Structural Anatomy
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/30455
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Browsing Structural Anatomy by Author "Fisher, Cara"
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Item A Case of An Accessory Levator Scapulae Muscle(2021) Mong, Joy; Wagner, Lianne; Fisher, CaraBackground: The levator scapulae is a posterior axioappendicular muscle that attaches the upper limb to the vertebral column. It originates from C1-C4 transverse processes and inserts on the margin of the superomedial angle of the scapula. This case report documents a variation of the musculature in the levator scapulae with a unilateral accessory muscle inserting into the trapezius instead of the scapula. There have been some documented cases of anatomical variations of levator scapulae, however these variations were usually found to be of atypical origin or insertion. There have not been any documented cases of an accessory levator scapulae muscle belly matching the morphology noted here. The clinical implications of anatomical variants such as this one must be considered. Case Information: During a detailed cadaver dissection, a left unilateral accessory muscle of the levator scapulae was discovered. It originated just anterior to the bulk of the levator scapulae at the C2 level and inserted into the superior descending trapezius. This accessory levator scapulae measured 6.5 cm long and 0.5 cm wide. Conclusion: Knowledge of anatomical variants of levator scapulae is relevant to clinicians working in the fields of surgery, neurology, radiology and musculoskeletal medicine. This muscle is frequently implicated in the etiopathology of neck and shoulder pain and increased tension in levator scapulae has also been linked to increased cervicogenic headaches. Structural variations, such as this, may be a contributing factor to postural abnormalities leading to chronic myofascial pain and headaches.Item Aberrant Extensor Digitorum Tendon Lies Superficial to Extensor Retinaculum(2021) Son, Benjamin; Evans, Zachary; Paez-Espinoza, Monserrat; Brevell, Bailey; Fisher, CaraBACKGROUND: The extensor digitorum muscle (EDM) is located on the posterior aspect of the forearm. The tendons of this muscle typically run deep to the extensor retinaculum (ER), which is a fibrous sheath that stabilizes and aligns the extensor tendons. ER has been used in the past as a graft source to treat Boxer's Knuckle, an injury of the metacarpophalangeal (MP) joint capsule. This indicates the minor role ER plays in physiologic function. EDM is innervated by the posterior interosseous nerve, a branch of the radial nerve, and is used in extending digits 2 through 5. CASE INFORMATION: This case report presents an anatomical variance that was found within a 66-year-old male cadaver's EDM. The most medial tendon of the extensor digitorum lies superficial to the extensor retinaculum. We have theorized that this anatomical variance would present itself in a similar manner as the palmaris longus tendon. CONCLUSION: To our knowledge, this anatomic variation has yet to be documented. The donor's medical history reports no motor dysfunction to the phalanges, thus it has been concluded that this variation contributed to no complications. The lack of previous documentation on this variant, both in scientific literature and the donor's personal medical history, leads us to suspect that the variant is either uncommon or not of mechanical significance.Item Accessory Iliacus Muscle with Split Femoral Nerve: A Case Report(2021) Barnes, Kalan; Kluber, Kristen; Lee, Yein; Fisher, CaraBackground: The femoral nerve originates from the anterior rami of nerve roots L2, L3, and L4 of the lumbar plexus. In its usual course, the femoral nerve descends down between the psoas major and iliacus muscles of the posterior abdominal wall where it supplies branches to the iliacus and pectineus muscles prior to entering the thigh through the femoral triangle. Subsequently, it splits into multiple branches to supply the muscles and skin of the anterior thigh. Case Information: Herein, we report a variant of this course where during routine dissection of the posterior abdominal wall, an accessory iliacus muscle and split femoral nerve was observed on the right side of a 75-year-old female cadaver. The femoral nerve had divided into two branches that passed anterior and posterior to the accessory iliacus muscle prior to leaving the pelvis. After the two branches descended below the inguinal canal, the posterior branch split again into medial and lateral branches. The original anterior branch combined with the medial branch before splitting again. In addition, the accessory iliacus muscle had its own tendon that inserted a few millimeters below the lesser trochanter of the femur. Conclusions: Knowledge of the existence of muscle and nerve variants is useful in determining the pathology and proper treatment for tendinopathies, compressive neuropathies, and other pathological states. In this study, a rare nerve variant and accessory muscle has been described along with potential clinical implications.Item Anatomic relationships in a set of thoracopagus twins(2021) Dickerson, Austin; Fisher, CaraBackground: Conjoined twins occur from aberrant embryogenesis, at an estimated incidence of 1 in 200,000 births, with many being stillborn. There are many subtypes of conjoined twins, with their classifications based on anatomical relationships between the two individuals. Similarly, twin survival to birth and potential for surgical separation are based largely on anatomy, especially organ sharing. In the field of pediatric surgery, advances have been made in the understanding of this unique condition and the factors that affect twin survival. This case details the specific anatomy of a set of conjoined female twins. Case Information: Detailed dissection of female conjoined twins reveals unique anatomic relationships and organ sharing between the two. The twins are thoracopagus, or joined at the thorax. Each twin has a separate head and a separate pair of upper and lower extremities. There are distinct, separate abdomens and pelves. The twins share a heart, diaphragm, and liver. Each has separate sets of lungs, and separate foregut, midgut, and hindgut structures. Conclusions: Medical and surgical management of conjoined twins depends largely on the highly variable anatomy and the resulting impacts on physiology. This case report details a set of thoracopagus twins and their unique anatomy. The twins share a heart, which occurs in nearly all thoracopagus twins, and is rarely compatible with life. While the medical history of the twins described here is unknown, a detailed dissection of this well-preserved specimen and exploration of anatomic relationships adds to the current literature and understanding of this unique condition.Item Anatomical Variation in a Deep Back Muscle and Possible Implications(2021) Floyd, Jillian; Meehan, Grace; Park, Clair; Riggs, Alison; Hayes, Olivia; Fisher, CaraBackground: The longissimus thoracis muscle is a part of the erector spinae muscle group, originating from the thoracolumbar fascia, and inserting onto the transverse processes of the first through twelfth thoracic spinevertebrae. The multifidus muscle originates from the posterior superior iliac spine (PSIS) and inserts into on the spinous processes; . iIt is involved in extension and stabilization of the vertebrae in localized movements. Dysfunctions of these muscles are often associated with low back pain, a common complaint among U.S. patients. Case Presentation: This case study describes a novel anatomical variation in the musculature of the deep back discovered during a routine dissection of a 72-year-old female cadaver. The variation identified in this subject is located unilaterally on the right side, from the PSIS, and ends at the transverse process of the third lumbar spinevertebrae. Conclusions: Based on our literature review, we have concluded that the variation is an atypical deep back muscle. Future studies could examine the effects of these variants, and their implication, in somatic and physiological dysfunctions, such as scoliosis.Item Bilateral Enlarged Testes: A Case Report(2021) Spore, Paul; Ly, Connie; Mathews, Joel; West, Lauren; Fisher, CaraBackground: The major components of the male reproductive system consist of the penis, scrotum, testes, and the epididymis. The testicles begin in the abdominal cavity in the fetus and descend through the processus vaginalis in the abdominal wall. If the processus vaginalis remains patent after birth, this can predispose a person to indirect inguinal hernias of the intestine. Case Information: During a routine cadaver dissection, a 76-year old male presented with bilateral enlarged testes, both nearly five times the size of an average male testis. Removal of the outer layers of the scrotum revealed solidified green, yellow, and grayish purulent exudate surrounding both testes between the layers of the parietal and visceral tunica vaginalis. The presentation of both testes differed greatly. The left testis was easily compressible and had a large varicocele, while the right testis was turgid and contained a large hematoma. The inferior pole of the left testis had extensive fibrous scarring and epididymal-testis junction and the anterior surface of left testis had two small nodules protruding from the tunica albuginea. In addition to the findings within the reproductive system, an indirect inguinal hernia was identified within the right spermatic cord. Conclusion: We believe the cause of the bilateral enlarged testes were from two different sources rather than a single disease or incident, due to the stark differences between the two. This case report attempts to further the understanding of the causes of enlarged testes and the relationship between gastrointestinal and reproductive disorders.Item Intermuscular Lipoma: A Case Report(2021) Bilbao, Jorge; Fisher, CaraBackground: Lipomas are the most common type of soft-tissue tumors. Superficial lipomas account for about 50% of all soft-tissue tumors and are usually found in the upper back, neck, proximal extremities, and abdomen. Deep-seated lipomas are far less common and usually found in the lower extremity, trunk, shoulder, and upper extremity. Case Presentation: In our study we report a case of a deep-seated, intermuscular lipoma with a rare location in the erector spinae musculature of the lower back. This mass was found during a routine dissection of a 68-year-old male cadaver and it serves to expand knowledge on the anatomical aspects of rare intermuscular lipoma locations. On gross examination, the lipomatous mass was seemingly circumscribed with a uniform, yellowish adipose color, lobulated surface, and soft consistency. Histological examination exhibited a discrete mass of uniform, mature adipocytes, which are clearly delineated from the surrounding musculature. Conclusions: These findings are diagnostic of a well-circumscribed intermuscular lipoma. It is important to note that these lesions are benign and have no metastatic potential. Knowledge of rare intermuscular lipoma locations is necessary for clinicians and surgeons during diagnostic and therapeutic procedures. It is necessary that current clinical guidelines take rare variants into consideration.Item Localizing the Course of the Radial Nerve Based on Anatomical Landmarks: A Cadaveric Study(2021) Barnes, Kalan; Powell, Jake; Beck, Cameron; Skinner, Matthew; Pientka II, William; Fisher, CaraPurpose: Iatrogenic radial nerve injury during the posterior approach to the humerus is a well-documented complication. The aim of this study is to define the course and variability of the radial nerve along the posterior humerus in relationship to the medial and lateral epicondyles. Methods: With the cadaver in a lateral position, the shoulder and elbow were flexed to 90 degrees and supported as done intraoperatively. The epicondyles of the humerus were aligned and tensioned to be held parallel to the operating table. The forearm was clamped in neutral to the supporting pipe. A posterior incision was made over the humerus to expose the triceps muscle. Dissection was continued to the bone and exposure of the radial nerve was completed with care. The location where the radial nerve intersected the medial and lateral edges of the humerus was marked. Images, with a ruler placed on the humerus, were taken of the posterior arm from a standard camera setup. ImageJ was utilized to measure the distance from the epicondyles to where the radial nerve crossed the humerus. Results: Measurements are currently being performed and analyzed in arms of 25 cadavers. Conclusion: Identification of the radial nerve allows for protection of the nerve during a posterior surgical approach to the humerus. This study allows for simple guidelines for orthopedic surgeons to identify the radial nerve and limit iatrogenic injury.Item Massage application to increase spread of local anesthesia in sciatic nerve blocks: a cadaveric study(2021) Robertson, Taylor; Fisher, Cara; Handler, Emma; Nash, DanielIntroduction: Sciatic nerve blockades are essential for treatment of a variety of lower limb pathologies. Due to the complexity and variation of anatomical landmarks, ultrasound (US) is used to guide injection of local anesthesia. In patients with thicker thigh girth (i.e., obese patients) excess tissue can distort US penetration, diminishing efficacy of the nerve block and/or post-operative pain. Dye tracing techniques have been used to test the effectiveness of nerve blocks, but there is little research on using massage to increase anesthetic spread. Therefore, this study will assess whether local massage can spread anesthetic proximal to the injection site. Methods: Fresh cadaveric legs were injected with 15cc's of 25:75 mixture of methylene blue dye and 0.5% bupivacaine. The specimens were divided into control (non-massage) and experimental (massage) groups. Nerve blockades with dye were performed by an anesthetist using US guidance at the popliteal fossa traveling proximally until the formation of the sciatic nerve, where the location was tagged. Immediately following, experimental specimens received repeated, proximally directed massages with the US transducer head. Specimens from both groups were dissected to expose the sciatic nerve. Measurements of the distance traveled from marked site of injection to proximal end of dyed area were measured and compared using statistical analysis. Results: Researchers expect significant difference in distance of injected materials proximal to injection site in the massage group compared to the experimental group. Conclusion: Post-injection massage can be used in clinical settings to increase efficacy of higher risk local anesthetic injections.Item Multiple Lateral Cervical Musculature Variation: A Case Report(2021) Wagner, Lianne; Mong, Joy; Fisher, CaraBackground: The paired anterior, middle, and posterior scalene muscles are found in the lateral neck. The anterior scalene originates from the transverse processes (TPs) of C3-C6 and inserts on the first rib. The middle scalene originates from the TPs of C2-C7 and also inserts on the first rib. The posterior scalene originates from the TPs of C5-C7 and inserts on the second rib. The levator scapulae also attaches to the cervical TPs, typically originating from C1-C4 and inserting on the angle of the scapula. This case report documents multiple anatomical variations of the scalenes and levator scapulae in the lateral neck. While there have been case studies on other scalene variations, there are no documented cases matching the morphologies noted here. Case Information: Detailed dissection revealed multiple muscle variations. The first, an accessory middle scalene muscle with two bellies. The superior belly originates at C1-C5 TPs, running in an inferomedial fashion, anterior to the middle scalene. The inferior belly runs in an inferior fashion, anterior to the middle scalene, with some fibers inserting on the middle scalene and the remainder merging with the first intercostal fibers. The second, an accessory levator scapulae muscle, with two bellies coming off the 3rd belly of levator scapulae and attaching to C5. The final variation, the posterior scalene muscle attaching to the first rib instead of the second. Conclusion: Some possible clinical implications of this variant include cervicogenic headaches, thoracic outlet syndrome, and compression of the brachial plexus.Item Plantaris Tendon Insertion Variant(2021) Spore, Paul; Fisher, CaraBackground: The plantaris muscle is thought to be a vestigial muscle and its tendon lies between the gastrocnemius and soleus muscles. It is most common for the plantaris tendon to insert onto the medial calcaneal tuberosity or onto the calcaneal tendon. The plantaris muscle and tendon insertion are thought to possibly play a role in calcaneal tendinopathy. Although it does not play a significant role in foot plantarflexion, it could possibly play a role in proprioception for the muscles that surround it. Case Information: Dissection of the posterior compartment of the left leg of a - year old embalmed female revealed a rare variation in muscular anatomy. The plantaris tendon inserted into the transverse inter-muscular septum between the tibia and the calcaneal tendon. The literature review revealed that this insertion point occurs approximately 3% of the time. Conclusion: While this variation in insertion is documented, it is the least common of the 5 types of plantaris tendon insertions. This case report attempts to further the understanding of the variance of plantaris tendon insertion points and how they can impact diagnosis and treatment of calcaneal tendinopathy.Item Tibialis Anterior and The Bridle Procedure(2021) Cronk, Jacob; Fisher, CaraBackground: The Bridle procedure is a surgical intervention for the treatment of foot drop due to common fibular nerve damage. It involves the transfer of the tibialis posterior tendon through the interosseus membrane and anastomosis to the tendons of the tibialis anterior and fibularis longus muscles. Case Information: A 54-year-old Caucasian male cadaver presented with abnormal anatomy of the tibialis anterior muscle. Dissection revealed a bifurcation of the tibialis anterior tendon at the level of the superior extensor retinaculum with one part of the tendon continuing to its normal insertion on the medial cuneiform and 1st metatarsal and the other part inserting on the lateral aspect of the cuboid. Further dissection revealed sutures at the point of insertion on the cuboid indicating that surgical fixation had been performed and that this was not an anatomical variation. It was subsequently identified as a "Bridle procedure." Atypically, both tibialis posterior and fibularis longus tendons remained attached to their typical insertions, while the tibialis anterior tendon was split longitudinally. The free part of the tibialis anterior was fixed to the cuboid rather than joined with the fibularis longus tendon. The authors suspect a modified version of the Bridle procedure, but identifying the specific name may be difficult given a limited medical history. Conclusions: This cadaveric case study illustrates a unique presentation of the reconstructed anatomy of a surgical procedure used in the treatment of foot drop or steppage gait pathologies.Item Variation of prevertebral musculature in cadaveric studies(2021) Dickerson, Austin; Fisher, CaraBackground: This case report documents muscular variation observed in a detailed dissection of the prevertebral region of multiple cadavers. The prevertebral region contains the muscles lying between the prevertebral layer of cervical fascia and the vertebral column. The deep location of these muscles means that they are often understudied during routine dissections. The prevertebral muscles lie in close proximity to numerous important neurologic and vascular structures, including the contents of the carotid sheath and the jugular foramen. The rectus capitis lateralis muscle, in particular, is used as a landmark in the microsurgical anatomy in certain extracranial approaches to the jugular foramen. The anatomical variations described in this report have little previous documentation in the literature, and their characterization here adds to the current understanding of variation in the region and its impact on surgical anatomy. Case Information: Detailed dissection of the prevertebral region of multiple embalmed cadavers revealed differing variations in the muscular anatomy. One such variation involved accessory muscles running in superolateral fashion over the anterior portion of the transverse processes of the atlas bilaterally. Conclusions: The muscular variation detailed in this report has implications in surgical approaches to surrounding structures, including the jugular foramen and its contents. Various approaches rely on specific landmarks, which have the possibility to be mistaken or obscured by anatomic variation in the region. Continued study and reporting of variation discovered in the prevertebral region can help characterize common deviations from normal anatomy and aid in surgical planning.