Manubriosternal joint: synchondrosis or symphysis? Analysis of morphology and aging in humans.

INTRODUCTION: The uncertainty about the morphological classification of the manubriosternal joint is historical in the field of Anatomy and is still under discussion. This makes it difficult to teach and diagnosing related matters, especially those that require radiological images. In fact, this subject lacks specific data. PURPOSE: This study aims to describe the morphology of the manubriosternal joint and its age-related changes. METHODS: Thirty specimens were divided in three groups: young adults up to 35 years of age, middle-aged adults ranging from 36 to 55, and older adults over 56 years. The subjects were labeled, and blind analysis were performed using the macroscopic and microscopic analysis. RESULTS: The large presence of isolated fibroblasts and chondrocytes and the lower degree of isogenic groups proved that the manubriosternal joint is a symphysis. Its age-related changes involve the reduction of thickness and hydrated characteristics, loss of uniformity and arrangement of the collagen fibers, hyalinization and the presence of focal lesions, that corroborate with the degenerative process. CONCLUSION: The manubriosternal joint is classified as symphysis and the main age-related changes is the relative thickness of the tissue.

Prediction of the mid-tracheal level using surface anatomical landmarks in adults: Clinical implication of endotracheal tube insertion depth.

Endotracheal tube (ETT) should be placed at the optimal level to avoid single lung ventilation or accidental extubation. This study was performed to estimate the mid-tracheal level by using surface anatomical landmarks in adult patients.Neck computed tomography images of 329 adult patients between the ages of 16 and 79 years were reviewed. In the midline sagittal plane, the levels corresponding to the vocal cords, cricoid cartilage, suprasternal notch, manubriosternal junction, and carina were identified. The surface distances from the cricoid cartilage to the suprasternal notch (extCC-SSN) and that from the suprasternal notch to the manubriosternal junction (extSSN-MSJ) were measured. The relationship between mid-tracheal level and the surface distances was analyzed using Bland-Altman plot.The difference between the extCC-SSN and the mid-tracheal level was -6.6 (12.5) mm, and the difference between the extSSN-MSJ and the mid-tracheal level was -19.2 (6.1) mm. The difference between the extCC-SSN and the mid-tracheal level was smaller in females compared with males [-1.7 (11.7) mm vs -12.8 (10.7) mm; P < 0.001].The mid-tracheal level, which is helpful in planning the insertion depth of an ETT, can be predicted by the surface distance between the cricoid cartilage and suprasternal notch in adults, especially in females.

[Relation between Body Height and Combined Length of Manubrium and Mesosternum of Sternum Measured by CT-VRT in Southwest Han Population].

OBJECTIVE: To establish the linear regression equation between body height and combined length of manubrium and mesostenum of sternum measured by CT volume rendering technique (CT-VRT) in southwest Han population. METHODS: One hundred and sixty subjects, including 80 males and 80 females were selected from southwest Han population for routine CT-VRT (reconstruction thickness 1 mm) examination. The lengths of both manubrium and mesosternum were recorded, and the combined length of manubrium and mesosternum was equal to the algebraic sum of them. The sex-specific linear regression equations between the combined length of manubrium and mesosternum and the real body height of each subject were deduced. RESULTS: The sex-specific simple linear regression equations between the combined length of manubrium and mesostenum (x3) and body height (y) were established (male: y = 135.000+2.118 x3 and female: y = 120.790+2.808 x3). Both equations showed statistical significance (P < 0.05) with a 100% predictive accuracy. CONCLUSION: CT-VRT is an effective method for measurement of the index of sternum. The combined length of manubrium and mesosternum from CT-VRT can be used for body height estimation in southwest Han population.

Relation between Body Height and Combined Length of Manubrium and Mesosternum of Sternum Measured by CT-VRT in Southwest Han Population / 法医学杂志

OBJECTIVE@#To establish the linear regression equation between body height and combined length of manubrium and mesostenum of sternum measured by CT volume rendering technique (CT-VRT) in southwest Han population.@*METHODS@#One hundred and sixty subjects, including 80 males and 80 females were selected from southwest Han population for routine CT-VRT (reconstruction thickness 1 mm) examination. The lengths of both manubrium and mesosternum were recorded, and the combined length of manubrium and mesosternum was equal to the algebraic sum of them. The sex-specific linear regression equations between the combined length of manubrium and mesosternum and the real body height of each subject were deduced.@*RESULTS@#The sex-specific simple linear regression equations between the combined length of manubrium and mesostenum (x3) and body height (y) were established (male: y = 135.000+2.118 x3 and female: y = 120.790+2.808 x3). Both equations showed statistical significance (P < 0.05) with a 100% predictive accuracy.@*CONCLUSION@#CT-VRT is an effective method for measurement of the index of sternum. The combined length of manubrium and mesosternum from CT-VRT can be used for body height estimation in southwest Han population.

Relationship of the Medial Clavicular Head to the Manubrium in Normal and Symptomatic Degenerated Sternoclavicular Joints.

BACKGROUND: Clavicular prominence is common in patients with symptomatic degenerative sternoclavicular arthritis. It is unclear if this is caused by enlargement or subluxation of the clavicle. The aim of this report is to describe a reproducible measurement technique to evaluate the relationship of the medial clavicular head to the manubrium. METHODS: One hundred normal sternoclavicular joints, twenty-five sternoclavicular joints with symptomatic degenerative arthritis, and twenty-five non-symptomatic sternoclavicular joints on the contralateral side were studied with three-dimensional (3D) reconstruction with use of computer modeling. The greatest width (anterior-posterior distance) and height (superior-inferior distance) of the clavicle in the sagittal plane were measured, and the positions of the anterior and superior borders of the medial clavicle and their distances to the frontal and axial planes, respectively, were evaluated. The ratio of the anterior-posterior distance to the anterior-frontal plane distance was measured to evaluate the anterior-posterior position of the clavicle and the ratio of the superior-inferior distance to the superior-axial plane distance was measured to evaluate its superoinferior position. If the ratio was not in the 95% normal range, the clavicle was defined as subluxated. The reproducibility of this technique was evaluated on the basis of the interobserver and intraobserver reliability. RESULTS: This technique showed good interobserver and intraobserver reliability. The mean anterior-posterior and superior-inferior distances were significantly larger in association with symptomatic sternoclavicular arthritis than in the normal sternoclavicular joints (p < 0001). The clavicle was subluxated anteriorly in twenty-two of the twenty-five cases of symptomatic sternoclavicular arthritis, but it was not subluxated superiorly. CONCLUSIONS: The medial clavicular head in patients with degenerative sternoclavicular arthritis is significantly larger than it is in the normal population, and it is usually subluxated anteriorly.

The “Angle of Louis”

The 'angle of Louis' is a well-known anatomical landmark. Formed by the junction between the manubrium and sternal body, it marks the level of the 2nd rib and defines the boundary between the superior and inferior mediastinum. Despite our familiarity with this angle, there remains confusion over the eponym. This is reflected by the variations of the name in the literature - Louis, Ludovici, Ludovicus, Ludwick and Ludwig - and the different people it has been attributed to. Sources have referenced the French clinician Antoine Louis, the French surgeon Alexandre Louis and the German physician Wilhelm Friedrich von Ludwig. Interestingly on investigating these potential candidates we found no formal description of the sternal angle in their writings. Pierre Alexandre comes closest however, when he describes a ‘prominence’ in the upper part of the chest which he relates to severe emphysema. We propose that the sternal angle was named in honour of Pierre Alexandre, although he did not himself characterise it as an anatomical landmark (AU)

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Antropometría del martillo en humanos: un estudio anatómico directo / Anthropometry of the malleus in humans: a direct anatomic study

El conocimiento morfométrico de las estructuras del oído medio, incluidos cada uno de los oscículos, es importante para la comprensión de su complejidad biomecánica. Las características estructurales y dimensionales del martillo son registradas en 23 martillos de población mestiza adulta Colombiana. Las medidas registradas involucran el área de la cabeza, el cuello, el manubrio, el proceso anterior y lateral y el área de la articulación incudo-maleolar. Tres de los diecinueve registros tomados en este estudio pudieron ser comparados concienzudamente con otros estudios que mostraron similitudes. El largo total del martillo fue de 8,18 mm DE 0,24, la longitud del manubrio fue de 4,91 mm DE 0,25 y la proporción del largo del manubrio y el largo total fue de 60,11 % DE 3,47. Conforme a la población estudiada no se logro encontrar variación individual o pareada en la anatomía del martillo lo que lo hace un hueso morfométricamente uniforme y estable.

Morphometric knowledge of middle ear structures, including each of the oscicles, is important for the understanding of its biomechanics complexity. The structural and dimensional characteristics of the malleus are registered in 23 samples of Colombian adult mestizo population. Registered measures involve the area of the head, neck, the manubrium, the anterior and lateral process and the area of the incudo-maleolar joint. Three of nineteen records taken in this study could be carefully compared to other studies, which showed similarities. The total length of the malleus was 8,18 mm SD 0.24, the length of the handle was 4.91 mm SD 0.25 and the ratio of the length of the manubrium and the malleus total length was 60,11% of 3.47. In accordance with the studied population, individual or paired variations were not found in the anatomy of the malleus that makes it a morphometrically uniform and stable bone.

Anatomic and morphometric analysis of manubrium sterni as a source of autograft for anterior cervical fusion surgery using quantitative 3-dimensional computed tomographic scans.

STUDY DESIGN: A morphologic study of manubrium sterni using 3-dimensional computed tomography (3D-CT). OBJECTIVE: To investigate the anatomic features of adult manubrium as a source of bone graft and to measure the sizes and available cancellous bone volume of manubrium. SUMMARY OF BACKGROUND DATA: Manubrium bone graft has been reported as a potential ideal material in anterior cervical fusion surgery, whereas the related applied anatomy is lacking in the literature. METHODS: One hundred twenty adult manubria from 68 male and 52 female patients were scanned and reformatted with 3D-CT. Configurations of manubrium was observed on 3D volume-rendered images. The breadths, height, medullar thickness, and thickness distribution of manubrium were evaluated. A safe area for procurement of graft was proposed and the available cancellous bone volume of manubrium was measured. RESULTS: Frontal manubrium bears a prominent pentagonal area, which was a bare area without muscle attachments. The breadths, height, and thickness of male manubrium were significantly larger than those of female manubrium. Maximal medullar thickness for male patient was 10.4 ± 1.1 (range, 8.8-12.8) mm, and for female patient it was 9.4 ± 1.4 (range, 6.6-11.9) mm. Minimal medullar thickness for male was 6.8 ± 1.1 (range, 4.9-9.4) mm, and for female it was 5.8 ± 0.9 (range, 4.2-7.4) mm. The thickest region of manubrium located at the level of lower clavicular notches, whereas the thinnest region located at the junction between upper two-thirds and lower third of manubrium. Available volume of cancellous bone was 10.1 ± 2.2 (range, 6.6-15.6) cm(3) in male and 7.7 ± 2.5 (range, 3.6-12) cm(3) in female. CONCLUSION: The size of male manubrium is significantly larger than that of female manubrium. Manubrium bone is far more sufficient for most adult anterior cervical fusion surgeries. Safe area for procurement of graft is defined as the upper two-thirds of manubrium, and the optimal site to access medullar cavity is suggested at bare area. However, because considerable variability of manubrium size exists, preoperative evaluation of manubrium is suggested to avoid pitfalls, especially when manubrium graft is intended in a female patient.

Simple method for determining the need for sternotomy/manubriotomy with the anterior approach to the cervicothoracic junction.

OBJECTIVE: Frequently, the cervicothoracic junction can be reached through a simple anterior approach. In some cases, access to this region requires a much more aggressive surgical intervention, such as manubriotomy or sternotomy. Information regarding the need for such interventions is particularly useful to have preoperatively to guide surgical planning as well as discussions regarding surgical risks and expected morbidities. Whereas methods utilizing magnetic resonance imaging have been proposed for determining the lowest level that can be accessed through a simple low cervical approach, we describe a simple technique using sagittal computed tomographic imaging. Our technique does not require any complex geometry and has given us very consistent results. METHODS: Computed tomographic sagittal reconstruction of the cervical and upper thoracic spine that includes the entire sternum is obtained. The lowest accessible disc space is determined by a straight line passing through and parallel to the disc space that also passes above the manubrium (the intervertebral disc line). RESULTS: Sagittal computed tomographic reconstructions obtained from 50 adult patients were reviewed, and the lowest disc space accessible from an anterior low cervical approach was determined. The most common accessible level was T1-T2 (23 patients), followed by C7-T1 (13 patients), T2-T3 (10 patients), and C6-C7 (4 patients). A 35-year-old man with T2-T3 compression fractures with kyphotic deformity was treated with T2 and T3 vertebrectomies and T1-T4 fusion through an anterior approach. CONCLUSION: We propose a simple and consistent method for determining the need for manubriotomy or sternotomy for anterior approaches to the cervicothoracic junction.

Bedside prediction of airway length in adults and children.

BACKGROUND: Malpositioning of the endotracheal tube within the airway leads to serious complications such as endobronchial intubation. Prediction of the correct depth of an endotracheal tube is important and should be individualized. The manubriosternal joint (MSJ) is on the same horizontal plane with the tracheal carina. We compared the straight length from the upper incisor to the MSJ in the fully extended position (incisor-MSJ extension length) with the length from the upper incisor to the carina after intubation with a flexible fiberoptic bronchoscope through the endotracheal tube in the neutral position (incisor-carina neutral length). METHODS: One hundred adults and 50 children were studied. Induction of anesthesia was achieved with 1.5 mg/kg propofol and 0.6 mg/kg rocuronium IV. The incisor-MSJ extension length was measured after adequate mask ventilation. After intubation, the endotracheal tube was positioned properly at the upper incisor teeth, and the incisor-carina neutral length was measured with the fiberoptic bronchoscope at the carina. RESULTS: The correlation between the incisor-MSJ extension length and the incisor-carina neutral length is significant (P < 0.001) in both adults and children. A formula for the regression line in adults (children) can be obtained as the incisor-carina neutral length (cm) = 0.868 (1.009) x the incisor-MSJ extension length (cm) + 4.260 (0.468) with a high coefficient of determination; r(2) = 0.88 (0.98). CONCLUSIONS: The airway length from the upper incisor to the carina in the neutral position can be predicted by the straight length from the upper incisor to the MSJ in the fully extended position.

Surgery in the cervicothoracic junction with an anterior low suprasternal approach alone or combined with manubriotomy and sternotomy: an approach selection method based on the cervicothoracic angle.

OBJECT: The authors propose an easy MR imaging method to measure and categorize individual anatomical variations within the cervicothoracic junction (CTJ). Furthermore, they propose guidelines for selection of the appropriate approach based on this new categorization system. METHODS: In the midsagittal section of the cervicothoracic MR imaging studies obtained in 95 Chinese patients, a triangle was drawn among 3 points: the suprasternal notch (SSN), the midpoint of the anterior border of the C7/T1 intervertebral disc, and the corresponding anterior border in the CTJ at the level of the SSN. The angle above the SSN was specified as the cervicothoracic angle (CTA). The spatial position between the brachiocephalic vein (BCV), the aortic arch, and the CTA was also measured. Based on these measurements involving the CTA, 3 different patient-specific categorizations are proposed to assist surgeons with selection of the appropriate anterior approach to the CTJ. Three categories of operative approach based on whether the most caudal part of the lesion site was above, within, or below the area of the CTA were classified. The patients were divided into long- or short-necked groups based on whether their own CTA was greater than (long necked) or less than (short necked) the average CTA. Finally, a left BCV was called superiorly located when it coursed above the manubrium. The method was evaluated in 21 patients with spinal bone tumors in the CTJ to illustrate the measurement of both the CTA and the great vessels, and corresponding approach selections. RESULTS: In this series of 95 patients, the most common vertebra above the SSN was T-3, especially the upper one-third of T-3. The mean CTA was 47.64 degrees . The left BCV was superior to the manubrium in 21.1% of the 95 cases, and 93.6% of the left BCVs were at the T-2 and T-3 levels. Type A and most Type B lesions could be addressed via a low suprasternal approach, or this approach combined with manubriotomy, if necessary. Type C lesions falling below the CTA will need alternative exposure techniques, including manubriotomy, sternotomy, lateral extracavitary, or thoracotomy. The spinal levels that could be exposed in the long-necked CTJ group were always 1 or 2 vertebral levels lower than those in the short-necked CTJ group during the anterior low suprasternal approach without the manubriotomy. CONCLUSIONS: Imaging of the thoracic manubrium should be routinely included on MR imaging studies obtained in the CTJ. It is important for the surgeon to understand the pertinent anatomy of the individual patients and to determine the feasible surgical approaches after evaluating the CTA and vascular factors preoperatively. An anterior low suprasternal approach, or this approach combined with manubriotomy, is applicable in most of the cases in the CTJ. It should be cautioned that preoperatively unrecognized variations of the left BCV above the SSN might result in potential intraoperative trauma during an anterior approach.

Transtympanic electrode positioning: manubrium is a poor guide.

BACKGROUND: Although a transtympanic electrode is commonly used for electrocochleography and electrically evoked auditory brainstem response, the variability of responses among healthy subjects is wide. The manubrium is the typical guidepost for electrode placement. This study addresses the hypothesis that electrode position relative to the round window niche is widely variable. STUDY DESIGN: : Postmortem anatomic dissection of 41 bequeathed adult crania (82 temporal bones). METHODS: Drill marks were made on the medial wall of the mesotympanum from 2 manubrium-based positions: 1.5 to 2 mm posterior to the umbo, and halfway between the umbo and the annulus posteroinferior. RESULTS: Distances to the lip of the round window niche ranged from 0.8 to 3.5 mm and from 1.8 to 4.5 mm for the 2 electrode sites, respectively. The posteriorly determined site was uniform on the promontory, but the posteroinferior site was into hypotympanic trabeculations in 81% of ears and into the jugular plate in 6%. Distances from the electrode sites to round window niche were not obviously associated with either the orientation of the manubrium in the head or the mastoid size. CONCLUSION: The location of a transtympanic positioned electrode using the manubrium as guidepost is not accurately predictable relative to the round window niche.

[Cervicomanubrial route for the ventral upper thoracic spine: technical note about six cases]. / Abord ventral transcervicomanubrial du rachis thoracique supérieur: note technique à propos de six cas.

Ventrolateral cervicotomy provides a narrowed working space for surgical management of upper thoracic spine. We report our experience about ventral upper thoracic spinal cord decompression with reconstruction and plating via the cervicomanubrial route. Six patients (24 to 75 years old) were operated on by the same operator (LN) by cervicomanubriotomy from 2002 to 2007 for upper thoracic spinal cord compression (one case of Pott's disease, three cases of metastases, one fracture, one invasive hemangio-epithelioma), with a good outcome in five patients. Lesions were located from the cervicothoracic junction down to the fourth thoracic vertebra (T4). In all cases, anterior spinal cord decompression, strut graft reconstruction (iliac bone in two cases, cement in four cases) and osteosynthesis were performed. In two cases, a second stage posterior decompression with fixation was performed. The approach begins by a left sided anterior cervicotomy, medial to the sternocleidomastoid muscle and lateral to the trachea and esophagus, associated with division of the infrahyoid muscles close to their insertion at the upper thoracic outlet followed by osteotomy of the manubrium sterni. Then, division of the thyropericardic fascia and thymus, control of the brachiocephalic vein, control of the thoracic lymphatic duct and the horizontal thoracic aorta are performed. The ventral part of fifth cervical vertebra body down to T4 is then exposed between the left primitive carotid artery laterally, the esophagus medially and the thoracic aorta caudally. Compared to total sternotomy without or with clavicle resection, cervicomanubriotomy seems to be a less aggressive, safe and reliable procedure.

[Clinical anatomy study on the acupuncture safety of tiantu (CV 22) and qishe (ST 11)].

OBJECTIVE: To study on the relation between the regional anatomy and safety of acupuncture at Tiantu (CV 22) and Qishe (ST 11). METHODS: In forty-six adult corpses, 92 sides were dissected to observe the partial anatomy structure of acupuncture path of Tiantu (CV 22) and Qishe (ST 11) and structure characteristics by the steel needle marked method and lay-by-lay dissection method. RESULTS: The bilateral the pleura returning lines behind the manubrium sterni interacted at the sternal angle plane accounted for 50.0% of the total specimens and at the first ribs plane accounted for 6.5% of the specimens; for needling the point Tiantu (CV 22), left brachiocephalic vein was at the same level or close to the manubrium sterni upper fringe in 43.5% of the specimens, the left brachiocephalic vein and the middle of manubrium sterni were at the same level in 56.5% of the specimens; for needling the point Qishe (ST 11), in 68 sides of the specimens, internal jugular vein were pierced, accounting for 73.9%, and in 24 sides of the specimens the left common carotid artery were pierced, accounting for 26.1%; in 50 sides of specimens the vagus nerve were touched by the steel needle, accounting for 54.3. CONCLUSION: In acupuncture of Tiantu (CV 22) and Qishe (ST 11), the needle not only easily injure the upper pleural cavity, but also damage the big blood vessel and the vagus nerve in the mediastinum and the cervical root.

A novel source of cancellous autograft for ACDF surgery: the manubrium.

There are a variety of techniques and biologic options when performing interbody fusion during an anterior cervical discectomy and fusion (ACDF). Autologous graft provides high rates of fusion; however, complications associated with donor site morbidity from the iliac crest have prompted some surgeons to use alternative graft material. Ten patients (8 men, 2 women) with cervical radiculopathy underwent single-level ACDF with plate fixation, titanium mesh cage, and cancellous autograft from the manubrium. Cancellous bone was obtained through a cortical window on the anterior aspect of the manubrium through a 2-cm transverse incision. A minimum 1-year clinical and radiographic follow-up for all patients evaluated fusion rates, donor site morbidity, and patient satisfaction. All patients had immediate postoperative resolution of radicular symptoms and radiographic evidence of solid fusion within 3 months. No patient complained of donor site pain and narcotic pain medication was not required after discharge. No complications associated with the manubrium donor site were noted; however, 1 female patient was dissatisfied with its cosmetic appearance. The manubrium is an effective, safe, and technically facile source of autologous bone graft that yields high fusion rates and patient satisfaction in contemporary ACDF surgery. This new technique to obtain cancellous graft from the manubrium combines the advantages of autologous bone without the morbidity of iliac crest harvest.

An experimental study of tympanic membrane and manubrium vibrations in rats.

Rats are potentially very useful for auditory research because the middle ear structures are easily approachable and because rats are relatively inexpensive. The goal of the present study was to better characterize the mechanics of the rat middle ear by measuring frequency responses at multiple points on the tympanic membrane and manubrium. A laser Doppler vibrometer was used to measure the vibrations. Measurements were made on 7 rats. Tympanic membrane vibrations are presented for 7 different points in the frequency range of 1-10 kHz. The repeatability of the measurements and the interanimal variability at the umbo are also presented. The vibration modes of the tympanic membrane and manubrium were investigated.

Anatomic landmarks for the cervical portion of the thoracic duct.

OBJECTIVE: Avoidance of injury to the thoracic duct during neurosurgical procedures involving the cervical region depends on a working knowledge of its location. This study evaluates superficial anatomic landmarks for the cervical portion of the thoracic duct that may be encountered in neurosurgery of the neck. METHODS: Fifteen dissections of human cadavers were performed to study the relationship between the proximal thoracic duct and superficial landmarks (e.g., the cricoid cartilage and sternal notch of the manubrium). RESULTS: The cervical portion of the thoracic duct was found to be approximated by a roughly 4.4-cm(2) region in the left supraclavicular area beginning approximately 2.0 cm lateral to the midline and 3.5 cm superior to the sternal notch, extending superiorly to a point roughly 3.5 cm from the midline and 2.5 cm inferior to the cricoid cartilage, and terminating within the venous system at a point approximately 4.5 cm lateral to the midline and 3.0 cm superior to the sternal notch. CONCLUSION: Through an increased appreciation for its location, injury to the thoracic duct may be minimized.

The anatomy of the nervous system of the hydrozoan jellyfish, Polyorchis penicillatus, as revealed by a monoclonal antibody.

Dissociated cells from the margin and tentacles of the hydromedusa Polyorchis penicillatus were centrifuged in a Percoll gradient to remove cnidocytes. The resulting formaldehyde-fixed cells were used to inoculate mice to produce monoclonal antibodies. One of the hybridomas, which secreted antibodies against all neurons, was cloned and designated as mAb 5C6. Immunohistochemical labelling with mAb 5C6 of whole-mount preparations and paraffin sections provided a far more complete picture of the organisation of the hydromedusan nervous system than was previously available when using neuronal labelling techniques that restrict labelling to certain neuronal types. Besides confirming anatomical features described in earlier studies these techniques allowed us to discover a number of new structures and to determine connections that were only suspected. Such findings included:1. The discovery of an arch-like connection between the swimming motor neuron network at the apices of the subumbrellar muscle sheets 2. An orthogonal network connecting each pair of radial nerves in each radius 3. Continuity of a central branch of the radial nerve with the radial innervation of the manubrium 4. Details of the sensory neuronal contribution to the microanatomy of the ocelli and cnidocyte batteries 5. Presence of specialised receptor cells in the margin at the bases of tentacles 6. Neurons apparently innervating the radial muscles of the velum 7. Isolated neurons in the peduncle and gonads

An unusual case of multiple mesosternal foramina.

We present an unusual example of multiple mesosternal foramina (MMF). The alignment of the paired defects is unlike any previously described. Although single sternal defects are often encountered, paired defects are quite uncommon. This is the first documented example of bilateral paired defects in the sternum.

CT anatomy of the mediastinal structures at the level of the manubriosternal angle.

The mediastinal structures said to lie on a horizontal plane at the level of the manubriosternal joint (manubriosternal plane) in the cadaver include the bifurcation of the trachea, the concavity of the arch of the aorta, and the azygos vein as it arches over the right principal bronchus to enter the superior vena cava. We have reviewed CT scans of the thorax in 51 subjects to determine 1) whether these structures lie consistently at this level in the living thorax and 2) the vertebral level of this plane. We found that the bifurcation of the trachea lay at the plane in 41% of subjects, that the plane passed through the concavity of the arch of the aorta in 49% of subjects, and that, although there was notable individual variation, the manubriosternal plane passed through the upper part of the fifth thoracic vertebra in 53% of cases.