Dissection and instruments

Dissection & Instruments

By Dr.T.C.Singel (prof. & HOD)

M.P.Shah (Govt.) Medical College,Jamnagar (Gujarat)

Mob: +91 9426988704E-Mail:- [email protected]

mailto:[email protected]

• 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 DISSECTIONand 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. Comprehensive study dissection2. Composite study dissection3. Composite window corridor dissection4. Unistructural dissection5. Comprehensive window dissection6. Dissection for embalming

1. Comprehensive study dissectionThis 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) scissors- small, big, straight, curved, angular 5) knife handle with blade 6) one piece scalpel 7) painting brush

2. Composite study dissectionIt 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.

• The instruments used are: dissection instruments box + chisel, hammer, bone cutter, bone cutting 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 dissectionCommonly 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.

• The instruments used are: dissection instruments box + chisel, hammer, bone cutter, bone cutting saw, retractors, pins (to fix up the skin flaps and maintain the relations of the structures in situ)

6. Dissection for embalmingIt 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 forceps-Small, Big, Mosquito, Forceps- Plain, Toothed, Hook retractor with eye, Retractors, Thread, Needle holder, Needle- Straight – cutting, Curved – cutting, Gauge piece

Dissection techniquesand instruments used

The dissection can be carried out as follow:1. Blunt dissection2. Sharp dissection3. Dissection for cleaning structures

I. To clean musclesII. To clean nervesIII. 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.

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.

Instruments required for 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).

• 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

• ScalpelDescriptions• 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 blade- It is handled in one piece and it is strong.It is reusable.

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

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

• Disadvantage of scalpel with disposable blade- The 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.

• 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.

DISSECTING FORCEPS / THUMB FORCEPS:

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.


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.

SCISSORS

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.

HAEMOSTATIC FORCEPS (ARTERY FORCEPS)

• 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.


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 HOLDER:

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.

NEEDLE

• 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

SAW:

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.

BONE CUTTING & BONE NIBBLER FORCEPS :

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.


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.

CHIESEL:

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

HAMMER / MALLET

• 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.

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

Routine and window dissection

• 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.

Education

Dissection and instruments