Two Types of the Sinus of Maier: An Anatomic Study.

PURPOSE: To show the morphological characteristics of two different types of the sinus of Maier, one with a lacrimal sac diverticulum supplied by separate canalicular openings, and the other with a terminal dilatation of the common lacrimal canaliculus. METHODS: Twelve coronal specimens (6 right and 6 left) from 6 Japanese cadavers (age range, 70-90 years at death) and 15 axial specimens of 11 Japanese cadavers (8 right, 7 left; age range, 45-89 years at death), fixed in 10% buffered formalin, were used. All specimens were stained with Masson's trichrome. RESULTS: The sinus of Maier, with a lacrimal sac diverticulum supplied by separate canalicular openings, was shown in one coronally sectioned group, with a diameter of 1.29 mm. The mucosa between both openings (0.282 mm length) comprised stratified squamous epithelia, which was characteristic of the lacrimal canaliculi. The diverticular mucosa was lined by a stratified columnar epithelium, which corresponded to the lacrimal sac. The sinus of Maier, with a terminal dilatation of the common lacrimal canaliculus and with a diameter of 0.51 mm, was demonstrated in one axially sectioned group. CONCLUSIONS: The morphological characteristics of two types of the sinus of Maier were described in this study. One type was the lacrimal sac diverticulum supplied by separate canalicular openings, and the other was the terminal dilatation of the common lacrimal canaliculus.

Medial canthal support structures: the medial retinaculum: a review.

The medial canthus is supported by several structures with a complicated 3-dimensional arrangement in a narrow space. Although the medial canthal tendon occupies a major portion of the area, the medial canthal support structures include the following entities: Horner's muscle, the medial rectus capsulopalpebral fascia including the medial check ligament, the medial horn of the levator aponeurosis, the medial horn supporting ligament, the medial horn of the lower eyelid retractors, the preseptal part of the orbicularis oculi muscle, and 3 variations of the Lockwood's ligament. We named the composite of these structures the "medial retinaculum," which is similar to the "lateral retinaculum" of the lateral canthus. Profound comprehension and consideration of the medial retinaculum warrants safe and effective surgery in the medial canthal region.

Histological study on the left common iliac vein spur.

The spur occasionally seen in a left common iliac vein was investigated by anatomical and histological examination of cadavers so the occurrence mechanism could be discussed. Spurs were found in six cases of the 28 cadavers (21.4%) and they were classified into few different kinds of composition of endosporia, tunica media and adventitia. It is considered that there may be different formation mechanisms and stages even in cases of similar anatomical finding. (English translation of J Jpn Coll Angiol 2013; 53: 43-47).

Consecutive microscopic anatomical characteristics of the lacrimal sac and nasolacrimal duct: cases with or without inflammation.

PURPOSE: We examined the consecutive microscopic anatomy of the lacrimal sac and nasolacrimal duct with or without conspicuous inflammation. METHODS: We used 18 postmortem lacrimal sacs and nasolacrimal ducts of 12 Japanese subjects (5 males, 7 females, aged 75-98 years at death). The removed mucosal wall was transversely sectioned. The first slice was cut around the internal canalicular punctum, the second slice was at the superior opening of the bony nasolacrimal canal, and the other four were harvested from the nasolacrimal duct. All specimens were dehydrated and embedded in paraffin, cut into 7-µm thick sections, and stained with Masson's trichrome. RESULTS: The lumen was larger in the lacrimal sac than in the nasolacrimal duct. The lacrimal sac wall was less developed than the nasolacrimal duct wall. All specimens but two showed a narrowed area in the nasolacrimal duct. Specimens without conspicuous inflammation showed some subepithelial inflammatory cell infiltration. Goblet cells were smaller in number in the lacrimal sac with an increasing tendency in the inferior direction. Specimens with conspicuous inflammation showed narrowed portions in the nasolacrimal duct, in which severe inflammation and exudate in the lumen was observed. The epithelium was denuded and goblet cells were lost. A specimen with focal inflammation illustrated similar findings in the inflammatory part, but the other parts were similar to the specimens without inflammation. CONCLUSIONS: Consecutive microscopic anatomical characteristics of the lacrimal sac and nasolacrimal duct were different from each other. A narrowed part of the nasolacrimal duct lumen is speculated to be a risk for obstruction.

Elastic nature of the lacrimal canalicular wall.

PURPOSE: To examine the elastic nature of the lacrimal canalicular wall. METHODS: Fifteen postmortem specimens of 11 Japanese individuals (8 right, 7 left; age range, 45-89 years at death) fixed in 10% buffered formalin were axially sliced parallel to the lower eyelid margin to include all 3 portions of the lacrimal canaliculi (intrasac, extrasac-extramuscular, and intramuscular portions). All specimens were stained with Elastica van Gieson. Microscopic photographs were taken and converted to white (elastic fibers) and black (the other tissues) images to measure the elastic fibers in an area in each portion. RESULTS: Six specimens in 4 individuals (2 right, 4 left; age range, 62-87 years) included all 3 portions. The area of elastic fibers in the intrasac portion (mean area, 125.8±93.6 white dot) was not significantly different from that in the extrasac-extramuscular portion (p=0.637: mean area, 268.5±150.2 white dots) but was significantly smaller than the areas in the intramuscular portion (p<0.001: mean area, 796.3±278.1 white dots) and Horner's muscle fascia (p<0.001: mean area, 1052.8±250.1 white dots). The area of elastic fibers in the extrasac-extramuscular portion was also significantly smaller than areas in the intramuscular portion (p=0.001) and Horner's muscle fascia (p<0.001). There was no significant difference in the area between the intramuscular portion and Horner's muscle fascia (p=0.172). CONCLUSIONS: The elastic nature of the lacrimal canalicular wall was different in areas with or without Horner's muscle envelope.

Anatomy of anterior ethmoidal foramen, medial canthal tendon, and lacrimal fossa for transcutaneous anterior ethmoidal nerve block in Japanese individuals.

PURPOSE: To examine the anatomical relationships of the anterior ethmoidal foramen (AEF), medial canthal tendon (MCT), and lacrimal fossa (LF) in Japanese individuals. METHODS: Thirty-eight orbits from 19 Japanese cadavers (7 men and 12 women; average age at death, 89.3 years) were used in this experimental anatomical study. The AEF, MCT, and superior border of the LF were exposed. The following distances were then measured: 1) from the point at the medial orbital rim directly anterior to the AEF to the superior border of the MCT (AEF-MCT), and 2) from the superior border of the LF to the superior border of the MCT (LF-MCT). RESULTS: (AEF-MCT) and (LF-MCT) distances were 9.40±1.92 (mean±standard deviation) and 4.21±1.18 mm, respectively. No values of (LF-MCT) exceeded the mean (AEF-MCT) (9.40 mm). CONCLUSIONS: The transcutaneous anterior ethmoidal nerve block can be reliably performed without injury to the lacrimal sac by inserting a needle approximately 9 mm superior to the superior border of the MCT.

Intra-sac portion of the lacrimal canaliculus.

PURPOSE: The aim of this study was to examine the length and diameter of the intra-sac portion of the lacrimal canaliculus and to propose a modified functional valve model at the common internal ostium. METHODS: We examined 14 eyelid and orbital specimens from 10 cadavers (seven right, seven left; aged 45-85 years at death), fixed in 10% buffered formalin. Sliced specimens were dehydrated and embedded in paraffin, cut into 7 µm thickness sections, and stained with Masson's trichrome. We then measured the length and diameter of the intra-sac portion of the lacrimal canaliculus. RESULTS: The average length of the intra-sac portion of the lacrimal canaliculus was 1344.9 µm (range, 920.2-1821.5 µm), and its average diameter was 287.5 µm (range, 199.1-523.3 µm). CONCLUSION: The intra-sac portion of the lacrimal canaliculus had an average length and diameter of 1344.9 µm and 287.5 µm, respectively. The lacrimal sac mucosa changes its thickness with autonomic stimulation, and the length and diameter of the intra-sac portion of the lacrimal canaliculus is likely changed concurrently. The long length and small diameter of the intra-sac lacrimal canaliculus presumably contribute to it acting as an autonomic functional valve at the common internal ostium.

Anatomy of deep lateral and medial orbital walls: implications in orbital decompression surgery.

BACKGROUND: Isolated deep lateral and combined medial orbital wall decompressions (balanced decompression) are well accepted for treatment of disfiguring proptosis and compressive optic neuropathy in patients with Graves' orbitopathy. However, cerebrospinal fluid leakage and/or optic nerve injury occasionally occur during these operations. PURPOSE: To describe the anatomy of the deep lateral and medial orbital walls and its surgical implications in orbital decompression. METHODS: We reviewed literature on the anatomy of the deep lateral and medical orbital walls. In addition, we performed cadaver dissection and computed tomographics studies to illustrate the anatomy. RESULTS: We provided an anatomical overview and elucidated the detailed surgical anatomy of the posterior and superior borders of the deep lateral orbital wall, the posterior and accessory ethmoidal foramina, and the frontoethmoidal suture. CONCLUSIONS: The anatomy of the deep lateral and medical orbital walls presented here will warrant safe and confident performance of orbital decompression surgery.

Influence of developing ligaments on the muscles in contact with them: a study of the annular ligament of the radius and the sacrospinous ligament in mid-term human fetuses.

The supinator muscle originates from the annular ligament of the radius, and the muscle fibers and ligament take a similar winding course. Likewise, the coccygeus muscle and the sacrospinous ligament are attached together, and show a similar fiber orientation. During dissection of adult cadavers for our educational curriculum, we had the impression that these ligaments grow in combination with degeneration of parts of the muscles. In histological sections of 25 human fetuses at 10-32 weeks of gestation, we found that the proximal parts of the supinator muscle were embedded in collagenous tissue when the developing annular ligament of the radius joined the thick intermuscular connecting band extending between the extensor carpi radialis and anconeus muscles at 18-22 weeks of gestation, and the anterior parts of the coccygeus muscle were surrounded by collagenous tissue when the intramuscular tendon became the sacrospinous ligament at 28-32 weeks. Parts of these two muscles each seemed to provide a mold for the ligament, and finally became involved with it. This may be the first report to indicate that a growing ligament has potential to injure parts of the "mother muscle," and that this process may be involved in the initial development of the ligament.

The narrowest part of the bony nasolacrimal canal: an anatomical study.

PURPOSE: To determine the narrowest diameter of the bony nasolacrimal canal. METHODS: Fifty-eight bony nasolacrimal canals from 29 Japanese cadavers (12 men and 17 women; average age at death, 83.4 years; range, 70-99 years) had been fixed in 10% buffered formalin before use. After exposing the medial (44 canals) or posterior half (14 canals) of the bony nasolacrimal canal, the part with the shortest anteroposterior or transverse diameter was determined on inspection. These positions from the canal entrance were measured, and the distance ratio, indicating where the shortest diameter was located in relation to the total length of the canal, was calculated. RESULTS: The shortest anteroposterior and transverse diameters were at the entrance to the canal in 32 of 44 canals (72.7%) and in 9 of 14 canals (64.3%), respectively. In the other canals, the shortest anteroposterior and transverse diameters were located at an average of 3.6 and 5.6 mm from the entrance, and the distance ratios were 29.0% and 46.7%, respectively. The mean shortest anteroposterior and transverse diameters were 5.6 and 5.6 mm, respectively. CONCLUSIONS: The shortest anteroposterior and transverse diameters were at the entrance of the canal in most of the bony nasolacrimal canals. These results are comparable with the rate of obstruction at the canal entrance in primary acquired nasolacrimal duct obstruction.

Anatomy of secretory glands in the eyelid and conjunctiva: a photographic review.

The eyelid and conjunctiva are main targets in ophthalmic plastic surgery. Although dry eyes are known to occasionally occur after ophthalmic plastic surgery, little attention has been paid to the secretory glands in the eyelid and conjunctiva. The secretary glands in the eyelid and conjunctiva contain the main lacrimal gland, accessory lacrimal glands of Wolfring and Krause, goblet cells, ciliary glands of Moll and Zeis, and the meibomian gland of the tarsal plate. Understanding the details of these glands is helpful in preventing and managing secretion reduction after oculoplastic procedures.

Horizontal orientation of the bony lacrimal passage: an anatomical study.

PURPOSE: To examine the horizontal orientation of the bony lacrimal passage. METHODS: The orbits and bony nasolacrimal canals (BNLCs) from 28 Japanese cadavers (11 men and 17 women; average age at death, 83.6 years; range, 70-99 years) were fixed and exenterated before use. After exposing the posterior halves of the lacrimal fossa (LF) and the BNLC, the authors measured the angles of the longitudinal axes of the LF and the BNLC relative to the sagittal line. Based on these values, the relative horizontal orientation of the LF and the BNLC was determined (ΔBNLC-LF). Positive angles of LF and BNLC were defined when the LF and BNLC were directed laterally against the sagittal line. A positive ΔBNLC-LF was defined as having a greater angle for the LF than for the BNLC. RESULTS: The mean LF and BNLC angles, and the ΔBNLC-LF were 11.9°, 0.1°, and 11.8°, respectively. The LF inclined laterally against the sagittal plane for all sides and the BNLC ran almost parallel to sagittal plane on average. The BNLC inclined inward against the sagittal line (0° or negative BNLC angle) for 28 sides (50.0%) and inclined outward (positive BNLC angle) for 28 sides (50.0%). The angle of the LF in women was statistically greater than that in men, though no gender BNLC angle or ΔBNLC-LF differences were determined. CONCLUSIONS: The horizontal angle of the bony lacrimal passage differs among individuals, with an equal split between medial and lateral inclinations of the BNLC with reference to the sagittal line.

Inferior oblique muscle origin: horizontal location in relation to ala nasi and its gender difference.

We studied the horizontal location of the inferior oblique muscle (IOM) origin in relation to the ipsilateral ala nasi and compared the results between genders in 76 orbits of 38 Japanese cadavers. Consequently, the IOM origin was located 1.2 mm laterally to the vertical line through the lateral margin of the ipsilateral ala nasi. No significant difference was noted between genders (males, 1.3 mm; females, 0.9 mm; P = 0.257, Student t test) or between sides (right, 1.1 mm; left, 1.3 mm; P = 0.570, Student t test). In contrast, the mean interalae-nasi distance was 39.8 mm and was significantly greater in males than that in females (males, 40.8 mm; females, 38.6 mm; P = 0.049, Student t test). The ala nasi can be used as a reference point irrespective of gender or side for identifying the IOM origin during oculoplastic surgery.

Analysis of the posterior ramus of the lumbar spinal nerve: the structure of the posterior ramus of the spinal nerve.

BACKGROUND: Knowledge of neural anatomy is fundamental for safe, efficacious use of regional anesthesia. Spinal column procedures, such as a facet joint block, require an accurate understanding of neural pathways relative to anatomic structure. Since Bogduk's report it has been known that human lumbar posterior ramus of the spinal nerve (PRSN) comprises three, equally sized primary branches. However, inconsistencies and controversy remain over the exact locations and pathways of the peripheral portions of the PRSN branches. In this study, the authors investigated the detailed anatomy of the human PRSN. METHODS: The authors performed ventral dissection in seven cadavers to determine the layout of the PRSN between T10 and L4 spinal segments. They captured three-dimensional images with a laser scanner. For fine detail analysis, specimens from another cadaver were subjected to a modified Spalteholz technique to render all nonnerve tissue transparent. Computer graphics were used to create a three-dimensional structural model. RESULTS: All three PRSN branches emanated from an ipsilateral origin and passed posterior to the transverse process. The medial PRSN branch consistently passed between the mammillary and accessory processes under the mammilloaccessory ligament. The intermediate branch passed between the longissimus and iliocostalis muscles and extended to the skin. The lateral branch traveled far lateral from the origin. CONCLUSIONS: The authors created a 3D model of the PRSN in the lumbar segment, which may be useful for planning surgical approaches to dorsal areas of the vertebral column. In addition, this knowledge may improve the accuracy of procedures involving the spinal column, particularly radiofrequency neurolysis of the facet joint.

The orientation of the lacrimal fossa to the bony nasolacrimal canal: an anatomical study.

PURPOSE: To examine the relative positions of the lacrimal fossa (LF) and the bony nasolacrimal canal (BNLC) in relation to each other and a reference plane. METHODS: Forty-two orbits and BNLCs from 21 Asian cadavers (9 men and 12 women; average age at death, 84.4 years; range, 70-99 years) had been fixed in 10% buffered formalin before use. After exposing the LF and the medial half of the BNLC, the authors measured the angles of the longitudinal axis of the LF and the BNLC relative to the aesthetic horizontal plane respectively. Based on these values, the relative orientation of the LF and the BNLC was determined and defined in terms of Δ BNLC-LF. A positive Δ BNLC-LF represents a nasolacrimal canal that descends posteriorly relative to the LF. RESULTS: The mean LF, BNLC, and Δ BNLC-LF were 9.5°, 19.8°, and 10.3°, respectively. In 39 passages (92.9%), the Δ BNLC-LF was positive, representing a nasolacrimal canal that is more posteriorly oriented than the LF. In 3 passages (7.1%), the Δ BNLC-LF was equal to or less than 0°; 2 of them (4.8%) had a straight course and 1 passage (2.4%) had a negative value. CONCLUSIONS: In most patients, the BNLC is directed more posteriorly than the LF. This finding may help in preventing an inadvertent false passage during probing and intubation in patients with epiphora.

The causative factors or characteristics of the Asian double eyelid: an anatomic study.

PURPOSE: To clarify the causative factor of Asian double eyelid. DESIGN: Experimental anatomic study. PARTICIPANTS: Twenty-six upper eyelids (13 right and 13 left) from 17 Japanese cadavers (9 males and 8 females, mean age at death: 73.1 years). METHODS: The specimens, obtained from the central part of the upper eyelids, were dehydrated, embedded in paraffin, cut into 7-µm thick slices and stained with Masson trichrome. Statistical analysis was based on the Mann-Whitney U test. Statistical significance was defined as p < 0.05. MAIN OUTCOME MEASURES: Orbicularis oculi muscle thickness and shape, with or without the levator extension, orbicularis oculi muscle bundle spacing, thickness of upper eyelid skin and subcutaneous tissue, fusional site between the levator aponeurosis and the orbital septum, with or without inferior drooping of fat tissue. RESULTS: The orbicularis muscle was thinner at the skin crease of a double eyelid than at 10 mm from the eyelid margin in the single eyelid group (p = 0.029). In 3 specimens the skin crease of double eyelid was at the tip of the bending orbicularis muscle, which was thick. Although the skin crease in the region of a double eyelid was thinner than in other parts of the skin, excluding the simple crease regions, other outcome measures were not shown as definite causative factors in creating the Asian double eyelid. CONCLUSIONS: The thickness of orbicularis oculi muscle or its bending shape, and the thickness of the skin at the skin crease, are major causative factors in Asian double eyelid formation.

Lateral canthal anatomy: a review.

The anatomy of the lateral canthus is analogous to that of the medial canthus, but with a less defined structure. Although the lateral canthal tendon occupies the major part of the lateral canthal anatomy, the lateral rectus capsulopalpebral fascia and other structures also play a significant role. Appropriate comprehension and consideration of the lateral canthal anatomy enable safe and effective performance in the lateral canthal surgeries. In this review, we present the lateral canthal anatomy along with updated topics. We discuss the lateral canthal tendon, lateral orbital thickening, lateral palpebral raphe, lateral canthal muscle, lateral rectus capsulopalpebral fascia, lateral check ligament, lateral retinaculum, and orbitomalar ligament.

Lacrimal sac septum.

A right orbit was exenterated from a male cadaver that was 85 years of age at death. It was microscopically shown for the first time that the lacrimal sac septum divided the lumen into two spaces. It consisted of fibrous tissue with a cavernous structure and was lined with stratified columnar epithelium similar to the lacrimal sac wall.

Horner's muscle contribution to lacrimal sac drainage.

PURPOSE: This study was designed to examine the anatomical relationship between Horner's muscle and the lacrimal sac at 3 representative levels of the lacrimal sac and to verify the contribution of Horner's muscle to lacrimal sac drainage. METHODS: Seven ocular specimens from 7 elderly Japanese cadavers, fixed in 10% buffered formalin, were analyzed. Axial sections were made parallel to the eyelid margin at 1 mm above the upper eyelid margin, 1 mm below the lower eyelid margin, and 3 mm below the lower eyelid margin. The vertical common fascial length, length of the lateral lacrimal sac wall, and the proportion between the 2 were measured for each specimen at the 3 levels. RESULTS: The vertical common fascial length and its proportion to the length of the lateral lacrimal sac wall were statistically the same at all 3 levels of the lacrimal sac. CONCLUSIONS: Based on the present anatomical findings, the activity of Horner's muscle may be the same for all sac levels, although this hypothesis should be examined by further experimental research, such as manometric studies of the sac at different levels along its length.