Anatomical Terminology - 2024.pdf

ANATOMICAL TERMINOLOGY Anatomical position, is the position that is globally adopted for anatomical and medical descriptions of the human body. Now, let’s describe the position the body is in when we refer to anatomical position. When a person is in the anatom...

ANATOMICAL TERMINOLOGY Anatomical position, is the position that is globally adopted for anatomical and medical descriptions of the human body. Now, let’s describe the position the body is in when we refer to anatomical position. When a person is in the anatomical position, they are standing straight up with their legs close together, their feet parallel to one another, toes directed forward, their arms are down at their sides with the palms of their hands facing forward, and they are keeping their head up and gazing straight forward. All descriptions of the body refer to the position shown here. Now, if we’re looking at someone in anatomical position, there are four imaginary planes that intersect the body to help us with anatomical descriptions. First, we have the median plane, which is an imaginary vertical plane going through the body’s midline, over structures such as the nose and belly button, separating the body into right and left halves. Second, are sagittal planes, which are also vertical planes, but aren't fixed, meaning that they could be placed anywhere parallel to the median plane, dividing the body into uneven left and right parts. You might also hear the term paramedian plane, which describes a sagittal plane that is near the median plane. Next, we have frontal planes, also known as coronal planes.  ANATOMICAL TERMINOLOGY These imaginary planes are also vertical, but perpendicular to the sagittal and median planes, meaning they go from left to right, separating the body into a front portion and a back portion.  ANATOMICAL TERMINOLOGY Finally, we have transverse planes, which are the only horizontal planes, and thus are also known as - you’ve guessed it! - horizontal planes. These planes are perpendicular to the median and sagittal planes as well, but they divide the body into an upper portion, and a lower portion. In radiology, it’s also common to use the term axial plane, which is short for transaxial plane. The use of planes allows us to cut the body into sections, which provide a view of depth. Longitudinal sections refer to sections that are cut along the longitudinal axis of a structure. Transverse sections, also known as cross sections, are perpendicular to the longitudinal axis. These sections are useful for understanding the relative depths of different internal structures and their position in relation to each other. Last but not least, oblique sections are sort of intermediate to the two sections we’ve talked about, since they’re not cut in a straight, defined plane, but rather in diagonal.  ANATOMICAL TERMINOLOGY Now, here are some examples of anatomical structures being shown in different planes and sections, see if you can identify them correctly! Alright! Now, when an anatomical structure is introduced, it is common to describe its position or location related to surrounding structures, and this is done with specific anatomical terms. Among the most frequently used terms, we have up and down directions, which are termed superior and inferior. Let’s go back to the anatomical position! Okay, so superior means towards the head, while inferior means towards the feet. So we can say that the chest is superior to the hip, but inferior to the neck. Another way of saying this is using the terms cranial and caudal. Cranial refers to the cranium, or head, while caudal refers to the cauda, which means tail in Latin. So, caudal means towards the tail or feet. In the human body, the cauda can either refer to the coccyx, which is the most inferior bone in the vertebral column, or simply to the feet. Keep in mind that the terms cranial and caudal are commonly used to describe embryological structures and their growth or development.  ANATOMICAL TERMINOLOGY Now, to indicate that a structure is in front of another, we use the terms anterior, as well as ventral, which literally means ‘belly’ in Latin. When referring to structures in the head or brain, we can also use the term rostral, which means nose or beak. For example, the nose is considered a rostral structure, and the frontal lobe of the brain is rostral to the cerebellum. On the other hand, to indicate a structure that is more towards the back, we can say it is posterior, or dorsal, which means ‘back’ in Latin. However, keep in mind that the term dorsum or dorsal surface can also be used to describe the superior part of a structure that projects out of the body anteriorly, like the nose or foot, as well as the posterior surface of the hand.  ANATOMICAL TERMINOLOGY On the other...hand, the anterior surface of the hand is known as the palmar surface. The sole is the inferior aspect of the foot which is referred to as the plantar surface. This may seem confusing, but if we think of a bear walking with its four paws touching the ground. The palmar and plantar surfaces are what would be touching the ground and the dorsal surfaces are the upper sides of the hands or feet that are not touching the ground. Now, to describe a structure’s relative proximity to the median plane, we use the terms medial and lateral. Medial refers to a structure that is closer to the midline or median plane, while lateral refers to a structure that is farther from it. So, when looking at the head, our eyes are closer to the midline than our ears. Therefore, we could express this by saying that our eyes are medial to our ears, and our ears are lateral to our eyes.  ANATOMICAL TERMINOLOGY Next, there’s external and internal, which refer to the proximity to the center of an organ or cavity, regardless of the direction. External indicates structures that are outside or further from the center, while internal means inside, or closer to the center. So, for example, our heart, which is in our chest cavity, is more internal, while the ribs are more external. Similar, yet different are the terms superficial, and deep. These terms are used in relation to the surface or the body. For instance, our skin is superficial to the muscles that lie deep to it. We can also use the term intermediate to express the position in between. So, a layer of fat between the skin and muscle layers could be considered intermediate.  ANATOMICAL TERMINOLOGY Lastly, the terms proximal and distal are used for structures that have a beginning and an end, such as the limbs, bones, or blood vessels. In the limbs, these terms describe the relative proximity of a structure to the trunk. For example, the thigh is proximal to the foot because it’s closer to the trunk, and of course we can say the foot is distal to the thigh. These terms are also useful in describing two ends of bones. For example, let’s take the humerus - the long bone of the arm. Its proximal portion helps form the shoulder joint, while the distal portion helps to create the elbow joint. Okay, let’s stop for a second and review what we’ve just learned. Take a look at the images. Which terms can you recognize?  ANATOMICAL TERMINOLOGY Don’t be alarmed if you couldn’t recall everything, as you go on studying anatomy, these terms will become second nature! Let’s move on to the four terms of laterality. When a structure is only found on one side of the body, it is said to be unilateral, such as the spleen. Conversely, paired structures found on both sides of the body, like the limbs, lungs or kidneys are bilateral. Now, structures and organs that are on the same side of the body are said to be ipsilateral, like the left arm and the left leg. Conversely, structures located on the opposite side of the body are described as contralateral, like the left and right hands. Now, there are also various terms used to describe the movements of the limbs and other body parts. Most of these movements are defined in relation to the anatomical position and the planes we have discussed already. The majority of movements in the body occur at joints between two or more bones. So, flexion and its counterpart extension are movements in the sagittal plane. Flexion indicates bending or decreases the angle between two parts of the body, bringing them closer together. Flexion usually involves movement in the anterior direction; the one exception to this is the knee, where the leg moves in the posterior direction during flexion.  ANATOMICAL TERMINOLOGY Some examples of flexion include bending your trunk forward, as well as bending your elbow or knee. The opposite movement is extension indicating straightening or increasing the angle between two parts of the body, bringing them farther away. Using the same examples, extension includes bringing your trunk backwards or posteriorly, as well as straightening your knee or elbow back to anatomical position.  ANATOMICAL TERMINOLOGY Similarly, when referring to the movement of the ankle, we can use the term dorsiflexion for flexion in the upward direction - where the toes move toward the shin - since the dorsal surface of the foot is the upper surface. Plantarflexion, “on the other foot” - pun intended - refers to flexion in the downward direction, where the foot and toes move toward the ground, like when you stand on your tippy-toes. Next, we have abduction and adduction, which are movements that generally occur in the frontal plane. Abduction refers to movement of the limbs away from the center or the median plane of the body, like when you spread your arms to the side. On the other hand, adduction describes movement of the limbs towards the midline, back into the anatomical position. Think of ‘ADDuction’ as in adding that part back towards the body! Now, keep in mind that structures in the midline like the neck or trunk may also move to the sides. This is referred to as lateral flexion or lateral bending.  ANATOMICAL TERMINOLOGY Now, at some joints like the hip and shoulder, if we sequentially perform flexion, abduction, extension and adduction - or these movements in the opposite order – we get a compound circular movement called circumduction. In circumduction, the proximal end of the joint remains fixed, while its distal end moves in a circular motion. Rotation may sound the same, but it actually involves movements that are done around the longitudinal axis of the body, like rotating your head and neck side-to-side when you want to say ‘no’. Rotational movement of the shoulder or hip joints that brings the anterior surface of the limb away from the median plane is called lateral or external rotation. If the movement brings the anterior surface of the limb closer to the median plane, it is called medial or internal rotation.  ANATOMICAL TERMINOLOGY Rotational movements of the forearm and hand are due to the medial and lateral rotation of the distal radius, the lateral bone in the forearm over the anterior aspect of the ulna, the medial bone of the forearm. These movements are specifically called pronation and supination. During pronation, the radius rotates medially, crossing over the distal ulna so that the palm of the hand faces posteriorly. Supination is the opposite movement where the radius rotates laterally, uncrossing the distal ulna so that the palm of the hand faces anteriorly. A helpful way to remember these movements is that to hold a bowl of soup, we need to be in a supinated position, while to dribble a basketball like a pro, we need to be in a pronated position. Similar terms are used to describe the direction and position of a person when lying horizontally. So, when a person lies on their back, with their face and abdomen facing upwards, they’re in the supine position. On the flip side, literally, when a person is lying on their abdomen with their face down, they’re in the prone position. Next, eversion and inversion are movements that are specific to the feet. Eversion refers to the movement of the sole of the foot laterally, or away from the median plane, while inversion describes the opposite movement, so medially, or towards the median plane. Complete eversion of the foot results in dorsiflexion as well, while complete inversion results in plantarflexion. These are the movements that occur when we sprain or roll our ankle.  ANATOMICAL TERMINOLOGY Now, the term opposable thumbs is related to the anatomical terms opposition and reposition. Opposition is when the thumb moves medially to touch one of the other four fingers - like when you begin snapping your fingers or when pinching someone! Reposition refers to moving the thumb back, or repositioning it, towards its anatomical position.  ANATOMICAL TERMINOLOGY Moving on, protrusion refers to an anterior movement of a body part, like when you stick out your tongue. Protrusion can also be done by the lips and the mandible - or lower jaw. Conversely, retrusion is the posterior movement of the tongue, lips or mandible. Protraction and retraction are very similar, but refer to the anterolateral or posteromedial movements of the shoulder blades or scapulae on the posterior chest wall. Retraction is when you bring your shoulders backward and the scapulae move posteromedially. Protraction is when you move the shoulders forward and the scapulae move anterolaterally along the chest wall. For example, a boxer is protracting when punching. Finally, we have elevation and depression, which are as simple as they sound. Elevation refers to movement of a body part superiorly, such as when shrugging your shoulders or opening your upper eyelids. On the other hand, depression defines movement of a body part inferiorly, such as lowering your shoulders from the shrugged position, or closing the upper eyelids.