateral intermuscular
septum
• INSERTION
lateral side of base of styloid process of
radius
• ACTION
flex the elbow joint, and assists in pronating
and supinating the forearm when these
movements are resisted
• NERVE
radial nerve C5, C6
EXTENSOR CARPI RADIALIS LONGUS
• ORIGIN
Distal one third of lateral supracondylar
ridge of humerus, and lateral intermuscular
septum
• INSERTION
dorsal surface of base of second metacarpal
bone, radial side
• ACTION
extends and abducts the wrist, and assists
in flexion of the elbow
• NERVE
radial nerve C5, C6, 7, 8
EXTENSOR CARPI RADIALIS BREVIS
• ORIGIN
common extensor tendon from lateral
epicondyle of humerus, radial collateral
ligament of elbow joint, and deep
antebrachial fascia
• INSERTION
dorsal surface of base of third metacarpal
bone
• ACTION
extends and assists in abduction of the wrist
• NERVE
radial C6, 7, 8
EXTENSOR DIGITORUM
• ORIGIN
Common extensor tendon fromlateral epicondyle of
humerus, and deep antebrachial fascia
• INSERTION
By four tendons, each penetrating a membranous
expansion on the dorsum of the second to fifth digits and
dividing over the proximal phalanx into medial and two
lateral bands. The medial band inserts into the base of the
middle phalanx while the lateral bands reunite over the
middle phalanx and insert into the base of the distal
phalanx.
• ACTION
Extends the metacarpophalangeal and, in conjunction with
the lumbricals and interossei, extends the interphalangeal
joints of the second through fifth digits. Assists in abduction
of the index, ring, and little fingers; and assists in extension
and abducting of the wrist.
• NERVE
Radial nerve, C6, 7, 8
EXTENSOR DIGITI MINIMI
• ORIGIN
Common extensor tendon from lateral
epicondyle of humerus, and deep
antebrachial fascia
• INSERTION
Into extensor expansion of little finger with
extensor digitorum tendon
• ACTION
Extends the metacarpophalangeal joint and,
in conjunction with lumbricals interosseus,
extends the interphalangeal joints of the little
finger. Assists in abduction of the little finger
• NERVE
radial nerve C6, 7, C8
EXTENSOR CARPI ULNARIS
• ORIGIN
Common extensor tendon fromlateral
epicondyle of humerus, by
aponeurosis from posterior border of
ulna, and deep antebrachial fascia
• INSERTION
base of fifth metacarpal bone, ulnar
side
• ACTION
extends and adducts the wrist
• NERVE
radial nerve C6, 7, C8
Deep layer
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Supinator
abductor pollicis longus
extensor pollicis brevis
extensor pollicis longus
extensor indicis
SUPINATOR
• ORIGIN
Lateral epicondyle of humerus, radial
collateral ligament of elbow joint, annular
ligament of radius, and superior crest of ulna
• INSERTION
Lateral surface of upper one third of body of
radius covering part of anterior and posterior
surfaces
• ACTION
supinates the forearm
• NERVE
radial nerve C5, C6, C(7)
ABDUCTOR POLLICIS LONGUS
• ORIGIN
posterior surface of body of ulna distal to
origin of supinator, interosseus membrane,
and posterior surface of middle one third of
body of radius
• INSERTION
base of first metacarpal bone, radial side
• ACTION
Abducts and extends the carpometacarpal
joints of the thumb; abducts (radial deviation)
and assists in flexion the wrist
• NERVE
Radial nerve C6, 7, C8
EXTENSOR POLLICIS BREVIS
• ORIGIN
Posterior surface of body of radius distal to
origin of abductor pollicis longus, and
interosseus membrane
• INSERTION
Base of proximal phalanx of thumb, dorsal
surface
• ACTION
Extends the metacarpophalangeal joint of the
thumb, extends and abducts the
carpometacarpal joint, and assists in abduction
(radial deviation) of the wrist
• NERVE
Radial nerve C6, 7, C8
EXTENSOR POLLICIS LONGUS
• ORIGIN
Middle one third of posterior surface of ulna
distal to origin of abductor pollicis longus,
and interosseus membrane
• INSERTION
Base of distal phalanx of thumb, dorsal
surface
• ACTION
Extends the interphalangeal joint and
assists in extension of the
metacarpophalangeal and carpometacarpal
joints of the thumb. Assists in abduction and
extension of the wrist.
• NERVE
Radial nerve, C6, C7, C8
EXTENSOR INDICIS
• ORIGIN
posterior surface of body of ulna distal to
origin of extensor pollcis longus, and
interosseus membrane.
• INSERTION
Into extensor expansion of index finger with
extensor digitorium longus tendon
• ACTION
Extends the metacarpophalangeal joint and,
in conjunction with the lumbricals and
interossei, extends the interphalangeal joints
of the index finger. May assist in adduction of
the finger
• NERVE
Radial nerve C6, 7, C8