Neurophysiologic maps of the cutaneous innervation of the external genitalia of the ewe

The area of skin supplied by the afferent fibers in a peripheral nerve is called the cutaneous area (CA) of that nerve. The CA responsive to movement of wool or hair in the genital regions were mapped in 17 ewes, with the identifications of the peripheral nerves and of the spinal nerves contributing to the pudendal plexus being checked at necropsy. Differences were found in the origins and extent of CA of the cutaneous branches from the sacral plexus. The CA of the caudal rectal nerves and of a nerve that passed caudally between the caudal vertebrae and the ventral sacrococcygeus muscle lay lateral to the anus and in the adjacent skin of the tail. The CA of the proximal cutaneous branch and of the distal cutaneous branch from the pudendal nerve (or plexus) overlapped craniocaudally (by approx one-half) the CA of the distal cutaneous branch extending ventrally and ending just caudal to the ipsilateral mammary gland. The deep perineal nerve innervated the skin immediately lateral to the anus and vulva. The dorsal nerve of the clitoris innervated hairs on the ipsilateral half of the vulva. Other fibers in the pudendal nerve were presumed to pass into the mammary branch of the nerve. They innervated the skin ventral to the vulva, the ipsilateral mammary gland, and (in some ewes) areas of the skin cranial to the mammary gland. The CA of the genitofemoral nerve included the ipsilateral teat and the inguinal fossa.(ABSTRACT TRUNCATED AT 250 WORDS)     

The spinal nerves that constitute the lumbosacral plexus and their distribution in the chinchilla

In this study, the spinal nerves that constitute the lumbosacral plexus (plexus lumbosacrales) (LSP) and its distribution in Chinchilla lanigera were investigated. Ten chinchillas (6 males and 4 females) were used in this research. The spinal nerves that constitute the LSP were dissected and the distribution of pelvic limb nerves originating from the plexus was examined. The iliohypogastric nerve arose from L1 and L2, giving rise to the cranial and caudal nerves, and the ilioinguinal nerve arose from L3. The other branch of L3 gave rise to the genitofemoral nerve and 1 branch from L4 gave rise to the lateral cutaneous femoral nerve. The trunk formed by the union of L4-5 divided into medial (femoral nerve) and lateral branches (obturator nerve). It was found that the LSP was formed by all the ventral branches of L4 at L6 and S1 at S3. At the caudal part of the plexus, a thick branch, the ischiadic plexus, was formed by contributions from L5-6 and S1. This root gave rise to the nerve branches which were disseminated to the posterior limb (cranial and caudal gluteal nerves, caudal cutaneous femoral nerve and ischiadic nerve). The ischiadic nerve divided into the caudal cutaneous surae, lateral cutaneous surae, common fibular and tibial nerve. The pudendal nerve arose from S1-2 and the other branch of S2 and S3 formed the rectal caudal nerve. The results showed that the origins and distribution of spinal nerves that constitute the LSP of chinchillas were similar to those of a few rodents and other mammals.     

Dorsal Nerve Root Origins of the Cutaneous Nerves of the Feline Pelvic Limb

The dorsal root origins of cutaneous nerves supplying the feline pelvic limb were determined electrophysiologically in 11 cats. Cutaneous nerves were surgically exposed and the presence or absence of an evoked potential in response to stimulation of individual dorsal roots was noted. The dorsal cutaneous branches of L3-L5 and S3, and the lateral cutaneous branch of L3 each arose solely from their parent spinal nerves. The L7, S1, and S2 dorsal cutaneous branches had multiple dorsal root origins. The lateral cutaneous femoral nerve originated from L3-L6 dorsal roots in 4 patterns of origin, and the saphenous nerve originated from L4-L6 dorsal roots in 2 patterns of origin. The lateral and caudal cutaneous sural nerves originated from L6-S1 roots in 2 and 3 patterns, respectively. The lateral and medial plantar nerves arose from L6-S2 roots in 4 and 2 patterns, respectively. The superficial and deep peroneal nerves originated from L6-S1 roots in 2 and 3 patterns, respectively. The caudal cutaneous femoral nerve or its branches arose from L7-S3 in 8 origin patterns. The dorsal nerve of the penis and the superficial perineal nerve arose from L7-S3 and S1-S3 roots, respectively, each in 4 patterns. A subtle correlation between plexus type and dorsal root origins of the cutaneous nerves was noted.     

Spinal nerve root origins of the cutaneous nerves of the canine pelvic limb

The spinal nerve root origins of the cutaneous nerves innervating the canine pelvic limb were determined in 12 barbiturate-anesthetized, healthy dogs by stimulating the dorsal roots L1-S3 and recording the evoked-action potentials from each cutaneous nerve. The dogs were then euthanatized, identification of each dorsal root and cutaneous nerve was verified by dissection, and the type of lumbosacral plexus (prefixed, median fixed, or postfixed) was determined. With one exception, the dorsal cutaneous branches and lateral cutaneous branches of L1-L3 originated only from their corresponding spinal nerve roots. The genitofemoral nerve received afferent fibers predominantly from L3-L4 nerve roots. The lateral cutaneous femoral nerve originated from L3-L5 nerve roots, and the saphenous nerve from L4-L6 nerve roots. The proximal caudal cutaneous sural nerve originated from L6-S1. The lateral cutaneous sural nerve originated from L5-S1; the deep and superficial fibular nerves arose primarily from L6-L7. The distal caudal cutaneous sural nerve originated predominantly from L7-S1, and the medial cutaneous tarsal nerve originated from L6-S1. The medial plantar nerve originated predominantly from L6-S1 roots, whereas the lateral plantar nerve originated from L6-S2 roots. The middle clunial nerve received afferent fibers primarily from S1-S2; the caudal clunial nerve received fibers from S1-S3. The caudal cutaneous femoral nerve originated predominantly from L7-S2. The dorsal nerve of the penis originated predominantly from S1-S2, and the superficial perineal nerve originated from S1-S3. One dog had a prefixed plexus, 8 dogs had median-fixed plexuses, and 1 dog had a postfixed plexus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrophysiologic Studies of the Cutaneous Innervation of the External Genitalia of the Female Dog

The cutaneous innervation of the external genitalia of the female dog was studied using electrophysiologic recording of evoked afferent activity in peripheral branches of the caudal cutaneous femoral, superficial perineal, and genitofemoral nerves, and the dorsal nerve of the clitoris. The observed cutaneous distribution was comparable to that of the male dog, with expected but relatively minor variation due to differences in morphology of the external genitalia. A speculative developmental sequence for the cutaneous innervation of the external genitalia was presented incorporating the distribution of the nerves studied to homologous structures between the sexes.     

Electrophysiologic studies of the cutaneous innervation of the pelvic limb of male dogs

The area of skin supplied by the afferent fibers in one cutaneous nerve is called the cutaneous area (CA) for that nerve. The CA of peripheral branches of lumbar and sacral spinal nerves responsive to the stimulation of hair follicle mechanoreceptors were mapped in 27 dogs. The amount of overlap among the CA was similar to that found for other CA of the body. The CA of peripheral branches of the sciatic nerve were restricted to the lateral, cranial, and caudal aspects of the pelvic limb distal to the stifle. The CA of the saphenous nerve was located on the medial side of the limb, except for a small area located on the lateral side of the crus. The distal part of the CA of the saphenous nerve was completely overlapped in the hind paw by branches of the superficial peroneal nerve laterally and the medial plantar branch of the tibial nerve medially. The CA for the deep peroneal nerve was located on the dorsal surface of the webbing between digits 2 and 3 and the adjacent skin of these digits. The CA of the plantar branches of the tibial nerve were small in comparison with the diameter of the nerve, suggesting that these branches contained nerve fibers supplying other, deeper structures in the hindpaw and that damage to these nerves would interfere with cutaneous sensation in only a small region on the plantar surface of the hindpaw. Knowledge of the CA of the various branches of the sciatic nerve allows more accurate localization of injury to the sciatic nerve or its branches by using areas of anesthesia.     

Afferent and Efferent Fibres in the Putative Caudal Cutaneous Femoral Nerve in the Sheep

Anatomical dissections supported by neurophysiological recordings have shown the putative caudal cutaneous femoral nerve in the sheep, when present, to contain afferent and efferent nerve fibres passing in both directions between the pudendal and sciatic nerves. Fascicles from the ventral branches of one or more sacral spinal nerves may join this interconnection directly: other fascicles either bypass the interconnection, or arise from it, and pass distally to innervate muscle and/or skin. We suggest that the interconnection should be regarded simply as part of the lumbosacral plexus.     

Neurophysiologic maps of cutaneous innervation of the hind limb of sheep

The area of skin supplied by afferent fibers in a peripheral nerve is called the cutaneous area (CA) of that nerve. The CA of hind limb nerves that were responsive to movement of wool/hairs were mapped neurophysiologically in 25 barbiturate-anesthetized sheep. The CA of the dorsal cutaneous branches of the caudal lumbar spinal nerves and of the sacral spinal nerves extended over the lateral aspect of the thigh. The CA of the lateral cutaneous femoral nerve was restricted to the stifle region, that of the saphenous nerve did not reach the digits, that of the deep peroneal nerve lay between the 3rd and 4th digits, and that of the lateral plantar nerve was confined to the lateral aspect of the 4th digit. The CA of the superficial peroneal nerve enveloped the dorsal, medial, and lateral aspects of the distal portions of the hind limb. In some sheep, the boundaries of the CA of the superficial peroneal nerve were juxtaposed caudally in such way that the medial plantar nerve did not have an autonomous zone. Differences in sizes of the CA resulted in corresponding differences in the overlap between adjacent CA and concomitant differences in the sizes of autonomous zones.     

Myelinated axons in peripheral nerves of adult beagle dogs: morphometric and electrophysiological measurements

The myelinated fibre composition and conduction velocities were measured for the ulnar, saphenous and caudal cutaneous sural nerves of 10 healthy beagle dogs. A systematic random sampling technique was used to estimate the fibre diameter frequency distributions and densities. Conduction velocities were measured from evoked compound nerve action potentials. All nerves showed bimodal diameter frequency distributions with modes being approximately the same for each nerve (2 to 4 microns and 8 to 10 microns or 10 to 12 microns). The variation in the average densities and in the shapes of histograms of the different nerves was slight; however, there was a wide variation for the same nerve in different individuals. The conduction velocities for the fastest conducting axons in the nerves ranged from 63 to 79 m s-1. These normal quantitative processes affecting peripheral nerves in the dog.     

Contrast-enhanced ultrasonography for evaluation of the blood perfusion of sciatic nerves in healthy dogs

Blood supply to the peripheral nerves is essential for fulfilling their structural and functional requirements. This prospective, experimental, exploratory study aimed to assess the feasibility of contrast-enhanced ultrasonography (CEUS) for evaluating blood perfusion of the sciatic nerve in normal dogs. Contrast-enhanced ultrasonography examinations were performed on the bilateral sciatic nerves after bolus injection of Sonazoid™ (0.015 mL/kg) in 12 healthy Beagles for 150 s. Then, qualitative assessment of the wash-in timing, degree and enhancement patterns, and quantitative measurement of the peak intensity and time to peak intensity were performed from the sciatic nerve. The results were compared to those obtained from the adductor muscle around the nerve and caudal gluteal artery. After contrast agent injection, the sciatic nerve was enhanced at approximately 13–14 s, immediately after wash-in of the caudal gluteal artery. The peak intensity of the sciatic nerve was significantly lower than that of the caudal gluteal artery and higher than that of the adductor muscle. The time to peak intensity was significantly slower than that of the caudal gluteal artery; but was not significantly different from that of the adductor muscle. There were no significant differences in the peak intensity and time to peak intensity between the left and right sciatic nerves. These results demonstrate the feasibility of CEUS to assess blood perfusion of the sciatic nerve in healthy dogs qualitatively and quantitatively. This result from healthy dogs could serve as a reference for further studies that evaluate the sciatic nerve under pathological conditions.     

Abstracts: LVII Annual Meeting of the Italian Society for Veterin Ary Sciences (SISVET), Ischia 2003

The Bactrian camel is an important domestic animal in some of the desert and semi-desert areas of the world. However, there is no detailed report about the nervous supply to the nasal cavity of the Bactrian camel. In the present study, seven heads of adult Bactrian camels were collected and the nerve distribution in the nasal cavity was dissected grossly. The results demonstrated that the nerves supplying to the nasal cavity included the olfactory nerve, the ethmoidal nerve from the ophthalmic nerve, and the caudal nerve from the maxillary nerve. The general patterns of nervous distribution in the nasal cavity of the Bactrian camel corresponded with those of other domestic animals. However, the terminal nerve was not observed by this gross anatomical method in the Bactrian camel.     

Extrinsic Cardiac Nerve Distribution in Goitred Gazelle (<Emphasis Type="Italic">Gazella subgutturosa</Emphasis>)

Extrinsic cardiac nerves and their patterns are described based on anatomical dissections of five goitred gazelle. Sympathetic cardiac innervation was mainly provided by the cervicothoracic and thoracic cardiac nerves. No left caudal cervicothoracic nerves, middle cervical cardiac nerves and vertebral cardiac nerves from the vertebral ganglion were observed. Parasympathetic cardiac innervation was supplied by the nerve fibres from the caudal vagal cardiac rami only. No cardiac rami from the cranial vagal cardiac nerves present in small ruminants were observed in this study. The caudal laryngeal and phrenic cardiac nerves also contributed to the cardiac innervation.     

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.     

Macro anatomical investigations of the cranial cervical ganglion in domestic pig (Sus scrofa domesticus)

In this study, the left and right cranial cervical ganglia (ganglion cervicale craniale) of eight young (four male, four female) domestic pigs weighing around 70-80 kg were inspected macro anatomically. The cranial cervical ganglion (CCG) was found cranio-ventrally of the distal ganglion of the vagus nerve, medial of the jugular process extremity, ventral of the atlas, dorsal of the epiglottis base and medial of the common root (CR) established by the internal carotid and occipital arteries. The internal carotid nerve and jugular nerve ramified from the cranial part of CCG. The jugular nerve gave branches that merged with the vagus and glossopharyngeal nerves. Other nerve branches originating from the cranial part of the ganglion reached to the external carotid artery and CR. The internal carotid nerve varied among cadavers in number of branches (two to four). These branches did not travel along the side of the internal carotid artery. The central part of CCG gave thin nerve branches that reached to various anatomical structures including the first and second cervical nerves, wall of the pharynx, accessory nerve, hypoglossal nerve, vagus nerve, external carotid artery and CR. The caudal part of CCG gave nerve branches that merged with the vagus, cranial laryngeal nerves, and common carotid artery. The external carotid nerves, which were two or three in number, also originated from the caudal part of CCG. In conclusion, the nerves ramifying from CCG of the pig varied in number among cadavers. Compared with literature raised in other species, there are also differences in number of nerve branches and course pattern of these nerves.     

Motor Fibers in the Canine Distal Caudal Cutaneous Sural Nerve—Dual Innervation of the Hind Limb Plantar Muscles

The function of the communicating branch of the distal caudal cutaneous sural (DCCS) nerve to the tibial nerve was investigated in 7 adult dogs and was found to contain the motor component of this nerve. This function was studied by direct visualization of the contraction of the hind limb plantar muscles and by direct electrophysiologic recording of motor unit action potentials in these muscles, following stimulation of the DCCS nerve. Contraction of all of the mm. interossei, the mm. lumbricales, the m. adductor digiti quinti and the m. adductor digiti secundi was observed with the stimulation of either the tibial or the DCCS nerves, although there was a qualitative variability in the plantar muscles exhibiting the strongest contraction with stimulation of the latter nerve. This communicating branch was not found in one of the experimental dogs, suggesting some individual variability in the DCCS nerve anatomy and subsequent function. This study conclusively demonstrated that the canine DCCS nerve contains both motor and sensory nerve fibers, which is similar to this nerve in the rat, but anatomically and functionally different to that in the human and the cat.     

Development and verification of saphenous, tibial and common peroneal nerve block techniques for analgesia below the thigh in the nonchondrodystrophoid dog

OBJECTIVE: To document simple and reliable local, infiltrating nerve blocks for the saphenous, tibial and common peroneal nerves in the dog. STUDY DESIGN: Laboratory technique development; in vivo blind, controlled, prospective study. ANIMALS: Twenty canine cadavers and 18 clinically normal, client-owned dogs. METHODS: A peripheral nerve blockade technique of the tibial, common peroneal, and saphenous nerves was perfected through anatomic dissection. Injections were planned in the caudal thigh for the tibial and common peroneal nerves, and in the medial thigh for the saphenous nerve. Cadaver limbs were injected with methylene blue dye and subsequently dissected to confirm successful dye placement. Clinically normal dogs undergoing general anesthesia for unrelated, elective procedures were randomly assigned to treatment (bupivacaine; n = 8) or control (saline; n = 8) nerve blocks of the nerves under study. Upon recovery from general anesthesia, skin sensation in selected dermatomes was evaluated for 24 hours. RESULTS: Cadaver tibial, common peroneal, and saphenous perineural infiltrations were successful in nonchondrodystrophoid dogs (100, 100, and 97%, respectively.) Intraneural injection was rare (1%; 1/105; tibial nerve) in cadaver dogs. In the treatment group of normal dogs, duration of loss of cutaneous sensation in some dermatomes (saphenous, superficial and deep peroneal nerve) was significantly different than control dogs; the range of desensitization occurred for 1-20 hours. No clinical morbidity was detected. CONCLUSIONS: This technique for local blockade of the tibial, common peroneal, and saphenous nerves just proximal to the stifle is easy to perform, requires minimal supplies and results in significant desensitization of the associated dermatomes in clinically normal, nonchondrodystrophoid dogs. CLINICAL RELEVANCE: This technique may be an effective tool for post-operative analgesia to the femoro-tibial joint and distal pelvic limb. Other applications, using sustained-release drugs or methods, may include anesthesia/analgesia in high-risk patients or as a treatment for chronic pelvic limb pain or self-mutilation.     

Macro and microstructural organization of the dog's caudal mesenteric ganglion complex (Canis familiaris-Linnaeus, 1758)

The caudal mesenteric ganglion (CMG) is located ventral to the abdominal aorta involving the initial portion of the caudal mesenteric artery. Its macro and microstructural organization was studied in 40 domestic dogs. From the CMG, there were three nerves: the main hypogastric, the left hypogastric and the right hypogastric. The main hypogastric nerve emits two branches: the left colonic nerve and the cranial rectal nerve. Afterwards they give rise to branches to the descending colon (colonic nerves) and rectum (rectal nerves). The cranial rectal nerve, and left and right hypogastric nerves were directed to the pelvic ganglia. The microscopic study permitted the observation of the histological organization of the CMG, which is a ganglionic complex composed of an agglomeration of ganglionic units. Each ganglionic unit is composed of three major cell types: principal ganglion neurones (PGNs), glial cells and small intensely fluorescent (SIF) cells, and they were separated by nerve fibres, septa of connective tissue (types 1 and 3 collagen fibres), fibroblasts and intraganglionic capillaries. Hence, the ganglionic unit is the morphological support for the microstructural organization of the CMG complex. Further, each ganglionic unit is constituted by a cellular triad (SIF cells, PGN and glial cells), which is the cytological basis for each ganglionic unit.     

Spinal Root Origin of the Radial Nerve and Nerves Innervating Shoulder Muscles of the Dog

The ventral spinal root origin of the radial nerve, its muscle branches, and brachial plexus nerves which supply shoulder and thoracic musculature was determined in the dog. Electrophysiological signal averaging techniques measured evoked potential from specific ventral spinal roots to individual muscle nerves. The entire radial nerve received input from the sixth cervical (C6) through the second thoracic (T2) spinal roots. The most significant (p less than .05) input to triceps brachii came from C8 while the deep ramus of the radial nerve received its largest input from C7. The brachiocephalicus, suprascapular, and subscapular nerves all received their most significant (p less than .05) innervation from C6. Approximately 90% of the evoked potential to the axillary nerve originated from C7. The thoracodorsal nerve received most of its innervation from ventral roots C7 and C8. The lateral thoracic nerve which innervates the cutaneous trunci muscle was supplied by ventral roots C8-T2. Examination of innervation patterns suggests that only modest variation of spinal root input to specific nerves occurred between individual dogs.     

Origin and distribution of the brachial plexus of the Van cats

Knowing the structure and variations of the plexus brachialis is important in neck and shoulder surgery. The knowledge of the brachial plexus reduces the injury rate of the nerves in surgical interventions to the axillary region. The major nerve trunks of the thoracic limb were the suprascapular, subscapular, axillary, radial, musculocutaneous, median and ulnar nerves. In Van cats, the brachial plexus was formed by the ventral branches of the spinal nerves, C6-C7-C8 and T1. The 7th cervical nerve was quite thick compared to the others. The subscapular nerve was the thinnest (on the right side, the average length was 6.55 ± 0.60 mm and on the left side was 6.50 ± 0.60 mm), and the radial nerve was the thickest (the average length on the right side was 28.48 ± 0.44 mm and on the left side was 29.11 ± 0.55 mm). The suprascapular nerve was formed by the ventral branch of the 6th cervical nerve. The subscapular nerves were formed by a branch originating from the 6th cervical nerve and the two medial and caudal branches originating from the 7th cervical nerve. No communicating branch between the ulnar nerve and the median nerve was observed in the palmar region. The axillary nerve was formed by the ventral branches of the 7th nerve, the musculocutaneous nerve was formed by ventral branches of the 6th and 7th cervical nerves, and the ulnar nerve was formed by ventral branches of the 8th cervical and the 1st thoracic nerves. The radial nerve was the thickest branch in the brachial plexus. In Van cats, the origin and distribution of nerves were similar to those reported in the literature for other species of cats, with the exception of the suprascapular, subscapular and axillary nerves.     

Gross anatomical study of the thoracolumbar primary dorsal branches and their course from the spinal cord to the skin in the cat

The course of spinal nerves and the corresponding cutaneous areas are fundamental for numerous therapeutic approaches used in complementary veterinary medicine. Positive effects of these methods are primarily based on segmental reflex arcs which are associated with the course of the spinal nerves. In this morphological study, the lateral cutaneous branches of the thoracolumbar dorsal branches from Th9 to L7 were examined in cats with special regard to their anatomical course. A four-layer dissection was carried out to reveal the course of nerves between the intervertebral foramina and their point of entry into the skin, starting in the dorsal midline. Dorsal branch courses and covered distances were documented and measured in each layer. The covered distance was evaluated by the Caudal Shift Index (CSI_n) on both body sides and within each layer. The ‘back region’ was used as relative dimensional unit, describing the distance between the cranial tips of two consecutive spinous processes. Overall, the mean CSI_n for dorsal branches of Th9 to L7 amounted to three back regions from the intervertebral foramen to the skin entry point of a dorsal nerve branch. This provides therapists with clues and should be put into practice, by extending the treatment area up to three segments caudally from the nerve exit point. Furthermore, the results of this study present new data on inferred lumbar dermatomes in cats, data which until now have only been transferred from other species. These results may serve as an anatomical foundation for manual therapies.