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The pathogenesis of damage to and the microsurgical anatomy of the infraorbital nerve are reviewed. Indications for surgery and a microsurgical technique for decompression and scar removal or anastomosis of the nerve are presented. Results from seven surgical cases indicate a high degree of successful regeneration, with complete return of sensation occurring in six cases.

The state of the palisade neural fibers (PNF) in the connective tissue of the internal follicle of the cat sinuous hair has been studied after the infraorbital nerve had been cut. Denervation of the sinuous hair is demonstrated to result in certain destructive changes in the PNF. Two days after the operation, cytoplasm becomes more dense, mitochondria undergo destruction, large vacuoles appear in the neural terminals. In the receptory specialized cells, as well as in the neural fiber lemmocytes, the number of the large vacuoles increases, electron opaque bodies appear. On the 7th day after the operation maximal destructive changes are noted. In 30 days after cutting the nerve, regeneration of the neural fibers, the PNF including, begins. In this connection the fate of the specialized cells after destruction of the receptor and their participation in the regenerative process is discussed. The data obtained demonstrate that there are some important functional connections between the axons and the specialized PNF cells. This is necessary to maintain the differentiated state of the receptor in question.

A double-blind investigation of the effect of adrenaline on conduction blockade was undertaken in six groups of rats (n = 12 or more) using a standardized injection of 0.4 ml of solution into the left infraorbital nerve. All six solutions contained lignocaine 0.25 g dl-1. In groups 1-3, the solutions were isotonic, in groups 4-6 the osmolarity was 0.6 isotonic. Solutions 1 and 4 contained potassium chloride 4 mmol litre-1 but no adrenaline; solutions 2 and 5 potassium chloride and adrenaline 5 micrograms ml-1 (1:200 000); solutions 3 and 6 adrenaline but no potassium chloride. The presence and duration of sensory blockade was determined from the reflex submandibular electromyographic response to periodic electrical stimulation of the homolateral and contralateral upper lips. In groups 1 and 4 (adrenaline absent) the mean durations of blockade (+/- SD) were 45 +/- 24 and 43 +/- 19 min. In groups 2, 3, 5 and 6 (adrenaline present) the durations of block averaged 97 +/- 4, 97 +/- 38, 105 +/- 21 and 92 +/- 16 min, respectively. Thus adrenaline approximately doubled the duration of blockade irrespective of osmolarity or potassium chloride concentration of the local anaesthetic solution (P less than 0.001).

56 patients were monitored for a period of 26 weeks following injury to one of the peripheral branches of the trigeminal nerve. A further 10 patients were followed up after periods of 1 to 9 years suffering impaired facial sensation. Tests showed that 50% of the patients returned to normal in 3 months and 60% in 6 months. The fine sensations of touch and temperature recovered first and the response to pricking and two-point discrimination occurred later. Not all patients recovered normal sensation. A small proportion continued to suffer disturbing sensations such as tingling, burning and formication.

Understanding the mechanisms by which clinical signs and symptoms are produced is a prerequisite to the correct appreciation of radiographic features. Radiographs of facial trauma are no different in this respect. This paper describes the specific clinical findings associated with each displaced bony fragment of the zygomatic complex fracture. Limitation of jaw movement and flattening of the cheek are produced by depressed fractures of the temporal process or zygomatic arch; unilateral epistaxis is a result of fractures of the zygomatic process of the maxilla or the floor of the orbit; paresthesia or anesthesia of the cheek results from fractures of the infraorbital process or orbital floor; unequal pupil heights is associated with fracture of the frontal process; and decreased extraocular muscle function with diplopia is caused by fractures of the orbital process, frontal process, or orbital floor. The clinical and radiographic findings are correlated with surgical management.

Two series of cases with isolated zygomatic bone fractures have been compared with regard to the treatment applied and its results, i.e. 258 cases treated by conventional methods, and 437 cases treated by osteosynthesis with miniaturized screwed plates (MSP). In the second series, reduction failure is eight times less frequent than in the first series, and fixation by plates is solid in the three spatial planes. The incidence of postoperative infra-orbital nerve sequelae was diminished by 50% in the second series. This easy, comfortable and efficient method is now used by the authors for the treatment of all unstable zygomatic fractures and in all cases presenting the following functional signs: limited buccal opening, diplopia by trapping, or involvement of the infra-orbital nerve.

The barrelfield is the cortical "map" of the ensemble of vibrissal follicles on the mouse whiskerpad. Earlier, we had shown that the skin of the embryonic whiskerpad, when put in culture before having received its innervation, is capable of producing vibrissal follicles arranged in a pattern similar to that formed in vivo; we had also demonstrated that the destruction of vibrissal follicles, and of the terminals that innervate them, leads to important modifications in the architecture of the barrelfield. Here we report on the architecture of barrelfields made to differ from normal as a consequence of radical modifications produced in the corresponding whiskerpad during gestation and at birth: transplantation of additional whiskerpads; rotations (of 90 degrees and 180 degrees) of one whiskerpad; removal and reimplantation of one whiskerpad; removal of one whiskerpad; and division of the infraorbital nerve. The results of these experiments, in which only the morphological correlates of a sensory cortical map have been studied, strengthen the hypothesis that the role played by the sensory periphery in the establishment of such an entity is, indeed, an important one.

(1) The effects of stimulation of the nucleus raphe magnus (NRM) and the periaqueductal gray (PAG) were tested on the digastric (jaw-opening) reflex and on the activity of functionally identified single neurons recorded in trigeminal (V) subnucleus oralis in the brain stem. Reflex and neuronal responses evoked by tooth pulp stimulation could be readily suppressed for 250--1000 msec by PAG and NRM conditioning stimuli. The effects were not specific for tooth pulp afferent inputs, however, since suppression was also apparent in jaw-opening reflex responses evoked by low-intensity electrical or tactile stimulation of oral-facial sites, and in the mechanically or electrically evoked responses of oralis neurons with localized low-threshold mechanoreceptive fields. (2) The modulatory effects on the jaw-opening reflex and oralis neuron activity were not altered by reversible cold block of synaptic transmission in V subnucleus caudalis. Thus it appears that the PAG- and NRM-induced effects on the reflex and oralis neurons are not dependent on relays via caudalis. (3) Some of the suppressive influences on responses to oral-facial stimuli could be reversed by the administration of the opiate antagonist naloxone. This suggests that some of the modulatory influences involve endogenous opiate-related mechanisms. (4) Many of the oralis neurons were identified as trigeminothalamic relay neurons on the basis of their antidromic response to ventrobasal thalamic stimulation; PAG and NRM conditioning produced not only a suppression of their orthodromic responses to oral-facial stimuli but also caused a decrease in the antidromic excitability of the relay neurons. This decrease may be indicative of raphe-induced postsynaptic inhibition of oralis neurons, and/or presynaptic facilitation of their thalamic endings.

A-scan ultrasonographic measurements of the differences between nerve and dural diameters of the retrobulbar optic nerve were made in 55 eyes of 30 patients with endocrine orbitopathy. This measurement was found to be enlarged in all cases. Extraocular muscle thickness measurements were also made ultrasonically in these eyes, and the degree of intervaginal distension was found to increase with increasing extraocular muscle involvement. These findings were consistent whether the patients were hyperthyroid, hypothyroid, or euthyroid clinically, and the findings occurred in the absence of any detectable functional optic nerve compromise. The cause of this subdural perineural enlargement remains unknown.

Normative data concerning the waves W1, W2, W3, P4, N5, P6 and N7 recorded from the scalp after stimulation of the infraorbital nerve have been collected from 96 healthy subjects, selected according to age and sex. Peak latency, inter-peak intervals, side-to-side asymmetry of inter-peak intervals, amplitude, amplitude ratio of some components versus W1 and side-to-side asymmetry of such ratio have been analysed as functions of age and sex. None of these parameters appeared to be affected by sex; computation of the correlation coefficient showed a significant (P less than 0.01), though slight, increase of value of the inter-peak intervals W1-W2 and W1-W3 with age. This increase was partially confirmed by analysis of variance. However, such differences are too small to be useful for practical applications, so only a single normative value is proposed for each parameter. The influence of stimulus strength on the amplitude of the W1 component has been studied in 10 more subjects; amplitude saturation of this wave has been found to take place at intensities between 4 and 6 times the sensory threshold. Increasing the stimulus rate from 1 to 3 pulses/sec did not affect any of the components. It is remarked that components W1, W2, W3 and, to a lesser extent, P4 are the ones to be considered useful in clinical practice.

The blink reflex was elicited in 50 children from birth to 3 years of age. In the awake state, the R1 response was always obtained; R2 responses, especially contralateral ones, were more difficult to elicit under 9 months of age. R1 latency and VIIth motor nerve conduction variations were a good witness of the peripheral nervous system maturation. The influence of the different states of waking and sleeping on these reflex responses was studied. These results and some of the mechanisms that underlie these changes are discussed.

The nerves in the vicinity of the orbital roof, their length, anastomoses and the distribution at the supraorbital margin are described. Included is the length of the trigeminal nerves between the orbital margin and the entrance area of the trigeminal nerve in the pons.

Fifty-two patients with zygomatic fractures were examined clinically and roentgenologically 1 to 4 years after treatment. Of these patients, 15 were treated with wiring fixation, 26 with antral packing using plastic tubing, and 11 with reduction only, without fixation. In the last group, the hospital stay was the shortest. These patients had also less complications and roentgenological changes when compared with the other groups. This was considered to be due to the fact that fractures not requiring fixation are initially less difficult than fractures requiring other treatment. At clinical examination, internal wiring fixation proved to be better than antral packing when hospital stay, restoration of the function of the infra-orbital nerve, the position of the eye, symmetry of the palpebral fissure and the final cosmetic results are considered. In the antral packing group, the result was better when jaw movements and occurrence of permanent diplopia were compared. The roentgenological examination revealed that the reduction results were more exact with internal fixation than with antral packing.

The purpose of the present works was to clarify whether the cranial nerves III, IV and VI carry proprioceptive afferent fibres from the extrinsic ocular muscles. In sheep the picture is now clear. The cranial nerves III, IV and VI carry many large proprioceptive fibres (12-16 micrometer) to the central nervous system. These nerves also contain many small fibres of the y-range (2-6 micrometer) which innervate the intrafusal muscle fibres in the spindles. In man the picture is still vague: most of the spindles are not typical, the large proprioceptive fibres (12-16 micrometer) and the small y-fibres (2-6 micrometer) are very few in the cranial nerves III, IV and VI. It is to be concluded that in sheep the cranial nerves III, IV and VI are not purely motor nerves to the extrinsic ocular muscles, but they also carry many of the large fibres of the proprioceptive function. In man, such large fibres are not found and the pathway of proprioceptive afferents from the orbital muscles is still not certain.

The central representation of a normal vibrissa nerve and the corresponding nerve after transection and regeneration of the infraorbital nerve has been studied by the use of transganglionic transport of horseradish peroxidase in the adult rat. The normal vibrissa nerve terminated in a well-defined area within nucleus caudalis and C1 dorsal horn. In contrast, the regenerated vibrissa nerve showed a widespread central termination pattern indicating a pronounced loss of somatotopic organization. These changes in somatotopic organization could contribute to an inability to correctly localize a sensory stimulus; this is a common clinical finding after peripheral nerve injury and regeneration.

The second division of the trigeminal nerve can be easily blocked by the intraoral route. The technique presented involves entering the greater palatine foramen, traversing the pterygopalatine canal with a needle, and depositing the local anesthetic solution into the superior aspect of the pterygopalatine fossa, where the trunk of the second division lies after the nerve exits the foramen rotundum. The indications, contraindications, technique, and anatomic considerations are presented. This is followed by a discussion of the possible complications as well as their prevention and remedy should they occur. While this is not a new technique, it as been a forgotten one.

Intraoral field block anesthesia for extraoral surgical procedures provides a technique which is both extremely safe and easy to administer. As with all local anesthetics, injected volumes should be monitored at all times. Hemostasis may be augmented, if necessary, with topical epinephrine solution. When vasoconstrictors are contraindicated, mepivacaine, Carbocaine, may be substituted for its inherent properties.

In 25 healthy volunteers the supraorbital nerve was stimulated and evoked potentials were recorded. Leads were placed on the scalp and along the ipsilateral eyebrow-mastoid line and were either referred to a non-cephalic reference (on the neck, or Cv7) or linked to form bipolar derivations. As template wave form was chosen the one obtained from derivation Cz-Cv7, which had an initial triphasic component with negative (SW1a), positive (SW1b), negative (SW1c) polarity (mean latencies 0.63, 0.95 and 1.43 msec), followed by 2 negative waves (SW2 and SW3, mean latencies of 2.20 and 2.89 msec). A final positive wave could be observed in most cases (SP4, mean latency of 4.08 msec). The records collected from the various derivations showed that each component (SW1, SW2, SW3 and SP4) had a different behaviour, thus suggesting separate origins. SW1 would originate from a volley travelling from the point of stimulation towards the mastoid, probably across the ophthalmic branch of the trigeminal nerve. The subsequent components would be generated by deeply situated structures: double pulse stimulation suggests that SW1, SW2 and SW3 are generated before the first synapse, whereas SP4 is a postsynaptic event. A strong similarity exists between the components evoked by stimulation of the supraorbital and the infraorbital nerves. Local anaesthetic block of the frontal nerve on the stimulated side and monitoring of the EMG activity of m. orbicularis oculi and m. frontalis ruled out any muscle contamination of the responses described in this paper.

Scalp responses following stimulation of the infraorbital nerve have been recorded in awake and anaesthetized subjects from non-cephalic (NCR) and vertex (VR) reference derivations. In awake subjects, after 3 very early potentials (W1, W2 and W3), 4 small components (P4, N5, P6 and N7) with widespread distribution have been constantly recorded from NCR derivations. Sometimes a further component, named N10, could be recorded in VR derivations on the scalp contralateral to the stimulus in the absence of earlier events. Large and inconstant waves were recorded following N7 in NCR and N10 in VR derivations. The muscular origin of these waves was demonstrated by simultaneous records taken from scalp and muscles. Records from NCR derivations in anaesthetized subjects showed that wave N7 was followed by a further event (N10) localized on the scalp contralateral to the stimulus and by a few slow waves. Wave N10 could also be recorded, in the absence of earlier events, from the VR derivation contralateral to the stimulus. All the responses recorded in these patients could be considered of neurogenic origin because curarization abolished any reflex activation of muscles. All the waves following W3 are of postsynaptic nature and, on the basis of their distribution and latency, we suggest that P4, N5, P6, N7 and N10 have their respective origins in the trigeminal nucleus, trigeminal lemniscus, thalamus, thalamic radiation and cortical projection of the stimulated area. It was also demonstrated that stimulation of lips and gums fails to evoke any neural event recordable from the scalp.

The normal organization of the rat's infraorbital (IO) nerve was studied using conventional electron microscopic (EM) methods. Just caudal to the infraorbital foramen, at the level of the anterior superior alveolar foramen, the nerve was composed of 18-25 fascicles which ranged from 575 to 87,923 micron2 in cross-sectional area. Complete axon counts from thin sections taken at this level demonstrated that the IO nerve contained an average of 19,740 (S.D. = 2054) myelinated and 13,319 (S.D. = 1159) unmyelinated axons. The average diameter (including the myelin sheath) for medullated fibers was 4.42 micron (S.D. = 1.76) and that for unmyelinated axons was 0.60 micron (S.D. = 0.16). The fiber diameter distributions for both myelinated and unmyelinated axons were essentially unimodal.

The latest generation CT scanners allow for spatial and contrast resolution within the orbit that has not previously been available. Utilization of these technological advances in association with appropriate techniques enables visualization of vascular and neural structures within the orbits that have not previously been emphasized in the literature. The CT scans were generated in both axial and coronal planes, using either 1 or 2 mm thick sections. All images were generated using ultrahigh resolution scanning techniques, available on the Picker 1200-SX scanner. The primary advantage of this system is the availability of secondary collimation of the X-ray beam at the detector, limiting detector aperture to only 1.3 mm. This, in association with utilization of the small focal spot and high sampling rate, aids in the visualization of divisions of the third and fifth nerves, as well as in the visualization of the sixth nerve within the orbit. Several branches of the ophthalmic artery within the orbit are also identified, including the infratrochlear and supratrochlear artery as well as the central retinal artery.

Each muscle of the extraocular muscles, containing abundant muscle spindles, was exposed to horseradish peroxidase (HRP) on 8 young pigs (2-month-old, 20-30 kg in body weight, both sexes). The results obtained are follows: The HRP-labelled neurons innervating the superior rectus muscle were always found in a crescent ventro-medio-dorsal fashion in the most medial position of the contralateral oculomotor nucleus. The HRP-labelled cells for the medial rectus muscle appeared close to the superior rectus group in the ipsilateral nucleus. The labelled cells for the inferior rectus muscle appeared in the ventrolateral position of the ipsilateral nucleus and those for the inferior oblique muscle in the area between the medial rectus and inferior rectus muscle groups. The labelled cells for the superior oblique muscle were found in the contralateral trochlear nucleus and those for the lateral rectus muscle bilaterally in the abducens nuclei, predominantly on the ipsilateral side and poorly on the contralateral side. The HRP-labelled cells were composed of large (alpha) and small (gamma) multipolar cells and of bipolar, oval or round (proprioceptive) cells, all intermingled together within the nucleus. The bipolar cells have been also identified in the 3 nuclei by means of Nissl staining technique. On this basis, they should be considered as the proprioceptive neurons. In the shrew-moles, the cell bodies of the proprioceptive neurons innervating the snout muscle spindles have been found close to the ipsilateral glossopharyngeal ganglion and those of the somatic sensory neurons in the ipsilateral trigeminal ganglion. In the pigs, no HRP-labelled cells were found in the trigeminal mesencephalic tract nucleus, but the HRP-labelled cells were found in the ipsilateral trigeminal and the superior cervical sympathetic ganglia. From the results, it could be emphasized that the proprioceptive neurons innervating the pig extraocular muscle spindles are located within the nuclei of the IIIrd, IVth and VIth cranial nerves.

A firm knowledge of orbital anatomy is mandatory for any surgical specialist dealing with this important region. An understanding of orbital anatomy can be acquired systematically by studying each of its component systems (skeletal, fascial, vascular, neural and muscular, and lacrimal). Frequent review of this topic, and the study of anatomic detail in cadaver and surgical dissections, should result in safer, more secure surgery in this complex area.

The fiber courses of the cat optic nerve were studied by using wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP), which was iontophoretically applied to electrophysiologically defined positions in the lateral geniculate nucleus (LGN). Grossly, there were two distinct bends along the length of the optic nerve. The ventrally flexing anterior bend was located approximately 2 mm from the eyeball, while the dorsally flexing posterior bend was found at some 6 mm distant. The optic nerve fibers showed a tendency to scatter toward the chiasm. At the optic nerve head, the fibers from the different retinal areas maintained the retinal topography in a simplified form according to the trajectory of optic fibers surrounding the optic disc. Between the anterior and posterior bends, the fibers from the pericentral, middle-temporal, and most upper areas of the dorsal retina migrated ventrally and were arranged in the middle of the lateral, middle, and medial parts of the optic nerve, respectively, while fibers from the middle-temporal area of the ventral retina migrated dorsally and scattered into the lateral half. The fibers from the temporal and nasal horizontal meridian areas tended to hold their respective positions in the lateral and medial halves of the optic nerve. As a result, in this level they displayed a complex retinotopy in that the fibers from each part of the retina were mixed. Passing the posterior bend, as the optic nerve proceeded toward the chiasm, the characteristic pattern became less defined. Near the chiasm, the retinotopy became very scattered, showing a partial dorsoventral inversion of the retinal topography with substantial overlapping. It was noted from the present findings that the fibers from ventral retina scattered more quickly than the fibers from the dorsal retina, which tended to hold their grouping until the anterior bend, but the central or pericentral retinal fibers proceeded without significant scatter as far as the posterior bend. The analysis of labelled ganglion cells suggested that even if fibers that arise from one certain "mode" of ganglion cells are selected, it is unlikely that they maintain their initial fiber topography along the entire length of the optic nerve.