{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T15:16:30Z","timestamp":1788362190252,"version":"build-2803163510"},"reference-count":34,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T00:00:00Z","timestamp":1788307200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background\/Objectives: The extramuscular branching pattern of the ulnar nerve shows substantial interindividual variability, limiting the value of single-pattern anatomical descriptions. It remains unclear whether the origins of its motor branches are spatially random or retain reproducible relationships with the neural, anthropometric, and musculotendinous organization of the forearm. This study characterized the normalized spatial distribution of the origins of the main ulnar motor branches supplying the flexor carpi ulnaris (FCU) and the ulnar portion of the flexor digitorum profundus (FDP), and examined their relationships with anatomical reference variables measured during dissection. Methods: A cross-sectional cadaveric study was conducted on 16 adult right upper limbs. Fifteen specimens were dissected fresh on the day they were received by the Body Donation Programme; one specimen was frozen at \u221280 \u00b0C, thawed overnight, and dissected the following morning. Standardized anatomical dissection identified 54 main motor branches arising from the ulnar nerve and confirmed their target muscles by direct anatomical continuity (36 FCU and 18 FDP branches). For quantitative mapping, only the origin of each branch on the parent ulnar nerve was recorded using a laser-guided Cartesian coordinate system. Anthropometric dimensions and topographical landmarks were normalized to the corresponding forearm dimensions. Spatial organization was characterized using centroids, 95% data ellipses, Euclidean centroid distances, and a specimen-level cluster bootstrap. Generalized estimating equations (GEE) were used for cluster-aware group comparisons and exploratory multivariable association analysis, while ROC analysis and leave-one-cadaver-out cross-validation quantified internal separation and stability within the cadaveric dataset. Results: FCU and FDP branch origins occupied reproducible but partially overlapping normalized spatial territories. Their centroids differed in location, and specimen-level bootstrap resampling supported the stability of the observed separation. Cluster-aware analyses confirmed differences in the proximodistal branch-origin coordinate and in the tendon-crossing landmark. In the multivariable GEE model, the normalized tendon-crossing landmark showed the strongest adjusted association with group membership, while the proximodistal coordinate also remained associated. Conclusions: Despite marked interindividual variation in ulnar nerve branching, the origins of its main motor branches exhibit reproducible population-level spatial organization. Their distributions are related to the anatomically confirmed target muscle and to normalized neural, anthropometric, and musculotendinous landmarks measured during dissection. This integrated reference framework supports interpretation of peripheral motor innervation as an organized spatial system rather than a collection of isolated variants. The findings provide an anatomical basis for future imaging and image-guided research; however, the exploratory regression and ROC analyses do not constitute a clinically validated diagnostic model.<\/jats:p>","DOI":"10.3390\/diagnostics16172830","type":"journal-article","created":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T14:35:29Z","timestamp":1788359729000},"page":"2830","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Population-Based Quantitative Spatial Mapping of Ulnar Motor Branch Origins in the Forearm: An Integrated Anatomical Reference Framework"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8952-6620","authenticated-orcid":false,"given":"Alexandre","family":"Mer\u00ed-Vived","sequence":"first","affiliation":[{"name":"School of Health Science Blanquerna, Universitat Ramon Llull, 08025 Barcelona, Spain"},{"name":"Unit of Human Anatomy and Embryology, Department of Surgery and Medical-Surgical Specialties, Faculty of Medicine and Health Sciences, University of Barcelona (Campus Cl\u00ednic), 08036 Barcelona, Spain"},{"name":"Faculty of Medicine, University of Vic\u2013Central University of Catalonia, 08500 Vic, Spain"},{"name":"Department of Medicine and Life Sciences, Pompeu Fabra University, 08003 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4763-4054","authenticated-orcid":false,"given":"Pedro V\u00edctor","family":"L\u00f3pez Plaza","sequence":"additional","affiliation":[{"name":"School of Health Science Blanquerna, Universitat Ramon Llull, 08025 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0956-3016","authenticated-orcid":false,"given":"Antoni","family":"Morral Fern\u00e1ndez","sequence":"additional","affiliation":[{"name":"School of Health Science Blanquerna, Universitat Ramon Llull, 08025 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manuel","family":"Llus\u00e0-P\u00e9rez","sequence":"additional","affiliation":[{"name":"Unit of Human Anatomy and Embryology, Department of Surgery and Medical-Surgical Specialties, Faculty of Medicine and Health Sciences, University of Barcelona (Campus Cl\u00ednic), 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-7516-5113","authenticated-orcid":false,"given":"Marcel","family":"Garc\u00eda-Cuesta","sequence":"additional","affiliation":[{"name":"Unit of Human Anatomy and Embryology, Department of Surgery and Medical-Surgical Specialties, Faculty of Medicine and Health Sciences, University of Barcelona (Campus Cl\u00ednic), 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9116-9167","authenticated-orcid":false,"given":"Aroa","family":"Casado Rodr\u00edguez","sequence":"additional","affiliation":[{"name":"Unit of Human Anatomy and Embryology, Department of Surgery and Medical-Surgical Specialties, Faculty of Medicine and Health Sciences, University of Barcelona (Campus Cl\u00ednic), 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1007\/s00330-001-1161-9","article-title":"Ultrasound of tendons and nerves","volume":"12","author":"Martinoli","year":"2002","journal-title":"Eur. Radiol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1051","DOI":"10.1007\/s00256-018-2917-5","article-title":"A review of main anatomical and sonographic features of subcutaneous nerve injuries related to orthopedic surgery","volume":"47","author":"Causeret","year":"2018","journal-title":"Skelet. Radiol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1276","DOI":"10.1212\/CON.0000000000000522","article-title":"Ultrasonography in peripheral nervous system diagnosis","volume":"23","author":"Walker","year":"2017","journal-title":"Continuum"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"687","DOI":"10.1016\/j.pmr.2016.04.006","article-title":"Ultrasound-guided peripheral nerve procedures","volume":"27","author":"Strakowski","year":"2016","journal-title":"Phys. Med. Rehabil. Clin. N. Am."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1043","DOI":"10.1007\/s00276-015-1448-1","article-title":"Motor branches of the ulnar nerve to the forearm: An anatomical study and guidelines for selective neurectomy","volume":"37","author":"Paulos","year":"2015","journal-title":"Surg. Radiol. Anat."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"282","DOI":"10.1097\/PHM.0000000000000007","article-title":"Anatomic localization of motor points of wrist flexors","volume":"93","author":"Song","year":"2014","journal-title":"Am. J. Phys. Med. Rehabil."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"923","DOI":"10.1586\/14737175.2014.936387","article-title":"Ultrasound-guided botulinum toxin injections in neurology: Technique, indications and future perspectives","volume":"14","author":"Walter","year":"2014","journal-title":"Expert Rev. Neurother."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Asimakidou, E., and Sidiropoulos, C. (2023). A Bayesian network meta-analysis and systematic review of guidance techniques in botulinum toxin injections and their hierarchy in the treatment of limb spasticity. Toxins, 15.","DOI":"10.3390\/toxins15040256"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1080\/02688697.2020.1823939","article-title":"Hyperselective neurectomy in the treatment of elbow and wrist spasticity: An anatomical study and incision design","volume":"38","author":"Yu","year":"2024","journal-title":"Br. J. Neurosurg."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"800","DOI":"10.3171\/jns.2006.104.5.800","article-title":"Quantitation of and landmarks for the muscular branches of the ulnar nerve to the forearm for application in peripheral nerve neurotization procedures","volume":"104","author":"Tubbs","year":"2006","journal-title":"J. Neurosurg."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1007\/s00276-009-0580-1","article-title":"The motor branches of median and ulnar nerves that innervate superficial flexor muscles: A study in human fetuses","volume":"32","author":"Dogan","year":"2010","journal-title":"Surg. Radiol. Anat."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"593","DOI":"10.3171\/2023.5.SPINE23210","article-title":"Proximal forearm nerve branching patterns: An anatomical study and its clinical significance","volume":"39","author":"Zancolli","year":"2023","journal-title":"J. Neurosurg. Spine"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"239","DOI":"10.1002\/(SICI)1098-2353(1998)11:4<239::AID-CA3>3.0.CO;2-M","article-title":"Biometry of the muscular branches of the median nerve to the forearm","volume":"11","author":"Canovas","year":"1998","journal-title":"Clin. Anat."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1002\/(SICI)1097-0193(200002)9:2<81::AID-HBM3>3.0.CO;2-8","article-title":"Mathematical\/computational challenges in creating deformable and probabilistic atlases of the human brain","volume":"9","author":"Thompson","year":"2000","journal-title":"Hum. Brain Mapp."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1064","DOI":"10.1016\/j.neuroimage.2007.09.031","article-title":"Construction of a 3D probabilistic atlas of human cortical structures","volume":"39","author":"Shattuck","year":"2008","journal-title":"NeuroImage"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1177\/096228029700600305","article-title":"Statistical methods in computational anatomy","volume":"6","author":"Miller","year":"1997","journal-title":"Stat. Methods Med. Res."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Grekousis, G. (2020). Analyzing geographic distributions and point patterns. Spatial Analysis Methods and Practice: Describe\u2013Explore\u2013Explain Through GIS, Cambridge University Press.","DOI":"10.1017\/9781108614528"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"599","DOI":"10.1016\/S0021-9290(02)00433-5","article-title":"Normalization of joint moments during gait: A comparison of two techniques","volume":"36","author":"Moisio","year":"2003","journal-title":"J. Biomech."},{"key":"ref_19","first-page":"467","article-title":"Normalizing physical performance tests for body size: A proposal for standardization","volume":"19","author":"Jaric","year":"2005","journal-title":"J. Strength Cond. Res."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"S19","DOI":"10.1016\/j.neuroimage.2004.07.021","article-title":"Computational anatomy: Shape, growth, and atrophy comparison via diffeomorphisms","volume":"23","author":"Miller","year":"2004","journal-title":"Neuroimage"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1016\/j.media.2019.04.002","article-title":"Computational anatomy for multi-organ analysis in medical imaging: A review","volume":"56","author":"Cerrolaza","year":"2019","journal-title":"Med. Image Anal."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"422","DOI":"10.1016\/j.neuroimage.2010.03.059","article-title":"Multivariate models of inter-subject anatomical variability","volume":"56","author":"Ashburner","year":"2011","journal-title":"Neuroimage"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Steyerberg, E.W. (2019). Clinical Prediction Models: A Practical Approach to Development, Validation, and Updating, Springer. [2nd ed.].","DOI":"10.1007\/978-3-030-16399-0"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1111\/j.1469-7580.2008.00864.x","article-title":"Structure-function relationships in tendons: A review","volume":"212","author":"Benjamin","year":"2008","journal-title":"J. Anat."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Jakobsen, J.R., and Krogsgaard, M.R. (2021). The myotendinous junction\u2014A vulnerable companion in sports: A narrative review. Front. Physiol., 12.","DOI":"10.3389\/fphys.2021.635561"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1111\/j.1469-7580.2008.01011.x","article-title":"The fascia of the limbs and back\u2014A review","volume":"214","author":"Benjamin","year":"2009","journal-title":"J. Anat."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"234","DOI":"10.1152\/japplphysiol.00565.2017","article-title":"Not merely a protective packing organ? A review of fascia and its force transmission capacity","volume":"124","author":"Wilke","year":"2018","journal-title":"J. Appl. Physiol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"a001735","DOI":"10.1101\/cshperspect.a001735","article-title":"Motor axon pathfinding","volume":"2","author":"Bonanomi","year":"2010","journal-title":"Cold Spring Harb. Perspect. Biol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1242\/dev.046441","article-title":"Developmental regulation of axon branching in the vertebrate nervous system","volume":"138","author":"Gibson","year":"2011","journal-title":"Development"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1038\/nrn3650","article-title":"Branch management: Mechanisms of axon branching in the developing vertebrate CNS","volume":"15","author":"Kalil","year":"2014","journal-title":"Nat. Rev. Neurosci."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Collins, G.S., Reitsma, J.B., Altman, D.G., and Moons, K.G.M. (2015). Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD): The TRIPOD Statement. BMC Med., 13.","DOI":"10.1186\/s12916-014-0241-z"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"e071058","DOI":"10.1136\/bmj-2022-071058","article-title":"Transparent reporting of multivariable prediction models developed or validated using clustered data (TRIPOD-Cluster): Explanation and elaboration","volume":"380","author":"Collins","year":"2023","journal-title":"BMJ"},{"key":"ref_33","first-page":"399","article-title":"Optimal location of botulinum toxin injection in the flexor carpi ulnaris muscle: A cadaveric study","volume":"27","author":"Kim","year":"2005","journal-title":"Surg. Radiol. Anat."},{"key":"ref_34","first-page":"648","article-title":"Localization of motor entry points and intramuscular nerve endings of the forearm muscles using modified Sihler\u2019s staining","volume":"24","author":"Crandall","year":"2011","journal-title":"Clin. Anat."}],"container-title":["Diagnostics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4418\/16\/17\/2830\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T14:44:05Z","timestamp":1788360245000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4418\/16\/17\/2830"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,2]]},"references-count":34,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["diagnostics16172830"],"URL":"https:\/\/doi.org\/10.3390\/diagnostics16172830","relation":{},"ISSN":["2075-4418"],"issn-type":[{"value":"2075-4418","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,2]]}}}