This composite educational resource explores the comparative anatomy of the trapeziometacarpal joint and thumb mobility in primates. Panel (A) and (B) provide clinical photographs of capuchin (Sapajus) hand specimens, identifying the trapezium (1) and metacarpal I (2). Panel (B) highlights the specific articular morphology, where the trapezium (1) presents a convex surface and the metacarpal base (2) presents a concave surface. Panel (C) is a schematic illustration demonstrating the interlocking nature of this saddle joint. Panels (D) and (E) present comparative 3D spatial diagrams of hand mechanics. Diagram (D) illustrates the capuchin hand, showing thumb movement primarily restricted to the z-axis due to a flat carpal arrangement. In contrast, Diagram (E) illustrates the human hand, demonstrating how the anterior position of the trapezium and a curved carpal arch allow the thumb to project above the palmar plane and move across x, y, and z axes. This comparative view illustrates the anatomical basis for true opponency in humans compared to the pseudo-opponency of non-human primates.

This figure illustrates the fluid mechanics and metachronal coordination of magnetic artificial cilia arrays attached to a curved, S-shaped substrate featuring both convex and concave geometries. The left column presents time-lapse snapshots of fluid velocity distribution over one actuation cycle (T), where color heatmaps represent velocity magnitude (µm/s) and vector arrows indicate flow direction. On the convex surface, magnetic strokes generate a predominantly leftward flow, while on the concave surface, the confinement induces vortex formation, specifically counterclockwise global vortices and propagating clockwise local vortices. The right column displays the corresponding cilium motion, distinguishing between 'magnetic strokes' (black arrows) and 'elastic strokes' (red arrows). The cilia exhibit metachronal coordination—coordinated wave-like movements—where the wave propagation direction depends on surface curvature. This biomedical engineering model demonstrates how surface topography can be used to control fluid transport and metachronal patterns, analogous to biological ciliary systems found in the respiratory tract or fallopian tubes.

This series of three axial CT images of the shoulder joint illustrates subjective morphological variations of the glenoid articular surface at its mid-level. The images demonstrate the relationship between the center of the glenoid fossa and the anterior and posterior articular rims to classify joint concavity. Image A shows a convex glenoid surface, where the center of the bone bulges outward toward the humeral head. Image B depicts a flat glenoid surface, showing a straight linear relationship where the center is level with the articular rims. Image C displays a standard concave glenoid surface, where the center of the fossa is deeper than the surrounding articular rims. These anatomical variations are clinically significant in the assessment of shoulder stability, shoulder hyperlaxity, and glenoid dysplasia. The images highlight the contrast between normal anatomy (concave) and variations found in patients with clinical hyperlaxity (convex or flat), providing educational insight into glenohumeral joint morphology and its impact on joint biomechanics.

This diagnostic image is an axial T2-weighted MRI of the knee joint with fat suppression, illustrating severe trochlear dysplasia classified as Dejour type C. The primary visual findings include a characteristic convexity of the lateral femoral condyle paired with significant hypoplasia of the medial femoral condyle, resulting in a flat or even convex trochlear surface rather than a normal concave groove. The patella is clearly lateralized and exhibits a lateral tilt relative to the femoral trochlea, indicating patellofemoral instability. High signal intensity fluid is visible within the joint space, and there are signs of chondral thinning and loss along the patellar facets. This image serves as a clinical example for orthopedic and radiological evaluation of recurrent patellar dislocation and developmental anomalies of the knee extensor mechanism.

This clinical photograph, divided into two panels (A and B), illustrates a manual therapy technique known as Mulligan's Movement with Mobilization (MWM) for the acromioclavicular (AC) joint. The procedure is performed on a seated patient with a suspected AC joint sprain. A mobilization belt or strap is utilized, passing over the patient's left acromioclavicular joint and anchored around the clinician's hip (out of frame) to apply a sustained inferior-posterior glide to the distal clavicle. Panel A shows the starting position: the clinician, wearing a white coat, stands behind the patient, stabilizing the shoulder girdle and applying the mobilization force. Panel B depicts the dynamic component of the technique, where the patient performs active shoulder flexion (reaching overhead with a clenched fist) while the clinician maintains the therapeutic mobilization glide. This orthopedic intervention is used to restore pain-free range of motion and joint arthrokinematics during shoulder rehabilitation. The images demonstrate the precise hand placement and belt orientation necessary for stabilizing the scapula while mobilizing the AC joint during active movement.

Clinical photograph illustrating a 'Mobilization with Movement' (MWM) technique for shoulder abduction in a patient with rotator cuff pathology. The image shows a healthcare professional in a white coat providing manual assistance to a patient's right shoulder. The patient's arm is elevated in a high degree of abduction. A yellow mobilization belt or resistance band is positioned around the proximal humerus to provide a sustained glide, likely lateral or inferior, aimed at improving joint arthrokinematics during active movement. The setting is a clinical rehabilitation environment, evidenced by a hospital bed with railings and medical signage in the background. This visual demonstrates a common physical therapy intervention used to increase range of motion and reduce pain in patients experiencing shoulder impingement or tendinopathy. The educational focus is on the manual application of orthopedic physical therapy techniques and the use of external aids to facilitate joint mobilization.

A clinical photograph illustrating a manual therapy technique for the wrist joint, specifically a weight-bearing lateral (ulnar) glide. The image depicts a physical therapist and a patient in a clinical setting. The patient stands with their forearm vertically oriented and the hand resting flat on a treatment table, simulating a weight-bearing position. The therapist is positioned to the left, utilizing a gray Mulligan belt (mobilization belt) looped around their own waist and the patient's distal forearm/wrist. This setup allows the therapist to use their body weight to provide a sustained lateral mobilization force. The therapist's hands are placed over the patient's wrist and hand to stabilize the joint and guide the glide direction. This technique is part of the 'Mobilization with Movement' (MWM) concept, typically used to improve range of motion and reduce pain in patients with musculoskeletal wrist dysfunction. The focus is on the biomechanical alignment and the application of manual force through specialized orthopedic equipment.