| ObjectiveThrough observation and measurement of posterior fossa foramen magnum and adjacent bony structures of the blood vessels and nerves in order to accumulate data and to select the area of anatomy related surgical approach to provide anatomical basis. MethodSelect specimens of 40 cases of adult skull base( regardless of gender), measured after posterior fossa foramen magnum associated structures, including specific indicators around the foramen magnum diameter, transverse diameter, subtype of the foramen magnum, hypoglossal canal from the middle of the mouth distance from the surface of the pitch from the median plane of the jugular vein; selected 15 adult cadaveric heads open skull cap, remove the brain, the cerebellum removed the curtain to expose the cerebellum. Flips cerebellum, observing and measuring the foramen magnum neurovascular, including vertebral artery, basilar artery, posterior inferior cerebellar artery, inferior cerebellar artery, hypoglossal nerve, glossopharyngeal nerve, the vagus nerve, nerve, observed blood vessels course and distribution, and measure its diameter, observed and measured adjacent neurovascular relationships. Pitch important structures in the shortest distance between the subject, the average of three measurements taken measurements, the data obtained were as mean ± standard deviation( x ± s, Min ~ Max) said. The resulting data were analyzed statistically. With P < 0.05 for significant boundaries, P < 0.01 significant differences limit. Results1. Before and after the foramen magnum diameter(36.3 ± 2.28, 28.8 ~ 45.8mm); around the foramen magnum diameter(30.0 ± 2.14, 21.2 ~ 38.4mm); foramen magnum Shape: oval 21 cases( 52.5%); diamond 5 cases( 12.5%); hexagonal seven cases( 17.5 %); pumpkin seed-shaped five cases( 12.5%); round 2 cases( 5%).2. The hypoglossal rim and inner tube midline distance(12.9 ± 1.38, 10.3~ 15.9mm); internal jugular vein hole rim and midline distance(21.2 ± 1.49, 19.2 ~ 24.8 mm).3. Vertebral artery near the outer diameter of the basilar artery(left: 1.64 ± 0.08, 1.49 ~ 1.79mm; Right: 1.56 ± 0.06, 1.43 ~ 1.69mm), on both sides there is a significant difference(p < 0.05); the left rough on the right side by the majority( Left: 13 cases, the right: 2 cases); sides straight 10 cases, 4 cases curved sides, one side of the flat side of the bend in 1 case. The artery and hypoglossal nerve close.4. The beginning part of the outer diameter of the basilar artery(4.18 ± 0.24, 3.64 ~ 4.61mm); basilar artery of flat-and curved, curved majority( four cases in which the flat type, accounting for 26.7%; curved 11 cases, 73.3%).5. Inferior cerebellar artery in the vertebral artery, basilar artery in starting from the most part from the outer diameter of 5( left: 1.41 ± 0.05, 1.32 ~ 1.49 mm, Right: 1.39 ± 0.07, 1.27 ~ 1.49mm), on both sides there was no significant difference(p > 0.05); cerebellar tortuous arterial stroke, was "S" shaped, divided into six segments: cisternal segment; bulbar segment; tonsil segment, bypass the lower edge portion of the cerebellar tonsils; marrow sail segment; transition section; branch segment. Traveling inferior cerebellar artery and the first Ⅸ, Ⅹ, Ⅺ closely related to the location of the brain can be divided into three types: dorsal type, accounting for 20%( 3 cases); ventral type, accounting for 20%( 3 cases); wear radiculopathy, 60%( 9 cases). Depending radi- culopathy wear through the nerve root, this type can be divided into: wear silk nerve stud who wear vagus nerve between the nerve root, the vagus nerve to wear silk stud who wear glossopharyngeal nerve and vagus nerve between persons.6. All from the bottom of anterior inferior cerebellar artery basilar artery, the initial outer diameter( left: 1.09 ± 0.10, 0.92 ~ 1.25 mm, Right: 1.09 ± 0.08, 0.96 ~ 1.23mm), on both sides there was no significant difference(p > 0.05), the artery emitted mainly from the lower 1 / 3 segments, two most side symmetry, found one case of unilateral double dry. In most cerebellar artery formation of arterial loop, bend the ear door directions, and facial nerve, vestibular cochlear nerve close. Arterial loop occurrence rate of 80%( 12 cases), which surround the facial nerve, cochlear nerve ventral surface, those above 25%( 3 / 12), wearing a facial nerve, cochlear nerve between 75%( 9 / 12).7. The upper end of the hypoglossal nerve brain areas extend from the bridge ditch about 4mm, a brain region length 13(8 ~ 20) mm. Mostly located in the dorsal vertebral artery( 13 cases), a few hypoglossal nerve roots gripping vertebral artery( two cases).8. Glossopharyngeal, and vagus nerve which three pairs of cranial nerves from the root down to a series of wires attached to the medulla oblongata olive sulcus, the lateral line, to form a separate jugular foramen nerve. In all three holes into the jugular vein arranged sequentially from front to back. The relationship between the posterior inferior cerebellar artery and the three cranial nerve is extremely close. Conclusions1. Anterior inferior cerebellar artery and the facial nerve, vestibular cochlear nerve is closely related to arterial loop with two points across the positional relationship between the nervous type and wear type. In acoustic neuroma operation, the general focus is the total resection of tumor and facial nerve, auditory nerve protection. However, under the protection of cerebellar artery trunk and branches should be used as one of the key operations, or due to injury can also cause dizziness, facial paralysis, hearing loss, outside of the brain stem and cerebellar infarction, and even death, especially when AICA coarser should pay attention.2. Inferior cerebellar artery and the first cranial nerve Ⅸ~Ⅺ closely divided across and through-type. Especially after suboccipital far lateral approach in the treatment of ventral cranial fossa tumors when, due to the long journey into the road, pay attention to the relationship between the artery and nerve anatomy. Vascular plexus traction should be gentle, to avoid injury, the error bar related structures. |
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