Anatomy of Back of fore arm and dorsum of hand

describes all the features of back of forearm and dorsum of hand. also describes the clinical importance of the structures.

1. Back of forearm and
dorsum of hand
Dr. Laxman Khanal
Assistant Professor
Department of Human Anatomy
11-11-2016

2. Objectives
•Learn the skeletal components of posterior
forearm and dorsum of hand.
•Identify the seven superficial and five deep
muscles of posterior forearm.
•Find the posterior interosseous nerve and artery.
•Findextensorretinaculumandidentifythe
structuresonthedorsalaspectofthewrist.
•Knowtheboundariesandcontentofanatomical
snuffbox.
•Differentcomponentsofdorsumofhand.

3. Q. Posterior interosseous artery is the branch of.
a.Radial artery b. Ulnar artery
c. Brachial artery d. Axillary artery
Q. How many muscles are found on back of forearm?
a.8 b. 10
c. 12 d. 7
Q. Posterior interosseous nerve is the branch of.
a.Radial nerve b. Ulnar nerve
c. Median artery d. Axillary nerve

4. Q. Identify the bone.
a.Trapezium
b.Scaphoid
c.Triquetral
d.Lunate

5. Q. Which is not true for the marked triangular space?
a.It contain radial artery
b.Floor is formed by scaphoid
c.Roof contain cephalic vein
d.Skin area is supplied by ulnar nerve

6. A
B
C
A
B
C
Median nerve
Ulnar nerve
Axillary nerve
Radial nerve
Musculocutaneous nerve

7. Introduction
•Forearmisdividedintotwocompartments(flexor
andtheextensor)bythepartitionformedby
radius,ulnaandinterosseousmembrane.
•Posterior interosseous nerveand arteryare chief
neurovascular structures of back of forearm.
•Seven superficial and 5 deep group of muscles are
present in this compartment.
•Wrist drop is the common sign in paralysis of these
muscles.

8. S
L
T
P

9. Fracture of distal end of radius
Distal end displaces dorsally
Distal end displaces ventrally

10. Colle’s or Smith ???

11. Muscles of extensor compartment of
forearm
Superficial group-seven muscles
1.Brachioradialis
2.Extensor carpi radialislongus
3.Extensor carpi radialisbrevis
4.Extensor digitorum
5.Extensor digitiminimi
6.Extensor carpi ulnaris
7.Anconeus
Allthesuperficialmuscles(exceptthree)takesoriginfrom
commonextensororiginoflatepicondyle.

12. BR
Extensor
retinaculum
Ex Digi Ex Digi mi
Ex C U
Superficial muscles
1.Brachioradialis
2.Ex carpi radialislongus
3.Ex carpi radialisbrevis
4.Ex digitorum
5.Ex digitiminimi
6.Ex carpi ulnaris
7.Anconeus

13. Superficial muscles
1.Brachioradialis
2.Ex carpi radialislongus
3.Ex carpi radialisbrevis
4.Ex digitorum
5.Ex digitiminimi
6.Ex carpi ulnaris
7.Anconeus

14. Deep group of muscles-5 in number
1.Abductor pollicislongus
2.Extensor pollicislongus
3.Extensor pollicisbrevis
4.Extensor indicis
5.supinator
None of these muscles cross elbow joint.

15. 1.Abductor pollicislongus
2.Extensor pollicisbrevis
3.Extensor pollicislongus
4.Extensor indicis
5.Supinator
Anatomical snuff box

16. Common interosseous artery
Anterior interosseous artery
posterior interosseous artery
Ulnar artery

17. •Posteriorinterosseousnerve
comes totheposterior
compartmentthroughthegap
betweentwolayersofsupinator
muscle.
•Posteriorinterosseousartery
comes totheposterior
compartmentthroughthegapin
proximalpartofIOM.

18. Anatomical snuff box
Theanatomicalsnuffboxisasurfaceanatomyfeature.It
appearsasatriangulardepressiononthelateralsurfaceof
thewristonfullextensionofthethumb.
Medial boundary-EPL
Lateral boundary-AbPL+EPB
Roof-Cephalic vein and superficial b/o radial nerve.
Floor-Scaphoid bone
Content-radial artery
Tendernessintheboxsignifiesfractureofscaphoidbone.

19. Anatomical snuff box, remember !!
1 bone-scaphoid
1 artery-radial artery
1 vein-cephalic vein
1 nerve-superficial b/o radial nerve
3 tendons-APL+EPB and EPL

20. U
R
Compartment 1= latboundary of anatomical snuff box
Compartment 3= medial boundary of anatomical snuff box
Compartment 4= four structures
Extensor retinaculum and its compartments
5
th
compartment for little finger

21. Nerve supply of posterior
compartment
•Allthemusclesonthebackof
forearmaresuppliedbythe
posteriorinterosseousnerveexcept
brachioradialis,extensorcarpi
radialislongus,andanconeus,
whicharesuppliedbytheradial
nervedirectly.
These three muscles ????

22. Superficial
muscle
Common interosseous artery
Post interosseous artery
Ant interosseous artery

23. Wristdrop:Thisconditionis
causedbyaradialnerveinjury
thatresultsinparalysisofthe
extensormusclesintheforearm.
DeQuervain’stenosynovitis:
causedbyrepetitivemovement
andinvolveabductorpollicis
longusandextensorpollicis
brevis.Movementsofthethumb
arepainful.

24. Dorsum of hand

25. Dorsum of hand
•Skin
•Superficial fascia-contain dorsal venous arch
•Superficial branch of radial nerve
•Dorsal branch of ulnar nerve
•Deep fascia
•Extensor tendons
Median nerve

26. Superficialveinsonthedorsal
aspectofthehandareoften
visibleandcanbeaccessedfor
numerousprocedures.
Basilic vein
Cephalic vein

27. Cutaneousinnervationofdorsumofhand
Radial Nerve
Ulnar Nerve
Median Nerve

28. Extensor tendons and
Dorsal digital expansion
Expansion of tendon of Ext Digitorumover the MP joint
which covers dorsal and lateral side of proximal phalanx like
a hood.

29. Dorsal digital expansion
•Itistriangularflatsheetofaponeurosisrelated
withthetendonofextensordigitorum(Expansion)
Foundindorsum(Dorsal)ofproximalphalanx
(Digital).
•Alsocalledasextensorhood.
•Providestheinsertionofthelumbricaland
interosseousmusclesandtheextensorindicisand
extensordigitiminimimuscles.

31. •Mallet finger
•Baseball finger
•Cricketer’s finger
Insertion of extensor tendon to the distal phalanx
is torn by forceful blow to the tip of finger.

32. Conclusion
•Muscles: 7+5
•Nerve: post interosseous nerve
•Artery: post interosseous artery
•Extensor retinaculum: 6 compartment with 9
muscles+1 artery +1 nerve.
•Anatomical snuff box : boundaries and contents.
•Formation of dorsal digital expansion.