Pre-spinal convergence between thoracic and visceral nerves of the rat

Dichotomizing sensory axons have been demonstrated in a number of species and are of significance in understanding the possible mechanisms underlying referred pain. The present study reviews work employing fluorescent dyes as tracers to demonstrate afferent dichotomization in the peripheral nervous system. Dichotomization between the intercostal and splanchnic nerves of the rat was demonstrated by means of intraneural transport of Diamidino yellow or Fast blue. Frequency of pre-spinal somato-visceral convergence averaged 2% (range 0.1-21%). Average frequency of convergence was 8.3% (range 2-23.1%) between internal and external intercostal nerves. Control experiments in which axoplasmic transport was inhibited by vinblastine ruled out the possibility of errors from non-axoplasmic transport of the markers. Thoraco-visceral pre-spinal convergence occurs in the rat and is variable in extent.

Variations of the ventral rami of the brachial plexus

We studied the variations in the ventral rami of 152 brachial plexuses in 77 Korean adults. Brachial plexus were composed mostly of the fifth, sixth, seventh and eighth cervical nerves and the first thoracic nerve (77.0%). In 21.7% of the cases examined, the fourth, fifth, sixth, seventh and eighth cervical and the first thoracic nerves contributed to the plexus. A plexus composed of the fourth, fifth, sixth, seventh and eighth cervical and the first and second thoracic nerves, and a plexus composed of the fifth, sixth, seventh eighth cervical nerves were also observed. The plexuses were classified into three groups according to cephalic limitation, and the plexus of group 2 in which the whole fifth cervical nerve enters the plexus, were observed the most frequent. The average diameter of the sixth and the seventh cervical ventral rami of the plexus was greatest and that of the fifth cervical was smallest. The largest nerve entering the plexus was the sixth or the seventh cervical nerve in about 79% of cases. The dorsal scapular nerve originated from the fifth cervical ventral ramus in 110 cases (75.8%). The long thoracic nerve was formed by joining of roots from the fifth, sixth, and seventh cervical nerves in 76.0% of cases. Also, a branch to the phrenic nerve, the suprascapular nerve, a nerve to the pectoralis major muscle and a nerve to the subscapular muscle arising from the ventral rami of the plexus were observed.

Free flap transfer of the cutaneous maximus muscle in the rat: comparison to the latissimus dorsi muscle flap

A new rat model of free muscle flap transfer is presented. Microvascular transplantation of the cutaneous maximus muscle flap is performed at the groin site, with anastomosis of the axillary vessels to the appropriate femoral vessels. This muscle flap has many useful attributes for experimental manipulation. It has a high success rate following transplantation, the anatomy is consistent, the dissection is straightforward, the length of pedicle is relatively long (10 mm), the vessels for repair are of sufficient size (1.0-1.35 mm diameter), and the microsurgical procedure can be performed in a relatively short period. The donor site deficit causes minimal impairment to animal mobility, and no evidence of limb ischemia is noted after ligation of the axillary vessels. The cutaneous area adjacent to the muscle is perfused by muscular perforators supplied by the flap pedicle; thus a skin island may be used to monitor the flap or to create a composite myocutaneous transfer. The cutaneous maximus muscle has mixed muscle types and anatomic dimensions similar to those of the latissimus dorsi muscle, and it provides ample tissue for pharmacological and biochemical studies, yet it presents easier dissection and microanastomoses than the latissimus flap, with more potential for versatility in application. The advantages of this muscle flap make it a very useful experimental model for flap transfer research.

[The muscular arch of the axilla and its nerve supply in Japanese adults]

We examined 94 axillary regions of 47 Japanese adults and found the muscular arch of the axilla (Maa) in five sides of three cadavers as well as the tendinous arch of the axilla (Taa) in two sides of two cadavers. The results are summarized as follows: 1) The frequency of Maa was 6.4% of the total bodies and 5.3% of the sides in this series. 2) In the left side of a 57-year-old male (No. 427), Maa was attached to the surface of the coracobrachialis muscle after fusing with the dorsal surface of the inserting tendon of the pectoralis quartus muscle. Both muscles were supplied by the caudal pectoral nerve (Npc) from the medial pectoral nerve. Moreover, in this same specimen, the sternalis muscle was recognized on the ventral surface of the pectoralis major muscle. In the left side of a 93-year-old female (No. 386), the cranial part of the muscular arch of the axilla (Cpa) was extended to the coracoid process by a tendon and attached to the abdominal part of the pectoralis major by two muscle bundles supplied by independent branches from Npc. One muscle bundle was attached to the lower margin of the abdominal part of the pectoralis major on the same plane, and the other bundle was located on the dorsal surface of the abdominal part. In a 74-year-old female (No. 411), the well-developed lateral part of the muscular arch of the axilla (Lpa) was attached to the inferior side of the tendinous arch. According to Ruge (1914) and Kasai et al. (1977), this arch was in the transition of the muscle bundle of Cpa to the arch. In the right side of the same specimen, only the thoracodorsal nerve (Ntd) was distributed into Lpa, whereas in the left side, only Npc supplied branches to Lpa. 3) The axillary arch was classified into 8 types based on the form and the supplying nerve of Cpa and Lpa. Cpa consisting of the muscle bundle is Type I, and Cpa consisting of the tendinous arch is Type II. We proposed that only Type II-A, with Cpa as tendinous arch and no Lpa, be designated as Taa (found in two cases), and the others as Maa. The following types were found in this study: Type I-A, consisting of only Cpa supplied by Npc (two cases); Type I-D, consisting of Cpa supplied by Npc and Lpa supplied by Ntd (one case); Type II-B, consisting of the tendinous arch and Lpa supplied by Npc (one case); Type II-D, consisting of the tendinous arch and Lpa supplied by Ntd (one case). 4) From the above findings, it can be suggested that Maa of varying shapes have been formed by a portion of the latissimus dorsi muscle supplied by Ntd, together with the pectoralis subcutaneous muscle, consisting of the pectoralis abdominalis, humeroabdominalis, humerodorsalis and ventrolateralis muscles supplied by Npc. The latter three muscles were proposed by Ura (1937) as the panniculus carnosus muscle, which was well developed in some lower mammalian orders. However, early investigators suggested that Maa was derived from the panniculus. Maa might have occurred as a rudimentary phylogenetic remainder in an early human embryonic stage.

Arrangement and innervation of the iliocostalis and longissimus muscles of the brown caiman (Caiman crocodilus fuscus: Alligatoridae, Crocodilia)

The axial musculature of the brown caiman was investigated in detail with particular attention to the nerve supply, using a binocular stereomicroscope. Due to the prominent development of the longissimus (Lo) and the iliocostalis (IC) muscles of the caiman, the pattern of distribution of the spinal nerves in the body wall was unique; there also was less differentiation of the external intercostalis. There were four primary divisions of the spinal nerves in the thoracic region of the caiman, from ventral to dorsal: the intercostal nerve, the IC nerve, the Lo nerve, and the dorsal main trunk. Thus, the classic concept of the organization of the spinal nerves may not be suitable for the caiman. These findings suggest that evolutionary changes in the dorsolateral axial musculature have brought about the rearrangement of the organization of the spinal nerves. In addition, each clearly segmented myotome of the Lo and IC was innervated by more than two segments of the spinal nerves (plurisegmental innervation). The manner of formation of the myotome and its innervation is discussed from the viewpoint of comparative and developmental anatomy.

Spread of injectate after stellate ganglion block in man: an anatomical study

Stellate ganglion injections were performed using methylene blue 20 ml in 20 cadavers before postmortem examination. There was spread of solution into the posterior mediastinum and over the apical pleura. There was no spread onto the thoracic sympathetic chain.

Upper thoracic dorsal rami: anatomic study of their medial cutaneous branches

The authors describe the distribution of the medial branches of the upper thoracic dorsal rami (T1 to T5 levels). At each level, after travelling through the erector spinae, they become superficial, and reach the apex of the spinous process of the corresponding vertebra. They then spread out laterally, innervating the skin. They can occasionally be compressed by paravertebral tendons, and this possibly contributes to certain forms of dorsal pain. Anastomosis of the dorsal cutaneous branch of the second thoracic nerve (T2) with the descending lateral branch of the accessory nerve has been observed. Its presence could explain the occasional clinical situations where there is no resultant paralysis from accidental surgical section of the latter nerve.

Nerves and nerve plexuses of the human vertebral column

The origin, distribution, and termination pattern of nerves supplying the vertebral column and its associated structures have been studied in the human fetus by means of an acetylcholinesterase whole-mount method. The vertebral column is surrounded by ventral and dorsal nerve plexuses which are interconnected. The ventral nerve plexus consists of the nerve plexus associated with the anterior longitudinal ligament. This longitudinally oriented nerve plexus has a bilateral supply from many small branches of the sympathetic trunk, rami communicantes, and perivascular nerve plexuses of segmental arteries. In the thoracic region, the ventral nerve plexus also is connected to the nerve plexuses of costovertebral joints. The dorsal nerve plexus is made up of the nerve plexus associated with the posterior longitudinal ligament. This nerve plexus is more irregular and receives contributions only from the sinu-vertebral nerves. The sinu-vertebral nerves originate from the rami communicantes and, in the cervical region, also from the nerve plexus of the vertebral artery. Thick and thin sinu-vertebral nerves are found. Most frequently three types of thick sinu-vertebral nerves are observed, i.e., ascending, descending, or dichotomizing ones. Finally, the distribution of the branches of the ventral and dorsal nerve plexuses and of the sinu-vertebral nerves is described.

Cutaneous branches from the dorsal rami of the cervical nerves, with emphasis on their positional relations to the semispinalis cervicis

The courses of the cutaneous branches arising from the dorsal rami of the cervical and the upper thoracic nerves were examined on 61 sides in 31 human adults, and their positional relations to the semispinalis cervicis muscle were particularly noted. Absence of the cutaneous branch from the dorsal rami of the lower cervical nerves was observed in 60 of the 61 cases; and in the one remaining case, all the cervical nerves except C1 gave off a cutaneous branch. A difference in course of the cutaneous branches was clearly observed between those from the upper cervical and the upper thoracic segments. That is, those of the former passed superficial to the semispinalis cervicis, whereas those of the latter were situated deep to it. The absence of cutaneous branches of the lower cervical segments could be classified into two types: continuous absence and alternate absence. In the former, which was observed in 53 cases (87%), cutaneous branches were absent in continuous segments. In the latter, which was observed in 7 cases (11%), they were absent in alternate segments. Dermatome problems are discussed on the basis of the present results. Keegan-Garrett's chart could be supported in the one exceptional case only.

Neuromuscular organization of the pectoralis (pars thoracicus) of the pigeon (Columba livia): implications for motor control

The pectoralis (pars thoracicus) of the domestic pigeon (Columba livia) is divisible into two anatomical parts, the pars sternobrachialis (SB) and the pars thoracobrachialis (TB). Innervation to this complex is from rostral and caudal branches of the brachial ventral cord. In four anesthetized pigeons, the distribution of muscle units associated with each nerve branch was mapped after prolonged stimulation of each nerve and subsequent analysis for muscle fiber glycogen. An additional three animals were used to analyze the morphology, distribution, and histochemical profiles of the muscle fibers in the SB and TB subregions. Fibers were characterized on the basis of their reactions for myofibrillar adenosine triphosphates (alkaline and acid preincubation) and reduced nicotinamide adenine dinucleotide diaphorase (NADH-D). The SB is primarily innervated by the rostral nerve branch and the TB by the caudal nerve branch. For two-thirds of the muscle's length, the SB is separated from the TB by an aponeurosis, the membrana intermuscularis (MI). SB and TB fibers located posteroventral to the caudal margin of the MI are innervated variously by both nerves. Two populations of fibers were recognized, distinguishable primarily by 1) fiber diameter and 2) density of the NADH-D reaction product. Compared to the TB, the SB possesses a higher average percentage of large fibers. Within the SB but not the TB the percentage of large fibers increases from deep to superficial. These data support our previous findings that the pars thoracicus of the pigeon is partitioned into at least two functional subunits, each with a potential for independent action on the wing during flight.

[Anatomical study of the ramification and intramuscular distribution of the intercostal nerves in man]

Minute dissection was performed on the ventral primary rami of the thoracic and the first lumbar nerves in the left half of an adult male cadaver in order to obtain more detailed data of the nerve supply to the muscles of the thorax and abdomen. The ribs, costal cartilages, sternum and vertebral column were removed to facilitate dissection. The origin, course and intramuscular distribution of the muscular branches of each nerve were examined in precise detail. The main findings are as follows: 1. The intercostal nerves The collateral branches were found in approximately 1/3 of the segments examined. Each branch rejoined the main trunk close to point in which the lateral cutaneous branch pierces through the intercostal muscles. Each lateral cutaneous branch arose from the main trunk proximal to the midaxillary line. The branch had some communications with the main trunk, and occasionally received a twig from the collateral branch. 2. The muscular branches 1) In general, the nerves to each intercostalis externus arose from the main trunk proximal to the costal angle. Additional slender twigs were occasionally found arising from the lateral cutaneous branch and joining the main supply nerve. 2) For the convenience of description of the nerve supply to the intercostalis interni et intimi, each intercostal nerve is divided into three parts from proximal to distal: part 1, the outside of the intercostalis intimus; part 2, between the intercostalis intimus and intercostalis internus; and part 3, inside the intercostalis internus. Branches to the intercostalis intimus arose in part 1, predominantly from the initial portion of the main trunk, either independently or with the branches of the intercostalis externus. In part 2, the branches generally originated as a common trunk with the branches of the intercostalis internus. 3) Branches to each subcostalis arose from the initial portion of the intercostal nerve belonging to the same intercostal space as the upper half of the muscle. The branches originated either independently or formed a common trunk with the branch to the intercostalis externus. 4) Branches to the transversus thoracis arose relatively independently from the third to sixth intercostal nerves. These branches ran inside of the nerves to the intercostalis internus and the common trunks of the intercostales internus and intimus branches, and entered the muscle from the anterior side. Each digit of the muscle was innervated by a nerve from the intercostal nerve corresponding to that costal attachment. The lower digit had an additional branch from the nerve of the upper adjoining space.(ABSTRACT TRUNCATED AT 400 WORDS)

Anatomical variation in the position of the proximal intercostal nerve

Anatomical study of the proximal intercostal nerve in cadavers revealed three nerve forms, depending on the relation between the nerve and adjacent ribs. This was found in the classical subcostal position in 16.6%, in the midzone in 73% and in the inferior supracostal position in 10%.

Structural changes in intercostal motoneurones following axotomy

Motoneurone disease (MND or amyotrophic lateral sclerosis) is a paralysing disease of unknown cause involving progressive, widespread muscle atrophy due to degeneration of spinal and other motoneurones and an accompanying loss of Betz cells in the motor cortex. A current hypothesis attributes the disease to the loss of a muscle-derived neurotrophic factor acting in concert with the normal age-related deterioration and loss of motoneurones. The roots of this hypothesis are traced through research based mainly on the developing neuromuscular system, and in particular on the age-related processes of natural motoneurone death during embryogenesis: the neonatal reduction of polyneuronal innervation and the age-dependent variations in motor nerve terminal sprouting in response to partial denervation. A consideration of the disease process itself in association with the review of earlier work provide the background for the present work which reexamines ultrastructurally the chromatolytic and later responses to axotomy and the muscle-dependent factors responsible for the reformation of the Nissl bodies.

Anatomical basis of modern thoracotomies: the latissimus dorsi and the "serratus anterior-rhomboid" complex

The latissimus dorsi and the "serrato-rhomboid" complex are the muscles most often involved in present-day thoracotomies for lung surgery. The present anatomic study emphasizes: the continuity between the serratus anterior and the rhomboid levator scapulae mass as a wide muscular sheet with a deep common fascia, extending the serrato-thoracic space (of Gillis) to the vertebral column as the rhomboserrato-thoracic space (the levator scapulae is situated higher up, above the ordinary thoracotomy); the presence of a "composite fascia" in the posterior angle between the seratus anterior and the rhomboid; the long costal attachment area and the presence of two differently oriented layers for the muscular digitations of the middle and inferior parts of the serratus anterior. With a rich vascular supply from multiple sources, the serratus anterior and latissimus dorsi are two large flat muscles with a single longitudinal nervous pedicle proceeding from the brachial plexus. To avoid esthetic (winged scapula) and functional sequelae, it is imperative to safeguard this single innervation as far as possible : by halting division of the serratus anterior before reaching its neurovascular pedicle in lateral or anterolateral thoracotomy, and by transecting the latissimus dorsi very low down in standard postero-lateral thoracotomy. The other muscles are simply freed and retracted.

The anatomy of the pectoral nerves and its significance to the general and plastic surgeon

It has previously been shown that in 62% of patients the medial pectoral nerve courses through the pectoralis minor muscle to innervate the lower half or two thirds of the pectoralis major muscle. In the other 38% of patients, the medial pectoral nerve exits around the lateral aspect of the pectoralis minor muscle. The lateral pectoral nerve courses on the undersurface of the pectoralis major muscle, innervating the proximal one third or more of the muscle. Consequently, when the pectoralis minor muscle is removed in a modified radical mastectomy, or dissection between the two muscles is performed, there is partial deinnervation of the pectoralis major muscle with partial atrophy and a decrease in size. Further, if the lateral pectoral nerve also is injured or removed, it can result in total deinnervation of the pectoralis major muscle with more severe atrophy and fibrosis of the muscle. In cosmetic augmentations, when the breast implant is placed behind the pectoralis major muscle, that muscle is partially deinnervated. In this clinical situation, this is believed to be advantageous because it allows the breast to project better. This paper details the anatomy of the pectoral nerves and discusses the clinical implications of surgery in this region as it relates to the size and function of the pectoral muscles.

[The 2 key muscles in thoracotomy for excision of the lung. The latissimus dorsi and the levator scapulae muscles]

Anatomical data related to the thoracotomies performed most frequently in lung surgery are described in some detail: continuity between serratus anterior and levator scapulae as a vide muscular sheet possessing a common deep aponeurosis (thoracolumbar fascia) extending Gilis' space to the vertebral column as the levator scapulae-thoraci space; presence of a "composite aponeurosis" in the posterior angle between serratus anterior and levator scapulae, covering the 8th rib triangle or triangle of auscultation; long costal insertion area and presence of two differently orientated muscle layers for the digitations, particularly of apical bundle. Supplied by a rich vascularization of multiple sources, the serratus anterior and latissimus dorsi are two muscles with single longitudinal nerve pedicles derived from brachial plexus. It is certainly the denervation which is responsible for the distal atrophy of these muscles "sectioned on the right of the selected ribs" following conventional thoracotomy. To avoid esthetic and functional sequelae this innervation must be preserved as far as possible by: interrupting division of serratus anterior anterior to long thoracic nerve and avoiding inclusion of axillary border of latissimus dorsi during lateral thoracotomy; sectioning the latissimus dorsi as low as possible--the other muscles being simply freed and inclined--during lateral thoracotomy.

The central projections of primary afferent neurons of greater splanchnic and intercostal nerves in the rat. A horseradish peroxidase study

The central projections of primary afferent fibers of the greater splanchnic nerve of the rat were investigated using the transganglionic horseradish peroxidase transport technique. In addition, the corresponding spinal ganglion cells and the preganglionic sympathetic neurons were demonstrated. For comparing visceral and somatic afferents, intercostal nerve afferents were labelled by the same technique. Splanchnic afferent dorsal root ganglion cells were found at segments T3 to T13 ipsilaterally, with the greatest density at T8 to T12. Labelled cells represented about 10%-15% of all neurons in the ganglia at maximal projection levels. They were randomly distributed within individual ganglia. The great majority were medium to small sized and round to slightly oval in shape. In the spinal cord, labelled visceral afferent axons were found maximally at T8 to T11, but could be detected in decreasing density up to T1 and down to L1. They were distributed over Lissauer's tract and the dorsal funiculus to a medial and lateral collateral pathway (MCP and LCP, respectively). The MCP, somewhat more prominent than the LCP, was destined primarily to clustered presumptive terminal fields in medial lamina I and outermost lamina IIa. Only a few axons continued further to laminae V and X. Splanchnic afferent axons, most likely derived from the MCP, formed a longitudinal bundle ventral to the central canal. The LCP consisted of more or less well-defined axon bundles emanating from the lateral Lissauer's tract and curving round the lateral edge of the dorsal horn and through the dorsolateral funiculus. Presumptive terminal sites of LCP axons are the lateral laminae I and IIa, the nucleus of the dorsolateral funiculus and the dorsal part of lamina V. A few LCP axons were seen in the vicinity of lateral dendrites of preganglionic sympathetic axons. Visceroafferent terminals were absent from laminae IIb-IV and VII. The possible consequences of the MCP/LCP duality for the central connections of splanchnic afferents are discussed. Some splanchnic afferents ascended to the gracile and cuneate nuclei, and rarely to the spinal trigeminal nucleus. These results fit into the general concept of visceroafferent terminal organization that has emerged during the last few years. Differences to other reports in the detailed arrangement of fibers and terminals are discussed. Somatoafferent cell bodies represented the vast majority of neurons in the respective spinal ganglia. Cell sizes encompassed the whole range from very small to very large without a clear predominance of one particular size class.(ABSTRACT TRUNCATED AT 400 WORDS)

The high thoracic sympathetic nerve system--its anatomic variability

Upon studying microscopically and macroscopically 18 resection preparations of upper thoracic sympathectomies it is clear that the variability in the anatomy of the sympathetic nervous system in connection with the spinal nervous system is higher than has always been described. A fine network of smaller and larger nerve bundles was found which connect the sympathetic and spinal nerve systems. Light microscopical perikarya were identified in many nerve bundles. These findings have an important impact on the concept of the effectiveness of thoracic sympathectomy.

Projections from the ventral respiratory group to phrenic and intercostal motoneurons in cat: an autoradiographic study

Anterograde transport of tritiated amino acids (leucine, lysine, and proline) was used to examine the spinal projections of respiratory premotor neurons in the ventral respiratory group (VRG) of cats. This population of neurons corresponds anatomically with the nucleus ambiguus-retroambigualis. Small volumes (20 to 50 nl) of tritiated amino acids were pressure ejected into the middle of the VRG through a micropipette which permitted simultaneous recording of respiratory modulated activity. In two cats injections were made caudal to the obex in regions which contained expiratory modulated neurons. In five cats injections were made rostral to the obex in regions containing inspiratory neurons. After a 2-week survival period, cats were anesthetized and perfused. The entire neuraxis was removed and processed using standard autoradiographic techniques. Transport of tritiated amino acids revealed a marked bilateral projection to lamina IX of the spinal cord at the C4 to C6 level and a primarily contralateral projection to laminae VIII and IX in the thoracic spinal cord. Distinct descending pathways to the phrenic motor neurons were observed in the lateral funiculus and in the ventral funiculus; descending fibers to the intercostal motoneurons in the thoracic cord appeared to be restricted to the ventral funiculus. Labeling of axon terminals in both the cervical and thoracic cords was confined to ventral horn regions which contain motoneurons. These results suggest that monosynaptic projections from brainstem bulbo-spinal neurons to spinal motoneurons are important in controlling respiratory movements of the diaphragm and intercostal muscles.

Acupuncture points of the brachial plexus

This publication is the third of a total of six papers intended to name acupuncture points following the anatomic nomenclatures. In the first publication, acupuncture points in the head are named using terminal branches of the trigeminal nerve and the muscles of facial expression. In the second publication, acupuncture points in the neck are named using the cutaneous nerves of the cervical plexus and neuromuscular attachments formed by the spinal accessory nerve on the trapezius muscle. In this third publication, acupuncture points existing on the upper limbs are described following the terminal branches of the brachial plexus.

Cutaneous innervation of the thorax and abdomen of the dog

The anatomy of the cutaneous nerves innervating the canine thorax and abdomen was investigated by gross dissection of 38 dogs. Additionally, the cutaneous areas innervated by the thoracic and abdominal cutaneous nerves were mapped in a 2nd group of 33 barbiturate-anesthetized male dogs, using electrophysiologic techniques. The skin of the thorax was innervated by dorsal cutaneous branches, lateral cutaneous branches, and ventral cutaneous branches of the spinal nerves. The dorsal cutaneous branches were branches of the dorsal primary branches of spinal nerves C6 and T2 through T11. The lateral cutaneous branches were branches of the ventral primary branches of spinal nerves T2 through T12. The ventral cutaneous branches were branches of the ventral primary branches of spinal nerves T2 through T10. The skin of the abdomen was innervated by dorsal and lateral cutaneous branches of spinal nerves T12 through L3 (and occasionally L4). The cutaneous areas of the dorsal cutaneous branches occupied the dorsal half of the scapular and thoracic regions and the dorsal 2/5 of the abdominal region. The cutaneous areas of the lateral cutaneous branches covered the major portion of the ventral half of the thorax and the ventral 3/5 of the abdomen. The cutaneous areas of the ventral cutaneous branches occupied the axilla and the ventral part of the thoracic wall.

Continuous intercostal nerve blockade. An anatomical study to elucidate its mode of action

India ink was injected through extradural catheters placed in the posterior intercostal space in 12 cadavers undergoing autopsy and the subsequent spread of the India ink was assessed under direct vision. The ink spread subpleurally to reach a number of intercostal spaces and medially to reach the paravertebral space. It is concluded that analgesia extending over a number of dermatomes is achieved by subpleural tracking of local anaesthetic to reach intercostal nerves above and below the one injected.

Relations between axon length and axon caliber. "Is maximum conduction velocity the factor controlling the evolution of nerve structure"?

A search was made for any existent relationship between the length of a nerve fiber and the caliber of its axon. This was done in the hope of defining morphological parameters useful for assessing conduction time. Four fiber populations were examined: (1) phrenic fibers in rat and rabbit during different phases of body growth; (2) phrenic fibers of mature animals of greatly different body size including mouse and cow; (3) rat intercostal nerves which vary in length by a factor exceeding 5 due to the funnel-shape of the thorax; and (4) ventral root fibers of the cow. In all of these fiber populations, there was no evidence for a direct relationship between the length of a fiber and its caliber. Rather, a tendency was noted for fiber caliber to approach certain ceilings independent of length. These data, seen in conjunction with other information on fiber structure, cast serious doubt on the widely accepted concept that maximum conduction velocity is the factor controlling nerve structure. A much more likely factor controlling the structure of myelinated nerve fibers is the capacity to modulate information by frequency coding of impulses.

[Numbering of the dorsal spinal nerve roots in man from the 12th thoracic nerve to the coccygeal nerve]

A bilateral study for locating the dorsal root filaments of specific nerves was accomplished from the twelfth thoracic to the coccygeal level and this using 26 fetal and 8 adult specimens. After laminectomy from the thoracic to coccygeal levels, incision of the dural sac permitted visualisation of the dorsal root filaments, the successive rootlets corresponding to each segmental level (T12 to Co1 ) were counted with the aid of a binocular microscope where they penetrated the spinal medulla at the posterior sulcus. Statistical evaluation shows that for each dorsal nerve the average number of root filaments is greater on the right compared with the left. Numbering the dorsal nerve root filaments in the cephalo -caudal direction allows to assert with 99% probability up to the L5 level and with 95% probability up to the S1 level that one is at a given spinal level of the respective segmental range; caudal-cephalic direction numbering permits to affirm with 99% probability up to the S1 level and 95% probability up to the L4 level that one is at a given spinal level of the respective segmental range.

Long thoracic nerve palsy: case report

Although the incidence of isolated long thoracic nerve palsy following acute spinal trauma is rare, one such case is presented with discussion of injury and treatment. The patient is a young man with paraplegia whose hospitalization was prolonged due to isolated right long thoracic nerve palsy. Palsy resulted form overstretching this nerve while using an overhead trapeze. Diagnosis was confirmed by electrodiagnostic studies. Full recovery occurred after 6 months.

Electrophysiologic studies of the thoracic limb of the horse

The cutaneous innervation of the thoracic limb was investigated in 18 barbiturate-anesthetized horses, using electrophysiologic techniques. The cutaneous area (CA) innervated by each cutaneous nerve was delineated in at least 4 horses by stroking the hairs with a small watercolor brush while recording from the nerve. Mapping of adjacent CA revealed areas of considerable overlap. The part of a CA of a given nerve supplied only by that nerve is referred to as its autonomous zone (AZ). In contrast to the standard textbook illustrations cutaneous branches of the axillary, radial, musculocutaneous, and ulnar nerves overlapped extensively in the antebrachium. Clinically testable AZ were found in the antebrachium for the caudal cutaneous antebrachial nerve of the ulnar nerve and in the carpus and manus for the cutaneous branches of the median, ulnar, and musculocutaneous nerves; AZ were not found for the cutaneous branches of the radial and axillary nerves.

Cobalt mapping of the nervous system: how to avoid artifacts

Infusion of cobalt ions into cut axons is an established method for tracing neuron projections in the central nervous system. Artifacts, where unintended neurons are stained, however, have been reported, leading to difficulties in interpretation. Experiments in the locust Schistocerca gregaria Forskål show that such artifacts can be induced through damage to axons caused by cutting peripheral nerves and by using high cobalt chloride concentrations (0.4M and above). Mixtures of cobalt and nickel chlorides and nickel chloride alone were introduced into different branches of the same nerve and developed with rubeanic acid to give precipitates of different colors in the two sets of axons. Preparations were examined with the light microscope, where mixing of ions would appear as intermediate colors, and by x-ray probe microanalysis. No evidence for leakage of metal ions from the filled axons or for ion uptake by other axons could be detected, provided that low concentrations of cobalt and nickel chlorides were used and nerve cutting was reduced to a minimum by making preparations in vivo. If extreme conditions are avoided when making the preparation, the risk of producing artifacts is minimized, thus enabling the cobalt method to be used with greater confidence for describing neuronal projections.

Anatomy of the intercostal nerve: its importance during thoracic surgery

Complications from attempts to block the intercostal nerves intraneurally before closure of a thoracotomy have resulted in hypotension with or without spinal block. Placement of a chest tube has resulted in transection of the intercostal nerve. The first of these complications can be avoided by not attempting intraneural block of the nerves intrathoracically. Avoidance of the latter requires careful dissection of the intercostal spaces and identification of the intercostal nerve, as opposed to stab insertion of a chest tube.

Spinal localization of the intercostal motoneurones innervating the upper thoracic spaces

At the rostral level of the thorax, the intercostal muscles participate both in postural and respiratory functions to a variable degree depending upon the considered muscle: external intercostal, intercartilaginous, internal intercostal, and triangularis sterni. In order to determine if these physiological properties are related to a special organization at the spinal cord level, we have used the retrograde transport of horseradish peroxidase as a tool for studying the spinal distribution of intercostal motor cells in the adult cat. Results suggest that the intercostal motoneurones could be distributed, in the ventral grey horn, among two areas according to the respiratory or postural muscle specialization.

Heterogeneity of the sympathetic innervation of rat interscapular brown adipose tissue via intercostal nerves

The interscapular brown adipose tissue (IBAT) of cold-acclimated white rats was partially denervated by cutting in most cases four of the five intercostal nerves going to one of its two bilaterally located, lobular pads. After 24 h the functional ability and the degree of residual sympathetic innervation of the pads and of their lobes were assessed (in separate groups of rats): the former by measuring tissue blood flow as an index of sympathetically mediated calorigenesis during exposure of the animals to -6 degrees C, the latter by measuring the residual noradrenaline (NA) content of the tissue. Only the four anterior intercostal nerves contributed significantly to the sympathetic innervation of IBAT pads. On average their contributions were unequal, but there was considerable variation between rats in the relative contribution of each nerve. The measurements on lobes of the pads indicated that the sympathetic fibers supplied by a given intercostal nerve were not distributed uniformly throughout the pad. For example, measurements of NA indicated that on average the fibers of the fourth nerve were four times as abundant in the lateral lobe as in the posterior lobe. But at this level of analysis also there was wide variation between rats. The variation in the participation of each intercostal nerve in the sympathetic innervation of rat IBAT and in the distribution of each nerve's fibers to different parts of the IBAT pad could be of genetic origin or it could reflect a considerable degree of flexibility during development of the innervation of IBAT. Because of the observation variation, it is suggested that if functional responses of IBAT evoked by electrical stimulation of intercostal nerves are to be recorded from a highly localized area of tissue, stimulation of all the nerves probably would be required to obtain responses that are consistent between animals.

Terminal sprouting of motoneurones is a local response to a local stimulus

Terminal sprouting was visualized in silver stained whole mounts of rat sternocostal muscles after resecting one segmental nerve. Sprouts were only found near denervated muscle fibres. The effective diffusion range of the sprout inducing factor released by denervated fibres was 50--100 micrometers. Individual terminals of the same motoneurone sprout independently of each other and only when they intercept the sprout inducing factor.

The importance of the anterior thoracic nerves in modified radical mastectomy

The medial anterior thoracic nerve supplies the pectoralis minor muscle and costal portion of the pectoralis major muscle. The lateral anterior thoracic nerve supplies the clavicular head and separately, three muscle groups of the sternal head. Any combination of these different muscle groups will become atrophic if the branches of the anterior thoracic nerves are injured. Muscle atrophy of the various groups of muscle bundles may not be apparent for as long as one year after the operation. These observations may be of some importance in the plastic reconstruction after modified radical mastectomy.

Intercostal nerve block: spread of india ink injected to the rib's costal groove

Three and five millilitre of india ink were injected bilaterally into the costal groove of the 9th or 10th ribs of 14 cadavers. The spread was observed and the costal groove of the rib injected was dissected, with the one above and one below. Nunn and Slavin's study (1980) of similar injections in two cadavers indicated that an injection of one costal groove blocked not only the intercostal nerve of that groove, but at least the one above and below it. The present study verified the author's previous report that only the intercostal nerve in the costal groove of the rib injected is anaesthetized.

[Preservation of the pectoral nerves in modified radical mastectomy]

Modified radical mastectomy with preservation of one or both pectoral muscles is the surgical treatment of choice in stage I and II breast cancer. A surgical anatomic study has been performed, based on post-mortem and intraoperative findings, to investigate origin and course of lateral and medial pectoral nerves and their relations to pectoral muscles and axillary lymphonodes. The results suggest that Patey-Meier operation can produce, in 80 per cent of cases, atrophy and fibrosis of the costoabdominal portion of the pectoralis major muscle as lateral pectoral nerve is generally dissected. On the contrary, radical mastectomy with both pectoral muscles preservation permit also to preserve the nerves during lymphadenectomy if they are recognized.

Electrophysiologic studies of cutaneous nerves of the thoracic limb of the dog

The cutaneous innervation of the thoracic limb was investigated in 36 barbiturate-anesthetized dogs, using electrophysiologic techniques. The cutaneous area (CA) innervated by each cutaneous nerve was delineated in at least five dogs by stroking the hair in the area with a small watercolor brush while recording from the nerve. Mapping of adjacent CA revealed areas of considerable overlapping. The part of the CA of a given nerve supplied by only that nerve is referred to as its autonomous zone. Of all nerves arising from the brachial plexus, only the suprascapular, subscapular, lateral thoracic, thoracodorsal, and cranial and caudal pectoral nerves lacked cutaneous afferents. The dorsal cutaneous branch of C6 had a CA, but no grossly demonstrable dorsal cutaneous branches for C7 C8, or T1 were found. The cervical nerves had ventral cutaneous branches, but no lateral cutaneous branches. Thoracic nerves T2-T4 had dorsal, ventral, and lateral cutaneous branches. The cutaneous branches of the brachiocephalic, axillary, musculocutaneous, radial, median, and ulnar nerves all had CA which were overlapped by adjacent CA, thus their autonomous zones were much smaller than the cutaneous areas usually depicted for these nerves in anatomy and neurology textbooks.

Serratus anterior paralysis in the young athlete

Ten cases of isolated, complete paralysis of the serratus anterior muscle were diagnosed in young athletes during a three-year period. One patient had recurrent partial paralysis of the serratus anterior muscle, the first such case reported. From studies on cadavera and clinical observations, we concluded that paralysis of the serratus anterior muscle results from a traction injury to the long thoracic nerve of Bell. Since full recovery usually occurs in an average of nine months, surgical methods of treatment should be reserved for patients in whom function fails to return after a two-year period. Non-strenuous use of the involved extremity with avoidance of the precipitating activity, followed by exercises designed to maintain the range of motion of the shoulder and to increase the strength of associated muscles, is advocated for treatment of acute or repetitive injuries to the long thoracic nerve of Bell.

Distribution of motor and sensory fibers in the intercostal nerves. Significance in reconstructive surgery

If the distribution of the types of nerve fibers in the various intercostal nerves is taken into consideration, an intercostal nerve segment can be an acceptable donor nerve graft for sensory and/or motor nerve replacements. We describe the distribution of motor and sensory axons in various segments of the upper and lower intercostal nerves.