MICRO
CNS (1).pptx

They synapse in the anterior horn motor grey matter

Info icon This preview shows pages 59–72. Sign up to view the full content.

They synapse in the anterior horn (motor grey matter) of the spinal cord, just prior to leaving the cord. 59
Image of page 59

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

This synapse is clinically very important because: The motor neurons above the level of this synapse (connecting the cerebral cortex and anterior horns) are termed upper motor neurons. where as Those below this level are termed lower motor neurons. 60
Image of page 60
Why is there difference between the upper motor neuron and lower motor neuron lesions, when they are a part of the same pathway i.e., (corticospinal tract) ? This occurs because of the release phenomenon. What happens is that, along with the corticospinal tract several other motor tracts also descends in the spinal cord. 61
Image of page 61

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

These tracts have inhibitory effect on the stretch reflexes and the muscle tones. As they travel along with the corticospinal tract, these tracts too are injured in upper motor neuron lesion . Injury to these tracts results in release of the inhibitory impulses which results in spasticity and hyperactive tendon reflexes. 62
Image of page 62
63
Image of page 63

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Upper motor neuron vs. lower motor neuron lesion UMN lesion is characterised by - (AI 99) a) Weakness & spasticity b) Fasciculations c) Rigidity d) Localised muscle atrophy A 64
Image of page 64
Remember The division of motor tract into upper motor neuron and lower motor neuron is limited not only to the spinal cord but they also involve the motor neurons of the brainstem. In the brain stem:- The upper motor neuron is part above the brainstem nuclei. Lower motor neuron is  cranial nerve. 65
Image of page 65

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

All are features of pyramidal tract lesion, Except - a) Involuntary movement (AI Sep. 96) b) Positive Babinski’s sign c) Spasticity d) Increased deep tendon reflexes A 66
Image of page 66
Involvement of pyramidal tract leads to all of the following except - {NBE/DNB Pattern] a) Spasticity b) Fasciculation c) Hyper-reflexia d) Positive babinski sign B 67
Image of page 67

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Distribution of weakness in Pyrimidal tract lesions- {NBE/DNB Pattern) a) Extensors more than flexors in lower limb b) Flexors more than extensors in upper limb c) Antigravity muscles are affected d) Antigravity muscles are spared 68
Image of page 68
Pyramidal-pattern weaknes:- The antigravity muscles are preferentially spared and stronger. The flexors of the upper limbs and the extensors of the lower limbs. The patient can develop a characteristic posture of flexed and pronated arms with clenched fingers, and extended and adducted legs with plantar flexion of the feet. 69
Image of page 69

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

In upper extremities:- - Relative sparing of the flexors - More involvement of the extensor In lower extremities:- - Predominant invovlement of the flexors with - Relative sparing of the extensor or 70
Image of page 70
Pyramidal weakness Loss of power most marked in the extensors muscles in the arms and flexors in the legs.
Image of page 71

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 72
This is the end of the preview. Sign up to access the rest of the document.
  • Winter '16
  • jean grey

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern