Dissection and instruments

Dissection & Instruments

By Dr.T.C.Singel (prof. & HOD)
M.P.Shah (Govt.) Medical College,
Jamnagar (Gujarat)
Mob: +91 9426988704
E-Mail:- drtcsingel@gmail.com

• I express my gratitude to my respected teachers.
–
–
–
–
–
–

Dr. D. N. Chhatrapati sir
Dr. B. R. Kulkarni sir
Dr. Dangarwala madam
Dr. G. N. Mankad sir
Dr. Buch sir
Dr. P. M. Raval sir
it is their guidance that made me what I am today.

Dissection
• Definition –
– The term “dissection” is a Latin equivalent of the Greek
term anatome, meaning to cut up.
– Dissection means to cut a part and see.
– Dissection means to separate and clean the structures

• Cadaver care and safety measures in dissection
lab.
– One must give respect to cadaver/dead body.

Cadaver - means preserved dead body.
– Maintain the dignity of cadaver and dead body.
– Cover the cadaver to prevent drying effect because once
the part is dried it can’t be restored.

SAFTY MEASURES
• Apron• To protect the clothing.

• Shoes/boot –
• Use shoes/boot because it gives safety to foot from dropped
scalpels or sharp instruments.

• Gloves –
• Use gloves to avoid the contact from preservatives and other
chemicals but the naked hand is best for palpation and feeling
the structures.
• So, one should avoid gloves as far as possible.

• Specs or goggles • While cutting bones use specs or goggles to protect the eyes
against any foreign body during cutting.

Seating arrangement– The seating arrangements has to be such that, everyone
can participate safely and can observe what is happening
on the dissection table, comfortably and safely.
• The dissection
lab must be
well
ventilated, to
prevent
suffocation
due to
formalin.

TYPES OF DISSECTION
and instruments used
• For different purposes various dissections are
carried out and for the various dissections, set of
instruments used differ.
• Here I have narrated the instruments according to
various types of dissection.
1.
2.
3.
4.
5.
6.

Comprehensive study dissection
Composite study dissection
Composite window corridor dissection
Unistructural dissection
Comprehensive window dissection
Dissection for embalming

1. Comprehensive study dissection
This is carried out for the routine dissection of
part of body or limb. In this study dissection is
carried out on a region as a whole. Students’
dissection instruments box is used.
• Dissection instruments box contains:
1) plain forceps 2) toothed forceps 3) pointed
forceps 4) scissorssmall, big, straight, curved, angular 5) knife handle
with blade 6) one piece scalpel 7) painting brush

2. Composite study dissection
It is carried out for demonstration and display
purpose. In this study dissection is carried out in a
particular region or a part of body where some
parts may be removed totally or partly.
• The instruments used are: dissection instruments
box + chisel, hammer, bone cutter, bone cutting
saw, retractors

3. Composite window corridor dissection
It is carried out for making museum specimens.
It appreciates the depth and relations of the deeper
structures.
saw, retractors, and very long needles

4. Uni-structural dissection
It is carried out for making museum specimens and
for study and demonstration of normal variations and
abnormalities in a given structure. Retaining some
important relations of a given structure all other
structures are removed.

The instruments
used are: dissection
instruments box +
chisel, hammer, bone
cutter, bone cutting
saw, retractors, and
bone nibbler

5. Comprehensive window dissection
Commonly called as window dissection.
• It is carried out for post graduate dissections.
Window dissection is carried out to demonstrate a
given structure in a given region with its relations.
In this dissection all the structures including skin are
preserved and as and when necessary they are
incised and regulated like a window in such a way
that all structures can be preserved back in-situ.
saw, retractors, pins (to fix up the skin flaps and maintain the relations
of the structures in situ)

6. Dissection for embalming
It is carried out for to embalm the dead body.
The common site of dissection for embalming
purpose is cervical region and/or femoral region.
The instruments used are:
• Along with dissection instruments box we need
Gloves, Cap Mask, goggles & guan, Saving kit,
Embalming apparatus with Murphy’s chamber &
controlling device and vessels cannula / vessels
catheter, Knife handle with blade , Artery forcepsSmall, Big, Mosquito, Forceps- Plain, Toothed, Hook
retractor with eye, Retractors, Thread, Needle
holder, Needle- Straight – cutting, Curved – cutting,

Dissection techniques
and instruments used
The dissection can be carried out as follow:
1. Blunt dissection
2. Sharp dissection
3. Dissection for cleaning structures
I. To clean muscles
II. To clean nerves
III. To clean vessels

4. Underwater dissection technique

1. Blunt dissection•
•
•
•

Blunt dissection means pulling/tearing instead of cutting.
This can be done by fingers, probe and scissors.
Fingers are the first and best dissecting instruments.
The next instrument is probe and next scissors with its back
edge.
• Vessels and nerves can be separated by scissors.
Scissors techniques –
• A closed pair of scissor is inserted into connective tissue or in
between two structures and then it is opened.
• During this process it tears the connective tissues in between
two structures and it cleans the two structures.

2. Sharp dissection
• It is done by scalpel and scissors.
• To cut the skin and reflect the flap, the scalpel is used.
• Otherwise, scalpels are not used because it may cut the
wanted and important structures.

3. Dissection for cleaning the structures
• To clean the muscles
– The surface of muscle is covered by fat and connective tissues.
– It can be cleaned with scissors. Scalpel can be used carefully.
– The border of the muscles is cleaned by fingers or prob.

• To clean the nerves
– The nerves are cleared by removing connective tissue around the
nerves with the help of probe and/or scissors.
– Don't use scalpel to clean the nerve because it may cut the branches of nerves.

• To clean the vessels
– Vessels are covered by fat and connective tissues.
– The connective tissue is tear or stripped or removed with
probe, scissor and forceps.
– Don't use scalpel to clean the vessels because it may cut the branches of
vessels.

4. Underwater dissection techniques
• Maze of fat and connective tissues can be dissected out and
removed by underwater dissection techniques.
• In this method, the dissection part/specimen is submerged in
water and it is trimmed out in the same condition. (That is in
the water.)
• This technique is used to prepare the museum’s specimens
and to prepare specimen for plastination.

Instruments required for Dissection
1. Skin marking pencils –
– Uses• It is used for surface marking of structures and to mark the
bony and other landmarks on cadavers.
• It is also used for marking skin incisions.

Instruments required for Dissection
2. Fingers –
– First dissecting tool is and must be finger.
– Always dissect first with finger then probe and then
scissors for blunt dissection.

• All metal instruments must be of stainless
steel metals.
3. Dissecting probe
• It is primary dissecting instrument.

– Uses –
• It is used for tearing connective tissues.
• It can also be used for feeling the structures like
vessels and nerves.

– Description –
• It has handle and other end is angular with a
rounded end (tip).

Scalpel
• Use –





It is use to cut and reflect the skin .
It is used to cut the tissue and dissection of tough connective tissue.
It is used to divide the vessels, pedicels and other structures.
It is used for the sharp dissection.

• Disadvantages –
 It may cut or injure the important structure during dissection.

• Scalpel
Descriptions
• Two parts –
»Handle
»Blade

• Types –
»Scalpel with fixed
handle and blade.
»Handle and blade are
separated. (Normally
separated handle and
blade are used.)

• Advantage of scalpel with fixed handle and bladeIt is handled in one piece and it is strong.
It is reusable.

• Disadvantage of scalpel with fixed handle and bladeSharpness of blade required frequent sharpening.

• Advantage of scalpel with disposable bladeVarious size, shape and curvatures of blade are available and used according
to the need.

• Disadvantage of scalpel with disposable bladeThe blades are use and throw.
Once sharpness is gone we have to use a new blade.
Handle has a slot for the fixing of the blade.
So, slot of the handle and surgical blade must be matching one otherwise it is
not used.

DISSECTING FORCEPS / THUMB FORCEPS:
• The shaft of dissecting forceps is closed by
thumb and fingers so it is known as thumb
forceps.
• Uses
• It is used for blunt dissection (i.e. for pulling or
tearing instead of cutting).
• It is used to grasp, lift and hold the tissues.
• Plain forceps is used to hold the delicate
structures like peritoneum, vessels, nerves and
muscles.
• Tooth forceps is used for better grip.
• Tooth forceps is used to insert the blade over
handle and to remove blade from handle.

Descriptions –

• It has two shafts and no joints.
• So, two shafts (blade) are joined at the top end and they have a spring
action.
• Objects are hold by tip when the shafts (blade) are pressed by thumb
and fingers.
• It provide firm grip on tissue and the firmness depends upon the
pressure on the shaft.
• The two consecutive movements can be done faster by the dissecting
forceps. (artery forceps also give firm grip but the two consecutive
movements are slow)

– Types
• Plain forceps.
• Tooth forceps / tissue forceps. (Tooth
forceps is used for gripping the tissue is
also known as tissue forceps.)

– Descriptions
• It has two parts one blade and other tip.
• Blade is long.
• On outer surface, there are serration for
better grip for handling.
• Plain forceps is having ridges and grooves
and tooth forceps is having tooth and
socket which prevent the slippage of the
tissue.

SCISSORS
Use
• It is used in cutting and
sectioning of tissue.
• It is used to cut tough
structures like
tendons, ligaments etc.
• For blunt dissection, straight
scissors is used.
• For delicate work, curved
scissors is used.

SCISSORS
– Description –
• It is having blade and body (handle) joined by pivot joint. (Axis
is formed by the screw).
• Blade
– It has two edges –
» Cutting edge
» Non cutting edge

SCISSORS
• Blade may be plain, curved or
having angle between shaft
and blade.
• According to that scissors are
known as
– Plain scissors
– Curved scissors
– Angular scissors
• The Curved scissor used for
the trimming purpose.
• The angular scissor is used
for the deeper structures.

• The tip of the blade may be
pointed or blunt.
• Pointed scissors may be
used for the blunt
dissection.

HAEMOSTATIC FORCEPS (ARTERY FORCEPS)
• Normally it is also known as artery forceps.
• Haemostatic forceps are used on
artery, veins and capillaries.

• Use :- It is used for strong grasping
and holding and catching.

• Disadvantage
• It crushes the delicate structures.
• When it is used as a holding
forceps, two consecutive holding of
structure is slow. (But in dissecting
forceps two consecutive movements
are fast.)

Descriptions
–Haemostatic forceps is
designed specifically to
catch/clamp and to crush the
tissue.

Parts
• Shaft of body (shank) :– It lies between joint and finger bows.

• Finger bow (ring):– It is used for holding the instruments.


• Catch / ratchet :– It lies between shaft and finger bow.
– When the catch / ratchet are pressed;
the blades are kept in closed position.
– 3 catches are for,
1. First catch for catching the tissue.
2. Second catch for clamping the tissue.
3. Third catch for crushing the tissue.

• Joints :– Joint is between the body and the blade.
– Joint may be pivot joint. (Screw form the axis).
– It may be the box joint. (Shaft passes in the slot of other shaft).

• Blades (jaw)
– The blade/jaw is having transverse serration on inner aspect.
– The blade may be straight or curved.

NEEDLE HOLDER:

Use
• It is used to hold the needle.

Parts
• Shaft of body (shank):– It lies between joint and finger bows.

• Finger bow :– It is used for holding the instruments.

NEEDLE HOLDER:
• Catch / ratchet :– It lies between shaft and finger bow.
– When the catch / ratchet are pressed;
the blades are kept in closed position.

NEEDLE HOLDER:
• Joint :– It is present between body and shaft.
– It is having modified box joint.
– Shaft passes in the slot of other shaft.

• Blades :– Blades are having cris-cross or
transverse serrations and in the
centre of the blade there is groove.

NEEDLE HOLDER:
• How to hold the needle holder
– Curved needle is hold by needle
holder, at the junction between
anterior 2/3 and posterior 1/3 of the
needle.
– This gives maximum mechanical
advantage of curved needle.
– If needle is hold nearer to the tip, the
mechanical advantage is less but the
penetrating power is more.
– If we hold needle nearer to
eye, chances of breakage of needle
nearer to eye is more.

NEEDLE HOLDER:
• Difference between haemostatic forceps and needle
holder:
Haemostatic forceps

Needle holder

1

Lighter instrument

Heavier instrument

2

Blades length 1/3 and
shaft length 2/3

Blades smaller

3

Transverse serration
on the inner side of
blades

Serrations –criss- cross or
transverse and groove in
blade

4

Joint screw type or
may be box type

Joint is box type only

NEEDLE
Use
• It is used to suture the skin, subcutaneous
tissues, connective tissues and other structures.
• It is also used to fix the structures together.
• It is also used to ligate around the tubular structure.

NEEDLE
• Description:
the needle may be curved or straight. It may be cutting or non
cutting.
– Eye
– Tip
– Body

• Eye:
– Eye allows the suturing thread to pass.
– It is the weakest part of the needle

• Tip:
– It is the pointed end of the body of the needle

• Body:
– It is tapering towards the tip.
– It may be triangular on cross section with a cutting edge.

SAW:

• Use
– It is use for cutting of bones.
– Now electrical saws are also available.

Description
– Handle- Pistol grip handle, which is design to
grip.
– Blade or edge-Edges is having two borders
cutting and non-cutting

BONE CUTTING & BONE NIBBLER FORCEPS :

Use – It is used to cut the small
and large pieces of
bones, edges of the
bones, spicules, spines
and processes of bones.
– It is used for tearing
away the remainings of
muscles, ligaments and
pieces of periosteum of
bone as it gives firm grip
on the tissue without
cutting them.


Description
– It has body or shaft, blades
and joints.

• body or shaft:– It is strong and convex on
outer side.
– The convex outer surface is
ridged for firm grip.
– The concave inner surface
of shaft is having
resistance which allows
sudden acute cutting force
for cutting the bones. (If
the gradual pressure is
allowed then first crush
and then may cut the
bones.)


• Joint

– It is having pivot or
modified box joint.
– Joints may be one or two
joints.

Advantage of two joint
– The cutting power is
increase with less effort by
these multiple lever
system.

• blades
– It is having two straight
and strong blades.

CHIESEL
:
Use
• It is used to cut the strong bones

Description
– It is having handle and shaft
– Handle
• On one end of handle, there is head, where the
hammer can be hit or stroked.
• On other end of handle, there is shaft.

– Shaft:
• The shaft is flat
• On one end, shaft is continues with the handle.
• On other end, shaft has cutting edge, cutting
edge is bevelled on one side.

HAMMER / MALLET

Use:
– It is used to hit or stroke.
– It is used along with chisel to
cut the bones.

Description:
– Handle
– Striking end

• Striking end is
heavier, which increase the
strength of the stroke

• Brain knife:

• Retractor:

comprehensive study(routine)
dissection and window dissection
comprehensive study(routine) dissection:
• comprehensive study(routine) dissection gives
better exposure of the structure in whole region.
• comprehensive study(routine) dissection is useful
for understanding & identification of structure and
relation in general.
• comprehensive study(routine) dissection is useful
for the gross anatomy study purpose but it may
increase the cadaveric wastage.

Routine and window dissection
WINDOW DISSECTION
- When a particular specific structure are required to
be demonstrated, window dissection is preferred
- It is done in given region
- It demonstrate the layer by layer relations of deeper
structure
- It prevent dryness of deeper structures
- It minimizes the wastage of body parts
- It is useful for the museum part preparation also
- It give better view of the relations among
skin, superficial fascia and deep fascia and other
structures

• I am thankful to Dr. Amit Singel, Dr. Dhaval
Talsaniya, Dr. K. P. Patravala (Ex. Prof & HOD) and Dr. Mohit
Changani for helping at each & every stages of this
presentation.

I would like to congratulate Anatomy Department
and
KLE
university’s,
J.
N.
Medical
College, Belgaum, for organizing CME on “postgraduate
intensive training program”. I feel proud to be a part of
this program which’ll help PG students of anatomy.

Dissection and instruments

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