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Sagittal plane
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| Sagittal plane | |
|---|---|
 The main anatomical planes of the human body, including mid-sagittal or median (red), parasagittal (yellow), frontal or coronal plane (blue) and transverse or axial plane (green) | |
 | |
| Details | |
| Identifiers | |
| Latin | plana sagittalia |
| TA98 | A01.2.00.003 |
| TA2 | 49 |
| FMA | 11361 |
| Anatomical terminology | |
The sagittal plane (/ˈsædʒɪtəl/; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections.[1] It is perpendicular to the transverse and coronal planes. The plane may be in the center of the body and divide it into two equal parts (mid-sagittal), or away from the midline and divide it into unequal parts (para-sagittal).
The term sagittal was coined by Gerard of Cremona.[2]
Variations in terminology
[edit]Examples of sagittal planes include:
- The terms median plane or mid-sagittal plane are sometimes used to describe the sagittal plane running through the midline. This plane cuts the body into halves (assuming bilateral symmetry),[3] passing through midline structures such as the navel and spine. It is one of the planes which, combined with the umbilical plane, defines the four quadrants of the human abdomen.[4]
- The term parasagittal is used to describe any plane parallel or adjacent to a given sagittal plane.[5] Specific named parasagittal planes include:
- The midclavicular line crosses through the clavicle.
- Lateral sternal and parasternal planes.[6]
The term sagittal derives from the Latin word sagitta, meaning "arrow". An image of an arrow piercing a body and passing from front (anterior) to back (posterior) on a parabolic trajectory with the upright bow that shot it would be one way to demonstrate the derivation of the term. Another explanation would involve the notching of the sagittal suture posteriorly by the lambdoidal suture —similar to feathers on an arrow. The Oxford English Dictionary indicates that sagittal in the sense of the sagittal suture along the vertex of the skull pre-dates other anatomical usage.[7]
- Sagittal axis or anterior-posterior axis is the axis perpendicular to the coronal plane, i.e., the one formed by the intersection of the sagittal and the transversal planes
- Coronal axis, medial-lateral axis, or frontal axis is the axis perpendicular to the sagittal plane, i.e., the one formed by the intersection of the coronal and the transversal planes.[8]
- Extension and flexion are the movements of limbs within the sagittal plane.[9]
- Abduction and adduction are terms for movements of limbs within the coronal plane.[10]
- Sagittal plane movements include flexion, extension, and hyperextension, as well as dorsiflexion and plantar flexion.[11]
Additional images
[edit]-
Sectional planes of the brain -
Identical twins at a gestational age of 15 weeks, shown in coronal and sagittal plane, respectively -
Brain anatomy (sagittal)
.png)
See also
[edit]References
[edit]- ^ Mark Vella (May 2008). Anatomy for Strength and Fitness Training. New Holland Publishers. pp. 16–. ISBN 978-1-84773-153-1.
- ^ Arráez-Aybar, Luis-A; Bueno-López, JL; Raio, N (2015). "Toledo school of translators and their influence on anatomical terminology". Annals of Anatomy - Anatomischer Anzeiger. 198: 21–33. doi:10.1016/j.aanat.2014.12.003. PMID 25667112.
- ^ "Median plane" at Dorland's Medical Dictionary
- ^ Kapit, Wynn (2014). The anatomy coloring book. San Francisco: Pearson. ISBN 9780321832016.
- ^ "parasagittal". Merriam-Webster dictionary. Retrieved 2019-02-20.
- ^ Yokochi, Chihiro; Rohen, Johannes W. (2006). Color Atlas of Anatomy: A Photographic Study of the Human Body. Hagerstown, MD: Lippincott Williams & Wilkins. pp. 2006. 217 p. ISBN 0-7817-9013-1.
- ^ "sagittal". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- ^ Movement Terminology (PDF). Arizona State University.
- ^ Winslow, Valerie (Dec 23, 2008). Classic Human Anatomy: The Artist's Guide to Form, Function, and Movement. Watson-Guptill. pp. 32–33. ISBN 978-0823024155.
- ^ Winslow, Valerie (Dec 23, 2008). Classic Human Anatomy: The Artist's Guide to Form, Function, and Movement. Watson-Guptill. pp. 34–35. ISBN 978-0823024155.
- ^ Kinematic Concepts for Analyzing Human Motion. In: Hall SJ. eds. Basic Biomechanics, 7e. McGraw-Hill; Accessed January 25, 2021.
Sagittal plane
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Definition and Characteristics
Anatomical Positioning
The sagittal plane is a vertical plane that runs parallel to the body's longitudinal axis, extending from the anterior (front) to the posterior (back) aspect in the standard anatomical position, where the body stands upright with feet together, arms at the sides, palms facing forward, and eyes directed forward.[9][10] This positioning divides the body or any of its parts into left and right portions, with the plane oriented perpendicular to the coronal and transverse planes.[11] In this configuration, the sagittal plane facilitates the visualization of movements and structures along the anteroposterior direction, such as flexion and extension of limbs.[12] A specific instance of the sagittal plane, known as the median or midsagittal plane, passes directly through the midline of the body, symmetrically separating the left and right halves into equal parts.[9][10] Planes parallel to the median plane but offset from the midline are termed parasagittal planes, resulting in unequal divisions of the left and right sides.[10] This hierarchical positioning ensures that all sagittal sections maintain a consistent anteroposterior alignment relative to the anatomical position, aiding in precise anatomical descriptions and imaging interpretations.[11][12]Division of the Body
The sagittal plane serves as a fundamental anatomical reference, acting as a vertical plane that extends longitudinally through the body from anterior to posterior, thereby dividing it into distinct left and right portions.[9] This division facilitates the spatial organization and analysis of bodily structures, allowing anatomists and clinicians to describe positions and relationships relative to the body's midline.[13] In the standard anatomical position, where the body stands upright with arms at the sides and palms facing forward, the sagittal plane aligns perpendicular to the ground, emphasizing its role in bilateral symmetry.[14] A specialized form of the sagittal plane, known as the median or midsagittal plane, passes precisely through the body's midline, bisecting it into two symmetrical halves of equal size.[15] This plane typically traverses central structures such as the vertebral column, the navel, and the nose, ensuring balanced separation that highlights the body's inherent symmetry in humans.[14] For instance, it divides the trunk into mirrored left and right sections, which is crucial for understanding organ placement and musculoskeletal balance.[9] Planes parallel to the median sagittal plane but offset from the midline are termed parasagittal planes, which divide the body into unequal left and right segments.[15] These planes vary in position and are particularly useful for isolating specific regions, such as dividing the torso asymmetrically to examine lateral structures like the liver or spleen.[13] In clinical contexts, parasagittal sections in imaging techniques like MRI provide detailed views of asymmetrical pathologies, enhancing diagnostic precision without requiring full bilateral exposure.[14]Relation to Other Planes
Comparison with Coronal and Transverse Planes
The sagittal plane, a vertical plane that divides the body into left and right portions, contrasts with the coronal plane, which is also vertical but divides the body into anterior and posterior sections, and the transverse plane, which is horizontal and separates the body into superior and inferior parts.[9] This fundamental difference in orientation allows each plane to provide unique perspectives for anatomical analysis: the sagittal plane facilitates examination of bilateral symmetry and midline structures, while the coronal plane highlights front-back relationships, and the transverse plane reveals cross-sectional layers from top to bottom.[11] In terms of directional alignment, the sagittal plane runs parallel to the body's rostral-caudal axis and perpendicular to the eyes or ears, enabling views of left-right divisions such as the cerebral hemispheres.[16] By comparison, the coronal (or frontal) plane aligns with the medial-lateral direction, running parallel to the eyes or ears to separate dorsal and ventral aspects, which is particularly useful for studying facial and thoracic structures.[11] The transverse plane, orthogonal to the body's long axis, cuts horizontally like slicing a bagel, dividing structures into upper and lower segments and aiding in the visualization of stacked body layers, such as in spinal cord sections.[17] These orthogonal relationships ensure that the three planes together provide a comprehensive three-dimensional framework for body orientation.[16] Key distinctions also arise in their applications: sagittal sections are ideal for assessing symmetry and longitudinal features, coronal slices emphasize depth from front to back, and transverse cuts offer horizontal overviews that integrate with axial imaging techniques.[9] For instance, in neuroimaging, sagittal views might reveal midline brain shifts, coronal planes expose lateral ventricle expansions, and transverse planes detect supratentorial lesions, each complementing the others without overlap in primary division.[16] This comparative utility underscores the planes' role in standardizing anatomical descriptions across medical and biological contexts.[11]Coordinate System Integration
In anatomical coordinate systems, the sagittal plane serves as one of the three principal orthogonal planes that define the orientation of the human body in three-dimensional space, alongside the coronal and transverse planes. This system typically employs a Cartesian XYZ framework aligned with the body's natural posture, where the origin is often placed at a reference point such as the center of mass or a standardized anatomical landmark like the umbilicus. The sagittal plane specifically bisects the body into left and right halves, running parallel to the anterior-posterior (Y) and superior-inferior (Z) axes while being perpendicular to the left-right (X) axis, enabling precise spatial referencing for anatomical descriptions and analyses.[18][19] Standard conventions for axis directions vary across applications but commonly follow either the Right-Anterior-Superior (RAS+) or Left-Posterior-Superior (LPS+) systems to ensure consistency in data representation. In the RAS+ convention, widely used in neuroimaging software like 3D Slicer, the X-axis points to the patient's right (increasing from left to right), the Y-axis points anteriorly (from posterior to anterior), and the Z-axis points superiorly (from inferior to superior); the sagittal plane thus corresponds to the YZ plane, where variations in X coordinate delineate left-right positions. Conversely, the LPS+ system, standard in DICOM imaging files, orients the X-axis positively to the left, Y to the posterior, and Z superiorly, requiring axis flips for RAS+ compatibility, but maintains the sagittal plane's perpendicularity to the X-axis for dividing the body laterally. These integrations facilitate transformations between coordinate spaces, such as from image voxels to anatomical orientations, ensuring accurate volumetric reconstructions.[18][19] In medical imaging and biomechanical modeling, the sagittal plane's integration with coordinate systems supports slice selection and 3D visualization; for instance, sagittal views in MRI or CT scans are reconstructed by sampling data perpendicular to the X-axis, allowing clinicians to assess midline structures like the spinal cord without distortion from left-right asymmetries. This framework also extends to standardized atlases, where the sagittal plane aligns with YZ coordinates at X=0 for the median position, aiding in inter-subject normalization and quantitative morphometry across populations. Such precise mapping is essential for applications in surgical navigation and finite element analysis of musculoskeletal dynamics.[20][19]Variations in Terminology
Median and Parasagittal Planes
The median plane, also known as the midsagittal plane, is a specific type of sagittal plane that passes directly through the midline of the body, dividing it into two symmetrical halves of equal size: the left and right sides.[10] This plane runs vertically from the anterior to the posterior aspect, aligned with the body's central axis, and is essential for describing symmetrical anatomical structures such as the vertebral column or the brain's central fissure.[21] In clinical contexts, the median plane serves as a reference for bilateral symmetry in procedures like midline incisions during surgery.[9] Parasagittal planes are sagittal planes parallel to the median plane but offset from the midline, resulting in divisions of the body into unequal left and right portions.[10] These planes are used to visualize or section specific regions, such as organs or limbs, without bisecting the body symmetrically; for example, a parasagittal cut through the abdomen might isolate the liver on one side.[21] Unlike the median plane, parasagittal planes vary in position and are often numbered or described by their distance from the midline (e.g., 2 cm lateral to the median plane) to aid in precise anatomical or imaging descriptions.[10] Both the median and parasagittal planes fall under the broader category of sagittal planes, which collectively enable longitudinal views of the body in medical imaging techniques like MRI or CT scans, facilitating the assessment of structures along the anteroposterior axis.[9] Their distinction emphasizes the importance of positional accuracy in anatomy, where the median plane represents perfect symmetry and parasagittal planes allow for targeted, asymmetrical analysis.[21]Etymology and Historical Usage
The term "sagittal" in anatomy derives from the Latin word sagitta, meaning "arrow," evoking the image of an arrow's straight path along the body's midline from anterior to posterior. This etymology reflects the plane's vertical orientation, which divides the body into left and right portions, paralleling the trajectory of an arrow piercing through. The anatomical application of "sagittal" first emerged in reference to the sagittal suture, the fibrous joint along the midline of the skull connecting the parietal bones, before extending to the broader body plane. The term was coined by Gerard of Cremona (c. 1114–1187), an Italian translator who rendered Arabic anatomical texts into Latin, introducing it during the 12th century.[22][23][24] Historically, descriptions of midline structures akin to the sagittal plane trace back to ancient scholars. Galen (c. 129–216 AD), a prominent Greco-Roman physician, described cranial sutures and venous structures, providing early observations on midline anatomy, though without the Latin term "sagittal." The term gained traction in European anatomy during the Renaissance, influenced by translations of classical texts. The modern conceptualization of the sagittal plane as a standardized anatomical reference solidified in the 16th century through Andreas Vesalius (1514–1564), whose seminal work De Humani Corporis Fabrica (1543) incorporated sagittal sections in illustrations and dissections, formalizing vertical midline divisions across the body. This usage expanded in the 19th century, with anatomist Friedrich Henle (1809–1885) in his Handbuch der systematischen Anatomie (1855) distinguishing sagittal from median, frontal, and horizontal planes, establishing their systematic application in descriptive anatomy. Subsequent refinements, such as those in 20th-century clinical anatomy texts, clarified terminology to avoid ambiguities like "midsagittal," prioritizing precision in medical education and imaging.[25][26]Applications in Anatomy
Musculoskeletal Analysis
The sagittal plane is fundamental to musculoskeletal analysis as it enables the evaluation of flexion and extension movements, which occur around a mediolateral (frontal) axis and involve anterior-posterior dynamics across the body's joints and muscles. This vertical plane divides the body into left and right halves, facilitating kinematic assessments of how forces and torques act on the musculoskeletal system during activities like walking or lifting.[27] In biomechanics, sagittal plane analysis quantifies joint angles, muscle lengths, and activation patterns, providing insights into load distribution and energy efficiency without the confounding influences of lateral deviations.[28] Key movements analyzed in this plane include flexion, defined as a decrease in the angle between two body segments (e.g., knee flexion from 0° to approximately 60° during swing phase of gait), and extension, an increase in that angle (e.g., hip extension up to 20° in terminal stance). Hyperextension, exceeding the anatomical position, is also examined, particularly at the knee or spine, to identify hypermobility risks. These motions engage primary muscle groups such as the quadriceps for knee extension and hamstrings for flexion, with electromyography (EMG) studies revealing peak activations during dynamic tasks to maintain joint stability.[29] For representative examples, shoulder flexion in overhead reaching demonstrates deltoid and biceps contributions, while ankle plantarflexion powers propulsion in locomotion.[14] In gait analysis, sagittal plane biomechanics are routinely assessed using motion capture systems to measure lower limb joint excursions, with normal hip flexion peaking at 30-40° in early swing and knee flexion at 60° mid-swing. Musculoskeletal models simulate these patterns to predict internal forces, showing that gastrocnemius-soleus activation contributes to ground reaction forces during push-off.[30] Deviations, such as reduced ankle dorsiflexion in cerebral palsy, correlate with increased energy expenditure and compensatory muscle overuse. Such analyses inform rehabilitation protocols, emphasizing sagittal-specific exercises to restore efficient movement. Spinal musculoskeletal evaluation heavily relies on sagittal plane imaging and metrics like the sagittal vertical axis (SVA), where misalignment beyond 5 cm indicates imbalance, leading to elevated paraspinal muscle fatigue and facet joint stress. Pelvic tilt adjustments in this plane, targeting anterior (nutation) or posterior (counternutation) shifts, activate core stabilizers like the iliopsoas and erector spinae to alleviate lumbar lordosis alterations in low back pain cases. Therapeutic tilting can help improve postural equilibrium by adjusting lumbar alignment.[31] In orthopedic contexts, these analyses guide interventions for sagittal deformities, prioritizing restoration of pelvic incidence (PI) alignment to minimize adjacent segment degeneration.[32]Organ and Tissue Visualization
The sagittal plane, by providing a vertical longitudinal section through the body, facilitates detailed visualization of midline and symmetric organs, revealing their anterior-posterior depth and superior-inferior extent that may be obscured in other orientations.[33] This view is particularly advantageous for assessing the spatial relationships between organs and surrounding tissues, such as the alignment of the spinal cord with vertebral structures or the craniocaudal dimensions of abdominal viscera.[34] In magnetic resonance imaging (MRI), sagittal acquisitions excel at delineating central nervous system organs, including the brain's midline structures like the corpus callosum, brainstem, and ventricular system, as well as the entire spinal cord from the foramen magnum to the conus medullaris. For the spine, sagittal MRI sequences highlight tissue contrasts between the cord, cerebrospinal fluid, and surrounding soft tissues, aiding in the detection of pathologies such as herniated discs or tumors.[35] Similarly, in the thorax, sagittal views of the heart display its longitudinal axis, from base to apex, allowing evaluation of chamber sizes, septal integrity, and great vessel orientations relative to adjacent lung and mediastinal tissues.[36] Computed tomography (CT) sagittal reconstructions, derived from volumetric data, enhance organ assessment in the abdomen and pelvis by providing reformatted views that surpass axial slices in depicting lesions or anomalies. For instance, sagittal CT images better visualize liver segments, portal vein branches, and focal hepatic pathologies due to improved depiction of vertical tumor extension and vascular relationships.[37] In the pelvis, these reconstructions clearly show the uterus, bladder, and rectum in a single plane, quantifying descents such as cystoceles (e.g., >1 cm below the pubococcygeal line) and their impact on adjacent tissues.[38] For kidneys, sagittal CT or MRI views illustrate their retroperitoneal positioning, calyceal systems, and relationships to the adrenal glands and psoas muscles, essential for identifying hydronephrosis or masses.[39] Ultrasound leverages the sagittal plane for real-time, non-invasive tissue and organ imaging, particularly in obstetrics and abdominal evaluations. In pelvic sonography, midline sagittal scans longitudinally profile the uterus from fundus to cervix, assessing endometrial thickness and myometrial integrity, while parasagittal sweeps target ovaries for follicular mapping and adnexal masses.[33] Abdominal transabdominal ultrasound in the sagittal orientation, with the probe angled cephalad, optimizes gallbladder visualization for wall thickness (<3 mm normal) and stone detection, using the liver as an acoustic window to adjacent structures like the right kidney.[39] This plane also aids in soft tissue assessment, such as muscle layers in the abdominal wall or fascial planes, by highlighting echogenic differences without radiation exposure.[40] Overall, the sagittal plane's utility in organ and tissue visualization stems from its ability to integrate depth and length scales, making it indispensable for diagnostic precision across modalities while minimizing the need for multiple acquisitions.[41]Clinical and Imaging Uses
Surgical Planning
In surgical planning, the sagittal plane provides critical visualization for assessing spinal alignment and deformity correction, enabling surgeons to predict postoperative balance and minimize complications in procedures such as osteotomies for adult spinal deformity. Tools like Surgimap Spine software facilitate detailed analysis of sagittal parameters, including the sagittal vertical axis (SVA) and pelvic incidence, to optimize osteotomy levels, types (e.g., pedicle subtraction osteotomy for up to 40° correction), and correction angles on a patient-specific basis. This approach addresses sagittal malalignment by simulating outcomes from full-length radiographs, improving spinopelvic harmony and reducing revision rates.[42][43] Preoperative planning in sagittal plane correction for spinal imbalance often compares geometric methods with validated formulas to achieve target SVA values (ideally 0–5 cm) and sacral slope (around 40°). In ankylosing spondylitis cases, software like ASKyphoplan has demonstrated effectiveness in closing wedge osteotomies, achieving mean SVA reductions of 232 mm and chin-brow vertical angle improvements of 24°, though actual results may require intraoperative adjustments with mean corrections of 15° for the sacral endplate angle. Computer-assisted planning further refines decision-making by simulating maneuvers like Smith-Petersen or pedicle subtraction osteotomies, translating virtual plans to real operations with statistical significance in achieving anticipated alignments (p > 0.01).[44][45][46] In neurosurgery, sagittal plane imaging is vital for midline approaches, where the superior sagittal sinus (SSS) is frequently displaced rightward from the anatomical midline (mean 3.7 mm at bregma, up to 16.3 mm), necessitating a 1.7 cm safety margin for burr holes to avoid vascular injury during craniotomies. Orthopedic applications extend to total knee arthroplasty (TKA), where sagittal balancing ensures equal flexion and extension gaps for implant stability; techniques adjust distal femoral cuts for extension and posterior condyle resections for flexion, with proposed X-ray-based methods achieving 80.6% accuracy for femoral components and 95.7% for tibial within ±2° of target alignment. For lower limb deformities, sagittal plane planning uses mechanical axes—such as joint line-based proximal femoral axes at 85° to the femoral head center—to identify correction apexes, complementing frontal plane strategies for precise osteotomies.[47][48][49][50]Medical Imaging Techniques
In medical imaging, the sagittal plane provides a longitudinal side view that divides the body into left and right portions, facilitating assessment of anteroposterior relationships and midline structures critical for diagnosing pathologies in the brain, spine, and musculoskeletal system. This plane is integral to multiple modalities, including magnetic resonance imaging (MRI), computed tomography (CT), ultrasound, and radiography, where it enables detailed visualization of anatomical continuity and alignment without the need for patient repositioning in volumetric techniques.[51][52] Magnetic resonance imaging excels in sagittal plane acquisition due to its ability to generate high-contrast images in multiple orientations, particularly for soft tissue evaluation. Sagittal MRI sequences, such as T1-weighted and T2-weighted, clearly depict midline brain components like the brainstem (medulla oblongata, pons, mesencephalon), cerebellum, diencephalon, telencephalon, corpus callosum, hypophysis, and craniocervical junction, while also revealing the spinal cord's continuity. The plane's perpendicular orientation to gyri and sulci enhances definition of these features, supporting stereotactic mapping via the bicommissural line and aiding detection of anomalies such as extradural lesions or trauma-induced narrowing. In orthopedics, sagittal MRI is the preferred single-plane view for anterior cruciate ligament (ACL) tear assessment in the knee, outperforming coronal and axial planes with accuracies up to 89.2% in deep learning models, though multi-plane integration improves overall diagnostic performance to 92.5%.[53][54] Computed tomography relies on multi-detector volumetric acquisition to reconstruct sagittal planes from axial source data, allowing seamless multi-planar reformatting without additional radiation exposure. This technique is vital for evaluating the extent of diseases across body regions, such as in high-resolution CT (HRCT) of the chest for idiopathic pulmonary fibrosis, where sagittal views complement axial and coronal reconstructions to assess vertical disease distribution and structural deformities. Sagittal CT reconstructions maintain low radiation doses while providing comprehensive anatomical context, as demonstrated in thoracic protocols scanning the entire chest in a single pass.[41] Ultrasound imaging employs the sagittal plane through longitudinal transducer orientations, directing the beam parallel to the body's long axis to capture structures' length and depth in real-time. This approach visualizes anterior-posterior and superior-inferior relationships, such as in abdominal scans for organ elongation or vascular patency, but requires lateral transducer shifts to access right-left details since these are not inherently displayed. Oblique adjustments by rotating the probe optimize alignment with non-perpendicular anatomy, making sagittal ultrasound essential for dynamic assessments in obstetrics, cardiology, and procedural guidance.[55] Radiography uses lateral projections to approximate sagittal views, particularly for skeletal evaluation, where full-spine teleradiography in standing position captures global sagittal balance parameters like pelvic incidence and lumbar lordosis. Digital systems enhance precision in assessing spinal alignment and deformities, with sagittal X-rays providing foundational data for surgical planning in scoliosis or kyphosis, though they offer limited soft tissue contrast compared to advanced modalities.[56]Division of the Body
The sagittal plane is a vertical plane that divides the body or any of its parts into left and right sections. It runs parallel to the body's longitudinal axis, from the anterior (front) to the posterior (back), and is perpendicular to both the coronal and transverse planes.[9] This division allows for the visualization and analysis of bilateral symmetry and lateral structures in anatomy and medical imaging.[3]Comparison with Coronal and Transverse Planes
In anatomical and medical imaging contexts, the sagittal plane integrates with the coronal and transverse planes to establish a three-dimensional Cartesian coordinate system for the human body. This system uses orthogonal axes aligned with the principal planes in the anatomical position, facilitating precise spatial descriptions, movement analysis, and visualization. The standard patient coordinate system (often denoted as LPS+ in DICOM conventions) defines:- The x-axis along the left-right direction (positive increasing toward the patient's left),
- The y-axis along the posterior-anterior direction (positive increasing anteriorly),
- The z-axis along the inferior-superior direction (positive increasing superiorly).[19]
Median and Parasagittal Planes
The median plane, also known as the midsagittal plane, is a specific type of sagittal plane that passes through the midline of the body, dividing it into two equal and symmetrical left and right halves when the subject is in the anatomical position.[9] This plane typically runs through central structures such as the navel, spine, and nose. Parasagittal planes are sagittal planes that are parallel to the median plane but do not pass through the midline, instead being offset to one side or the other. These planes divide the body into unequal left and right portions.[14] The term "parasagittal" emphasizes their proximity and parallelism to the median plane without coinciding with it.Etymology and Historical Usage
The term "sagittal" derives from the Latin word sagitta, meaning "arrow", reflecting the plane's orientation from anterior to posterior, similar to the direction of an arrow's flight.[58] This terminology was coined by Gerard of Cremona (c. 1114–1187), a key figure in the Toledo School of Translators, who introduced it while translating Arabic medical texts, such as Avicenna's Canon of Medicine, into Latin during the 12th century. These translations significantly shaped European anatomical nomenclature, with terms like "sagittal" enduring in modern usage.[59]Musculoskeletal Analysis
In musculoskeletal analysis, the sagittal plane is essential for quantifying joint kinematics and kinetics during locomotion and posture maintenance. Gait analysis in the sagittal plane examines angular displacements and velocities at the hip, knee, and ankle joints throughout the gait cycle, enabling identification of abnormalities such as reduced knee flexion in osteoarthritis or excessive lumbar lordosis in compensatory mechanisms.[60] Postural assessment utilizes sagittal plane views to measure parameters like the cranio-vertebral angle and pelvic tilt, which inform evaluations of forward head posture or sagittal imbalance that can lead to musculoskeletal pain and dysfunction.[61] Biomechanical modeling in the sagittal plane simulates muscle activations and joint moments, supporting applications in orthopedics for predicting outcomes of surgical corrections or designing assistive devices to restore natural movement patterns.[5]Organ and Tissue Visualization
The sagittal plane is essential for visualizing the anterior-posterior relationships and side profiles of organs and tissues in anatomical studies and dissections. In the head, sagittal sections reveal midline structures of the brain, including the corpus callosum, ventricles, brainstem, and pituitary gland, allowing assessment of symmetry and internal architecture.[13][62] In the thorax, it displays the heart's position relative to the lungs and great vessels, while in the abdomen, sagittal views illustrate the continuous layout of the digestive tract from esophagus through stomach, intestines, to rectum, alongside organs like the liver, kidneys, and spleen. Pelvic sagittal sections highlight the bladder, reproductive organs, and rectum in their vertical alignment. These views aid in understanding spatial orientations and interconnections without the overlap seen in other planes.[63][64]Surgical Planning
The sagittal plane plays a vital role in surgical planning across various medical fields, enabling precise visualization and correction of anatomical alignments. In spine surgery, particularly for adult spinal deformity, surgeons analyze sagittal balance using tools like Surgimap Spine software to plan osteotomies and instrumentation, aiming to restore optimal spinopelvic alignment and improve postoperative outcomes.[42] In neurosurgery, sagittal plane imaging from MRI or CT scans assists in trajectory planning for approaches to midline structures, such as the brain's corpus callosum or spinal cord, helping to minimize tissue damage and enhance precision.[52] For orthopedic procedures like total knee arthroplasty (TKA), sagittal plane balancing ensures equal flexion and extension gaps, promoting stability and function of the prosthetic joint.[49]Medical Imaging Techniques
In medical imaging, the sagittal plane is essential for acquiring and reconstructing cross-sectional views that slice the body from anterior to posterior, facilitating detailed examination of midline and longitudinal structures. Magnetic resonance imaging (MRI) routinely utilizes sagittal acquisitions to provide high-contrast images of soft tissues, such as the brain's midline ventricles, corpus callosum, and brainstem, as well as the spinal cord and vertebral column.[5] This plane is particularly advantageous in MRI for evaluating neurological conditions, including tumors, demyelination, and congenital anomalies, due to its multiplanar capability without ionizing radiation.[13] Computed tomography (CT) scans, especially multi-slice or volumetric CT, enable sagittal reformations from axial data sets, allowing visualization of bony structures like the spine and pelvis with excellent spatial resolution.[41] Sagittal CT views are commonly used for assessing spinal sagittal balance, fractures, and degenerative changes, often in preoperative planning for orthopedic and neurosurgical interventions.[5] Techniques such as low-dose EOS imaging further support sagittal plane analysis with reduced radiation exposure compared to traditional CT.[5]References
- https://training.seer.cancer.[gov](/page/.gov)/anatomy/body/terminology.html