Anatomic-Topographic Investigation of the Branches of the Dorsal Ramus of Thoracic Spinal Nerves.

INTRODUCTION: Percutaneous radiofrequency facet denervation (PRFD) by thermocoagulation is a useful treatment for nonspecific thoracic pain syndrome. To guarantee that maximal thermal lesion is applied to the nerve, it is essential to have precise knowledge of the topography of the thoracic dorsal branches of the spinal nerves. This special anatomy was investigated, and the results were compared with the existing technique for PRFD, where the active needle tip is placed in the junction of the superior articular process and the transverse process. METHODS: Twenty thoracic spines of cadavers (10 females and 10 males) embalmed according to Thiel's method were bilaterally dissected. After careful removal of skin and subcutaneous fat tissue, the lateral and medial branches were traced centrally. In addition, the articular branch to the thoracic facet joint was traced peripherally. The distance of the medial branch to the inferior articular process at the level of the nerve passing the superior costotransverse ligament was measured. RESULTS: The dorsal branch bifurcates into lateral and medial branches medial to the superior costotransverse ligament. The medial branch runs laterally first to pass in between two parts of the intertransverse ligament running dorsally and to turn medially superficial to this ligament. The zygapophysial branch always originated from the medial branch passing the inferior articular process laterally by running caudally to turn medially and send branches to the capsule of the zygapophyseal joint. The distance of the medial branch lateral to the inferior articular process was constantly 3 mm. CONCLUSIONS: The current technique of PRFD at the thoracic spine targets the medial branch distal to the separation of the articular branch, rendering the lesion ineffective at denervating the zygapophyseal joint. For selective thermocoagulation of the articular branches of the thoracic zygapophyseal joint, a new technique should be developed. We propose an anatomically informed needle position that can now be confirmed clinically.

Variations in the anterior thoracic wall with sternalis muscle and accessory pectoralis major muscle.

PURPOSE: The new type of the sternalis muscle needs to be recognized, and the accessory pectoralis major muscle (AcPM) was found between the pectoralis major and minor muscle. It needs to be acknowledged those two different variations can exist in one case. METHODS: The muscle was found on a 73-year-old male cadaver during the dissection class for the anterior thoracic wall. It was proceeded to identify the adjacent structures with precise dissection. RESULTS: The cadaver had sternalis muscle bilaterally. Both side sternalis muscles had a medial and lateral belly and attached to pectoral fascia and rectus abdominis sheath. The pectoralis major muscle (PMaj) had a more profound slip attached to the costal cartilage of rib 4 and 5, which is AcPM. The pectoral nerve traveled through the clavipectoral fascia to the AcPM and through PMaj to the sternalis muscle. CONCLUSIONS: This study presented a new type of sternalis muscle. Two different variations were developed along with the pectoral nerve. It needs to be recognized in the diagnostic images, the muscle rehab outcome, and the surgical complication.

Variation of surgical anatomy of the thoracic portion of the long thoracic nerve.

Decompression of the long thoracic nerve (LTN) is a potentially beneficial procedure for selected patients with LTN palsy. The aim of this work is to describe the surgical anatomy of the thoracic part of the LTN and highlight its variations. A retrospective review of patients undergoing exploration of the LTN was performed. Preoperatively, all patients had serratus anterior dysfunction and underwent electromyographic (EMG) assessment. All patients had an initial trial of nonoperative management. The surgical procedures were undertaken by the senior author. The anatomy of the LTN and the associated vasculature was recorded in patient records, and with digital photography. Forty-five patients underwent LTN exploration. Two patients with iatrogenic injury were excluded, leaving 43 patients for analysis. Mean age was 36 years. Sixty-seven percent of cases involved the dominant side. Trauma was the commonest cause, followed by neuralgic amyotrophy. Four patients had typical features of serratus anterior dysfunction but with normal EMG studies. Two distinct patterns of LTN anatomy were noted. In 79% of cases, a single major nerve trunk coursing along serratus anterior was observed and classified as a type I LTN. In 21% of cases, two equal major branches of the nerve were identified, which was classified as a type II LTN. Approximately one in five patients may have two major branches of the LTN. This is of clinical relevance to those who undertake any thoracic procedures, as well as those who are considering exploration of the LTN.

Anatomic variations of the intrathoracic nerves and the neural connections of the second and third thoracic sympathetic ganglia to the brachial plexus.

INTRODUCTION: This study investigated morphological variations of the intrathoracic nerves and the neural connections of the second and third thoracic sympathetic ganglia to the brachial plexus based on the existence of the intrathoracic nerves and the rami communicantes. MATERIALS AND METHODS: Fifty thoracic sympathetic trunks from 26 Korean adult cadavers were used. RESULTS: The first intrathoracic nerve connecting the first and second thoracic nerves was observed on 36 sides (72%), and the second intrathoracic nerve connecting the second and third thoracic nerves was found on three sides (6%). There were either one (62%) or two (10%) first intrathoracic nerves, and only one second intrathoracic nerve (6%). The neural connections of the second and third thoracic sympathetic ganglia to the first thoracic nerve were classified into three types based on the existence of the intrathoracic nerves: Type I (68%) had only the first intrathoracic nerve, Type II (26%) had no intrathoracic nerve, and Type III (6%) had both the first and second intrathoracic nerves. Types I, II, and III were further subdivided into 10, 6, and 3 types, respectively, according to the types of the rami communicantes arising from the second and third thoracic sympathetic ganglia. CONCLUSIONS: Improved knowledge of the variations in intrathoracic nerves and upper thoracic sympathetic ganglia will be helpful to thoracic surgeons when they are disrupting the sympathetic supply to the hand for treating palmar hyperhidrosis, and contribute to successful diagnoses and treatments.

Comparative anatomy of the brachial plexus and shoulder nerves of the Sapajus.

BACKGROUND: The capuchin is a neotropical primate that presents easy reproduction in captivity and is used in scientific research. The objective of this work was to describe the structure and the branching pattern of the brachial plexus of the capuchin and to compare the results with data from the literature for humans, chimpanzees, baboons and Callithrix. METHODS: Twelve specimens were used: eight males and four females. No animals were killed for the purpose of this study. RESULTS: The brachial plexus of Sapajus sp was constituted mainly from the ventral roots of the last four cervical spinal nerves, from C5 to C8, mainly, and the first thoracic nerve (T1). CONCLUSIONS: The pattern of formation of the brachial plexus of the capuchin monkey was more similar to that of Callithrix and baboons, perhaps because they are the only primates in this study to be essentially quadrupedal.

Ultrasonographic anatomy of the long thoracic nerve: A reappraisal using high frequency (24-MHz) probe.

PURPOSE: The purpose of this study was to analyze the potential of ultrasound with a high frequency probe (24-MHz) in the assessment of the long thoracic nerve (LTN) and describe ultrasonographic landmarks that can be used for standardization. MATERIAL AND METHODS: Ultrasonography analysis of the LTN was done on 2 LTNs in a cadaver specimen and then on 30 LTNs in 15 healthy volunteers (12 men, 3 women; mean age, 28.8±3.8 [SD] years; age range: 24-39 years) by two independent radiologists (R1 and R2) using a 24-MHz probe. Interrater agreement was assessed using Kappa test (K) and intraclass correlation coefficient (ICC). RESULTS: In the cadaver, dissection confirmed that the India ink was injected near the LTN in the middle scalene muscle. In volunteers, visibility of the LTN above the clavicle was highly reproducible for the branches arising from C5 (R1: 87% [26/30]; R2: 90% [27/30]; K=0.83) and from C6 (R1: 100% [30/30]; R2: 97% [29/30]; K=0.94). Where the nerve emerged from the middle scalene muscle, the mean diameter was 0.85±0.24 (SD) mm (range: 0.4-1.6mm) for R1 and 0.9±0.23 (SD) mm (range: 0.4-1.7mm) for R2 (ICC: 0.96; 95% CI: 0.92-0.98%). Along the thoracic wall, where LTN run along the lateral thoracic artery, the mean diameter was 0.83±0.19 (SD) mm (range: 0.5-1.27mm) for R1 and 0.89±0.21 (SD) mm (range: 0.6-1.2mm) for R2 (ICC: 0.86; 95% CI: 0.72-0.93%). CONCLUSION: The LTN can be analyzed with ultrasound using high-frequency probe by using the C5 and C6 roots, the middle scalene muscle above the clavicle and the lateral thoracic artery on the chest wall as landmarks.

Analysis of the positional relationship of the long thoracic nerve considering clinical treatment.

INTRODUCTION: The long thoracic nerve (LTN) has a risk of being damaged during chest surgery and should be considered when performing anesthesia such as a serratus anterior plane block (SAPB). We analyzed the relationship between landmarks-the fourth to ninth intercostal space (ICS) at the midaxillary line (MAL), through which the distal part of the LTN passes-and the LTN. MATERIALS AND METHODS: We used 25 specimens from 17 embalmed Korean cadavers. The MAL, level of rib and ICS, and regions 5 cm anteroposterior to the MAL (aMAL/pMAL) were established to measure the position of the LTN crossing the MAL, pathway of the LTN, and entering points of the LTN to the SA. RESULTS: The LTN crossed the MAL in 76% of the specimens. The LTN crossed the MAL within the fifth to sixth rib level in 70.8%. Seventy-six percent of the branches entered the SA within the fourth to sixth ICS. The fifth rib and ICS were the most frequent regions aMAL; however, several branches were found pMAL. The LTN entered the SA in 92.6% of the specimens within 3 cm anterior and 1 cm posterior to the MAL. CONCLUSIONS: We set the danger zone as 4 cm near the MAL at the fourth to sixth ICS for thoracotomy. In addition, we proposed the fifth ICS in aMAL at the superficial plane as the alternative injection point for SAPB when blocking the LTN, and the fifth ICS in pMAL at the deep plane to prevent blocking the LTN.

Anatomical Evaluation of a Conventional Pectoralis II Versus a Subserratus Plane Block for Breast Surgery.

BACKGROUND: Pectoralis I and II (Pecs I/Pecs II) blocks are modern regional anesthetic techniques performed in combination to anesthetize the nerves involved in breast surgery and axillary node dissection. Pecs II spread and clinical efficacy is thought to be independent of whether injection occurs between pectoralis minor and serratus anterior or deep to serratus anterior. Injecting deep to serratus anterior onto the rib may be technically easier; however, our clinical experience suggests that this approach may be less effective for axillary dissection. We undertook a cadaveric study to evaluate a subserratus plane approach for use in breast and axillary surgery. METHODS: Ultrasound-guided blocks using methylene blue dye were performed on 4 Genelyn-embalmed cadavers to assess and compare dye spread after a conventional Pecs II and a subserratus plane block at the third rib. RESULTS: Conventional Pecs II injection demonstrated staining of the intercostobrachial nerve, third intercostal nerve, thoracodorsal nerve, long thoracic nerve, medial pectoral, and lateral pectoral nerve. The subserratus plane produced significantly less axillary spread, incomplete staining of the medial pectoral, and very minimal staining of the lateral pectoral nerve. Dye spread was limited to the lateral cutaneous branches of the intercostal nerves in both injections. CONCLUSIONS: In our cadaveric study, injecting deep to serratus plane produced significantly less axillary spread. For breast surgery excluding the axilla, both techniques may be effective; however, for axillary dissection, the conventional Pecs II is likely to produce superior analgesia and additionally may help achieve complete coverage of the deeper pectoral nerve branches.

Innervation of the clavicular part of the deltoid muscle by the lateral pectoral nerve.

INTRODUCTION: The innervation pattern of the clavicular head of the deltoid muscle and its corresponding topography was investigated via cadaveric dissection in the present study, focusing on the lateral pectoral nerve. MATERIALS AND METHODS: Fifty-eight upper extremities were dissected and the nerve supplies to the deltoid muscle and the variability of the lateral pectoral and axillary nerves, including their topographical patterns, were noted. RESULTS: The clavicular portion of the deltoid muscle received a deltoid branch from the lateral pectoral nerve in 86.2% of cases. Two topographical patterns of the lateral pectoral nerve were observed, depending on the branching level from the brachial plexus: a proximal variant, where the nerve entered the pectoral region under the clavicle, and a distal variant, where the nerve entered the pectoral region from the axillary fossa around the caudal border of the pectoralis minor. These dissection findings were supported by histological confirmation of peripheral nerve tissue entering the clavicular part of the deltoid muscle. CONCLUSIONS: The topographical variations of the lateral pectoral nerve are relevant for orthopedic and trauma surgeons and neurologists. These new data could revise the interpretation of deltoid muscle atrophy and of thoracic outlet and pectoralis minor compression syndromes. They could also explain the residual anteversion function of the arm after axillary nerve injury and deficiency, which is often thought to be related to biceps brachii muscle function.

Anatomical entrapment of the dorsal scapular and long thoracic nerves, secondary to brachial plexus piercing variation.

Circumscapular pain is a frequent complaint in clinical practice. The dorsal scapular and long thoracic nerves course through the neck, where they may become entrapped between or within adjacent scalene muscles. Additionally, a high frequency of brachial plexus "piercing" variants have recently been documented, and it is unclear how they influence branching patterns distally along the brachial plexus. In the project reported here we strived to identify and quantify variations in dorsal scapular nerve and long thoracic nerve secondary to brachial plexus piercing variation. Ninety brachial plexuses from human cadavers (45 female/45 male) were evaluated to identify nerve branching patterns, specifically piercing versus non-piercing variants in the brachial plexus roots and nerves. Anatomical entrapment of the dorsal scapular nerve and long thoracic nerve was found in high frequencies (60.8% and 44.6%, respectively). Anomalous brachial plexus piercing variants were associated with higher frequencies of distal nerve branches also coursing through the scalene musculature, and there was a statistically significant correlation between brachial plexus and long thoracic nerve piercings (p = 0.027). Anatomical entrapment of nerves within scalene musculature is common and may be causative factors for idiopathic circumscapular pain, dorsalgia, and dysfunction of scapulohumeral rhythm. This study revealed a link between anatomical arrangement of the brachial plexus and occurrence of long thoracic nerve entrapment, which may lead to a series of cascading neurologic effects in which affected individuals may suffer from increased incidence of thoracic outlet syndrome and long thoracic nerve entrapment resulting in additional symptoms of interscapular pain and compromised shoulder mobility.

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.

Anatomical study of the ventral rami of thoracic spinal nerves in Sapajus apella (Primates: Cebidae).

This study aimed to describe the gross anatomy of the ventral rami of the thoracic spinal nerves in capuchin monkey (Sapajus apella) and compare with humans and other primate species. Eight specimens, prepared in 10% formalin solution and dissected following routine standard techniques, were used. The animals presented 13-14 pairs of thoracic spinal nerves emerging from the intervertebral foramen and divided into dorsal and ventral rami. The ventral rami of the first 12 or 13 pairs represented intercostal nerves and the latter referred to the subcostal nerve. The intercostal and subcostal nerves gave off muscular and cutaneous branches (lateral and ventral), which promote innervation of muscles and skin associated with the chest and abdominal wall. Atypical anatomy was verified for the 1st, 2nd and 7th to 13th intercostal nerves as well as for the subcostal nerve. The morphological characteristics were similar to those observed in humans and some non-human primates, especially in the absence of collateral branches.

Anatomical Variations of the Pectoralis Major Muscle: Notes on Their Impact on Pectoral Nerve Innervation Patterns and Discussion on Their Clinical Relevance.

BACKGROUND: The presented study attempts to classify individual anatomical variants of the pectoralis major muscle (PM), including rare and unusual findings. Rare cases of muscular anomalies involving the PM or its tendon have been presented. An attempt has also been made to determine whether anatomical variations of the PM may affect the innervation pattern of the lateral and medial pectoral nerves. MATERIAL AND METHODS: The research was carried out on 40 cadavers of both sexes (22 males, 18 females), owing to which 80 PM specimens were examined. RESULTS: Typical PM structure was observed in 63.75% of specimens. The most frequently observed variation was a separate clavicular portion of the PM. In one female cadaver (2.5% of specimens) the hypotrophy of the clavicular portion of the PM was noticed. In two male cadavers (5% of specimens) the fusion between the clavicular portion of the PM and the deltoid muscle was observed. In one of those cadavers, small sub-branches of the lateral pectoral nerve bilaterally joined the clavicular portion of the deltoid muscle. The detailed intramuscular distribution of certain nerve sub-branches was visualized by Sihler's stain. PM is mainly innervated by the lateral pectoral nerve. In all specimens stained by Sihler's technique, the contribution of the intercostal nerves in PM innervation was confirmed. CONCLUSIONS: Surgeons should be aware of anatomic variations of the PM both in planning and in conducting surgeries of the pectoral region.

The Source and the Course of the Articular Branches to the T4-T8 Zygapophysial Joints.

OBJECTIVE: To define the source and the course of the articular branches to the midthoracic zygapophysial ("z") joints. DESIGN: Cadaveric dissection. SETTING: The Gross Anatomy Laboratory of the Duke University School of Medicine. SUBJECTS: Ten human cadaveric thoraces. METHODS: Gross and stereoscopic dissection of dorsal rami T4-T8 was performed bilaterally on 10 adult embalmed cadavers. The medial and lateral branches were traced to their origins from the dorsal rami, and the course of the articular nerves was documented through digital photography. Radio-opaque wire (20 gauge) was applied to the nerves. Fluoroscopic images were obtained to delineate their radiographic course with respect to osseous landmarks. RESULTS: Forty-eight inferior articular branches were identified. Three (6.3%) originated from the medial branch and 44 (91.7%) from the dorsal ramus. One was indeterminate. Fifty-one superior articular branches were identified. Eight (15.7%) originated from the medial branch and 43 (84.3%) from the dorsal ramus. In 12% of cases (6/50), there was side-to-side asymmetry in the origins of the articular branches. Nerves were commonly suspended in the intertransverse space. The articular branches contacted an osseous structure in only 39% of cases. As previously reported, a "descending branch" was not identified in any specimen. CONCLUSIONS: Articular branches to the T4-T8 z-joints have substantial inter- and intraspecimen variability of origin. They typically arise from the dorsal ramus rather than the medial branch and frequently do not contact any osseous structure to allow percutaneous needle placement.

The pecs anesthetic blockade: A correlation between magnetic resonance imaging, ultrasound imaging, reconstructed cross-sectional anatomy and cross-sectional histology.

The interfascial thoracic wall blockades Pecs I and Pecs II are increasingly applied in breast and axillary surgery. Despite the clear anatomical demarcations depicted at their introduction, the clinical outcome is more variable than would be expected based upon the described anatomy. In order to elucidate factors that explain this variability, we evaluated the spread of each injection-medial Pecs I, lateral Pecs I, the deep injection of the Pecs II-separately. A correlation of in vivo landmarks and ultrasound images with ex vivo ultrasound, reconstructed anatomical planes, histology and magnetic resonance imaging. The medial Pecs I, similar to the sagittal infraclavicular block positioning with needle position medial to the pectoral branch of the thoracoacromial artery, reaches the medial and lateral pectoral nerves. The lateral Pecs I, below the lateral third of the clavicle at the level of the third rib with needle position lateral to the pectoral branch of the thoracoacromial artery, additionally spreads to the axilla and reaches the intercostobrachial nerve. The deep Pecs II injection spreads to the lateral cutaneous part of the III-VI intercostal nerves and reaches the long thoracic nerve. The variability of the Pecs anesthetic blockades is driven by the selected Pecs I approach as only the lateral approach stains the intercostobrachial nerve. The pectoral branch of the thoracoacromial artery can serve as the landmark to differentiate the needle position of the medial and lateral Pecs I block. Clin. Anat. 32:421-429, 2019. © 2019 Wiley Periodicals, Inc.

Predictable Location of Breast Sensory Nerves for Breast Reinnervation.

The sensory innervation to the breast originates from the medial and lateral cutaneous branches of the third to fifth intercostal nerves, which are at risk for injury or loss during mastectomy. Providing reinnervation after mastectomy was introduced almost 20 years ago, but it is not widely performed, perhaps because of the difficulty of locating a recipient nerve. The authors have performed cadaveric dissections to allow for precise anatomical localization of the lateral intercostal branch providing breast sensation. Bilateral chest dissections were performed on 10 female cadavers. The lateral intercostal nerve providing sensation to breast tissue was identified. The distances from the sternum, the midclavicular line, and the lateral pectoralis minor-in addition to nerve diameter-were measured. The nerve was successfully identified bilaterally in all cadavers. The majority of nerves (16 of 20) exited from under the fourth rib. The average distance from the sternum was 13.1 ± 1.3 cm (range, 10 to 15 cm) and the average distance from the midclavicular line was 11.8 ± 2.2 cm (range, 8 to 16 cm). The nerve exited at the lateral border of the pectoralis minor or within 2 cm from the lateral border for all cadavers. The diameter of the nerve was consistently 2 mm. The nerve traveled under the thoracodorsal vessels, aiding in identification. The authors identified the predictable location of the lateral intercostal nerve providing sensation to the breast. The authors hope that by enabling surgeons to locate this nerve, more well-conducted studies will be performed investigating techniques and outcomes for breast reinnervation.

Pectoral Block Failure May Be Due to Incomplete Coverage of Anatomical Targets: A Dissection Study.

BACKGROUND AND OBJECTIVES: The popularization of ultrasound-guided nerve blocks in cosmetic and reconstructive breast surgery calls for better anatomical understanding of chest wall innervation. When inserting subpectoral implants, pain from pocket dissection, stretching of muscle, and release of costal attachments may be relieved by blocking the pectoral nerves in the interpectoral (IP) space.We describe the variable anatomy of the pectoral nerves in the IP space in order to define the area to be covered for sufficient blockade, based on cadaver dissections. METHODS: Twenty-six fresh cadavers were dissected bilaterally. The number, location, and course of the pectoral nerves were recorded. Distances to surface landmarks (sternum, clavicle, and costae) and ultrasound landmarks (thoracoacromial artery [TAA] and pectoralis minor muscle [Pm]) were recorded. RESULTS: The lateral pectoral nerve and the TAA entered together into the IP space 8.9 cm (range, 8.0-12.0 cm) lateral to the midsternal line. The medial pectoral nerve (MPN) had between 1 and 4 branches that pierced the Pm, and 69% had additional branches lateral to the Pm. The muscle-piercing MPN branches were located 3.8 cm (range, 0.4-8.1 cm) and the lateral MPN branches 5.4 cm (range, 3.0-8.4 cm) from the lateral pectoral nerve. The IP course was 2.6 cm (range, 0.7-6.5 cm). All specimens were asymmetrical in location or number of MPN branches. CONCLUSIONS: The MPN branches that innervate the lower part of the pectoralis major muscle are asymmetrical and variable in location and length; all located in a triangular area easily defined by sonographic landmarks, lateral to the TAA.

Cadaveric Study of the Articular Branches of the Shoulder Joint.

BACKGROUND AND OBJECTIVES: This cadaveric study investigated the anatomic relationships of the articular branches of the suprascapular (SN), axillary (AN), and lateral pectoral nerves (LPN), which are potential targets for shoulder analgesia. METHODS: Sixteen embalmed cadavers and 1 unembalmed cadaver, including 33 shoulders total, were dissected. Following dissections, fluoroscopic images were taken to propose an anatomical landmark to be used in shoulder articular branch blockade. RESULTS: Thirty-three shoulders from 17 total cadavers were studied. In a series of 16 shoulders, 16 (100%) of 16 had an intact SN branch innervating the posterior head of the humerus and shoulder capsule. Suprascapular sensory branches coursed laterally from the spinoglenoid notch then toward the glenohumeral joint capsule posteriorly. Axillary nerve articular branches innervated the posterolateral head of the humerus and shoulder capsule in the same 16 (100%) of 16 shoulders. The AN gave branches ascending circumferentially from the quadrangular space to the posterolateral humerus, deep to the deltoid, and inserting at the inferior portion of the posterior joint capsule. In 4 previously dissected and 17 distinct shoulders, intact LPNs could be identified in 14 (67%) of 21 specimens. Of these, 12 (86%) of 14 had articular branches innervating the anterior shoulder joint, and 14 (100%) of 14 LPN articular branches were adjacent to acromial branches of the thoracoacromial blood vessels over the superior aspect of the coracoid process. CONCLUSIONS: Articular branches from the SN, AN, and LPN were identified. Articular branches of the SN and AN insert into the capsule overlying the glenohumeral joint posteriorly. Articular branches of the LPN exist and innervate a portion of the anterior shoulder joint.

Anatomical Evaluation of the Thoracolumbar Nerves Related to the Transversus Abdominis Plane Block Technique in the Dog.

Transversus abdominis plane (TAP) is a fascial plane containing the thoracolumbar nerve branches that innervate the abdominal wall. Limited information is available on the anatomical organization of these nerve branches in the dog, which is of great importance for the success of the TAP block anaesthetic technique. The aim of this study was to describe the origin and conformation of thoracolumbar nerves running through the TAP in 20 hemi-abdominal walls of 10 adult mongrel dog cadavers with an average body weight of 12.6 kg (range: 9.6-15.6). The abdominal walls were dissected from superficial to deep direction, the skin and both obliquus externus abdominis and obliquus internus abdominis muscles were dissected and reflected dorsally to expose the transversus abdominis muscle and the thoracolumbar nerve branches located in this plane. The anatomical features of ventral nerve branches were described. The thoracic nerve branches: T7-T12 and costoabdominalis; and the lumbar nerve branches: iliohypogastricus cranialis, iliohypogastricus caudalis, ilioinguinalis and cutaneus femoris lateralis were identified in all the cadavers. Anatomical variations related to the presence or absence within the TAP of the T7, T8 and T9 nerve branches were found. These variations should be taken into account when planning the TAP block technique in dogs.