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Anatomy
Written by Tim Sheppard MBBS BSc. Last updated 9/11/10

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What is anatomy?

The strict definition of anatomy depends upon the context, but put simply it is the study of structure, in relation specifically to 'organic beings'. As far as we're concerned, it's about the structure of the human body - what goes where, what each part of the body is called, what blood vessels provide which bit, etc.

The body is split up into different sections to make it easier to deal with - you can't just refer to the 'top', 'bottom' and 'sides' of the body! Instead, you refer to bits like the abdomen and the thorax. There are also lots of special terms for orientation, because sometimes it's difficult to know what the 'top' is - after all, if someone stands on their head, which is the top end?

Before studying the body itself, it's probably best to have a look at the anatomical terms listed below, because some definitions are important to realise before plunging straight into all that anatomy has to offer.

Initially it is worth remembering that the anatomical position shows the body facing towards you, with palms of the hands, eyes, and head facing forwards, feet together, arms to the sides.

The image on the left shows the skeleton, complete with some organs and muscles, of a body in the anatomical position. Notice, only, that the feet are facing outwards instead of forwards.


What is coronal?

Coronal is a plane, slicing through an anatomical body (i.e. anything from the whole body, to just an organ). It goes vertically, passing from one side of the body to the other such that the original body is separated into front and back parts.

Sometimes there is a helpful way of remembering planes, but coronal is one of the difficult ones if it isn't immediately obvious. I suppose I always consider it in relation to the face - it leaves the face 'intact', running parallel to the plane of the face, and it is the only plane of those given here that does this.


What is sagittal?

Sagittal is a plane, slicing through an anatomical body (i.e. anything from the whole body, to just an organ). It goes vertically, passing from one side of the body to the other such that the original body is separated into left and right parts.

The best way of remembering the sagittal plane is to consider that sagittal also means arrow. If you fire an arrow at someone, it would strike the person in the front, facing towards the back - if powerful enough, the arrow would pass from the front to the back. In that respect, this marks out the sagittal plane.


What is transverse?

Transverse is a plane, slicing through an anatomical body (i.e. anything from the whole body, to just an organ). It goes horizontally, passing from one side of the body to the other such that the original body is separated into top and bottom parts.

The best way of remembering the transverse plane is to consider that transverse also means horizontal. This plane is also known as the horizontal plane, though it is generally more frequently referred to as transverse.


What is oblique?

Oblique is a plane, slicing through an anatomical body (i.e. anything from the whole body, to just an organ). It goes diagonally, passing from one side of the body to the other at an angle somewhere between the transverse and one of the horizontal planes.

The best way of remembering the oblique plane is to consider that oblique basically just means diagonal. Throughout the field of anatomy, oblique refers to a diagonal or slanted direction, not just the plane. It is important to remember that oblique means diagonal, as it comes up in all sorts of areas, in different contexts, and referring to different aspects of the diagonal direction.


What are anterior and posterior?

The coronal plane separates an anatomical body into front and back parts. However, anatomists prefer to use different words, because 'front' and 'back' are vague when refering to orientations that can change.

Accordingly, in their wisdom, anatomists have chosen to refer to front as anterior or ventral. In this section of the site, anterior will generally be used - and it will be used a lot - to refer to things that are at the front. If something is facing anteriorly, it is facing 'forwards'.

In a similar vein, they chose to call back, posterior or dorsal. In this section of the site, posterior will generally be used to refer to things that are at the back. If something is facing posteriorly, it is facing 'backwards'.


What are superior and inferior?

The transverse plane separates an anatomical body into top and bottom parts. However, anatomists prefer to use different words, because 'top' and 'bottom' are vague when refering to orientations that can change.

Accordingly, in their wisdom, anatomists have chosen to refer to top as superior, rostral or cephalic. Superior obviously means higher up, rostral also means higher up (or towards the beak) and cephalic often refers to the head; these are helpful ways of remembering what they mean. In this section of the site, superior will generally be used - and it will be used a lot - to refer to things that are at the top. If something is facing superiorly, it is facing 'upwards'.

In a similar vein, they chose to call bottom, inferior or caudal. Inferior and caudal both mean lower down, which is a helpful way of remembering what they mean. In this section of the site, inferior will generally be used to refer to things that are at the bottom. If something is facing inferiorly, it is facing 'downwards'.


What is the midline?

The midline is an imaginary line that runs down the centre of the body, equidistant from the two sides, separating the body into two imaginary parts - left and right.

On a normal human, the midline will pass through the centre of the head, between the eyes, along the nose, down the neck, down the centre of the chest and abdomen, and between the legs.


What are medial and lateral?

Medial refers to areas closer to the midline. Lateral refers to areas further from the midline. Something facing medially faces towards the midline, while something facing laterally faces away from the midline.

Medial movement obviously, therefore, refers to movement towards the midline, while lateral movement means movement away from the midline.


What are flexion and extension?

Flexion is a lot like it sounds. You've probably heard of 'flexing' a muscle. In order to 'flex' your arm has to undergo flexion. Flexion refers to the movement of something (usually a limb) and it regularly involves moving it away from the anatomical position. If you have your arm in the anatomical position (i.e. resting by your side) then when you flex it, you move it away from the anatomical position.

Conversely, extension is simply the opposite. It often involves moving something towards the anatomical position, because when your arm is flexed, moving it out of that flex will involve returning it to your side. Flexion and extension are opposites, and apply to all your limbs.

Although flexing your arms involves moving them forwards by bending at the elbow, the structure of the legs is such that when you 'flex' them you move them backwards. Indeed, flexion of the legs involves bending at the knee, which results in movements backwards. It is still movement away from the anatomical position, and extension still returns the leg to the anatomical position, but it works differently because the knee joint is set up differently.

It's also worth noting that it depends on the joint that you're talking about. Flexion of the knee involves moving the leg backwards, but flexion of the hip involves bringing the leg up and forwards, because that is the movement available at the hip. They produce movements in quite different directions, but have the same name because they are both flexion.


What are abduction and adduction?

Abduction involves movement away from the midline. Unfortunately its opposite has an immensely similar name - adduction. Adduction is, obviously, movement towards the midline, and again, these two movements work quite happily with the limbs. There are not particular complications here, because the definitions are quite simple. Another way of phrasing it is that abduction is lateral movement, and adduction is medial movement.

Since the names are so similar, it's probably a good idea to have some way of remembering which is which. The best way that I have found is that when talking about alien abduction, you're talking about someone being taken away, so abduction is movement away from the midline. Adduction is just the opposite, then. Another way of looking at it is to consider which comes first alphabetically - and it's abduction, so this comes first. Of course, this latter way of learning it isn't full proof, because you can have adduction of the leg from the anatomical position, in which case adduction comes first. However, it's helpful to consider a couple of ways of remembering, and find which one is best for you.


What is ipsilateral?

Ipsilateral basically means the same side. When you have an illness or an abnormality or just something wrong on one side of the body, you may want to let someone know about something else in relation to it. The word 'ipsilateral' gives an opportunity to describe one thing in relation to another.

For instance, if I had broken my arm, I might want to let someone know that I had broken my leg as well. The question is, is it the leg on the same side of the body, or the other one? If I had broken my left arm, then the ipsilateral leg would be the left leg.


What is contralateral?

Contralateral basically means the opposite side. If you have a particular problem on one side of the body (e.g. you couldn't move your right leg) then it's really important to know what's on the other side. The word 'contralateral' gives you that opportunity to describe one side of the body in relation to the other.

For example, if I had numbness on the right side of my abdomen, I would probably want to know if it also affected my left side. The left side is the contralateral side of my abdomen.


What are proximal and distal?

Proximal and distal are terms used to describe how close something is to the centre of the body. For instance, the upper limb is connected at the shoulder. The proximal end of the upper limb is therefore the shoulder, while the distal end is the fingertip. The further away from the body you go, the more distal you go; the closer to the body you go, the more proximal you go.


Further Reading