1) The document discusses the anatomy and surgical procedure of trephining the paranasal sinuses in various animal species. It describes the locations and landmarks for trephining the frontal and maxillary sinuses in horses, cattle, and buffalo. 2) The key steps for trephining the frontal sinus include making a skin incision, using a trephine to create an opening, breaking the median septum to establish communication between sinuses and nasal cavity, and daily irrigation until infection is removed. 3) Anatomy like the irregular compartments and communicating openings in the sinuses is important to understand for accurate trephining. The maxillary sinus is more commonly affected in horses while the frontal

1. VETERINARY COLLEGE HASSAN
VETERINARYANATOMY
SUBMITTED TO:
Dr Rajashailesh N M
HOD
Dept of Veterinary Anatomy
SUBMITTED BY:
Swaroop R
Jr MVSc
Dept of VSR
TREPHENING

2. Trephining is the surgical procedure in which a hole is created in the skull by the removal of
circular piece of bone, while a trepanation is the opening created by this procedure
(Stone and Miles, 1990).
TREPHENING
Trephination (also known as trepanning or burr holing) is a
surgical intervention where a hole is drilled, incised or scraped
into the skull using simple surgical tool

3. Sinuses: Anatomy
There are five pairs of paranasal sinuses :
1. Frontal
2.Maxillar
3.Sphenopalatine
4. Ethmoidal
5. Lacrimal
The topographical anatomy of the frontal and maxilary sinuses is of clinical importance.
The empyma of these sinuses is very common in the domestic animals.
Hence there is need to trephine open these sinuses to flush out the exudate.

4. Sinuses of cattle
1.Cornual diverticulum of frontal
sinus
2. Frontal sinus
3. Anterior-medial part of frontal
sinus
4. Lacrimal sinus
5. Maxillary sinus
6. Palatine sinus.

5. TREPHINATION OF PARANASAL SINUSES
The equine paranasal sinuses (PNS) are an intricate area of the head.
All of these spaces communicate with each other and the nasal passage either directly or
indirectly.
 A thorough understanding of the spatial structural relationships will improve one's ability to
interpret imaging studies and plan the best approach to the PNS.
 Trephination of the PNS is a basic procedure that can be readily performed in the field, and
familiarity with anatomy is the most important aspect of the procedure.

6. INDICATIONS
1. Sinusitis and pus in the sinuses.
2. Neoplasms in the sinuses.
3. Fracture of related bones.
4. Horn cancer in cattle and buffalo.
5. Dental fistula.
6. Alveolar periostitis.
7. Presence of any foreign body/cyst/parasite in sinuses.

7. SURGICALANATOMY-HORSE
 Frontal sinus in horse is not so extensive as that
of cattle.
The median septum divides right and left
sinuses.
The frontal sinus is divided into frontal and
turbinate parts and further sub divided in small
compartments by number of body plates.
Each compartment communicates with each
other by small openings.
The frontal bone lines the roof of sinus which
extends anteriorly with anterior margin of orbit
and caudally to temporal condyles and laterally
to the foot of the supraorbital process.

8. 1.Frontal sinus
2. Anterior compartment of maxillary sinus;
3. Posterior compartment of maxillary sinus;
4. Palatine sinus.
Sinuses of horse.

9.  The turbinate part is located in the posterior part of the dorsal turbinate bone
covered by nasal and lacrimal bones.
 The turbinate part is separated from the nasal cavity by a thin tissue of dorsal
turbinate bone.
 The frontal and maxillary sinuses communicate with each other through a large
fronto-maxillary opening, which is situated ventral to the osseous canal and
medial wall of the orbit.
The frontal sinus has no direct communication with the nasal cavity.

11. Site for trephining
The point of frontal sinus trephine is placed 2.5cm lateral to the midline of skull on a horizontal
line running from the upper border of the orbit across to a similar point on the other side.

12. SURGICAL TECHNIQUE - FRONTAL
SINUS
1. Make a ‘V’ shaped skin incision at the site of trephining and expose the periosteum.
2. With the help of a trephine of appropriate size open the frontal sinus through the turbinate
portion.
3. Establish a communication between the sinus and nasal cavity with a curved mare catheter.
Apply slight pressure to break the median septum, felt with finger through the trephining opening.
4. Place a gauge in the sinus and daily irrigation with 1:1000 potassium permanganate may be
done till complete infection is removed.
5. Skin wound is sutured after complete removal of the infection

13. left; Under standing sedation following skin preparation
and local anaesthesia, a 3 cm vertical skin and periosteal
incision is made over the frontal sinus.
Right; a 10 mm diameter, modified tungsten carbide
metalwork drill bit used for sinus trephination.
Use of modified drill to enter the CFS. The welded flange,
approximately 3 cm from its tip, prevents the drill from
suddenly penetrating the sinus too deeply and possibly
damaging the ethmoturbinates.

14. Horse with sinus lavage
catheter inserted in its right
concho-frontal sinus.
Sinoscopy (using a frontal sinus portal) shows a single piece of
inspissated pus lying on the floor of the caudal maxillary sinus
of a horse with chronic low-grade primary sinusitis. The
sinusitis resolved following its removal using transendoscopic
biopsy forceps

15. SURGICALANATOMY FRONTAL SINUS
CATTLE AND BUFFALO
a) Largest and involves whole of frontal bone.
b) Median septum separates right & left sinuses.
c) The boundaries of frontal sinus are:
i. Anteriorly, an imaginary transverse line from inner canthus of one orbit to the other.
ii. Posteriorly squamous part of the occipital bone.
iii. Laterally, supraorbital process and the lateral border of frontal bone.
iv. Medially, median septum.
v. Caudally sinus extends for a variable distance into cornual process.

16. d) The sinus is very irregular and is divided into numerous diverticulae by ridges and
partial septae.
e) Several small openings from middle nasal meatus communicate directly with each
sinus.
f) The anterior portion of frontal sinus communicates with the lacrimal part of
maxillary sinus through a large opening which remains closed by a mucous membrane
in living state.

17. SITE OF OPERATION FRONTAL SINUS
Cattle & Buffalo
a) 4 cm from the posterior edge of the orbital cavity and just dorsal to the temporal canthus or
where the bulging of bone is seen to drain out postorbital diverticulum.
b) Posterior to a line joining the center of the orbit and 2-3 cm from the mid line to drain out
medial part.
c) For drainage of turbinate part-site is same as in horse.

18. 1.Opening for main portion of frontal sinus
2.Frontal sinus
3. Opening for lowest portion of frontal sinus
4. Opening for anterior frontal sinus
5. Opening for turbinate portion of frontal sinus
6. Opening for maxillary sinus.
Location for trephine sites in the sinuses of cattle

19. MAXILLARY SINUS
a) Maxillary sinus is the largest sinus in horse. It is divided into anterior and posterior compartments by an
oblique septum.
b) It is formed by the superior maxillary, lacrimal, malar and posterior turbinate bones.
c) The boundaries of this sinus are:
i) Medially- Maxilla, ventral turbinate and lateral mass of the ethmoid bone.
ii) Posteriorly – The border extends upto transverse plane in front of root of the supraorbital process.
iii) Anteriorly- Line drawn from the anterior end of the facial crest to the infraorbital foramen parallel to the
facial crest.
iv) Ventrally- Alveolar part of maxilla.
d) The sinus is irregular and four cheek teeth project into it.
e) The sinus communicates with frontal sinus and nasal cavity.

20. SITE OF OPERATION
The anterior maxillary sinus is trephined at above 2.5-3.0 cm posterior and 2 cm medial to the
lower end of the zygomatic ridge.
b) Posterior maxillary sinus is trephined about 2 cm medial to the lower end of the zygomatic
ridge

21. Maxillary sinusotomy in a 3-year-old horse showing the small size
of both maxillary sinuses and the intervening maxillary septum.
The lateral aspect of the alveoli are approximately 1 cm from the
maxillary wall
Trephination of the left rostral maxillary sinus. Left: Skin and
muscle incision in an aseptically prepared site. Right: Drilling
through the maxillary bone using a soft tissue guard to reduce
skin and muscle damage

22. Inspissated pus being removed from a horse with chronic
primary sinusitis via a fronto-nasal sinusotomy
Standing sinusotomy of the rostral and caudal maxillary sinuses
in a horse with primary sinusitis has allowed mucoid and
mucopurulent exudate to drain from the caudal maxillary and
rostral maxillary sinuses, respectively

24. MAXILLARY SINUS - CATTLE
AND BUFFALO
a) It is situated anterior to orbital cavity and is formed by lacrimal, malar and the body of maxilla.
It is single and doesn’t communicate with frontal sinus.
b) It is irregular sinus. The roots of last three or four check teeth project into it.
c) The boundaries of maxillary sinus are: i) Dorsally – Lacrimal bulla, little below the point of
bifurcation of the zygomatic process of malar.
ii) Posteriorly- Base of alveoli and maxillary tuberosity.
iii) Anteriorly – Line joining infraorbital foramina to the orbital rim
. iv) Laterally- Maxilla, lacrimal and malar bones.
v) Medially- Irregular bone plates.
d) The maxillary and palatine sinuses communicate freely with each other

25. Trephination site for access to the bovine
maxillary sinus
 The landmarks for the trephination site for the bovine maxillary sinus are the medial canthus of the eye
and the facial tuberosity.
 A line is drawn between the facial tuberosity and the canthus.
 The trephination site is 1 cm ventral to the midway point of this line to avoid the nasolacrimal duct.
 The soft tissue and bone is considerably thicker than at the equivalent trephination sites (rostral and
caudal maxillary sinuses) in the horse

26. The left radiograph shows the continued presence of the fluid
line. The area of increased radioopacity seen previously is no
longer present. The trephination site is marked with a coin on
the right radiograph.
Lateral radiograph with the horizontal fluid line
(arrows) clearly visible in the right maxillary sinus.
Lateral radiograph taken after 10 days of antibiotic
therapy. The fluid line in the maxillary sinus is still
clearly visible. There appears to be an area of
increased radioopacity adjacent to the maxillary
sinus (arrows).

27. CONCLUSION
Anatomy of paranasal sinuses is essential for successful trephining.
Maxillary sinus is more affected in Horse
Frontal sinus more affected in Cattle
Post operative care is more essential

28. REFERENCES
Barakzai, S.Z., KANE‐SMYTH, J.U.S.T.I.N.E., Lowles, J. and Townsend, N., 2008. Trephination of the
equine rostral maxillary sinus: efficacy and safety of two trephine sites. Veterinary
Surgery, 37(3), pp.278-282.
Dixon, P.M. and O'Leary, J.M., 2012. A review of equine paranasal sinusitis: medical and surgical
treatments. Equine Veterinary Education, 24(3), pp.143-158.
Crilly, J.P. and Hopker, A., 2013. Case report: diagnosis and treatment of maxillary sinusitis in an
Aberdeen Angus cow. Livestock, 18(6), pp.230-235.
Applied Anatomy Of Domestic Animals-R L Bharadwaj, Rajesh Rajput,K S Roy