The contents of the intracranial cavity are largely supplied by the circle of Willis anastomosis. The internal carotid arteries and vertebral arteries supply the anterior and posterior circulatory components of the anastomosis respectively. This article will focus on the internal carotid artery (ICA) and it's complex journey from the extra-cranial region to the intracranial space.
I know some of you are going to scroll down and think I'm not reading all that! For those of you, I have a small summary paragraph at the end. If you're more a "bring it on kinda person", then read the whole thing. I realise the basal ganglia can be a confusing topic, hence this post, if you come across terms your not familiar with, you can look them up in my neuroanatomy primer post.
In this post, I will be discussing the neuroanatomical differentiation between an upper motor neuron (UMN) and lower motor neuron (LMN) facial palsy. The two pathologies in the title could also be differentiated in other ways, for example, the speed of onset, additional symptoms and signs, etc.; however understanding the neuroanatomy in the context of the clinical picture, is the best way of avoiding making a grave error.
The aim of this post is to clarify some basic neuroanatomy terms and to give you a sound foundation. Before we start, a quick bit of housekeeping, I use the British spelling for neurone (also used by Gray's Anatomy, The Anatomical basis of clinical practice) as opposed to the American spelling neuron. Abbreviations used include CNS: central nervous system, PNS: peripheral nervous system, SNS: sympathetic nervous system and PSNS: parasympathetic nervous system.