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Anatomical terminology is a specialized system of terms used byanatomists,zoologists, andhealth professionals, such asdoctors,surgeons, andpharmacists, to describe the structures andfunctions of thebody.[1]
This terminology incorporates a range of unique terms, prefixes, and suffixes derived primarily from Ancient Greek and Latin. While these terms can be challenging for those unfamiliar with them, they provide a level of precision that reduces ambiguity and minimizes the risk of errors. Because anatomical terminology is not commonly used in everyday language, its meanings are less likely to evolve or be misinterpreted.
For example, everyday language can lead to confusion in descriptions: the phrase "a scar above the wrist" could refer to a location several inches away from the hand, possibly on the forearm, or it could be at the base of the hand, either on the palm or dorsal (back) side. By using precise anatomical terms, such as "proximal," "distal," "palmar," or "dorsal," this ambiguity is eliminated, ensuring clear communication.[2]
To standardize this system ofterminology,Terminologia Anatomica was established as an international reference for anatomical terms.[3]
Anatomical terminology follows a regularmorphology, with consistentprefixes andsuffixes used to modify differentroots. The root of a term often refers to anorgan ortissue. For example, the Latin namemusculus biceps brachii can be broken down:musculus meaning 'muscle',biceps meaning 'two-headed', andbrachii referring to the arm (brachial region). The first term identifies the structure, the second indicates the type or instance of the structure, and the third specifies its location.[4]
Anatomical structures are often described in relation to landmarks, such as theumbilicus,sternum, or anatomical lines like the midclavicular line (from the center of the clavicle). The termcephalon or cephalic region refers to the head, which is further divided into thecranium (skull),facies (face),frons (forehead),oculus (eye area),auris (ear),bucca (cheek),nasus (nose),os (mouth), andmentum (chin). The neck is known as thecervix or cervical region. Examples of structures named for these areas include thefrontalis muscle,submental lymph nodes,buccal membrane andorbicularis oculi muscle.
To reduce confusion, some terms are used specifically for certain body regions. For instance, in the skullrostral refers to proximity to the front of the nose and is primarily used when describing theskull's position, especially in comparison to other animals.[5]: 4 Similarly, in the arms, different terms help clarify the "front", "back", "inner" and "outer" surfaces. For example:
Additional terminology is used to describe the movement and actions of the hands and feet, and other structures such as the eyes.
International morphological terminology is used by thecolleges ofmedicine anddentistry and other areas of thehealth sciences. It facilitates communication and exchanges between scientists from different countries of the world and it is used daily in the fields ofresearch,teaching andmedical care. The international morphological terminology refers tomorphological sciences as abiological sciences' branch. In this field, the form and structure are examined as well as the changes or developments in the organism. It isdescriptive andfunctional. Basically, it covers thegross anatomy and themicroscopic (histology andcytology) of living beings. It involves bothdevelopment anatomy (embryology) and the anatomy of the adult. It also includescomparative anatomy between different species. The vocabulary is extensive, varied and complex, and requires a systematic presentation.
Within the international field, a group of experts reviews, analyzes and discusses the morphological terms of the structures of thehuman body, forming today'sTerminology Committee (FICAT) from theInternational Federation of Associations of Anatomists (IFAA).[6][7] It deals with the anatomical, histological and embryologic terminology. In theLatin American field, there are meetings calledIberian Latin American Symposium Terminology (SILAT), where a group of experts of thePan American Association of Anatomy (PAA)[8] that speakSpanish andPortuguese, disseminates and studies the international morphological terminology.
The current international standard for human anatomical terminology is based on theTerminologia Anatomica (TA). It was developed by theFederative Committee on Anatomical Terminology (FCAT) and theInternational Federation of Associations of Anatomists (IFAA) and was released in 1998.[9] It supersedes the previous standard,Nomina Anatomica.[10]Terminologia Anatomica contains terminology for about 7500 human gross (macroscopic) anatomical structures.[11] For microanatomy, known ashistology, a similar standard exists inTerminologia Histologica, and for embryology, the study of development, a standard exists inTerminologia Embryologica. These standards specify generally accepted names that can be used to refer to histological and embryological structures in journal articles, textbooks, and other areas. As of September 2016, two sections of the Terminologia Anatomica, including central nervous system and peripheral nervous system, were merged to form the Terminologia Neuroanatomica.[12]
The Terminologia Anatomica has been perceived with considerable criticism regarding its content including coverage, grammar and spelling mistakes, inconsistencies, and errors.[13]
Anatomical terminology is often chosen to highlight the relative location of body structures. For instance, an anatomist might describe one band of tissue as "inferior to" another or a physician might describe a tumor as "superficial to" a deeper body structure.[4]
Anatomical terms used to describe location are based on a body positioned in what is called thestandard anatomical position. This position is one in which a person is standing, feet apace, with palms forward and thumbs facing outwards.[14] Just as maps are normally oriented with north at the top, the standard body "map", or anatomical position, is that of the body standing upright, with the feet at shoulder width and parallel, toes forward. The upper limbs are held out to each side, and the palms of the hands face forward.[4]
Using the standard anatomical position reduces confusion. It means that regardless of the position of a body, the position of structures within it can be described without ambiguity.[4]
In terms of anatomy,anatomical lines are theoretical lines used to divide the body into regions, such as the nine regions of the abdomen.Axillary lines provide reference points for theunderarm region
In the front, the trunk is referred to as the "thorax" and "abdomen". The back as a general area is thedorsum or dorsal area, and the lower back is the lumbus orlumbar region. The shoulder blades are thescapular area and the breastbone is thesternal region. Theabdominal region is the area between the chest and thepelvis. The breast is also called the mammary region, the armpit as theaxilla and axillary, and thenavel as the umbilicus andumbilical. The pelvis is the lower torso, between the abdomen and thethighs. Thegroin, where the thigh joins the trunk, are the inguen and inguinal area.
The entire arm is referred to as the brachium and brachial, the front of the elbow as the antecubitis andantecubital, the back of the elbow as theolecranon or olecranal, theforearm as the antebrachium and antebrachial, thewrist as thecarpus and carpal area, thehand as the manus and manual, the palm as the palma and palmar, thethumb as the pollex, and thefingers as the digits,phalanges, and phalangeal. Thebuttocks are the gluteus or gluteal region and the pubic area is thepubis.
Anatomists divide the lower limb into the thigh (the part of the limb between thehip and theknee) and the leg (which refers only to the area of the limb between the knee and theankle).[14] The thigh is thefemur and the femoral region. The kneecap is thepatella and patellar while the back of the knee is the popliteus andpopliteal area. The leg (between the knee and the ankle) is the crus and crural area, the lateral aspect of the leg is theperoneal area, and the calf is the sura and sural region. The ankle is the tarsus and tarsal, and the heel is the calcaneus or calcaneal. The foot is the pes and pedal region, and the sole of the foot is the planta and plantar. As with the fingers, the toes are also called the digits, phalanges, and phalangeal area. The big toe is referred to as the hallux.
To promote clear communication, for instance about the location of a patient's abdominal pain or a suspicious mass, theabdominal cavity can be divided into eithernine regions or four quadrants.[4]
The abdomen may be divided into four quadrants, more commonly used in medicine, subdivides the cavity with one horizontal and one vertical line that intersect at the patient's umbilicus (navel).[4] The right upper quadrant (RUQ) includes the lower rightribs, right side of theliver, and right side of thetransverse colon. The left upper quadrant (LUQ) includes the lower left ribs,stomach,spleen, and upper left area of thetransverse colon. The right lower quadrant (RLQ) includes the right half of thesmall intestines,ascending colon, right pelvic bone and upper right area of thebladder. The left lower quadrant (LLQ) contains the left half of the small intestine and left pelvic bone.[14]
The more detailed regional approach subdivides the cavity into nine regions, with two vertical and two horizontal anatomical lines drawn according to landmark structures. The vertical; or midclavicular lines, are drawn as if dropped from the midpoint of eachclavicle. The superior horizontal line is thesubcostal line, drawn immediately inferior to the ribs.[4] The inferior horizontal line is called theintertubercular line, and is to cross the iliac tubercles, found at the superior aspect of the pelvis.
The upper right square is the right hypochondriac region and contains the base of the right ribs. The upper left square is the left hypochondriac region and contains the base of the left ribs. The epigastric region is the upper central square and contains the bottom edge of the liver as well as the upper areas of the stomach. The diaphragm curves like an upside down U over these three regions.
The central right region is called the right lumbar region and contains the ascending colon and the right edge of the small intestines. The umbilical region is central square and contains the transverse colon and the upper regions of the small intestines. The left lumbar region contains the left edge of the transverse colon and the left edge of the small intestine.
The lower right square is the right iliac region and contains the right pelvic bones and the ascending colon. The lower left square is the left iliac region and contains the left pelvic bone and the lower left regions of the small intestine. The hypogastric region is the lower central square and contains the bottom of the pubic bones, upper regions of the bladder and the lower region of the small intestine.[14]
When anatomists refer to the right and left of the body, it is in reference to the right and left of the subject, not the right and left of the observer. When observing a body in the anatomical position, the left of the body is on the observer's right, and vice versa. These standardized terms avoid confusion. Examples of terms include:[5]: 4
Each locational term above can define the direction of avector, and pairs of them can defineaxes, that is, lines of orientation. For example, blood can be said to flow in a proximal or distal direction, and anteroposterior, mediolateral, and inferosuperior axes are lines along which the body extends, like the X, Y, and Z axes of aCartesian coordinate system. An axis can be projected to a correspondingplane.
Anatomy is often described inplanes, referring to two-dimensionalsections of the body. Asection is a two-dimensional surface of a three-dimensional structure that has been cut. A plane is an imaginary two-dimensional surface that passes through the body. Three planes are commonly referred to in anatomy and medicine:[4][5]: 4
Anatomical terms may be used to describe the functional state of an organ:[citation needed]
The termanatomical variation is used to refer to a difference in anatomical structures that is not regarded as a disorder. Many structures vary slightly between people, for example muscles that attach in slightly different places. For example, the presence or absence of thepalmaris longus tendon. Anatomical variation is unlikecongenital anomalies, which are considered a disorder.[16]
Joints, especiallysynovial joints allow the body a tremendous range of movements. Each movement at a synovial joint results from the contraction or relaxation of the muscles that are attached to the bones on either side of the articulation. The type of movement that can be produced at a synovial joint is determined by its structural type.
Movement types are generally paired, with one being the opposite of the other. Body movements are always described in relation to the anatomical position of the body: upright stance, with upper limbs to the side of body and palms facing forward.[14]
Terms describing motion in general include:
These terms refer to movements that are regarded as unique to the hands and feet:[18]: 590–7
Muscle action that moves the axial skeleton work over ajoint with anorigin andinsertion of the muscle on respective side. The insertion is on the bone deemed to move towards the origin during muscle contraction. Muscles are often present that engage in several actions of the joint; able to perform for example both flexion and extension of theforearm as in thebiceps andtriceps respectively.[14] This is not only to be able to revert actions of muscles, but also brings on stability of the actions thoughmuscle coactivation.[19]
The muscle performing an action is theagonist, while the muscle which contraction brings about an opposite action is theantagonist. For example, an extension of the lower arm is performed by the triceps as the agonist and the biceps as the antagonist (which contraction will perform flexion over the same joint). Muscles that work together to perform the same action are calledsynergists. In the above example synergists to the biceps can be thebrachioradialis and thebrachialis muscle.[14]
The gross anatomy of a muscle is the most important indicator of its role in the body. One particularly important aspect of gross anatomy of muscles ispennation or lack thereof. In most muscles, all the fibers are oriented in the same direction, running in a line from the origin to the insertion. In pennate muscles, the individual fibers are oriented at an angle relative to the line of action, attaching to the origin and insertion tendons at each end. Because the contracting fibers are pulling at an angle to the overall action of the muscle, the change in length is smaller, but this same orientation allows for more fibers (thus more force) in a muscle of a given size. Pennate muscles are usually found where their length change is less important than maximum force, such as the rectus femoris.[20]
Skeletal muscle is arranged in discrete muscles, an example of which is thebiceps brachii. The tough, fibrous epimysium of skeletal muscle is both connected to and continuous with thetendons. In turn, the tendons connect to theperiosteum layer surrounding the bones, permitting the transfer of force from the muscles to the skeleton. Together, these fibrous layers, along with tendons and ligaments, constitute thedeep fascia of the body.[20]
Movement is not limited to only synovial joints, although they allow for most freedom. Muscles also run oversymphysis, which allow for movement in for example thevertebral column by compression of theintervertebral discs. Additionally, synovial joints can be divided into different types, depending on their axis of movement.[21]
The body maintains its internal organization by means of membranes, sheaths, and other structures that separate compartments, called body cavities. The ventral cavity includes the thoracic and abdominopelvic cavities and their subdivisions. The dorsal cavity includes the cranial and spinal cavities.[14]
Aserous membrane (also referred to as a serosa) is a thin membrane that covers the walls oforgans in thethoracic andabdominal cavities. The serous membranes have two layers;parietal and visceral, surrounding a fluid filled space.[4] The visceral layer of the membrane covers the organ (the viscera), and the parietal layer lines the walls of the body cavity (pariet- refers to a cavity wall). Between the parietal and visceral layers is a very thin, fluid-filled serous space, or cavity.[4] For example, thepericardium is the serous cavity which surrounds the heart.[4]
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This article incorporatestext available under theCC BY 4.0 license.Betts, J Gordon; Desaix, Peter; Johnson, Eddie; Johnson, Jody E; Korol, Oksana; Kruse, Dean; Poe, Brandon; Wise, James; Womble, Mark D; Young, Kelly A (February 26, 2016).Anatomy & Physiology. Houston: OpenStax CNX. 1.6. Anatomical Terminology.ISBN 978-1-93-816813-0. ID: 14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@8.24.Archived from the original on March 16, 2018. RetrievedMarch 15, 2018.
This article incorporates text from afree content work. Licensed under CC BY 4.0. Text taken fromAnatomy and Physiology, J. Gordon Bettset al, Openstax.
