Download Extensor Compartment of the Forearm Deep layer

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Extensor Compartment of the Forearm: Deep layer
DEEP LAYER OF EXTENSORS
"true" deep layer
Supinator
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o
Supinator
Attachments of the Supinator to the
Epicondyle of humerus
Radial collateral ligament
Annular ligament of radius
Ulnar Supinator crest and fossa
Ulnar posterior surface
Interosseous membrane
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o
o
Extensor Indicis
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o
Abductor pollicis longus
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o
o
the Supinator wraps around the
radius to insert into the anterior
surface of it. Together with the
brachialis it forms the floor of
the cubital fossa
Extensor Pollicis Longus
these originate from the proximal, middle and distal thirds of the ulna (as a
generalization). They emerge in the surface in the furrow that forms in the
extensor compartment
Abductor Pollicis Longus
o
o
Extensor Indices
Which shares an extensor
tendon sheath with the
Extensor Digitorum tendon
Posterior interosseous nerve
originates from the posterior surface of the distal third of
the ulna, and the interosseous membrane
inserts into the extensor expansion of the index finger
extends the index finger, enabling independent extension
helps extend the hand at the wrist
"outcropping" deep layer
o
o
Extensor Pollicis Brevis
deep branch of radial nerve which pierces it on its way
to transforming into the posterior interosseous nerve
originates from everywhere... the lateral humeral
epicondyle, the radial collateral ligament, the annular
ligament, the supinator fossa and the crest of ulna
inserts into the lateral posterior and anterior surfaces of
the proximal third of radius
it supinates the forearm, turning the arm to face anteriorly
and superiorly when the forearm is flexed. It is the
PRIME MOVER for slow unopposed suination
The supinator forms the floor of the cubital fossa together
with brachialis. It is a sheet-like muscle, and it envelops
the radius.
o
Posterior interosseous nerve
originates from the posterior surface of the proximal
radius and ulna, as well as the interosseous membrane
inserts into the base of the 1st metacarpal, and
occasionally also the trapezium.
abducts and extends the thumb at the carpometacarpal
joint
shares a common tendon sheath with the extensor
pollicis brevis at the wrist
Extensor Pollicis Brevis
Common sheath for the
tendons of the extensor
pollicis brevis and abductor
pollicis longus
o
o
o
o
o
o
o
Posterior interosseous nerve
originates from the posterior surface of the distal third of
the ulna, and the interosseous membrane
inserts into the dorsum of the base of the proximal
phalanx of the thumb
extends the proximal phalanx of the thumb at the
metacarpophalangeal joint; also extends the
carpometacarpal joints of the thumb.
partly covered by the abductor pollicis longus
its tendon is immediately medial to the APL
these two tendons form the anterior boundary of the
anatomical snuffbox.
Extensor Pollicis Longus
o
o
o
Extensor digitorum tendon
o
Extensor expansion
Medial band attaches to the base of
the middle phalanx
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o
Lateral bands attach to the
base of the distal phalanx
The hood which attaches to the palmar tendon
Posterior interosseous nerve
originates from the posterior surface of the middle third
of the ulna, and the interosseous membrane
inserts into the dorsum of the base of the distal phalanx
of the thumb
extends the distal phalanx of the thumb; also extends
the metacarpophalangeal and the carpometacarpal joints
of the thumb. It also rotates the thumb laterally.
It enjoys its own tendon sheath at the wrist; it passes
medially over the dorsal tubercle of radius, using it as a
pulley.
the EPL forms the posterior border of the anatomical
snuffbox
APL inserts into the base of 1st metacarpal
EPB inserts into the base of proximal phalanx
EPL inserts into the base of distal phalanx