The Innervation of Canine Hip Joint Capsule: An Anatomic Study

To clarify the contributions of the nerves supplying the canine hip joint capsule for clinical application, cadaver study of six healthy mongrel dogs was performed. The pelvises and hindlimbs of cadavers were dissected and fixed in formaldehyde. Innervation of the joint capsule was investigated with the aid of an operative microscope. As a result, the canine hip joint capsule receives multiple innervations from articular branches of four nerves. They are articular nerve fibres of femoral, obturator, cranial gluteal and sciatic nerves from the cranioventral, caudoventral, craniolateral and dorsolateral directions of the joint, respectively. No branch originating from the caudal gluteal nerve was observed innervating the hip joint capsule. Our data provides useful information for research on the canine hip joint, including pain analysis with hip disorders and surgical nerve blockade to relieve pain.     

Contrast‐enhanced ultrasonography is a feasible technique for quantifying hepatic microvascular perfusion in dogs with extrahepatic congenital portosystemic shunts

Extrahepatic‐congenital portosystemic shunt is a vascular anomaly that connects the portal vein to the systemic circulation and leads to a change in hepatic microvascular perfusion. However, an assessment of hepatic microvascular perfusion is limited by conventional diagnostic modalities. The aim of this prospective, exploratory study was to assess hepatic microvascular perfusion in dogs with extrahepatic‐congenital portosystemic shunt using contrast‐enhanced ultrasonography (CEUS) using perfluorobutane (Sonazoid^®). A total of 17 dogs were included, eight healthy dogs and nine with extrahepatic‐congenital portosystemic shunt. The time‐to‐peak (TTP), rising time (RT), and rising rate (RR) in the hepatic artery, portal vein, and hepatic parenchyma, as well as the portal vein‐to‐hepatic parenchyma transit time (ΔHP‐PV) measured from time‐intensity curve on CEUS were compared between healthy and extrahepatic‐congenital portosystemic shunt dogs. The RT of the hepatic artery in extrahepatic‐congenital portosystemic shunt dogs was significantly earlier than in healthy dogs (P = 0.0153). The TTP and RT of the hepatic parenchyma were significantly earlier in extrahepatic‐congenital portosystemic shunt dogs than in healthy dogs (P = 0.0018 and P = 0.0024, respectively). ΔHP–PV was significantly shorter in extrahepatic‐congenital portosystemic shunt dogs than in healthy dogs (P = 0.0018). CEUS effectively revealed changes in hepatic microvascular perfusion including hepatic artery, portal vein, and hepatic parenchyma simultaneously in extrahepatic‐congenital portosystemic shunt dogs. Rapid hepatic artery and hepatic parenchyma enhancements may reflect a compensatory increase in hepatic artery blood flow (arterialization) caused by a decrease in portal vein blood flow and may be used as an additional diagnostic test to distinguish extrahepatic‐congenital portosystemic shunt dogs from healthy dogs.     

Contrast-enhanced ultrasonography to assess blood perfusion of skeletal muscles in normal dogs

This study evaluated perfusion of skeletal muscle using contrast enhanced ultrasonography in humerus, radius, femur and tibia in normal dogs. Contrast enhanced ultrasonography for each region was performed after injecting 0.5 mL and 1 mL of contrast medium (SonoVue) in every dog. Blood perfusion was assessed quantitatively by measuring the peak intensity, time to the peak intensity and area under the curve from the time–intensity curve. Vascularization in skeletal muscle was qualitatively graded with a score of 0–3 according to the number of vascular signals. A parabolic shape of time–intensity curve was observed from muscles in normal dogs, and time to the peak intensity, the peak intensity and area under the curve of each muscle were not significantly different according to the appendicular regions examined and the dosage of contrast agent administered. This study reports that feasibility of contrast enhanced ultrasonography for assessment of the muscular perfusion in canine appendicular regions.     

CONTRAST‐ENHANCED ULTRASONOGRAPHY OF THE PANCREAS IN HEALTHY DOGS AND IN DOGS WITH ACUTE PANCREATITIS

Pancreatitis is the most frequent disease affecting the exocrine pancreas in dogs and reliable diagnostic techniques for predicting fatal complications are lacking. Contrast‐enhanced ultrasound (CEUS) improves detection of tissue perfusion as well as organ lesion vascular pattern. Objectives of this prospective case control study were to compare perfusion characteristics and enhancement patterns of the pancreas in healthy dogs and dogs with pancreatitis using CEUS. Ten healthy dogs and eight dogs with pancreatitis were selected based on physical examination, abdominal ultrasound, and blood analysis findings. A CEUS study of the pancreas was performed for each dog and two observers who were aware of clinical status used advanced ultrasound quantification software to analyze time‐intensity curves. Perfusion patterns were compared between healthy and affected dogs. In dogs with acute pancreatitis, mean pixel and peak intensity of the pancreatic parenchyma was significantly higher than that of normal dogs (P = 0.05) in between 6 and 60 s (P = <0.0001–0.046). This corresponds to a 311% increase in mean pixel intensity in dogs with acute pancreatitis compared to healthy dogs. Wash‐in rates were greater and had a consistently steeper slope to peak in dogs with pancreatitis as opposed to healthy dogs. All dogs with pancreatitis showed a decrease in pixel intensity 10–15 days after the initial examination (P = 0.011) and their times to peak values were prolonged compared to the initial exam. Findings from the current study supported the use of CEUS for diagnosing pancreatitis, pancreatic necrosis, and disease monitoring following therapy in dogs.     

Applications of a semitendinosus muscle flap in two dogs

The proximal half of the semitendinosus muscle can be used as a versatile vascularized local transposition flap to reconstruct anatomic faults in the adjacent perineum in dogs. The flap is easy to dissect, and the arc of rotation is considerably beyond the midline. The location, size, and direction of the major vascular pedicle from the caudal gluteal artery is conducive to dependable flap perfusion.     

Effects of triple pelvic osteotomy on anatomic structures of the pelvic region in the dog

Triple pelvic osteotomy has been used in dogs to maintain normal form and anatomical function of the hip in canine hip dysplasia. Pelves subjected to triple pelvic osteotomy undergo several architectural changes of different magnitudes. The aim of this study was to determine the positional changes of the anatomical structure of the pelvis after unilateral triple pelvic osteotomy in five mongrel dogs. Atrophy of the middle gluteal muscle, reduction in tension of the external and internal obturator muscles, compression on the caudal gluteal vein and entrapment of the sciatic nerve at the level of the ilial body were the most remarkable findings in the study. From an anatomical standpoint, it is suggested that the lateral rotation of the acetabulum should be kept minimal to guarantee least alterations in the normal anatomic architecture of the pelvic region.     

ULTRASONOGRAPHIC ASSESSMENT OF THE CANINE SCIATIC NERVE

To describe the ultrasonographic technique for investigation of the canine sciatic nerve, four canine cadaver pelvic limbs, two live healthy dogs, and five canine patients with suspected peripheral sciatic nerve lesions were examined with a high-resolution linear ultrasound transducer. The caudal part of the lumbosacral trunk and the origin of the sciatic nerve were visualized through the greater ischiatic foramen. The two components of the sciatic nerve, common peroneal and tibial nerves, were distinguished along the entire length of the nerve, until they branched at the level of the distal femur. In healthy live dogs they appeared as two adjacent hypoechoic tubular structures with internal echotexture of discontinuous hyperechoic bands, surrounded by a thin rim of highly echogenic tissue. The common peroneal component had a smaller diameter and was on the cranial aspect of the tibial component. An ultrasonographic lesion compatible with a peripheral nerve sheath tumor was found in one dog. Improved understanding of the ultrasonographic anatomy of the sciatic nerve supports clinical use of this modality.     

Ultrasound‐guided approach for axillary brachial plexus,femoral nerve,and sciatic nerve blocks in dogs

Objective To describe an ultrasound‐guided technique and the anatomical basis for three clinically useful nerve blocks in dogs. Study design Prospective experimental trial. Animals Four hound‐cross dogs aged 2 ± 0 years (mean ± SD) weighing 30 ± 5 kg and four Beagles aged 2 ± 0 years and weighing 8.5 ± 0.5 kg. Methods Axillary brachial plexus, femoral, and sciatic combined ultrasound/electrolocation‐guided nerve blocks were performed sequentially and bilaterally using a lidocaine solution mixed with methylene blue. Sciatic nerve blocks were not performed in the hounds. After the blocks, the dogs were euthanatized and each relevant site dissected. Results Axillary brachial plexus block Landmark blood vessels and the roots of the brachial plexus were identified by ultrasound in all eight dogs. Anatomical examination confirmed the relationship between the four ventral nerve roots (C6, C7, C8, and T1) and the axillary vessels. Three roots (C7, C8, and T1) were adequately stained bilaterally in all dogs. Femoral nerve block Landmark blood vessels (femoral artery and femoral vein), the femoral and saphenous nerves and the medial portion of the rectus femoris muscle were identified by ultrasound in all dogs. Anatomical examination confirmed the relationship between the femoral vessels, femoral nerve, and the rectus femoris muscle. The femoral nerves were adequately stained bilaterally in all dogs. Sciatic nerve block. Ultrasound landmarks (semimembranosus muscle, the fascia of the biceps femoris muscle and the sciatic nerve) could be identified in all of the dogs. In the four Beagles, anatomical examination confirmed the relationship between the biceps femoris muscle, the semimembranosus muscle, and the sciatic nerve. In the Beagles, all but one of the sciatic nerves were stained adequately. Conclusions and clinical relevance Ultrasound‐guided needle insertion is an accurate method for depositing local anesthetic for axillary brachial plexus, femoral, and sciatic nerve blocks.     

Anatomical and experimental studies of brachial plexus, sciatic, and femoral nerve-location using peripheral nerve stimulation in the dog

OBJECTIVE: To investigate the anatomy of the brachial plexus, sciatic, and femoral nerves for the use of a peripheral nerve-stimulator to perform nerve blocks in dogs. STUDY DESIGN: Prospective experimental trial. ANIMALS: Four canine cadavers and four healthy adult dogs weighing 23 +/- 2.5 kg. METHODS: Phase I: in four canine cadavers, an anatomical study was conducted to evaluate accurate needle-insertion techniques. Phase II: the utility of these techniques, and the value of electrostimulation, were evaluated in four anesthetized dogs in lateral recumbency (medetomidine, 5 microg kg(-1)/ketamine 5 mg kg(-1)) using an electrical stimulator and shielded needles. RESULTS: For the brachial plexus, the needle was inserted cranial to the acromion, medial to the subscapularis muscle, at an angle of approximately 20-30 degrees in relation to a plane vertical to the surface on which the animal was lying, oriented parallel to the long axis of the animal, in a ventro-caudal direction. For the sciatic nerve, the needle was inserted just cranial to the sacrotuberous ligament, through the gluteus superficialis muscle, at an angle of approximately 60 degrees in relation to the horizontal plane, in a ventro-cranial direction, and up to the level of the ischium. For the femoral nerve, the needle was inserted perpendicular to the skin, just cranial to the femoral artery, and directed a little caudally. Using a peripheral nerve-stimulator, all nerves were located, and muscle contractions were elicited at a current of 0.2-0.4 mA. No complications were observed during the procedures. CONCLUSION: Electrostimulation of peripheral nerves is useful in locating the branches of the brachial plexus as well as the sciatic and femoral nerves in dogs. CLINICAL RELEVANCE: Peripheral nerve stimulation increases the reliability of a nerve block when compared with blind needle-insertion.     

Anatomical Variations of the Blood Vascular System in Veterinary Medicine

Traditional veterinary anatomical models describe the branches of the caudal gluteal artery as the iliolumbar, cranial gluteal, lateral caudal, satellite of the ischiatic nerve and dorsal perineal arteries. However, some classical veterinary anatomy textbooks often indicate variations the general organization of the arterial tree, without giving any pattern of origin or illustrations of the different branching. The aim of this study was to investigate the presumptive variability of the caudal gluteal artery. Two hundred and thirty‐two pelvic halves from 116 adult dogs were examined. Twelve anatomical variations were found, nine occurring in more than 5% of the dogs, and three in <5%. A ‘long‐type’ internal iliac artery, which means short caudal gluteal and internal pudendal arteries, was identified, while a ‘perineal trunk’ was observed as an interesting arterial variation. If the caudal segment alone is taken into consideration, identical vascular patterns in both hemi‐pelvises are found in 17% of the dogs. Significant statistical correlation was found for four different types of anatomic variations and gender, two types of variations and body size, one type of variation for body side and one type of variation for head shape.     

Contrast enhanced ultrasonography of kidney in conscious and anesthetized beagle dogs

Contrast enhanced ultrasound (CEUS) is useful to evaluate tissue perfusion in the kidney. In veterinary medicine, sedation or anesthesia may be required in uncooperative or panting patients. The aim of this study was to evaluate and compare the normal kidney perfusion patterns in conscious and anesthetized dogs using CEUS. Eight healthy beagles were used in this study. Scanning was performed in conscious dogs using manual restraint (conscious group), or under general anesthesia using tiletamine-zolazepam and medetomidine (TZM group) or medetomidine (M group). The contrast agent (Sonovue^®) was administered as an IV bolus. The peak intensity (PI), time to peak enhancement from injection (TTP₀) and the time to peak enhancement from the initial rise (TTP_up), upslope, downslope and area under the curve (AUC) were analyzed. Compared to the cortical values in the conscious group, TTP₀ was significantly delayed in the TZM group, and upslope, TTP₀ and TTP_up were significantly different in the M group. The AUCs in the TZM and M groups were not different from those in the conscious group. The upslope of renal medullary perfusion was significantly decreased in the TZM and M groups. TTP₀ and TTP_up were also significantly delayed in these groups. The AUC of the medulla was significantly decreased in the M group. Therefore, TZM is useful as an anesthetic protocol when performing CEUS, and the obtained data may serve as reference values in the evaluation of renal perfusion using CEUS in dogs under anesthesia.     

CONTRAST‐ENHANCED ULTRASONOGRAPHY OF THE NORMAL CANINE ADRENAL GLAND

Contrast‐enhanced ultrasonography is useful in differentiating adrenal gland adenomas from nonadenomatous lesions in human patients. The purposes of this study were to evaluate the feasibility and to describe contrast‐enhanced ultrasonography of the normal canine adrenal gland. Six healthy female Beagles were injected with an intravenous bolus of a lipid‐shelled contrast agent (SonoVue^®). The aorta enhanced immediately followed by the renal artery and then the adrenal gland. Adrenal gland enhancement was uniform, centrifugal, and rapid from the medulla to the cortex. When maximum enhancement was reached, a gradual homogeneous decrease in echogenicity of the adrenal gland began and simultaneously enhancement of the phrenicoabdominal vessels was observed. While enhancement kept decreasing in the adrenal parenchyma, the renal vein, caudal vena cava, and phrenicoabdominal vein were characterized by persistent enhancement until the end of the study. A second contrast enhancement was observed, corresponding to the refilling time. Objective measurements were performed storing the images for off‐line image analysis using Image J (ImageJ^©). The shape of the time–intensity curve reflecting adrenal perfusion was similar in all dogs. Ratios of the values of the cortex and the medulla to the values of the renal artery were characterized by significant differences from initial upslope to the peak allowing differentiation between the cortex and the medulla for both adrenal glands only in this time period. Contrast‐enhanced ultrasonography of the adrenal glands is feasible in dogs and the optimal time for adrenal imaging is between 5 and 90 s after injection.     

DYNAMIC COMPUTED TOMOGRAPHY TO MEASURE TISSUE PERFUSION IN SPONTANEOUS CANINE TUMORS

Dynamic computed tomography (CT) is widely used in humans to determine tumor perfusion via time–attenuation curves. Five types of time–attenuation curves have been identified and shown to have prognostic relevance in humans. The goal of our study was to assess the feasibility of this technology in spontaneous canine tumors and to determine time–attenuation curves and perfusion patterns in different tumor types. Thirty-one dogs with tumors accessible for biopsy were evaluated (15 carcinomas, 16 sarcomas). Dynamic CT was performed at the level of the largest tumor cross-section. Time–attenuation curves were calculated and ratios from the tumor to a contralateral artery were derived for wash-in, peak attenuation, time to peak attenuation, wash-out, and perfusion. Median perfusion was significantly higher and median time to peak ratio was significantly shorter in carcinomas and bone sarcomas compared with soft tissue sarcomas ( P =0.03 and 0.01). There was a trend of lower median upslope and wash-out ratio in soft tissue sarcomas in comparison with carcinomas ( P =0.06 and 0.09). Although peak ratio was lowest in soft tissue sarcomas, differences were not significant ( P =0.3). The most common type of time–attenuation curve for all tumors had a slow to moderately rapid wash-in with a low to moderate attenuation peak followed by a plateau phase. In conclusion, dynamic CT is feasible and time-activity curve-derived measurements differed between spontaneous canine tumors. More data has to be collected in a larger number of patients and correlated with response to treatment and outcome.     

CONTRAST‐ENHANCED ULTRASONOGRAPHIC CHARACTERISTICS OF ADRENAL GLANDS IN DOGS WITH PITUITARY‐DEPENDENT HYPERADRENOCORTICISM

A noninvasive method for quantifying adrenal gland vascular patterns could be helpful for improving detection of adrenal gland disease in dogs. The purpose of this retrospective study was to compare the contrast‐enhanced ultrasound (CEUS) characteristics of adrenal glands in 18 dogs with pituitary‐dependent hyperadrenocorticism (PDH) vs. four clinically healthy dogs. Each dog received a bolus of the contrast agent (SonoVue®, 0.03 ml/kg of body weight) into the cephalic vein, immediately followed by a 5 ml saline flush. Dynamic contrast enhancement was analyzed using time–intensity curves in two regions of interest drawn manually in the caudal part of the adrenal cortex and medulla, respectively. In healthy dogs, contrast enhancement distribution was homogeneous and exhibited increased intensity from the medulla to the cortex. In the washout phase, there was a gradual and homogeneous decrease of enhancement of the adrenal gland. For all dogs with PDH, there was rapid, chaotic, and simultaneous contrast enhancement in both the medulla and cortex. Three distinct perfusion patterns were observed. Peak perfusion intensity was approximately twice as high (P < 0.05) in dogs with PDH compared with that of healthy dogs (28.90 ± 10.36 vs. 48.47 ± 15.28, respectively). In dogs with PDH, adrenal blood flow and blood volume values were approximately two‐ to fourfold (P < 0.05) greater than those of controls. Findings from the present study support the use of CEUS as a clinical tool for characterizing canine adrenal gland disease based on changes in vascular patterns.     

ULTRASONOGRAPHY OF PERIPHERAL NERVES DURING WALLERIAN DEGENERATION AND REGENERATION FOLLOWING TRANSECTION

Ultrasonography was performed on sciatic, tibial and/or peroneal nerves and interosseous muscles in 7 dogs using a ultrasound machine with a 7.5 MHz linear array transducer. A tibial nerve was transected near the distal aspect of the bellies of the gastroenemius muscle. Serial neurologic examinations, electromyography, and ultrasonography were performed before and after surgery. Dogs were euthanized at variable intervals and histopathology performed on nerve samples. In sagittal images, normal nerves had hyperechoic walls with multiple internal linear echoes. In transverse images, the nerves were round or oval hyperechoic structures with internal punctate echoes. After transection, the proximal stump was consistently seen whereas the distal stump and nerve were harder to identify. Neuromas were present in all 5 dogs followed beyond 2 days and appeared as hypoechoic bulbous swellings most apparent at 3 weeks after surgery. Only 1 dog developed a neuroma large enough to be considered of potential clinical significance. Four dogs were followed beyond 2 months. Regeneration was evidenced by a steady growth of nerve with an irregular outline (2 dogs) or by a knobby connection between the proximal and distal stumps (1 dog). Regeneration was not detected in 1 dog.     

Relationship of Femoral Intramedullary Pins to the Sciatic Nerve and Gluteal Muscles after Retrograde and Normograde Insertion

An anatomic analysis of retrograde and normograde intramedullary (IM) pinning of proximal, midshaft, and distal femoral fractures was performed in 28 canine cadavers. For all fracture locations, normograde pins were significantly more cranial in the middle gluteal muscle than retrograde pins (p less than 0.01). There was no significant difference between pinning techniques in craniocaudal position of the IM pin in the superficial gluteal muscle. In distal fractures, normograde pins were placed significantly more lateral than retrograde pins in the superficial gluteal muscle (p less than 0.01). One of 15 normograde pins and 9 of 13 retrograde pins were located in the medial half of the trochanteric fossa. Normograde pins were significantly more lateral in the trochanteric fossa than were retrograde pins in midshaft fractures (p less than 0.01). Normograde pins were significantly (p less than 0.01) farther from the sciatic nerve than retrograde pins when the hip was positioned at coxofemoral flexion angles of 85 degrees in midshaft and 110 degrees in distal fractures. Seven of 13 retrograde pins, but none of 15 normograde pins, contacted the sciatic nerve. Normograde pinning of the femur may be less likely to induce sciatic nerve injury, particularly in midshaft and distal fractures.     

Ultrasonographic study of a modified axillary approach to block the major branches of the brachial plexus in dogs

ObjectiveTo provide ultrasonographic mapping of the axillary region of dogs to facilitate identification of the major branches of the brachial plexus in relation to the axillary artery.Study designProspective study.AnimalsA total of two dog cadavers and 50 client-owned, healthy dogs weighing >15 kg.MethodsIn Phase 1, anatomical dissections were performed to identify the relation of the major brachial plexus nerves to the axillary artery. In Phase 2, with the dogs in dorsal recumbency with thoracic limbs flexed naturally, the axillary space was scanned using a linear array probe oriented on the parasagittal plane until the axis transverse to nerves was found. Then, the transducer was rotated to a slight lateral angle approximately 30° to midline. The examination aimed to identify the axillary artery and the musculocutaneous, radial, median and ulnar nerves in addition to determining their position and distribution in four predefined sectors.ResultsThe musculocutaneous nerve was observed in all animals cranial to the axillary artery. The radial, ulnar and median nerves were distributed around the axillary artery, with >90% on the caudal aspect of the axillary artery (sectors 1 and 2).Conclusions and clinical relevanceUltrasonography identified the location of the brachial plexus nerves near the studied sectors, providing useful guidance for performing a brachial plexus nerve block.     

Distribution of innervation and circulation in porcine cervical trachea

The circulation and innervation to porcine cervical trachea were studied in 54 animals in situ. The antemortem response of porcine tracheal muscle was measured isometrically during selective injection of acetylcholine into the cranial thyroid arterial circulation. A predominantly unilateral (70.4%), rather than bilateral (3.7%), arterial circulation was identified; a cranial thyroid artery was not demonstrated in 25.9% of swine, suggesting dominant perfusion from the caudal thyroid circulation. After animals were killed, dye injection through the dominant cranial thyroid trunk demonstrated homogeneous perfusion of the muscle in all instances. In 20 of these animals, the distribution of parasympathetic innervation to porcine tracheal muscle was studied by selective electrical stimulation of the vagus nerves in situ. Tracheal smooth muscle response was measured isometrically, using settings (20 v, 20 Hz) causing maximal contractile force. Bilateral electrical stimulation caused active tracheal tension of 23.2 +/- 1.9 g/cm. Unilateral stimulation of the left vagus nerve caused 17.8 +/- 1.5 g/cm contraction, which was significantly greater than the response caused by selective stimulation of the right vagus nerve (12.1 +/- 1.6 g/cm; P less than 0.001). Innervation to porcine cervical trachea, although bilateral, is derived predominantly from the left vagus nerve; circulation is derived almost always from the left cranial thyroid artery.     

Cytotoxicity and cytokine production by bovine alveolar macrophages challenged with wild type and leukotoxin-deficient Mannheimia haemolytica

The aim of this study was to investigate the use of ultrasound (US) guidance to perform sciatic and saphenous nerve blocks in dogs. Five dogs were sedated with medetomidine and butorphanol. A high-resolution US transducer was used to locate the nerves, guide placement of the needle and visualise the perineural injection of lidocaine 2%. Electrostimulation was used to confirm correct placement prior to the sciatic block. Nerve functions were evaluated over a 3 h period following administration of atipamezole. Successful identification of the nerves and the quality of the blocks were recorded. Location of the nerves, complete sensory block of the saphenous nerve, and partial to complete sensory and motor blocks of the sciatic nerve were achieved in all dogs. The resultant US guidance is potentially valuable for blocking the sciatic and saphenous nerves in dogs, although further work will be required to ensure a complete block of the sciatic nerve.     

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.