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1.Brachioradialis
2.Superficial Radial n.
3.Radial Artery
4.Flexor Carpi Radialis
5. Median Nerve
6.Flexor Digitorum Superficialis
7.Ulnar Artery
8.Ulnar Nerve
9. Flexor Carpi Ulnaris
Nerves of the
Anterior
Compartment
NERVES OF THE ANTERIOR
COMPARTMENT
NERVES OF THE ANTERIOR
COMPARTMENT MEDIAN NERVE
---The median nerve
leaves the cubital
fossa by passing
between the two
heads of pronator
teres.
---It continues
downward adherent
to the posterior
surface of the flexor
digitorum
superficialis.
----At the wrist it emerges
between the lateral
margin of the tendons
of flexor digitorum
superficialis and the
tendon of flexor carpi
radialis. Here it lies
posterior to the
palmaris longus tendon.
----The median nerve
enters the palm by
passing posterior to the
flexor retinaculum
BRANCHES OF THE MEDIAN NERVE
1. Muscular branches
in the cubital fossa
to the pronator
teres, the flexor
carpi radialis, the
palmaris longus,
and the flexor
digitorum
superficialis.
2. Articular branches
to the elbow joint.
3. Anterior interosseous
nerve, which arises as it
emerges from between
the two heads of the
pronator teres muscle.
It runs down on the
anterior surface of the
interosseous membrane.
Give branches from to
the flexor pollicis longus,
the lateral half of flexor
digitorum profundus, and
the pronator quadratus.
4. Palmar cutaneous
branch, Which passes to
the skin over the lateral
part of the palm.
NERVES OF THE ANTERIOR
COMPARTMENT .ULNAR NERVE
The ulnar nerve
enters the forearm
from behind the
medial epicondyle
of the humerus.
Note that it crosses
the medial ligament
of the elbow joint
and passes
between the two
heads of the flexor
carpi ulnaris.
.
The nerve pass
downward between the
flexor carpi ulnaris and
the flexor digitorum
profundus muscles.
At the wrist observe that
the nerve lies between
the tendons of the
flexor carpi ulnar and
the flexor digitorum
superficialis muscles.
The ulnar nerve enters
the palm lateral to the
pisiform bone, anterior
to the flexor
retinaculum.
BRANCHES OF THE ULNAR NERVE
1. Muscular
branches to the
flexor carpi
ulnaris and to the
medial half of the
flexor digitorum
profundus.
2. Articular
branches to the
elbow joint.
3. Palmar cutaneous
branch, which arises in
the middle of the
forearm and supplies the
skin over the hypothenar
eminence.
4. Dorsal branch, or
posterior cutaneous
branch, which is large
and passes medially
between the tendon of
flexor carpi ulnaris and
the ulna and is
distributed on the
posterior surface of the
hand and fingers.
LATERAL PART OF POSTERIOR
(EXTENSOR) COMPARTMENT OF
FOREARM
Definition: portion of
the posterior fascial
compartment of the
forearm that
includes the “lateral
wad” muscles;
brachioradialis and
extensores radiales.
The posterior compartment of the forearm
contains 11 muscles, divided into deep and
superficial layers.
Superficial

brachioradialis
Blood supply
anterior and posterior

extensor carpi radialis longus
interosseous arteries

extensor carpi radialis brevis
(branches of the ulna
artery via the common

extensor digitorum
ulna artery

extensor digiti minimi

extensor carpi ulnaris
Deep

supinator

extensor pollicis longus

extensor pollicis brevis

abductor pollicis longus

extensor indicis
Nerve supply


The aconeus is sometimes considered part all muscles in the extensor
compartment are supplied
of the posterior compartment of the
by the radial nerve
forearm rather than in the posterior
compartment of the arm
MUSCLES OF THE
POSTERIOR FOREARM
Seven superficial and
five deep muscles
occupy the posterior
forearm.
 The superficial group
arises mostly from the
posterior aspect of the
lateral epicondyle of
the humerus by a
common tendon.
 The muscles are
supplied by
(1) the radial nerve or
(2) its deep branch, which
continues as the
posterior interosseous
nerve

There are seven muscles in
this layer, brachioradialis,
extensor carpi radialis
longus,
extensor carpi radialis
brevis,
extensor digitorum,
extensor digiti minimi,
extensor carpi ulnaris and
anconeus.
Apart from the anconeous and
brachioradialis, all continue
as tendons into the hand,
and can also be referred to
as extrinsic hand muscles
BRACHIORADIALIS
Attachments: Originates
from the proximal
surface of the supra
epicondylar ridge of the
humerus, and attaches
to the distal end of the
radius, just before the
radial styloid process
Actions: Flexes at the
elbow
Innervation: Radial nerve
EXTENSOR CARPI RADIALIS LONGUS AND
BREVIS
These extensor muscles are
found laterally on the
forearm.
The extensor carpi radialis
brevis lies deep to the
longus.
Attachments: The ECRL
originates more proximally,
from supracondylar ridge,
while the ECRB originates
from the lateral epicondyle.
Their tendons attach to the II
and III metacarpal bones
Actions: Extension and
abduction of the wrist
Innervation: Radial nerve
EXTENSOR DIGITORUM
The main extensor of the fingers,
this muscle makes up most of
the posterior surface of the
forearm.
Attachments: Originates from the
lateral epicondyle.
In the distal part of the forearm,
the muscle tendon splits into
four, and inserts into the
extensor hood of each finger.
Actions: Extends medial four
fingers at the MCP and IP joints
Innervation: Radial nerve
A fibrous sheet on the back
of each finger is known
as the extensor
expansion, or dorsal
aponeurosis, and it
contains a hood of
transverse fibers.
The expansion is
penetrated by the
extensor tendon, which
then divides into three
slips: a central slip to
the base of the middle
phalanx and two
collateral bands, which,
fused with expansions
from the interossei and
lumbricals, unite and
proceed to the base of
the distal phalanx.
EXTENSOR DIGITI MINIMI
This mucles lies medially
and slightly deep to the
extensor digitorum.
Attachments: Originates
from the lateral condyle
of the humerus, and
attaches, with the
extensor digitorum
tendon, into the extensor
hood of the little finger
Actions: Extends the little
finger, and contributes to
extension at the wrist
Innervation: Radial nerve
EXTENSOR CARPI ULNARIS
This is found on the medial
side of the forearm.
Attachments: Originates
from the lateral condyle,
and attaches to the base
of metacarpal V.
Actions: Extension and
adduction of wrist
Innervation: Radial Nerve
ANCONEUS
The most medial of the muscles
in the extensor compartment
of the forearm. It is blended
with the fibres of the triceps
brachii, and can be hard to
distinguish from it.
Attachments: Originates from
the lateral epicondyle,
and attaches to the posterior
and lateral part of the
olecrannon
Actions: Moves the ulna during
pronation and extends at the
elbow joint
Innervation: Radial Nerve
