Extensor retinaculum of the wrist: gross anatomical correlation with MR imaging after ultrasound-guided tenography with emphasis on anatomical features in wrist dorsiflexion responsible for tendon impingement.

OBJECTIVE: To demonstrate the anatomy of the extensor retinaculum (ER) of the wrist using gross anatomical correlation with magnetic resonance (MR) imaging before and after ultrasound-guided tenography in four different positions, emphasizing the morphological appearance of the ER that occurs with dorsiflexion of the wrist to define the nature of extensor tendon impingement in athletes who perform repetitive wrist dorsiflexion. MATERIALS AND METHODS: Institutional policies were followed regarding cadaver use. Ten upper extremities were harvested from fresh cadavers. MR imaging before and after ultrasound-guided tenography of the wrist was performed, followed by gross anatomical correlation. Two radiologists interpreted the MR images and sections by consensus for the anatomical landmarks of the ER, and morphological changes occurring during dorsiflexion of the wrist were analyzed and measured. RESULTS: The ER of the wrist appeared as a band of low signal intensity on T1- and PD-weighted images. Because of its orientation, axial images were best suited to depict the ER anatomy; specifically, localization of the bony landmarks and the septal attachments. On sagittal images, a consistent appearance of the ER was seen: appearing with fusiform morphology in the neutral position, and becoming shortened and thickened at the abutment point where the extensor tendons of the fourth compartment had a curved excursion during dorsiflexion. The width and thickness of the ER in neutral position averaged 13.56 mm and 1.67 mm respectively. In wrist dorsiflexion, the average width and thickness changed to 8.68 mm and 2.15 mm respectively. CONCLUSION: Magnetic resonance imaging is a useful technique to demonstrate the ER of the wrist, the septal attachments, and morphological changes that occur during dorsiflexion of the wrist, which potentially can lead to impingement of the extensor tendons.

Capsular ligaments of the hip: anatomic, histologic, and positional study in cadaveric specimens with MR arthrography.

PURPOSE: To demonstrate the anatomy of the capsular ligaments of the hip by using magnetic resonance (MR) arthrography. MATERIALS AND METHODS: Institutional policies were followed regarding cadaver use. MR arthrographic images of 10 fresh human cadaveric hips were obtained by using a positioning device to arrange the hip joint in different controlled positions. MR appearances of the capsular structures were noted and correlated with those seen on anatomic slices and dissections. Two readers working in consensus graded the visibility of these structures. Tissue samples were collected for histologic analysis. An MR positional study was performed to evaluate the length of these capsular ligaments and the subjective classification of their appearance as either taut or lax in extension, flexion, abduction, adduction, and internal and external rotation. RESULTS: The hip capsule inserts proximally and continuously to the acetabular rim periosteum. Distally, it has a firm anterior insertion at the femoral intertrochanteric line and no posterior osseous insertion. The inferior band of the iliofemoral ligament was best evaluated in the sagittal, axial, and axial oblique planes, and it serves a restrictive function in extension; the superior band of the iliofemoral ligament was best evaluated in the coronal and axial oblique planes, and it serves a restrictive function in external rotation; the ischiofemoral ligament was best evaluated in the axial and axial oblique planes, and it serves a restrictive role in internal rotation; the pubofemoral ligament was best evaluated in the sagittal plane, and it serves a restrictive function in abduction; and the zona orbicularis could be evaluated equally well in any imaging plane. CONCLUSION: MR arthrography enables visualization of the capsular ligaments of the hip.

Ultrasound assessment of the lateral collateral ligamentous complex of the elbow: imaging aspects in cadavers and normal volunteers.

OBJECTIVE: The Lateral Collateral Ligamentous complex (LCL) is an important stabiliser of the elbow. It has a Y-shaped structure with three components. In this study, we sought to describe the ultrasound aspect of the individual components of this ligamentous complex and to evaluate the performance of ultrasound in both cadavers and in normal subjects. METHODS: Ten cadaveric elbow specimens underwent high-frequency ultrasound. Two specimens were sliced and two were dissected for anatomical correlation. Ten elbows of normal subjects were also evaluated by ultrasound. The findings were compared. RESULTS: The three components of the LCL could be visualised in all specimens and normal subjects with the exception of the proximal portion of one specimen. In 80% of the specimens and 100% of the healthy volunteers the proximal portion of the LCL could be separated from the extensor tendons. CONCLUSION: High-resolution ultrasound can assess all components of the LCL of the elbow and can distinguish them from surrounding structures.

High-resolution ultrasound evaluation of the trapeziometacarpal joint with emphasis on the anterior oblique ligament (beak ligament).

INTRODUCTION: The anterior oblique ligament is one of the main stabilizers of the trapeziometacarpal joint. Insufficiency of this ligament is closely linked to degenerative joint disease. High-resolution musculoskeletal ultrasound has advantages over magnetic resonance imaging (availability, dynamic nature, cost, patient comfort). This study evaluates the feasibility of ultrasound of the anterior oblique ligament. MATERIAL AND METHODS: Ten cadaveric thumb specimens and 10 volunteers with normal trapeziometacarpal joints underwent imaging with high-frequency ultrasound. An ultrasound-guided, progressive dissection technique was used to confirm the ultrasound findings. Two radiologists reviewed the images in consensus. The detectability of the ligament was rated. RESULTS: The anterior oblique ligament was identified and measured in 90% of the specimens and 100% of the volunteers. The ultrasound findings correlated well with the dissections. This ligament appeared as a thin hypoechogenic structure in the ulnar-most part of the trapeziometacarpal joint, with a thickness that varied from 1.0 to 2.0 mm. Detectability of this ligament was good in 66% of the specimens and 100% of the volunteers. CONCLUSION: Ultrasound evaluation of the anterior oblique ligament of the trapeziometacarpal joint is feasible with state of the art equipment.

Tibiofibular syndesmotic ligaments: MR arthrography in cadavers with anatomic correlation.

PURPOSE: To use magnetic resonance (MR) imaging and MR arthrography to characterize the normal anatomy of the tibiofibular syndesmotic ligaments with standard and oblique imaging planes in cadavers. MATERIALS AND METHODS: Ten cadaveric ankle specimens were obtained and used in accordance with institutional and HIPAA guidelines, and informed consent for research was obtained from relatives of the deceased. MR imaging was performed before and after intraarticular administration of contrast material. Proton-density-weighted MR images were correlated with anatomic slices. RESULTS: The anterior inferior tibiofibular ligament (AITFL) had a variable number of bands in all specimens. A separate distal band was identified in all specimens, revealing a more horizontal course than other components of the AITFL and attaching more medially to the anterior margin of the tibial plafond. The posterior inferior tibiofibular ligament (PITFL) and inferior transverse ligament were best seen in coronal oblique planes. The posterior intermalleolar ligament was observed in all specimens and had a variable appearance that ranged from a thin strand to a thick cord. The interosseous ligament (IOL) coursed obliquely to attach proximally to the tibia and insert distally in the fibula. This ligament was fenestrated with separate anterior and posterior fibers. The anterior fibers were more proximal, and the posterior fibers were more distal, attaching to the fibula in close proximity to the PITFL. Coronal images best depicted the course of the IOL. CONCLUSION: Oblique imaging planes parallel to the long axis of the ligament better display the normal anatomy of the tibiofibular syndesmotic ligaments when compared with standard imaging planes. (c) RSNA, 2010.

Detailed MRI-anatomic study of the lateral epicondyle of the elbow and its tendinous and ligamentous attachments in cadavers.

OBJECTIVE: The objective of our study was to document discrete bone landmarks in the lateral epicondyle of the humerus that represent the "footprints" of those tendons and ligaments that attach to it using MRI-anatomic correlation in cadavers. MATERIALS AND METHODS: Thirty-three dried humeral specimens were inspected to document bone landmarks in the lateral epicondyle. MRI with anatomic correlation was performed in 10 additional cadaveric elbows. The locations of the tendinous and ligamentous attachments to the lateral epicondyle were determined with respect to the same osseous landmarks. RESULTS: The surface of the lateral epicondyle ranged from a flat surface to a surface with up to six discrete landmarks: superior tubercle, anterior tubercle, posterior tubercle, intertubercular sulcus, rough area surrounding the tubercles, and epicondylar ridge. The radial collateral ligament attached to the superior aspect of the intertubercular sulcus and inferior aspect of the superior tubercle and was indistinguishable from the attachment of the lateral ulnar collateral ligament. The extensor carpi radialis brevis, extensor digitorum communis, and extensor digiti minimi had a common origin in the superior aspect of the lateral epicondyle. The extensor carpi ulnaris tendon arose from the posteroinferior aspect of the lateral epicondyle. CONCLUSION: Our investigation documents osseous landmarks that are useful in the identification of the footprints of the tendons and ligaments that attach to the lateral epicondyle. Knowledge of these structures contributes to correct interpretation of MR images in persons with tendinous and ligamentous abnormalities in this region.

Morphology of the distal radioulnar joint: cadaveric study with MRI and MR arthrography with the forearm in neutral position, pronation, and supination.

OBJECTIVE: The purpose of this study was to evaluate the physiologic extent and thickness of the cartilage and bare areas of the distal radioulnar joint with gross anatomic examination, MRI, and MR arthrography with the forearm in neutral position, maximal pronation, and maximal supination. MATERIALS AND METHODS: MRI and MR arthrography were performed on 10 cadaveric specimens (mean age at death, 82.9 years; range, 56-97 years) with the forearm in neutral position, maximal pronation, and maximal supination. Cartilage surface and thickness were assessed, and degenerative changes and bare areas were evaluated in consensus by two musculoskeletal radiologists. Gross anatomic and histologic examinations were used as the reference standard. RESULTS: MRI in maximal pronation and supination was helpful in evaluation of the ulnar cartilage. In the axial plane, any change in cartilage thickness in the ulnar head was related to chondral degeneration. In the coronal plane, cartilage thickness proved to be an unreliable sign in the assessment of chondral degeneration. The presence of osteophytes in the proximal aspect of the joint was easily detected and proved to be a reliable criterion for joint degeneration. Bare areas were found at the proximal and volar attachments of the joint capsule. CONCLUSION: Detailed knowledge of the anatomy of the distal radioulnar joint should allow more accurate assessment of degenerative changes and localization of erosions in inflammatory joint disease. Imaging with the forearm in maximal pronation and supination can improve visualization of the cartilage of the ulnar head.

Accessory head of biceps brachii muscle: anatomy, histology, and MRI in cadavers.

OBJECTIVE: The purpose of our study is to describe and define an anatomic variation located close to the bicipital groove using MRI with gross anatomic and histologic correlation in cadavers. MATERIALS AND METHODS: Ten fresh male human shoulders were harvested and used in this investigation. They were derived from persons with a mean age of death of 78.9 years (age range, 58-92 years). MR arthrography using proton density-weighted sequences was used to obtain images in axial, coronal, and sagittal planes. After imaging, the specimens were cut in axial, coronal, and sagittal sections using a band saw. The slices were then photographed to allow correlation with the MR arthrographic images, followed by histologic analysis. RESULTS: Two anomalous tendons, both intimate with the tendon of the long head of the biceps brachii muscle in the bicipital groove, were recognized. The origin of both tendons was in the greater tuberosity near the articular capsule. These structures had a muscular belly that was joined with the other biceps bellies. At the level of the bicipital groove, the anomalous tendons appeared as hypointense structures in proton density-weighted images, with a mostly flat morphology in axial and coronal planes. The average dimensions of these structures were 45.5 (craniocaudal)x6.2 (anteroposterior)x0.85 (mediolateral) mm. CONCLUSION: The MR images, gross anatomic inspection, and histologic information led us to conclude that these anomalous structures were accessory heads of the biceps brachii muscle.

Edematous processes within Kager fat pad: magnetic resonance imaging, gross anatomical, and histological studies in cadavers with clinical correlation.

OBJECTIVE: To demonstrate the anatomical features of Kager fat pad (KFP) and its fasciae using magnetic resonance imaging, gross anatomy, and histology in cadavers; and to correlate the data with image findings in patients. METHODS: The KFP was analyzed in 10 fresh human cadavers and 152 clinical cases. The retrospective clinical study was institutional review board approved. The specimens were studied by magnetic resonance imaging and sectioned for anatomical/histological correlation. Clinical cases were selected to evaluate the frequency, distribution, and patterns of edema/inflammation in KFP. The square of the Pearson product moment correlation coefficient and Student t tests were performed. RESULTS: Fasciae about KFP are double layered and derived from the union of the fascia of the leg and flexor and peroneal retinacula. Edema in KFP could be divided into diffuse, confined anteriorly, confined posteriorly, and confined externally. Confined patterns of edema were associated with paratenonitis and fluid in the Achilles bursae (P < 0.05). CONCLUSIONS: Four patterns of edema occur in KFP. Paratenonitis and bursal fluid were associated with confined edematous patterns. The double layer about KFP may contain edema that affects this region.

Proximal tibial osteophytes and their relationship with the height of the tibial spines of the intercondylar eminence: paleopathological study.

OBJECTIVE: Tibial spiking (i.e., spurring of tibial spines), eburnation, and osteophytes are considered features of osteoarthritis. This investigation employed direct inspection of the medial and lateral tibial plateaus in paleopathological specimens to analyze the frequency and morphological features of osteoarthritis and to define any relationship between the size of osteophytes and that of the intercondylar tibial spines. MATERIALS AND METHODS: A total of 35 tibial bone specimens were evaluated for the degree of osteoarthritis and presence of eburnation. Each plateau was also divided into four quadrants and the presence and size of bone outgrowths were recorded in each quadrant. The "medial/lateral tibial intercondylar spine index" for each specimen was calculated as follows: (medial/lateral intercondylar tibial spine height)/(anteroposterior width of the superior tibial surface). The relationships between medial and lateral tibial height indexes with the degree of osteoarthritis were then tested. RESULTS: Osteophytes were observed more frequently in the anterior quadrants of both tibial plateaus than in the posterior quadrants (29 vs 16 for the medial tibial plateau [p = 0.01] and 28 vs 20 for the lateral tibial plateau [p = 0.04]). Eburnation was seen more frequently in the posterior regions of both tibial plateaus than in the anterior regions (17 vs 5, p < 0.01). In specimens with no signs of osteoarthritis the lateral intercondylar tibial index was significantly lower than that in specimens with some degree of osteoarthritis (p = 0.02). The medial intercondylar tibial index of the specimens with no signs of osteoarthritis was not significantly different from that of the specimens with some degree of osteoarthritis (p = 0.45). There was a positive correlation between the lateral spine height index and the overall grading of osteoarthritis, (r = 0.6, p < 0.01). In the anteromedial and posteromedial quadrants of the lateral tibial plateau, the association between the lateral intercondylar tibial spine index and the grade of osteophytes was 0.5 (p < 0.01) and 0.7 (p < 0.01) respectively. CONCLUSION: Spiking of the lateral tibial intercondylar spine is associated with osteophyte formation and osteoarthritis. Eburnation occurs mainly in the posterior parts of the tibial plateaus while osteophytes arise mainly in the anterior parts. These findings suggest that stresses occurring in the flexed knee may contribute to many of the morphological abnormalities of osteoarthritis.

Differences between radial and ulnar deviation of the wrist in the study of the intrinsic intercarpal ligaments: magnetic resonance imaging and gross anatomic inspection in cadavers.

OBJECTIVE: To demonstrate how radial and ulnar deviation of the wrist can affect the visualization of the intrinsic intercarpal ligaments using magnetic resonance (MR) imaging, MR arthrography and gross anatomic inspection in cadavers. MATERIALS AND METHODS: The detectability of the intrinsic intercarpal ligaments of ten fresh human wrists was analyzed in coronal, axial and sagittal images in the neutral position and in radial and ulnar deviation with MR imaging and MR arthrography. The findings were then correlated with gross anatomic inspection. Additionally, quantitative measurements including the radiocarpal distances and capitate angles were performed. RESULTS: Differences were noted in the visual conspicuity of only the intercarpal ligaments of the proximal carpal row with different techniques and wrist positions. The average width of the radiocarpal joint was 0.62 mm, 1.55 mm and 2.0 mm (radial side) and 3.78 mm, 2.25 mm and 1.16 mm (ulnar side) in radial deviation, neutral position, and ulnar deviation of the wrist, respectively. Statistically, these maneuvers produced significant opening in the ulnar side during radial deviation (Student's t-test; P = 0.0005) and in the radial side in ulnar deviation (P = 0.007). CONCLUSION: Significant differences in the width of the radiocarpal joint were observed during radial and ulnar deviation of the wrist, influencing the visualization of the intrinsic ligaments, mainly the scapholunate and lunotriquetral ligaments. The use of MR arthrography with radial and/or ulnar deviation has the potential to improve diagnosis in clinical cases in which injury to one or both of these ligaments is suggested.

Chiasma crurale: intersection of the tibialis posterior and flexor digitorum longus tendons above the ankle. Magnetic resonance imaging-anatomic correlation in cadavers.

PURPOSE: To determine the precise anatomy and magnetic resonance (MR) imaging appearance of the chiasma crurale in cadavers, paying special attention to degenerative changes MATERIAL AND METHODS: Twelve fresh human ankles were harvested from 11 nonembalmed cadavers (mean age at death 77 years) and used according to institutional guidelines. MR imaging and MR tenography were used to investigate the anatomy of the chiasma crurale using proton density-weighted sequences. The gross anatomy of the chiasma crurale was evaluated and compared to the MR imaging findings. Histology was used to elucidate further the structure of the chiasma crurale. RESULTS: Above the chiasma, five specimens had a small amount of fat tissue between the tibialis posterior and flexor digitorum longus tendon. In all specimens both tendons had a sheath below the chiasma but not above it. At the central portion of the chiasma there was no soft tissue between the tendons, except in two specimens that showed an anatomic variant consisting of a thick septum connecting the tibial periosteum and the deep transverse fascia of the leg. In MR images, eight specimens showed what were believed to be degenerative changes in the tendons at the level of the chiasma. However, during gross inspection and histologic analysis of the specimens, there was no tendon degeneration visible. CONCLUSION: At the central portion of the chiasma, there is no tissue between the tibialis posterior and flexor digitorum longus tendons unless there is an anatomic variant. At the chiasma crurale, areas with irregular tendon surfaces are normal findings and are not associated with tendon degeneration (fraying).

Can osseous landmarks in the distal medial humerus be used to identify the attachment sites of ligaments and tendons: paleopathologic-anatomic imaging study in cadavers.

OBJECTIVE: To describe osseous landmarks that allow identification of the attachments of the ligaments and tendons in the distal medial aspect of the humerus. MATERIALS AND METHODS: Reliable osseous landmarks in the distal medial aspect of the humerus were identified in 34 well-preserved specimens from a paleopathologic collection. These osseous landmarks were then sought in magnetic resonance (MR) images of ten cadaveric elbow specimens so that the ease of their visualization and optimal imaging plane could be assessed. To assign these osseous landmarks to specific attachments of the tendons and ligaments in the distal medial humerus, we cut the specimens in slices and photographed and examined them. Subsequently, the prevalence of these osseous landmarks as well as the attachment sites of the tendons and ligaments in this location was determined. RESULTS: We determined ten reliable osseous landmarks in the distal medial aspect of the humerus, their prevalence and ease of identification, and their relationship to the attachments of the tendons and ligaments at the medial distal humerus. CONCLUSION: It is possible to use osseous landmarks at the distal medial humerus to facilitate identification of the different attachments of tendons and ligaments when MR images of the elbow are assessed.

Ulnomeniscal homologue of the wrist: correlation of anatomic and MR imaging findings.

PURPOSE: To evaluate the anatomy of the ulnar side of the wrist in the region of the triangular fibrocartilage (TFC) complex, with special focus on the ulnomeniscal homologue (UMH) and its relationship to surrounding structures. MATERIALS AND METHODS: Institutional review board approval and informed consent were not required. Ten upper extremities were harvested from the nonembalmed cadavers of four women and six men (age range at death, 56-97 years; mean age at death, 83 years) and used according to institutional guidelines. Magnetic resonance (MR) imaging and MR arthrography of the wrist were performed with the wrist in neutral position, maximal ulnar deviation, and maximal radial deviation by using intermediate-weighted sequences. The specimens were cut into 4-mm-thick sections that corresponded to the MR imaging planes. The gross anatomic features of the UMH and its relationship to adjacent structures were evaluated and compared with imaging findings. UMH variants, as described in previous articles on purely anatomic studies, were sought on MR images. MR findings of the wrist in neutral position were compared with those of the wrist in maximal ulnar and radial deviations. Histologic examination was used to further elucidate the structure of the UMH. RESULTS: The UMH displayed complex anatomic features because of its obliquely oriented course. However, it could be divided into styloid, radioulnar, and collateral components and a distal insertion. The UMH variants described in previously published studies could be identified, but evaluation results were highly dependent on the wrist position at imaging. CONCLUSION: The anatomy of the UMH is complex. For assessment of the UMH and the ulnar side of the TFC complex, coronal MR arthrography with the wrist in neutral position or radial deviation might be superior to standard MR imaging.

Anterior ankle impingement and talar bony outgrowths: osteophyte or enthesophyte? Paleopathologic and cadaveric study with imaging correlation.

OBJECTIVE: Bony "spurs" are a major component of anterior ankle impingement syndrome. The two major accepted hypotheses on the origin of these bony spurs are osteophyte formation due to repetitive microtrauma and enthesophyte development because of recurrent capsular or ligamentous traction. The purpose of this study was to provide a detailed evaluation of the bony outgrowths that arise on the anterior aspect of the talus and correlate them with the sites of capsular attachment. MATERIALS AND METHODS: Twenty-eight well-preserved talus bones from the San Diego Museum of Man were assessed regarding the presence of outgrowths on the anterior aspect of the talus. The distance of the outgrowths from the talar head was measured. The results were correlated with measurements of capsular attachment on the anterior aspect of the talus derived from MR arthrographic images in 13 cadaveric ankles. RESULTS: The average distance of capsular attachment from the talar head in the medial aspect of the bone was 10.63 mm and in the lateral part was 12.04 mm. The mean distance of bony spurs from the talar head in the medial and lateral parts of the talus was 17.2 and 12.5 mm, respectively. Medially, the talar spurs developed more proximally on the neck compared to the capsular attachment (p < 0.01). Laterally, this difference was not significant (p = 0.26). CONCLUSION: On the medial part of the anterior talus, bone development appears to occur in an intraarticular location (i.e., osteophytes). Laterally, the outgrowths develop extraarticularly and appear to result from capsular and ligamentous traction (i.e., enthesophytes).

Ligaments of the posterior and lateral talar processes: MRI and MR arthrography of the ankle and posterior subtalar joint with anatomic and histologic correlation.

OBJECTIVE: MRI and combined ankle and posterior subtalar MR arthrography in cadavers were used to evaluate the ligaments of the posterior and lateral talar processes. Subsequent anatomic and histologic correlation was performed. MATERIALS AND METHODS: Ten cadaveric ankles were used. Routine radiography and MRI were initially performed. Ankle and posterior subtalar MR arthrography, followed by anatomic and histologic analysis, was then performed to allow better assessment of the ligaments of the lateral and posterior talar process. RESULTS: In all subjects, MR arthrography provided superior delineation of the articular and periarticular structures, as well as the ligaments. The lateral talocalcaneal and medial talocalcaneal ligaments were best seen in the axial and coronal planes, respectively. The axial plane was best for visualizing the fibulotalocalcaneal ligament, and the sagittal plane was best for evaluating the posterior talocalcaneal ligament. The anterior and posterior talofibular ligaments and the posterior tibiotalar ligament (superficial and deep portions) were best seen in the axial plane. Histologic analysis was correlated to anatomic sectioning and showed the attachment sites of these ligaments. CONCLUSION: Combined ankle and posterior subtalar MR arthrography enhances visualization of the ligaments attaching to the posterior and lateral talar processes, including the posterior, lateral, and medial talocalcaneal and fibulotalocalcaneal ligaments.

Annular ligament of the elbow: MR arthrography appearance with anatomic and histologic correlation.

OBJECTIVE: As part of the lateral ligament complex of the elbow, the annular ligament has an adjunctive role in stabilizing the proximal radioulnar joint. Knowledge of the anatomy of this ligament may enhance our understanding of its functional role in maintaining integrity of the elbow joint in fracture and dislocation. The purpose of this study is to provide a detailed analysis of the anatomy of the annular ligament using MR arthrography with anatomic and histologic correlation in cadavers. MATERIALS AND METHODS: MR arthrography of six fresh cadaveric elbows using coronal, axial, and sagittal planes was performed after injection of intraarticular contrast material. The MR arthrography appearance of the annular ligament was correlated with anatomic sectioning and histologic analysis. RESULTS: On MR arthrography, the axial and sagittal planes provided the best evaluation of the annular ligament. Although the anterior attachment of annular ligament was a single band, the posterior attachment was fenestrated in two of six specimens. Anatomic inspection confirmed the MR observations. On histology, the annular ligament appeared to be part of a complex supporting structure continuous with the elbow joint capsule, adjacent ligaments, and muscles. CONCLUSION: The annular ligament is a complex structure formed from the capsule, lateral collateral ligamentous complex, and supinator muscle that act in unison to stabilize the proximal radioulnar joint. Its posterior attachment to the ulna can be fenestrated normally. A detailed analysis of anatomy of this ligament allows us to better understand its functional role in fractures and dislocations of the elbow joint.

Distal attachment of the brachialis muscle: anatomic and MRI study in cadavers.

OBJECTIVE: The purpose of this study was to use MRI and anatomic correlation in cadavers to delineate the anatomic features of the distal attachment of the brachialis muscle. MATERIALS AND METHODS: MRI was performed on 13 cadaveric elbows. The MRI findings were compared with those in anatomic sections and histologic preparations. The brachialis muscle of one cadaver was dissected. RESULTS: The dissected brachialis muscle had two heads, superficial and deep. The attachment of the superficial head to the ulnar tuberosity was farther distal than that of the deep head. The attachments of all aspects of the muscle included a tendinous layer rather than purely muscular structures. Histologic analysis showed no direct communication between the brachialis and biceps brachii tendons or between the brachialis tendon and joint capsule. CONCLUSION: Familiarity with the anatomic features of the distal brachialis muscle and tendon is essential for accurate assessment of these structures.

Fibulotalocalcaneal ligament: magnetic resonance imaging findings with cadaver correlation.

OBJECTIVE: The objectives of this study were to determine whether the fibulotalocalcaneal (FTC) ligament of the ankle, described in anatomical literature, can be identified on magnetic resonance (MR) imaging studies. METHODS: Magnetic resonance imaging was performed on 6 cadaver ankles, which were then sectioned axially. The posterolateral ankle was inspected on MR imaging and cadaver sections for ligamentous thickening corresponding to the components of the FTC ligament: main stem and talar and peroneocalcaneal laminae. RESULTS: The entire FTC ligament or components of it were seen in 5 (83%) of 6 ankles. In 3 (50%) of 6, all 3 components were present. The main stem of the FTC ligament attached to the posteromedial aspect of the lateral malleolus and then divided inferiorly into 2 laminae: The talar lamina extended horizontally to the talus, and the peroneocalcaneal lamina descended vertically to the calcaneus. CONCLUSIONS: The FTC ligament is a sheetlike extrinsic ligament, which is in continuity with the deep posterior crural fascia of the ankle and is visible on MR imaging.

Popliteomeniscal fascicles: anatomic considerations using MR arthrography in cadavers.

OBJECTIVE: This study was performed to examine the normal MR arthrographic anatomy of the popliteomeniscal fascicles with specific reference to the number of popliteomeniscal fascicles, thickness and course of the fascicles, and presence of other posterior attachments from the medial aponeurosis of the popliteus musculotendinous region. MATERIALS AND METHODS: Multiplanar 1.5-T MR arthrography of 10 cadaveric knees was performed using a quadrature knee coil. Specimens were frozen and sectioned in the sagittal (n = 4), axial (n = 3), and coronal (n = 3) planes. MR images and anatomic specimens were correlated by two musculoskeletal radiologists. RESULTS: Three popliteomeniscal fascicles were identified on MR arthrography: anteroinferior and posterosuperior fascicles in all 10 knees and posteroinferior fascicles in four of the knees. The posterosuperior popliteomeniscal fascicle was uniform in thickness, and the anteroinferior popliteomeniscal fascicle was variable in thickness. The anteroinferior popliteomeniscal fascicle formed a conjoined fibular attachment with the popliteofibular ligament. A medial aponeurotic extension from the popliteus musculotendinous region gave rise to the posteroinferior popliteomeniscal fascicle, which extended upward and attached to the inferomedial aspect of the posterior horn of the lateral meniscus. Additional attachments from the medial aponeurosis of the popliteus musculotendinous region to the posterior cruciate ligament, posterior capsule, oblique popliteal ligament, and posterior meniscofemoral ligament of Wrisberg were seen. CONCLUSION: Three popliteomeniscal fascicles were identified on MR arthrographic images. The popliteus muscle-tendon unit forms robust attachments in the superior, inferior, medial, and lateral oblique aspects, highlighting its importance in posterolateral stability of the knee.