Variations in Size and in Symmetry of Foramina of the Human Skull

Table 1 Paired Foramina

Foramen

Average Size (mm)

Largest Size (mm)

Smallst Size (mm)

Anterior Ethmoid 2.27 x 1.14 8 x 3 0.64 x 0.64

Carotid Canal 7.13 x 5.29 12 x 5 5.5 x 4

Foramen Ovale 7.11 x 3.60 8 x 7 5 x 2

Foramen Rotundum 3.26 x 2.66 4.5 x 3.5 2 x 2

Foramen Spinosum 2.39 x 1.96 4 x 3 1 x 1

Greater Palatine 4.01 x 2.16 8 x 3 1.67 x 1.67

Hiatus for the Greater Petrosal 0.77 x 0.68 3 x 2 0.3 x 0.3

Hiatus for the Lesser Petrosal 0.37 x 0.37 0.83 x 0.83 0.3 x 0.3

Hypoglossal (Exocranial) 4.66 x 3.21 7.5 x 5 2 x 0.92

Infraorbital Foramen 3.42 x 2.40 6 x 4 1.67 x 1.67

Innominate 2.13 x 1.1 4 x 3 0.3 x 0.3

Internal Acoustic Meatus 4.27 x 3.78 6 x 5 3 x 3

Lacrimal 0.71 x 0.67 4 x 1 0.3 x 0.3

Lesser Palatine 0.86 x 0.73 3.5 x 1.5 0.3 x 0.3

Mandibular 3.29 x 3.51 6.5 x 6 1 x 1

Mastoid Foramen 1.26 x 1.09 5.5 x 5 0.3 x 0.3

Mental Foramen 2.43 x 1.76 5.5 x 3 0.52 x 0.52

Nasolacrimal 5.30 x 4.45 7 x 7 3.5 x 3.5

Optic Foramen 5.02 x 4.16 7 x 5 3.5 x 3

Parietal foramina permagna 0.67 x 0.67 1.67 x 1.67 0.3 x 0.3

Post. Condylar 2.94 x 2.56 6 x 4.5 0.41 x 0.41

Posterior Ethmoid 1.23 x 0.82 4 x 1.5 0.41 x 0.41

Stylomastoid 1.66 x 1.56 2.5 x 2 1.07 x 1.07

Superior Alveolar 0.57 x 0.57 1.07 x 1.07 0.3 x 0.3

Superior Orbital 1.85 x 1.15 3.5 x 1.5 0.52 x 0.52

Trochlear 0.76 x 0.73 1.28 x 0.83 0.3 x 0.3

Vesalius 0.79 x 0.59 3 x 2 0.3 x 0.3

Unpaired Foramina

Foramen Magnum 33.8 x 28.3 41 x 53 24 x 23

Incisive Canal Length 2.76 x 2.39 5.5 x 4 0.46 x 0.46

Canal Average Length (mm) Longest Length (mm) Shortest Length (mm)

Infraorbital Canal 27.7 35 22

There was no significant difference between the average size of the foramina on the right and the average size of the foramina on the left, for any pair of foramina. Therefore, the "average size" was calculated by taking the average of both the right and left for each pair of foramina. When multiple openings were present for a foramen, all the openings were measured and used in the calculation of the average size. Table 2 Symmetry of Paired Foramina

Foramen

Absent Bilateral

Present Unilateral

Bilateral Same Size

Bilateral >0.5mm Diff

Anterior Ethmoid 0/90(0%) 1/90(1%) 65/90(72%) 24/90(27%)

Carotid Canal 0/100(0%) 0/100(0%) 77/100/(77%) 23/100(23%)

Foramen Ovale 0/96(0%) 0/96(0%) 40/96(42%) 56/96(58%)

Foramen Rotundum 0/98(0%) 0/98(0%) 90/98(92%) 8/98(8%)

Foramen Spinosum 0/92(0%) 1/99(1%) 77/92(84%) 14/92(15%)

Greater Palatine 0/99(0%) 0/99(0%) 67/99(68%) 32/99(32%)

Hiatus for the Greater Petrosal 0/100(0%) 0/100(0%) 87/100(87%) 13/100(13%)

Hiatus for the Lesser Petrosal 15/100(15%) 11/100(11%) 72/100(72%) 2/100(2%)

Hypoglassal (Exocranial) 0/100(0%) 0/100(0%) 41/100(41%) 59/100(100%)

Infraorbital 0/98(0%) 0/98(0%) 73/98(74%) 25/98(26%)

Innominate 65/100(65%) 17/100(17%) 9/100(9%) 9/100(9%)

Internal Acoustic Meatus 0/100(0%) 0/100(0%) 91/100(91%) 9/100(9%)

Lacrimal 28/100(28%) 31/100(31%) 35/100(35%) 6/100(6%)

Lesser Palatine 0/99(0%) 3/99(3%) 77/99(78%) 19/99(19%)

Mandibular 0/100(0%) 0/100(0%) 92/100(92%) 8/100(8%)

Mastoid 1/99(1%) 10/99(10%) 47/99(47%) 41/99(41%)

Mental 0/100(0%) 0/100(0%) 80/100(80%) 20/100(20%)

Nasolacrimal 0/46(0%) 0/46(0%) 38/46(83%) 8/46(17%)

Optic Canal 0/97(0%) 0/97(0%) 82/97(85%) 15/97(15%)

Parietal 20/99(20%) 30/99(30%) 33/99(33%) 16/99(16%)

Post. Condylar 10/100(10%) 36/100(36%) 18/100(18%) 36/100(36%)

Posterior Ethmoid 0/98(0%) 0/98(0%) 78/98(80%) 20/98(20%)

Stylomastoid 0/99(0%) 0/99(0%) 98/99(99%) 1/99(1%)

Superior Alveolar 1/91(1%) 0/91(0%) 86/91(95%) 4/91(4%)

Superior Orbital 50/100(50%) 31/100(31%) 14/100(14%) 5/100(5%)

Trochlear 92/100(92%) 6/100(6%) 2/100(2%) 0/100(0%)

Vesalius 41/100(41%) 24/100(24%) 25/100(25%) 10/100(10%)

Infraorbital Canal 0/98(0%) 0/98(0%) 64/98(65%) 34/98(35%)

Although 100 skulls were examined, not every foramen in the skull was useable due to breakage or inaccessibility. The number of useable skulls for each pair of foramina is given as the denominator. The four colums represent:

1. the number of skulls in which neither foramina of the pair was present
2. the number of skulls in which only one of the two foramina of the pair was present
3. the number of skulls in which both of the foramina of the pair were present and the same size within 0.5 mm
4. the number of skulls in which both of the foramina were present but there was greater than 0.5 mm difference in the size of the two foramina.

Variation in the Shape of the Superior Orbital Fissure

Riferimenti dell’opera originale

Elenco riportato come compare nella fonte, senza normalizzazione dei formati bibliografici.

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