scholarly journals Functional anatomy of human extraocular muscles during fusional divergence

2018 ◽  
Vol 120 (5) ◽  
pp. 2571-2582 ◽  
Author(s):  
Joseph L. Demer ◽  
Robert A. Clark
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Anatomy ◽  
Rectus Muscle ◽  
Lateral Rectus ◽  
Medial Rectus ◽  
Resonance Imaging ◽  
Cross Sectional ◽  
Mr Relaxation ◽  
Ocular Motor System

We employed magnetic resonance imaging to quantify human extraocular muscle contractility during centered target fusion and fusional divergence repeated with each eye viewing monocularly at 20 cm through 8Δ and at 400 cm through 4Δ base in prism. Contractility, indicated by posterior partial volume (PPV) change, was analyzed in transverse rectus and in medial and lateral superior oblique (SO) muscle compartments and by cross-sectional area change in the inferior oblique (IO). At 20 cm, 3.1 ± 0.5° (SE) diverging eye abduction in 10 subjects was associated with 4.2 ± 1.5% whole lateral rectus (LR) PPV increase ( P < 0.05) and 1.7 ± 1.1% overall medial rectus (MR) PPV decrease attributable to 3.1 ± 1.8% reduction in the superior compartment ( P < 0.025), without change in its inferior compartment or in muscles of the aligned eye. At 400 cm, 2.2 ± 0.5° diverging eye abduction in nine subjects was associated with 6.1 ± 1.3% whole LR PPV increase ( P < 10−5) but no change in MR, with compartmentally similar relaxation in the LR and MR of the aligned eye. Unlike convergence, there were no IO or SO contractile changes for divergence to either target nor any change in rectus pulley positions. Results confirm and extend to proximal divergence the unique role of the superior MR compartment, yet no MR role for far divergence. Corelaxation of aligned eye LR and MR combined with failure of MR relaxation during divergence is consistent with the limited behavioral range of divergence. NEW & NOTEWORTHY Magnetic resonance imaging shows that the lateral rectus muscle must overcome continued contraction by its opponent the medial rectus when humans diverge their visual axes to achieve single, binocular vision. While the upper but not lower compartment of the medial rectus assists by relaxing for near targets, it does not do so when targets are far away. This behavior violates Sherrington’s law of reciprocal action of antagonists and conventional assumptions about the ocular motor system.

scholarly journals Natural Course of Hematoma in Lateral Rectus Muscle Followed by Magnetic Resonance Imaging

2005 ◽  
Vol 206 (4) ◽  
pp. 361-364 ◽  
Author(s):  
Hideyuki Onami ◽  
Hiroshi Kunikata ◽  
Masayoshi Hojo ◽  
Yoichi Nakagawa ◽  
Makoto Tamai
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Rectus Muscle ◽  
Natural Course ◽  
Lateral Rectus ◽  
Resonance Imaging ◽  
Lateral Rectus Muscle

Magnetic Resonance Imaging of the Medial Rectus Muscle of Patients with Consecutive Exotropia after Medial Rectus Muscle Recession

Ophthalmology ◽  
2010 ◽  
Vol 117 (10) ◽  
pp. 1876-1882 ◽  
Author(s):  
Takashi Negishi ◽  
Akiko Hikoya ◽  
Haruo Isoda ◽  
Yoko Tsuchiya ◽  
Mayu Sawada ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Rectus Muscle ◽  
Medial Rectus ◽  
Resonance Imaging ◽  
Consecutive Exotropia

scholarly journals Dynamic Magnetic Resonance Imaging- a sensitive tool in managing consecutive exotropia

2016 ◽  
Vol 7 (2) ◽  
pp. 202-205
Author(s):  
Rajan Kumar Labh ◽  
TD Ghose ◽  
S Ganesh
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Large Angle ◽  
Dynamic Magnetic Resonance Imaging ◽  
Lateral Rectus ◽  
Medial Rectus ◽  
Resonance Imaging ◽  
Excellent Outcome ◽  
Dynamic Magnetic Resonance ◽  
Consecutive Exotropia

Background: Proper evaluation and accurate diagnosis are crucial in managing a case of strabismus. Objective: Report a case of prolonged large angle complicated consecutive exotropia where dynamic Magnetic Resonance Imaging helped us to diagnose and simplify the management plan. Case: A 19-year-old male presented with outward deviation of both eyes for last 16 years with right face turn, without diplopia and trauma. However, he had history of two consecutive squint surgeries, a month apart, at the age of 3 years. Observation: Visual acuity (best corrected) in the right and left eye was 6/36 and 6/6 respectively. Extraocular movements revealed minus (-) 4 adduction deficits in the left eye with right eye suppression. Prism Alternate Cover Test (PACT) showed 65 prism diopter (PD) base in (BI), for primary and near gazes with lateral incommitance and without any pattern. Forced Duction Test (FDT) showed restriction of the left lateral rectus. Dynamic Magnetic Resonance Imaging revealed posterior insertion of the left medial rectus with thinning of the tendinous insertion of the left lateral and medial rectus in neutral position. On adduction of left eye, there was slight increased bulk of the left medial rectus. Medial Rectus (MR) advancement 5.5 mm and Lateral Rectus (LR) recession 9mm was done. Repeat FDT showed improvement in resistance. After 3 month, the patient had excellent outcome with 5 PD primary position exotropia and 2 units of improvement in left eye adduction. Conclusion: Precise workup and appropriate investigation decreases the undue interventions with excellent outcome in a case of large angle consecutive XT. 

scholarly journals Cross-sectional anatomy, computed tomography, and magnetic resonance imaging of the banded houndshark (Triakis scyllium)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sang Wha Kim ◽  
Adams Hei Long Yuen ◽  
Cherry Tsz Ching Poon ◽  
Joon Oh Hwang ◽  
Chang Jun Lee ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Computed Tomography ◽  
Magnetic Resonance ◽  
Soft Tissues ◽  
Imaging Techniques ◽  
Evolutionary Developmental Biology ◽  
Phylogenetic Position ◽  
Ct Scanner ◽  
Resonance Imaging ◽  
Cross Sectional

AbstractDue to their important phylogenetic position among extant vertebrates, sharks are an invaluable group in evolutionary developmental biology studies. A thorough understanding of shark anatomy is essential to facilitate these studies and documentation of this iconic taxon. With the increasing availability of cross-sectional imaging techniques, the complicated anatomy of both cartilaginous and soft tissues can be analyzed non-invasively, quickly, and accurately. The aim of this study is to provide a detailed anatomical description of the normal banded houndshark (Triakis scyllium) using computed tomography (CT) and magnetic resonance imaging (MRI) along with cryosection images. Three banded houndsharks were scanned using a 64-detector row spiral CT scanner and a 3 T MRI scanner. All images were digitally stored and assessed using open-source Digital Imaging and Communications in Medicine viewer software in the transverse, sagittal, and dorsal dimensions. The banded houndshark cadavers were then cryosectioned at approximately 1-cm intervals. Corresponding transverse cryosection images were chosen to identify the best anatomical correlations for transverse CT and MRI images. The resulting images provided excellent detail of the major anatomical structures of the banded houndshark. The illustrations in the present study could be considered as a useful reference for interpretation of normal and pathological imaging studies of sharks.

scholarly journals Magnetic resonance imaging template to standardize reporting of anal fistulas

2021 ◽  
Author(s):  
I. Sudoł-Szopińska ◽  
G. A. Santoro ◽  
M. Kołodziejczak ◽  
A. Wiaczek ◽  
U. Grossi
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Treatment Strategies ◽  
Cross Sectional Study ◽  
Resonance Imaging ◽  
Anal Fistulas ◽  
Cross Sectional ◽  
Radiology Reports ◽  
Colorectal Surgeons ◽  
Magnetic Resonance Imaging Mri

AbstractAnal fistula (AF) is a common referral to colorectal surgeons. Management remains challenging and sometimes controversial. Magnetic resonance imaging (MRI) is commonly performed in initial workup for AF. However, reports often lack key information for guiding treatment strategies. It has been shown that with structured radiology reports, there is less missing information. We present a structured MRI template report including 8 key descriptors of anal fistulas, whose effectiveness and acceptability are being assessed in a cross-sectional study (NCT04541238).

scholarly journals Relationship between abnormalities detected by magnetic resonance imaging and knee symptoms in early knee osteoarthritis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Seiya Ota ◽  
Eiji Sasaki ◽  
Shizuka Sasaki ◽  
Daisuke Chiba ◽  
Yuka Kimura ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Knee Osteoarthritis ◽  
Cartilage Damage ◽  
Resonance Imaging ◽  
Mri Findings ◽  
Radiographic Evidence ◽  
Cross Sectional ◽  
Meniscal Lesions ◽  
Magnetic Resonance Imaging Mri

AbstractWe investigated the prevalence of magnetic resonance imaging (MRI) findings and their relationship with knee symptoms in women without radiographic evidence of knee osteoarthritis (KOA). This cross-sectional cohort study included 359 Japanese women without radiographic evidence of KOA (Kellgren‒Lawrence grade < 2). All participants underwent T2-weighted fat-suppressed MRI of their knees. Structural abnormalities (cartilage damage, bone marrow lesions [BMLs], subchondral cysts, bone attrition, osteophytes, meniscal lesions, and synovitis) were scored according to the whole-organ MRI score method. Knee symptoms were evaluated using the Knee Injury and Osteoarthritis Outcome Score. Participants were divided into early and non-KOA groups based on early KOA classification criteria. Logistic regression analysis was performed to evaluate the relationship between MRI abnormalities and knee symptoms. Cartilage damage was the most common abnormality (43.5%). The prevalences of cartilage damage, BMLs, subchondral cysts, bone attrition, meniscal lesions, and synovitis were higher in patients with early KOA than in those without. Synovitis (odds ratio [OR] 2.254, P = 0.002) and meniscal lesions (OR 1.479, P = 0.031) were positively associated with the presence of early KOA. Synovitis was most strongly associated with knee pain and might be a therapeutic target in patients with early KOA.

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