Structural Anatomy
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/30827
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Browsing Structural Anatomy by Author "Fisher, Cara L."
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Item Bilateral Seminal Vesicle Hypoplasia(2022) Cabrero, Daniel; Butson, Carter; Brown, Kerrie; Costello, Kathryn; Fisher, Cara L.Background: Seminal vesicles, two coiled sacs located posteriorly to the male bladder and lateral to the ampulla of the ductus deferens, play a vital role in male fertility. The duct of the seminal vesicle joins with the ampulla of the ductus deferens forming the ejaculatory duct, which then opens into the prostatic urethra. Producing about 70% of male semen, the seminal gland secretes alkaline fluid that contains fructose, prostaglandins, proseminogelin, and other substances that aid in successful fertilization. Contraction of the seminal vesicles releases seminal fluid into the ejaculatory duct where it mixes with spermatozoa from the ductus deferens. Little to no secretions from the seminal vesicles would likely result in male infertility due to the absence of fructose, the primary energy source for motile spermatozoa. Seminal vesicles can be affected by infection, cysts, tumors, hypoplasia, and congenital disease, but isolated seminal vesicle abnormalities are a very uncommon occurrence. There are a few disease states in which seminal vesicle abnormalities do occur. For example, Zinner syndrome is associated with renal agenesis and seminal vesicle hypoplasia or cysts. A Hoxa 13 gene mutation is associated with reduced seminal vesicle size and abnormal morphology, diminished dorsolateral ductal branching of the prostate, and agenesis of the bulbourethral gland. The complete bilateral absence of seminal vesicles can occur following a radical prostatectomy, where the prostate and seminal vesicles are excised together. Case Information: A pelvic dissection of an 82-year-old male donor during a first-year medical anatomy course revealed bilateral seminal vesicle hypoplasia. The seminal vesicle tissue was abnormally tough and embedded within enlarged prostatic tissue. The ductus deferens appeared normal and bilaterally intact. No other significant abnormalities in the reproductive tract nor the kidneys were noted. Conclusions: Based on our current research and ideas, seminal vesicle hypoplasia with no other concurrent reproductive abnormalities is unusual. Apart from the small seminal vesicles, our cadaver had a complete, bilateral set of male internal reproductive organs and an enlarged prostate with no signs of cancer treatment, ruling out the possibility of radical prostatectomy. Due to the presence of an intact urinary tract, Zinner syndrome is unlikely. The most promising possibility for this abnormality is a mutation of the Hoxa 13 gene based on the similarities between this mutation's presentation and our findings.Item Bilaterally Absent Cephalic Veins: A Case Study(2022) Cronk, Jacob; Fajkus, Austin; Do, Tina; Fisher, Cara L.Background: The cephalic vein (CV) is one of the primary veins of the upper limb. It is a superficial vein located on the anterolateral surface of the arm and is a common site for venous access. The typical course begins along the radial aspect of the wrist and forearm where it joins with the median cubital vein (MCV) at the antecubital fossa and continues proximally through the superficial fascia, lateral to the biceps brachii muscle, and into the deltopectoral groove of the shoulder. It terminates by draining into the axillary vein in the deltopectoral triangle. The absence of the CV or variations in its location could have important implications for vascular procedures, such as Arteriovenous (AV) fistulas, which utilize the CV as the primary vein for preparing patients for long-term hemodialysis access. Case Information: An elderly Caucasian male cadaver presented with complete bilateral absence of the CV proximal to the antecubital fossa. Dissection revealed enlarged basilic veins (BV) and MCVs that crossed superficially to the bicipital aponeurosis and continued distally along the anterolateral side of the forearms towards the hands. Both limbs also showed a small anastomosis between the large MCV and the deep brachial vein (DBV) just distal to the bicipital aponeurosis. The BV on the right limb gives off one branch as the MCV that continues along the radial aspect of the forearm. Additionally, two smaller branches emerge and circumvent the medial epicondyle of the humerus and rejoin to form one vein that continues along the medial aspect of the forearm. The left limb showed an interesting anastomotic ring within the portion of the vein that would normally represent the MCV just distal to the bicipital aponeurosis. In contrast to the right limb, there was only one smaller branch from the BV that coursed around the medial epicondyle and travelled along the dorsal aspect of the forearm. The absence of the CV in the deltopectoral groove of both shoulders was also noted. Conclusions: This cadaveric case study illustrates a unique presentation of the upper limb venous architecture. With a significant portion of the U.S population requiring hemodialysis and/or developing end-stage renal disease, there has been an increase in the number of AV fistula procedures performed each year. Therefore, having a greater awareness of the variations of the CV may help to prevent complications in vascular procedures that require its use.Item Hyposplenia(2022) Patterson, Tyler; Ramirez, Cynthia; Park, Chanyang; Sabbaghi, Tiffany; Patel, Kavita; Fisher, Cara L.Background: The spleen is the largest secondary lymphoid organ in the human body. It is an intraperitoneal organ, located in the left upper quadrant, posterior to the stomach and inferior to the diaphragm from the T8-T11 vertebral levels. The typical size of the spleen is 6 cm in width and 10 cm in length, with a depth length of 3 cm. Embryonically, it is derived from mesenchyme in the dorsal mesogastrium, and during fetal development in utero, the spleen transiently functions in the production of blood cells during fetal development. During adulthood, the spleen acts as a major repository for phagocytic cells, lymphocytes, and platelets, with a primary function of blood filtration. Hyposplenia is reduced size and function of the spleen. It is a condition that can complicate many diseases, such as sickle cell anemia, alcoholic liver disease, and many autoimmune disorders. Functional hyposplenia is characterized mostly by defective immune responses against pathogens. This cadaver case report presents the clinical condition of hyposplenia. Case Information: First-year medical students engage in anatomy courses in which routine cadaver dissections are performed. An abnormally small spleen was found in the upper abdominal cavity of a 66-year-old female. The donor presenting with the hyposplenia outlined in this case report passed from acute liver failure of uncertain etiology, chronic kidney disease, and peripheral artery disease. A typical spleen as compared to the cadaver's spleen indicated the cadaver's spleen was drastically reduced in size. The donor's spleen measured 2.72 cm in width and 4.38 cm in length, with a depth of 1.39 cm. Conclusions: In contrast to splenomegaly, the clinical determinant of a small spleen, hyposplenia, is unclear. However, there are potential causes for the spleen's size to decrease. Exposure to radiation, sickle cell disease, diabetes and chronic alcoholism are all hypotheses for this change in size. Patients with a defect in Kupffer cell function in relation to alcoholism have a predisposition to hyposplenism. In this case, the donor had the pathologies of diabetes and liver disease. The cause of death of acute liver failure of uncertain etiology could have been linked to the consumption of alcoholic beverages and their effects on the liver, as well as the effect on the Kupffer cells in the spleen.Item Massage application to decrease anesthetic spread in brachial plexus blocks: A cadaveric study(2022) Coffman, Taylor; Fisher, Cara L.; Handler, Emma; Nash, DanielIntroduction: Peripheral nerve blocks of the brachial plexus have become increasingly popular for upper limb surgery due to the benefits of using regional anesthesia. However, anesthetic from supraclavicular nerve blocks can spread medially and anesthetize the phrenic nerve, leading to partial paralysis of the diaphragm, also known as hemidiaphragmatic paresis. The addition of ultrasound guidance has reduced the incidence of phrenic nerve involvement due to the ability to see the spread of anesthetic in real time. There has been little research focused on whether or not ultrasound massage could manipulate anesthetic distally down the arm and away from the phrenic nerve. The aim of this study is to determine if ultrasound massage can be used to minimize the spread of anesthesia medially. Methods: Four fresh frozen cadavers were injected with 15 mls of a 25:75 mixture of methylene blue and 2% lidocaine. The specimens were divided into control (n=4) and massage (n=4) groups. A nurse anesthetist used ultrasound guidance to perform a supraclavicular block. Immediately following injection, the massage group received 5 distally directed massage strokes with the ultrasound transducer. After 15 minutes, both groups were dissected and measurements of anesthetic spread were taken. The medial spread was measured in all four cadavers and distal spread was measured in three out of the four. Results: Spread of anesthetic medially was not reduced in the massage group when compared to the control group. Distal spread of the anesthetic was increased in the massage group when compared to the control group (p< 0.05). Conclusions: The similarity of medial spread between the two groups implies ultrasound massage application will not prevent phrenic nerve palsy any more than a traditional supraclavicular block. The increased distal spread of the anesthetic suggests this technique can improve anesthesia to the brachial plexus by increasing the area the anesthetic travels. Significance: The incidence of phrenic nerve palsy during a supraclavicular block has decreased since the introduction of ultrasound, but some reservations persist when using the technique in non-healthy patients. Phrenic nerve palsy can cause respiratory distress in patients with pre-existing respiratory condition. Given the small sample size, continued study of this method is needed to further evaluate if this method could be used to reduce incidence of phrenic nerve palsy.Item Massage application to increase the spread of local anesthesia in sciatic nerve blocks: A cadaver study(2022) Robertson, Taylor; Fisher, Cara L.; Handler, Emma; Nash, DanielIntroduction: Sciatic nerve blocks are essential for surgical treatment of various lower limb pathologies. Due to the complexity and variation of anatomical landmarks, ultrasound (US) guided injection of local anesthesia has become common practice. In patients with thicker thigh girth (i.e., obese patients) excess tissue may distort US penetration thereby diminishing efficacy of the nerve block and/or cause severe 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 manipulate anesthetic spread. Therefore, the aim of this study is to assess the effects of massage to manipulate local anesthesia spread in sciatic nerve blocks. We hypothesize massaging after injection will increase the spread of local anesthesia compared to non-massage post injection. Methods: Forty un-fixed cadaveric legs were injected with a mixture of methylene blue dye and 2% Lidocaine Hydrochloride. Specimens were divided into non-massage (control) (n=20) and massage (n=20) groups. Sciatic nerve blocks were performed by a nurse anesthetist using US guidance at the popliteal fossa traveling proximally until the sciatic nerve was identified and the location was tagged. Immediately following, massage group specimens received five repeated proximally directed massages with the US transducer head. Specimens from both groups were then 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. Results: Spread of local anesthesia in the inferior-superior direction was significantly higher in the massage group than the control group (p≤0.05). Conclusions: Massaging post-injection caused a greater spread of local anesthesia during sciatic nerve block. Significance: Sciatic nerve block techniques often utilize nerve stimulation to identify the sciatic nerve location. This may be due to lack of US penetration through the gluteus maximus muscle. In patients with thicker thigh girth due to subcutaneous fat, imaging visibility may be more difficult as well. Our findings suggest that clinicians may block the sciatic nerve at a more distal location with US guidance and manipulate the anesthesia to the region of interestItem Study of Cadaveric Posterior Circumflex Humeral Artery Variations(2022) Fajkus, Austin; Do, Tien; Cronk, Jacob; Fisher, Cara L.Purpose: There are concerns regarding the sequelae of blood clots post-vaccination due to suboptimal administration techniques with the ongoing incentive for vaccination against the Coronavirus Disease 2019 (COVID-19). Specifically, the risk of administering the intramuscular (IM) vaccine into an artery in the deltoid region. The posterior circumflex humeral artery (PCHA) is a small branch originating from the third part of the axillary artery, classically traveling with the axillary nerve, through the quadrangular space, to run along the inferior aspect of the deltoid muscle. This study investigates the presence and prevalence of variations of the PCHA not traversing in its classical path. Methods: Detailed dissection was performed on bilateral shoulders of 10 (n=20) human cadavers. The PCHA was identified in all 20 shoulders and their anatomic locations were assessed and categorized. Results: Of the 20 shoulders studied, 15% had anatomical variations of the posterior circumflex humeral artery traveling superiorly into the upper deltoid. Conclusions: Recent studies have highlighted the possibility of erroneous injection of the COVID-19 vaccine into the bloodstream as a risk of post-vaccination blood clots. The high prevalence of arterial variations revealed in this study provides an impetus for further research investigating the relationship between the variation in arterial anatomy and injection site "safe zones."Item Unilateral Levator Scapulae Anatomical Variant in Female Cadaver(2022) Frangenberg, Alexander; Fisher, Cara L.Background The levator scapulae (LS) muscle is a superficial extrinsic muscle of the back, most commonly originating on the posterior aspect of the transverse processes of the first through fourth cervical vertebrae and inserting on the superior aspect of the medial border of the scapula. These attachment sites further indicate the action of the LS, which along with the trapezius and rhomboid muscles, function to elevate the scapula during overhead upper extremity movements and shrugging of the shoulders. This elevation of the scapula also causes the scapula to rotate clockwise, thus tilting the glenoid cavity inferiorly. If the scapula is fixed, the LS may also function to rotate the neck laterally at the cervical attachment points. The most common pathology of the LS is termed "levator scapulae syndrome" and is commonly due to poor posture, resulting in chronically achy, tight, and tender neck muscles that may impede movement and illicit excess pain. Case Information Dissection of the posterior cervical region and deep upper back on an embalmed 41-year-old female cadaver revealed a unilateral accessory muscle of the left LS muscle. This accessory slip inserted perpendicularly onto the broad aponeurotic fibers of the serratus posterior superior muscle, deep to the rhomboid major muscle. This anatomical variant is present in the literature and is a common site of accessory muscle attachment for the LS. Conclusions This case report describes the anatomical findings in-depth and discusses their prevalence in the literature. Interestingly, the literature indicates a higher predominance of unilateral LS accessory muscles in women compared to men, and this case report further supports this finding. Damage to the LS may be caused by high-velocity injuries, however, the most frequent presentation is implicated in cases of chronic neck pain due to poor posture. Due to the high rates of neck pain diagnosis in U.S. adults from an increasingly sedentary and technology-prevalent lifestyle, variations in muscular anatomy to the LS should not be overlooked. Such variations could play a role in the presence of chronic neck pain through the interaction with vascular and neurologic factors and should be considered during diagnosis and surgery of the region.Item Unilateral Renal Hypoplasia(2022) Wieters, Matthew; Tran, Kylie; Smith, Zane; Thayyil, Hibaa; Weber, Landan; Fisher, Cara L.Background: Unilateral renal hypoplasia can occur as a result of, or in conjunction with, comorbidities such as hypertension, vascular diseases, pyelonephritis, and congenital developmental disorders. Contralateral renal compensation with hypertrophy of the sister kidney is one of the common sequelae of unilateral renal hypoplasia in addition to chronic renal failure (CRF) due to dysfunctional filtration and impaired blood pressure regulation. The incidence of renal hypoplasia according to epidemiological studies is 1 in 400 births. This case report examines the potential causes of a hypoplastic kidney found in the retroperitoneum of an 80-year-old female cadaver. Case Information: Detailed dissection of the left retroperitoneal space of the subject revealed a morphologically hypoplastic kidney with dimensions of 40 mm in length, 21 mm in width, and 13.5 mm in thickness. Hemisection of the kidney revealed cortical thinning as well. Contralateral compensation by the right kidney led to hypertrophic dimensions of 112 mm in length, 64 mm wide, and 46 mm in thickness. Average kidney pole-to-pole length is around 102 mm for the left kidney and 99 mm for the right kidney in women aged 80-89 years. Blood supply to the hypoplastic kidney appeared normal initially, however, upon measurement, the left renal artery was found to be much narrower at 1.72 mm in width in comparison to a typical renal artery diameter of 5 mm. The left renal vein exiting the hypoplastic kidney measured 57 mm in length compared to an average left renal vein length of 60-100 mm. The ureter exiting the left hypoplastic kidney was 1 mm wide while the right ureter measured 3.75 mm in width. No clear pathological characteristics were visualized in the kidney, such as cysts or tissue dysplasia. An additional finding of this case was an abdominal aortic aneurysm (AAA) measuring 140.5 mm from the inferior base at the common iliac artery bifurcation up to the superior border where the superior mesenteric artery branches. The AAA measured 40 mm wide and 27.75 mm in thickness. Conclusions: The compensatory enlarged right kidney and altered dimensions of the artery and vein associated with the hypoplastic kidney indicate potential for abnormal vasculature affecting overall kidney growth and function. The thin cortex also indicates reduced nephrotic function. Renal hypoplasia and impaired renal function predispose an individual to conditions such as hypertension or chronic renal failure. If patients present with a hypoplastic kidney, physicians can monitor potential chronic conditions and provide proper intervention. Likewise, physicians should be aware that patients with chronic cardiovascular and renal conditions are at a greater risk of developing an atrophic kidney if left untreated. Although a definitive etiology is unable to be determined due to a lack of sufficient past medical history, investigation into the relationships of anatomical variants adds to the current literature and understanding of this condition.