Dear list members,

I have been following the discussion about bilateral innovation with
interest and have a little more to add.  I consulted the anatomy bible ie
Gray's on the matter to see what they had to say.  They describe the medial
(or anterior) corticopsinal tract as consisting of 10 - 15 % of the
corticospinal fibbers descending from the motor cortex.  They agree that
they do not cross in the brainstem, but state that the fibres cross at
spinal segmental levels. This raises questions regarding whether the
innervation involved is bilateral or not.  

In addition, both Gray and other authors state that, in hunans, this tract
disappears in the upper thoracic region and essentially supplies muscles in
the neck and upper thorax.  If this is the case then one must query it's
ability to innervate the abdominal and lower back muscles as there have much
lower nerve supplies.

It is suggested that the function of the medial/anterior corticopsinal tract
is innervation of the muscles involved in the subconscious system which
involves a number of ocular and auditory reflexes and responds to incoming
sensory stimuli as part of our survival repossess.  This system involves
co-ordinated actions controlled by several nuclei of the reticular
formation.  An example of input to which this 'old' system (evolutionarily
speaking) responds 'instinctively' includes 'seeing something 'out of the
corner of the eye' and ducking out of the way before really becoming
conscious of the fact that one was about to walk into the branch of a tree.


    
Jenny Morris
Senior lecturer in physiotherapy

Physiotherapy
Colchester Institute
Sheepen Rd
Colchester
CO3 3LL
Essex
UK

Phone:  01206 - 518199 (518165 - ansaphone)
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> ----------
> From: 	[log in to unmask][SMTP:[log in to unmask]] on behalf
> of Owen Moore[SMTP:[log in to unmask]]
> Reply To: 	[log in to unmask]
> Sent: 	Friday, June 23, 2000 5:51PM
> To: 	[log in to unmask]
> Subject: 	RE: bilateral innervation
> 
> Dear Sheila,
> Top reply....I can now get my head around the concept!
> If you do manage to stumble across some references...drop them onto the
> mailbase!
> In addition, would you be interested in helping me start a motor control
> mail group?
> Regards,
> Owen
> 
> 	-----Original Message-----
> 	From:	[log in to unmask] [SMTP:[log in to unmask]]
> 	Sent:	Thursday, June 22, 2000 7:26 AM
> 	To:	[log in to unmask]
> 	Subject:	Re: bilateral innervation
> 
> 	Dear Owen,
> 	My understanding of bilateral innervation in this instance stems
> from the 
> 	work of Kuypers [apologies for spelling] who retraced on cadavers
> the 
> 	peripheral nerves and came up with the classification of medial /
> lateral 
> 	pathways rather than pyramidal / extrapyramidal.  He observed that
> the medial 
> 	pathways innervated the more proximal muscle groups including the
> trunk. He 
> 	also observed that the descending ventral corticospinal tract did
> not cross 
> 	over but that at spinal level it sent a branch to the opposite side.
> I don't 
> 	have my reference to hand but my knowledge stems from lectures
> delivered by 
> 	Shirley Stockmeyer.
> 	I understand your dissatisfaction with the lack of up to date
> published 
> 	papers related to neurological physiotherapy. As a physiotherapist
> working in 
> 	neuro I am always disheartened when I read observations like yours
> about pts 
> 	in neuro who only think of "tone". It is crutial to my assessment of
> a 
> 	patient that I include soft tissue and joint ranges as the ability
> to gain 
> 	the correct alignment is crutial to the recruitment of the
> appropriate 
> 	muscles indeed once correct alignment has been facilitated muscle
> activity 
> 	can often be generated in previously inactive muscles. I do not
> intend to 
> 	give a complete account of my perceptions of current neuro practice
> but it 
> 	recognises that the level of tone in an individual muscle at any one
> time is 
> 	the combination of a complex physical, neural, environmental and
> emotional 
> 	factors.
> 	I do have a different experience with regard to lack of control in
> trunk 
> 	muscles post stroke.  I find often that patient's have difficulty
> with 
> 	recruiting their postural system and compensate with the use of
> their 
> 	movement system, which if allowed to persist can result in a change
> in the 
> 	percentages of muscle type to slow twitch, reinforce these neural
> pathways 
> 	and thus compromise their ability to perform their previous usual
> function. I 
> 	certainly do not dispute that they have limb problems however as
> recognised 
> 	by musculoskeletal therapists we can not look at them in isolation,
> the 
> 	concept of dynamic stability [muscle imbalance, core stability] is
> crutial to 
> 	the principals of normal movement and the bobath concept.    
> 
> 	Sheila McEwan
> 	Super III Physio
> 
> 	      
> 
> 
> 
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