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| Humerus | |
|---|---|
| Name | Humerus |
| Latin | Humerus |
| Partof | Upper limb |
| System | Skeletal system |
| Articulations | Glenohumeral joint, Elbow, Radius, Ulna |
Humerus The humerus is the long bone of the Upper limb that extends from the shoulder to the elbow. It forms key articulations with the Scapula at the Glenohumeral joint and with the Radius and Ulna at the Elbow, serving as an attachment for numerous muscles including those innervated by the Axillary nerve, Radial nerve, and Musculocutaneous nerve. The bone's morphology and development are central to fields such as Orthopedics, Paleontology, Forensic anthropology, and Radiology.
The proximal end features the rounded head that articulates with the Glenoid cavity of the Scapula and the anatomical neck separating the head from the tubercles: the greater tubercle and lesser tubercle, which provide attachment sites for Supraspinatus, Infraspinatus, Teres minor, and Subscapularis (rotator cuff muscles). The surgical neck lies distal to the tubercles and is a common fracture site, relevant to injuries involving the Axillary nerve and posterior circumflex humeral vessels originating from the Axillary artery. The shaft contains the deltoid tuberosity and a spiral radial groove that transmits the Radial nerve and deep brachial artery; the proximal and distal thirds differ in cross-sectional geometry reflecting biomechanical loading patterns studied by Wolff's law and investigators at institutions like Mayo Clinic and Johns Hopkins Hospital.
Distally, the humerus expands into the medial and lateral epicondyles, the trochlea articulating with the Ulna and the capitulum articulating with the Radius. The olecranon fossa, coronoid fossa, and radial fossa accommodate corresponding processes during elbow flexion and extension; these features are routinely assessed in examinations at centers such as Cleveland Clinic and Massachusetts General Hospital.
Ossification of the humerus begins in utero with a primary center in the shaft and secondary centers at the proximal and distal ends. Growth plate (physis) activity occurs under regulation by endocrine factors including Growth hormone, Thyroid hormone, and sex steroids evaluated in research at Harvard Medical School and Stanford University School of Medicine. Developmental anomalies such as congenital pseudoarthrosis, physeal arrest after trauma, and conditions described by Achondroplasia or Osteogenesis imperfecta influence humeral length and morphology; pediatric orthopedics units at Great Ormond Street Hospital and Boston Children's Hospital manage such cases. Embryological patterning involves HOX gene expression characterized in laboratories at institutions like Max Planck Institute and Cold Spring Harbor Laboratory.
The humerus transmits forces between the shoulder girdle and forearm during manipulative and locomotor activities observed in disciplines including Kinesiology and experimental studies at University of Oxford and University of Cambridge. It serves as the lever arm for major muscles: the deltoid elevates the arm, the biceps brachii flexes the elbow and supinates the forearm, while the triceps brachii extends the elbow; these muscle actions are clinically evaluated in examinations at Mayo Clinic and during athletic training at facilities associated with FIFA and IOC. Neurovascular relationships—particularly the close association of the Radial nerve with the spiral groove—are functionally significant in trauma and surgical approaches taught at Royal College of Surgeons programs.
Fractures of the humerus occur at predictable sites: surgical neck fractures risk injury to the Axillary nerve, midshaft fractures may injure the Radial nerve causing wrist drop, and distal supracondylar fractures in children risk neurovascular compromise of the Brachial artery and median nerve; management protocols are standardized by bodies like the American Academy of Orthopaedic Surgeons and British Orthopaedic Association. Degenerative changes at the proximal humerus contribute to shoulder osteoarthritis treated by procedures developed at Hospital for Special Surgery and prosthetic designs from companies such as Stryker and Zimmer Biomet. Tumors—primary lesions like osteosarcoma and metastatic deposits from Breast cancer, Prostate cancer, and Lung cancer—involve multidisciplinary care at centers including MD Anderson Cancer Center and Memorial Sloan Kettering Cancer Center. Congenital deformities, growth arrests, and metabolic bone diseases such as Rickets and Osteoporosis alter humeral integrity; therapeutic approaches include interventions endorsed by World Health Organization guidelines.
Across mammals, the humerus shows variation according to locomotor mode documented in comparative studies at Smithsonian Institution and Natural History Museum, London. In primates such as Homo sapiens, Pan troglodytes, and Gorilla gorilla, humeral morphology reflects manipulative abilities and brachiation; fossil humeri from hominins like Australopithecus afarensis and Homo neanderthalensis contribute to interpretations of locomotor evolution by teams at The Leakey Foundation and Max Planck Institute for Evolutionary Anthropology. In cursorial mammals (e.g., Equus ferus caballus) and fossorial species (e.g., Mole (Talpidae)), the humerus exhibits adaptations in robustness and muscle attachment sites studied by researchers at Royal Veterinary College and University of California, Davis. Avian and reptilian humeri differ markedly, with pneumatized bones in birds such as Gallus gallus linked to flight mechanics researched at Imperial College London.
Radiography, computed tomography, magnetic resonance imaging, and ultrasound are standard modalities for assessing humeral pathology; imaging protocols are described in textbooks from Radiological Society of North America and practiced at specialized centers like Mayo Clinic and Cleveland Clinic. Anthropometric measurements of humeral length and robusticity inform stature estimation in forensic cases handled by agencies such as the FBI and Interpol and by anthropologists at Smithsonian Institution. Advanced techniques—finite element analysis, 3D modeling, and dual-energy X-ray absorptiometry (DXA)—are employed in biomechanical and osteoporosis research at Massachusetts Institute of Technology and Karolinska Institute.
Category:Bones of the upper limb