Download forearm posterior compartment " "

" forearm posterior compartment "
compartments of the forearm
Posterior Fascial
compartment
Muscles:
** The superficial group
1. Extensor carpi radialis brevis
2. Ex. digitorum
3. Ex. digiti minimi
4. Ex. carpi ulnaris
5. anconeus
** The deep group
1.supinator
2.Abductor pollicis longus
3.Ex. pollicis brevis
4.Ex. pollicis longus
5.Ex. indicis
Blood supply:
Posterior & anterior
interosseous arteries
Nerve supply:
Deep branch of the radial nerve
(posterior interosseous nerve).
1
Lateral Fascial
compartment
In some books it
regarded as part
of Posterior
compartment
Muscles:
1.Brachioradialis
2.extensor carpi
radialis longus
1. Blood supply:
branches of the
radial and
brachial arteries
Nerve supply:
Radial nerve
Anterior
fascial
compartment
* Muscles of the Lateral Compartment of the Forearm :
1. Brachioradialis :
--Origin : Lateral supracondylar ridge of humerus Upper
two thirds
--Insertion : Base of styloid process of radius
-- Action : 1. rotates forearm to the midprone position
2. flexes forearm at elbow joint , because it
crossing the elbow joint
* So it named as karate muscle ) ‫( عضلة الكاراتيه‬
2. Extensor carpi radialis longus
--Origin : lower third of lateral supracondylar ridge of
humerus ( below the oridin of Brachioradialis )
-- Insertion : dorsal surface of base of second metacarpal bone
-- Action : Extends abducts wrist
 Ant or Post ‫في الطب كلمة وحدة بتفرق !! الزم تحدد‬
Insertion
Flexor
Palmar surface " anterior "
of the base of metacarpal
bones
Extensor
Dorsal surface " posterior "
of the base of metacarpal
bones
** Both muscles have common structures:
1. Origin : Lateral supracondylar ridge of humerus
2. Blood supply : branches of the radial and brachial
arteries . ( brachial artery cross from medial to lateral in the
spiral groove with the median nerve , then the branches give
the ant & pos branches which give the B.S to the muscles ).
3. Nerve supply : Radial nerve before it divides into
superficial and deep branches (Radial nerve also give the
lateral half of brachialis " has double nerve supply " ) .
*Suggested Question * All of the following muscles have
double ( dual ) innervation Except :
a. Brachialis ( Musculocutaneous , radial nerves )
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b. Deltoid ( Axillary nerve )
c. Pectoralis major ( Lateral , medial Pectoral nerves )
d. Flexor digitorum profundus ( Anterior interosseous, ulnar )
e. Subscapularis ( Upper , Lower Subscapular nerves )
‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬
: Main nerves ‫ " نحن مطالبين فقط بـمعرفتها للـ‬Root value " ‫أما بالنسبة للـ‬
Median , ulnar , Axillary, Radial nerves
****Radial nerve : Its branch from the posterior cord of
brachial plexus , in the arm it passing in the spiral groove with
profunda brachii artery. it piercing the lateral intermuscular
septum above the lateral epicondyle it give superficial and
deep branches in the cubital fossa " the most lateral structures ".
* * Deep branch of radial nerve (Posterior interosseous
nerve) :
1. descends in the downward in Post Comp between the
superficial and deep muscles.
2. pierces the Supinator muscle
3. then it winds around the neck of the radius ( weak point "
if there is injury in the neck then the injury will happen for
the the deep branch and occur finger drop only ,, because
deep branch give the pos compartment muscles # except
anconeus # which extend the fingers) .
# In comparison with Radial nerve injury it'll occur complete
hand drop including the fingers
• It eventually reaches the posterior surface of the wrist
joint.
• Branches :
1. Muscular branches
2. Articular branches to the wrist and carpal joints
3
A
Anconeus
B
Brachioradialis
E
Extensor carpi
radialis longus
* Superficial Branch of the radial Nerve( anterior
interosseous nerve ) : it passes through the anterior
compartment under the cover of the brachioradialis , in the
insertion of brachioradialis it passes deep to the tendon and
runs in the lateral two thirds of the posterior surface of the
hand and skin over the proximal phalanges for lateral three
and a half fingers. " in the roof of snuff box "
# Snuff box
-Floor : scaphoid "common side of fracture" and trapezium crapal
bones
-Anteriorly: *abductor pollicis longus & ex. pollicis brevis
-Posteriorly : *extensor pollicis longus.
-Roof : superficial branch of radail nerve
-Content :radial artery "knowing the pulsation "
Contents of the Pos. Fascial Compartment of the
Forearm
# Musles
** The superficial group
1. Ex. carpi radialis brevis





O:Lateral epicondyle of humerus. " common origin "
I: Dorsal surfaces of base of 3rd metacarpal.
Lies deep to extensor carpi radialis longus.
A:Extends and abducts wrist.
NS: Posterior interosseous nerve.
2. Ex. digitorum
 O: Lateral epicondyle of humerus
 I: Base of dorsal surfaces of middle and distal phalanges.
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-- Forms four tendons, each passes into a finger , so they run
dorsally in the dorsum of the finger where is the extensor
fibrous expansion "dorsal digital expansion" ( fibrous tissue
for the insertion of the tendon ,, It has 3 slips :
*. one middle :attaches with middle phalanx
*. two lateral : attach with the base of distal phalanx
There job : fix the tendon of dorsal digital expansion
 A:Extends all joints of hand and fingers
# there is Connection between the tendon of Ex. digitorum & Ex.
digiti minimi called :" fibrous connection "
3. Ex. digiti minimi
 O: Lateral epicondyle of humerus
 I: Dorsal digital expansion of little finger along with the
tendon of extensor digitorum.
 A:Extends MCP &IP joints of little finger
Little finger has 1 tendon and connect with other tendon
4. Ex. carpi ulnaris
 O: Lateral epicondyle of the humerus
 I: base dorsal surface ( base of 5th metacarpal )
 A: Extends and adducts the wrist
 NS: Posterior interosseous nerve.
# flexor .corpi ulnaris ( NS): ulnar nerve
5. anconeus
 Small muscle behind the elbow joint.
 O: lateral epicondyle of humerus.
 I: Post surface &Lat aspect of Olecranon process , post
surface of ulna.
 A: Weak extensor of elbow
 NS: Radial Nerve
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** The deep group
1.supinator "V. important "
Two heads
 O: Superficial head: * lat epicondyle of humerus, * radial
collateral lig of elbow( lig in elbow joint in
the lateral
side between humerus and radius )
* annular lig( lig surrounding the head of radius )
 Deep head : supinator crest of ulna,post part of triangular
area in front of it ( ulna )
 I: neck and upper part of the shaft of radius
 A: Supination + extension of the forearm and hand
# But the biceps: supination + flexion " screwing muscle "
 NS: Posterior interroseous nerve.
** Muscles which pass to the thumb :
2.Abd pollicis longus " ant boundary of snuff box "
 O: post surfaces of the radius & ulna & interosseous memb.
 I: - Radial side of base of 1st metacarpal .
-Trapezium ) ‫( ممكن تكون موجودة‬
 A: Abd and ext of thumb at carpometacarpal joint
 NS: Posterior interroseous nerve
3.Ex. pollicis brevis " ant boundary of snuff box "
 O: Post surface of radius & interosseous memb.
 I:Dorsal surface of base of prox phalanx of thumb.
 A:Extends prox phalanx and metacarpal of thumb.
 NS: Posterior interroseous nerve.
4.Ex. pollicis longus "post boundary of snuff box "
 O: Posterior surface of ulna & interosseous memb.
 I:Dorsal surface of distal phalanx of the thumb
 A:Extends all joints of the thumb
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 NS: Posterior interosseous nerve.
5.Ex. indicis
 O: Posterior surface of ulna distal to extensor pollicis longus,
interosseous memb .
 I:Ulnar side of tendon of extensor digitorum for index finger,
ends in the dorsal digital expansion of the index
 A:Extension of Index finger.
 NS: Posterior interosseous nerve
** Index has 2 separate tendons and no connection with other
tendons. ( see fig 2 )
# The most important function of the hand :
Opponent (done by the thumb " counting against the other
fingers" , writing position ( flexion at the metacarpophalangeal
joint and extension in interphalangeal joint and medial rotation )
Arteries of the Post Fascial Compartment of the
Forearm
•
The anterior and posterior interosseous arteries arise
from the common interosseous artery, a branch of the
ulnar artery
• They pass downward on the anterior and posterior
surfaces of the interosseous membrane, respectively, and
supply the adjoining muscles
( Blood supply ) and bones. (Nutrient artery)
** They end by taking part in the anastomosis around the
wrist joint. ( 6 arteries )
-Ant & post interosseous artery
-Ant & post carpal of brachial artery
-Ant & post carpal of ulnar artery
• The radial artery reaches the back of the hand by passing
between the lateral collateral ligament of the wrist joint
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and the tendons of the abductor pollicis longus and
extensor pollicis brevis " floor of the snuff box "
# Extensor Retinaculum
• Fibrous sheath of deep fascia attached:
^ medially with styloid process of ulna & pisiform
bone & the hook of the hamate .
^laterally with lower part of radius
its a thickening of deep fascia that stretches across the back
of the wrist and holds the long extensor tendons in position.
• converts the grooves on the posterior surface of the distal
ends of the radius and ulna into six separate tunnels for
the passage of the long extensor tendons
• Each tunnel is lined by a synovial sheath (fibrous sheath
has afluid to make lubrication around the tendon before
and after Ex. Retinaculum ) , which extends above and
below the retinaculum on the tendons
• The tunnels are separated from one another by fibrous
septa that pass from the deep surface of the retinaculum
to the bones
• The upper and lower borders of the retinaculum are
continuous with the deep fascia of the forearm and hand,
respectively
# Carpal Tunnel
• Tunnel deep of Ex. retinaculum spically for the median
nerve , it names as median nerve tunnel. It found under
flexor retinaculum .
• The median nerve lies between the tendons of the flexor
digitorum superficialis and the flexor carpi radialis
muscles
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"Structures on the Posterior Aspect of the Wrist"
* structures pass superficial to the Ex. retinaculum
from medial to lateral ) 2 nerves , 2 veins )
1. Dorsal cutaneous branch of the ulnar nerve (supply medial
one third of the dorsum of the hand + one and half of
proximal phalanx )
2. Basilic vein
3. Cephalic vein
4. Superficial branch of the radial nerve ( letral two thirds
+three and half of dorsal phalanx )
* structures pass beneath the Ex. retinaculum
from medial to lateral ( tendons for the fingers )
1. Extensor carpi ulnaris tendon
2. Extensor digiti minimi tendon runs to Little finger
3. Extensor digitorum and extensor indicis tendons share a
common synovial sheath
4. Extensor pollicis longus tendon
5. Extensor carpi radialis longus and brevis
6. Abductor pollicis longus and the extensor pollicis brevis
" See fig 1 "
‫وما نيل المطالب بالتمني ولكن تؤخذ‬
‫الدنيا غالبة‬
 Thank you all 
Best Wishes
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Figure 1
Figure 2
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