Figure 1a (figures to be opened in separate URL by clicking figre 1a)

 

Infraorbital Foramen in South Indian Population: Anthropometric Measurements and Their Clinical Relevance

Dr.Sarala Devi.K.V*, Dr.Udhaya. K*, Dr. Deepti Shastri**

*  Assistant professor, **  Head of Department,

  Department of Anatomy,V.M.K.V.Medical College, Salem

  Abstract:

Aim: The aim of the study was to determine the location and morphology of Infraorbital foramen (IOF) which is useful in guiding the surgeons while performing regional nerve blocks.

Materials and method: 125 adult skulls of both sex (82 males and 43 females) irrespective of age was utilized for our study. The shape, orientation, location in relation with teeth and distance from infra orbital margin (IOM) and presence of accessory foramina were observed by direct inspection. The location of infra orbital foramen from IOM was measured by using the vernier caliper.

Results: The majority of IOF were oval shaped in male skulls (54.7%) and on left side (52.8%). The majority of IOF were directed inferomedially (65.8% in males; 67.8% in females) and on right side (68.6%). The majority of IOF were vertically oriented to 2nd premolar teeth (43% in both sexes and on both sides). The mean distance of infra orbital foramen from the infra orbital margin was 6.50mm. Accessory foramen were noticed in 9.6% skulls.

Conclusion: The results of our study may be considered while performing surgical procedures in relation to infra orbital foramen.

Key words:

            Skull, infra orbital foramen (IOF), accessory infra orbital foramen (AF), infra orbital margin (IOM)

Introduction:

             Infraorbital foramen is situated on the anterior surface of maxilla about 1cm

below the Infraorbital margin (Gardner, 1988 1; William et al, 1989 2). The Infraorbital nerve, continuation of maxillary division of trigeminal nerve after passing through the Infraorbital canal, appears on the face through IOF and terminates by dividing into palpebral, nasal and labial branches to supply skin over the lower eyelid, conjunctiva, lateral aspect of external surface of nose and upper lip (McMinn RMH, 1990 3; Moore KL et al, 1999 4). Several authors have worked on the morphometric assessment of IOF (Gruber, 1878 5; Gozdziewski et al, 1979 6; Chung et al, 1995 7; Testut et al, 1954 8). The presence of supernumerary foramina also has been documented (Berry, 1975 9; Bergman et al, 1988 10). Hence the knowledge of the morphology of IOF is important for providing the guidance in local anesthesia, maxillofacial, plastic surgical operations and radio ablative neurotomy procedures.

Material and methods:

            One hundred and twenty five South Indian skulls (82 males and 43 females) of unknown age were selected from the department of Anatomy, Vinayaka Mission’s Kirupanandha Variyar Medical College and Annapoorana Medical College, Vinayaka Mission’s University, Salem. Both sides of each skull were assessed by direct inspection. The shape, location, direction of IOF and accessory foramina were observed.

1) The shape of IOF was recorded as an oval or round opening (figure 1a, 1b).

2) The location of IOF was determined with the following measures:

            A) The distance of IOF from the point on the IOM where the zygomaticomaxillary suture meets the margin. The measurement was made by using vernier caliper capable of measuring to the nearest 0.01mm (figure 2a).

            B)  The vertical orientation of IOF to the occlusal plane of upper teeth (figure 2b). 3) The direction of the IOF was assessed by direct inspection and was described as downward medially (DM), vertically downward (VD), medially (M) and downward anteriorly (DA) (figure 3a, 3b, 3c and 3d).

4) The presence of accessory foramina was recorded (Figure 4a, 4b).

            The complete data of frequencies and measurements were tabulated according to gender and sides. They were analyzed using Statistical Package for Social Studies

(SPSS) version 12. The mean, standard deviation, minimum and maximum for the measurements, confident interval were assessed. The mean values of measurements were compared between sides and genders.

Exclusion criteria of study:

Foetal and child skulls and destroyed sides of adult skull are excluded from the study. Also edentulous sides were excluded while studying the orientation of IOF with the teeth. But in spite of the all exclusions, it is absolutely certain that the studied foramens belonged to same original skulls and the statistical analysis could show reliable results.  

 

 

Observation:

            Total skulls examined :            125 (250 sides)

            Male skulls                  :              82 (65.6%)

            Female skulls               :              43 (34.4%)

            No: of sides not able to examine due to destruction: male – 3; female – 3; right – 4; left – 2.

            N – 244 sides.

             Investigation of IOF in 125 skulls revealed that the shape of IOF was oval on right side in 59 (48.8%) foramina, on left side in 65 (52.8%) foramina, in 88 (54.7%) foramina from male skull and in 36 (43.4%) foramina from female skull; round on the right side in 62 (51.2%) foramina, on the left side in 58(47.2%) foramina, in 73 (45.3%) foramina in male skulls and in 47 (56.6%) foramina from female skulls.

            Regarding the location of IOF, the mean distance from the IOM was found to be 6.65mm in males and 6.2mm in females; 6.57mm on the right side and 6.42mm on the left side. The minimum distance recorded was 3mm and maximum was 12mm. The mean distance observed in most of the skulls (N – 244 sides) found to be 6.50mm, standard deviation was 1.744; 95% confident interval was 6.28 – 6.72mm (Table I, II).

            The tooth most commonly found in the same vertical level with the IOF was upper second premolar in 80(43%) skulls followed by between 2nd and 1st molar in 59 (31.7%) skulls. No significant sex or side differences were observed (Table III). 

            The IOF was directed inferomedially in 162 foramina (66.4%), vertically downwards in 59 (24.2%) foramina, medially in 20 (8.2%) foramina and downwards anteriorly in 3 (1.2%) foramina (Table IV).

              Accessory foramina were also found in 12 skulls. The number of AF ranged from single to double. Single foramen was found in 7 male (5.6%) and 4 female skulls (4.8%) of which 2 male skulls showed AF bilaterally. Double AF was noted in one male skull (0.8%). Most of the accessory foramina were identified on the left side. The mean distance of AF from the main foramen was 7.07mm. About 92.3% of AF were present superomedial to the main IOF (Figure 5).

Discussion:

            Since the Infraorbital nerve and vessels emerge through IOF and the knowledge of anatomical features of IOF is very important for the surgeons dealing with maxillary region, eg., in the surgeries for fracture of zygoma (Le Fort II) (Du Tolt and Nortje 11), intra or extra – oral anesthesia ( Hollinshed 12; Figun and Garino 13)

            The distance of IOF in reference to IOM had been reported to lie between 4 – 10mm. (Aziz 14; Chung et al 7, Zide DM 15) (Table V). The mean distance between IOF and IOM in our study was found in close range with Cutright et al 16, Elias et al 17, Boopathi et al 18). But the mean distance in our study was lower than that of Aziz et al 14, Apinhasmit 19).  The knowledge of location of IOF is mandatory to avoid injuries of eye during nerve block and to identify danger zone of its location during dissection of the comminuted fracture of anterior maxillary wall or inferior orbital wall.

            Different shapes of IOF were reported by many authors (Boopathi et al 18, Kazkayasi et al 20, and Elias et al 17). The results of our study were similar to those of Apinhasmit and Boopathi. We could not find semi lunar or triangular shape as reported by Boopathi et al.          

            Most of the IOF was found to point inferomedially as revealed by Ellias and Apinhasmit. Our findings also coincided with them. We made out IOF directed also medially in 8.2% of skulls and anteriorly downwards in 1.2% skulls. But we could not find data to compare in the available literature. It is essential to know the direction of IOF while passing needle to block the nerve and to direct the probe in radiofrequency neurotomy procedures.

             Our study documented that the tooth most commonly noted in the same vertical line was 2nd premolar in the upper jaw (80%) and too agreed with Apinhasmit (85%) 19.   

            Gruber reported first the presence of accessory IOF and described 5 independent foramina. Kadanoff et al 21 found it doubled in 9%, tripled in 0.5% and greater than 3 in 0.3%. Bressan et al 22 demonstrated AF in 5.4% males, 4.26% in females with high frequency on the left side in both males and females. According to Hanihara and Ishida 23, AF were more commonly found in Northeast Asian skulls. Boopathi et al 18 reported AF in 16.25% of skulls in South Indians. In present study, incidence of AF was lower when compared with that of Elias, Boopathi, but similar to Bressan. Regarding double AF, present study coincides with the findings of Kadnoff.  The surgeons must remember this during nerve block since injury to any branch can result in sensory loss and incomplete nerve block.

Conclusion:

            The knowledge obtained from anthropometric study conducted in South Indians by present authors may provide guidance to the maxillofacial surgeons, anesthesiologists to localize infra orbital foramen and so may be considered for the better outcome of diagnostic or therapeutic procedures.

 

 

Table I           

            Distance of IOF from IOM (mm)

 

 Gender

 

Mean

N

Standard deviation

Male

6.65

161

1.667

Female

6.20

83

1.859

Side

Right

6.57

121

1.793

Left

6.42

123

1.699

                   Total

6.50

244

1.744

 

 

 

 

 

 

 

 

 

 

 

 

 

 

            Male – 95%,   confident interval – 6.31-6.91; min – 3, max – 12

Female – 95%, confident interval – 5.8 – 6.61; min – 4, max -12

Right – 95%,   confident interval — 6.25 -6.87; min – 4, max – 12

Left   — 95%,   confident interval — 6.12 – 6.73, min – 3, max – 11.

Table.II.

Frequency of distance of IOF

Valid(mm)

frequency

percentage

Valid %

Cumulative %

3

2

0.8

0.8

0.8

4

29

11.9

11.9

12.7

5

47

19.3

19.3

32.0

   

47

19.3

19.3

51.2

7

55

22.5

22.5

73.8

8

36

14.8

14.8

88.5

9

15

6.1

6.1

94.7

10

7

2.9

2.9

97.5

11

4

1.6

1.6

99.2

12

2

0.8

0.8

100.0

       Total

244

100.0

100.0

 

 

                                                Table III.                        

 Orientation of IOF with the teeth.

 

Teeth

Gender

Total

Side

 

Total

Male

Female

Total

Right

Left

1st MO 21 (15.9%) 5    (9.3%) 26(14%) 12(12.9%) 14(15.1%) 26(14%)
2ndPM/MO 40 (30.3%) 19 (35.2%) 59 (31.7%) 28 (30.1%) 31 (33.3%) 59 (31.7%)
1st/2ndPM 16 (12%) 4(7.4%) 20(10.8%) 14(15.1%) 6(6.5%) 20(10.8%)
2nd PM 55(41.7%) 25(1.9%) 80(43%) 38(40.9%) 42(45.2%) 80(43%)
2nd MO 0 1(1.9%) 1(0.5%) 1(1.1%) 0 1(0.5%)
Edentulous 29 29 58 28 30 58
Total 161 83 244 121 123 244

 

1st MO =  first molar;  2nd PM/ MO = between second premolar and first molar;

 

1st/2nd PM  =  between first and second premolar;  2nd PM = second premolar; 2nd MO =

 

second molar teeth.

 

 

 

Table IV.                               

   

     Direction of IOF.

 

 

Direction

Gender

 

Total

Side

 

 Total

male

Female

Right

Left

DM

106 (65.8%) 56(67.5%) 162 (66.4%) 83(68.6%) 79 (64.2%) 162 (66.4%)

VD

43 (26.7%) 16(19.3%) 59 (24.2%) 28(23.1%) 31(25.2%) 59 (24.2%)

AD

1(0.6%) 2(2.4%) 3 (1.2%) 10(.8%) 2(1.6%) 3 (1.2%)

MED

11(6.8%) 9(10.8%) 20 (8.2%) 9 (7.4%) 11 (8.9%) 20 (8.2%)

Total

161 83 244 121 123 244

 DM = downward medially; VD  = vertically downwards; AD  = anteriorly downwards;

 MED  = medially

Comparison of our study with previous studies

 

Study

No: of samples

Mean±SD;

distance of IOF

from IOM (mm)

Shape (%)

Accessory foramen (%)

Round

Oval

Aziz et al

47

8.3±1.9

 

 

15

Cutright et al

80

6.4±0.3

 

 

 

Kazkayasi et al

35

7.19±1.39

38

34.3

 

Kazkayasi et al

10

 

40

30

5

Elias et al

210

6.71±1.70

 

 

15.23

Agthong et al

110

7.9±0.02

 

 

4

Apinhasmit et al

106

9.23±2.03

20.8

50

3.8

Gupta

79

7.0±1.6

 

 

 

Boopathi et al

80

6.57±1.7

24.4

53

16.25

Our study

125

6.50±1.7

49.2

50.8

9.6

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Figure 1a

An unusual origin of the right vertebral artery from the thyrocervical trunk – a case report
A study on Metopic Suture in Adult South Indian Skull, Shanta Chandrasekaran*, Deepti Shastri**