Editing Electrocardiography (section)

===Limb leads===
[[File:Limb leads of EKG.png|600px|thumbnail|right|The limb leads and augmented limb leads (Wilson's central terminal is used as the negative pole for the latter in this representation)]]
[[File:EKG leads.png|300px|thumb]]
Leads I, II and III are called the ''limb leads''. The electrodes that form these signals are located on the limbs – one on each arm and one on the left leg.<ref>{{Cite web |url=https://www.nottingham.ac.uk/nursing/practice/resources/cardiology/function/limb_leads.php |title=Limb Leads – ECG Lead Placement – Normal Function of the Heart – Cardiology Teaching Package – Practice Learning – Division of Nursing – The University of Nottingham |publisher=Nottingham.ac.uk |access-date=15 August 2009}}</ref><ref>{{Cite web |url=https://library.med.utah.edu/kw/ecg/ecg_outline/Lesson1/index.html#orientation |title=Lesson 1: The Standard 12 Lead ECG |publisher=Library.med.utah.edu |url-status=dead |archive-url=https://web.archive.org/web/20090322042804/https://library.med.utah.edu/kw/ecg/ecg_outline/Lesson1/index.html |archive-date=22 March 2009 |access-date=15 August 2009}}</ref> The limb leads form the points of what is known as [[Einthoven's triangle]].<ref>{{cite journal |last1=Jin |first1=Benjamin E. |last2=Wulff |first2=Heike |last3=Widdicombe |first3=Jonathan H. |last4=Zheng |first4=Jie |last5=Bers |first5=Donald M. |last6=Puglisi |first6=Jose L. |title=A simple device to illustrate the Einthoven triangle |journal=Advances in Physiology Education |date=December 2012 |volume=36 |issue=4 |pages=319–324 |bibcode=2012BpJ...102..211J |doi=10.1152/advan.00029.2012 |pmc=3776430 |pmid=23209014 }}</ref>
* Lead I is the voltage between the (positive) left arm (LA) electrode and right arm (RA) electrode:
:<math>
I = LA - RA
</math>
* Lead II is the voltage between the (positive) left leg (LL) electrode and the right arm (RA) electrode:
:<math>
II = LL - RA
</math>
* Lead III is the voltage between the (positive) left leg (LL) electrode and the left arm (LA) electrode:
:<math>
III = LL - LA
</math>