11. CNS (Motor) (1) Flashcards
- Neurone:
- Neurone: consists of a cell body (soma), axon and presynaptic terminal Not a nerve
- Nerve:
- Nerve: group of axons usually consisting of varying combinations of sensory, motor, and autonomic neurones
- Nerve:
- Nerve: group of axons usually consisting of varying combinations of sensory, motor, and autonomic neurones
- Sensory neurone:
- Sensory neurone: a neurone with sensory receptors that when stimulated conveys sensory information to the brain
- Sensory neurone:
- Sensory neurone: a neurone with sensory receptors that when stimulated conveys sensory information to the brain
- Motor neurone:
- Motor neurone: a neurone that when stimulated produces a motor response (e.g muscle contracting)
- Lower motor neurone (LMN):
- Lower motor neurone (LMN): AKA anterior/ ventral horn cell, alpha motor neurone or gamma motor neurone —-> Neurone providing the presynaptic terminal at the neuromuscular junction
- Upper motor neurone (UMN):
- Upper motor neurone (UMN): neurones controlling LMNs. Found throughout CNS.
- Upper motor neurone (UMN):
- Upper motor neurone (UMN): neurones controlling LMNs. Found throughout CNS.
- Efferent:
- Efferent: refers to the direction of neuronal information travelling away from a point of reference e.g LMNs
- Efferent:
- Efferent: refers to the direction of neuronal information travelling away from a point of reference e.g LMNs
- Afferent:
- Afferent: refers to the direction of neuronal information travelling towards a point of reference e.g. sensory neurones
- Afferent:
- Afferent: refers to the direction of neuronal information travelling towards a point of reference e.g. sensory neurones
- Interneurone:
- Interneurone: a neurone that connects two other neurones and may be excitatory or inhibitory when stimulated
- Agonist muscle:
- Agonist muscle: muscle that produces a movement of interest when contracting e.g flexion at the elbow = biceps is the agonist —> Agonists can be antagonists for different movements
- Antagonist muscle:
- Antagonist muscle: muscle that opposes movement of interest when contracting e.g for elbow flexion = triceps is the antagonist —-> Antagonist can be an agonist for a different movement
- Paresis:
- Paresis: partial paralysis
- Paresis:
- Paresis: partial paralysis
- Hemiparesis:
- Hemiparesis: partial paralysis on one half of the body
- Contralateral:
- Contralateral: refers to opposite side of a region of interest
- Ipsilateral:
- Ipsilateral: refers to same side as region of interest
- Ipsilateral:
- Ipsilateral: refers to same side as region of interest
- Tracts:
- Tracts: groups of axons that convey similar sensory or motor information
Anatomical areas affecting motor function:
* Motor function refers…
- Motor function refers to the smooth (coordinated) and effective movement in an autonomic fashion ( without thought )
Anatomical areas affecting motor function:
* Motor function refers…
- Motor function refers to the smooth (coordinated) and effective movement in an autonomic fashion ( without thought )
Cerebrum=
Cerebellum=
Spinal chord=
Brain stem=
Cerebrum=
Cerebellum=
Spinal chord=
Brain stem=
Anatomical areas affecting motor function:
* Grey matter =
* Area where _______ movements are initiated
* Brainstem also has UMNs that control _____ muscle
- site in motor strip of UMN
- voluntary movements are initiated
- postural
- Brainstem and spinal chord have ____ either for cranial or somatic muscles in the body
LMNs
Midbrain:
Cerebrum:
Cerebellum:
What is the basal ganglia?
- Produces automatic movement
- Where cell bodies are located
- Help motor cortex plan movement involved in automatic planning
Initiation of movement:
How are UMNs activated? (2)
- UMNs when activated are the central signal to initiate muscle contraction and movement
- Cell bodies of UMNs to the upper and lower limbs and trunk are found in the primary motor cortex of the frontal lobe In pre central gurus anterior to middle cerebral fissure
How do signals travel from axons to LMNs?
How are UMNs derived and how do they travel down the spinal cord? (5)
- UMNs are derived from both sides of the cerebral hemisphere Left and right primary motor cortices
- Axons cross/decussate in the medulla oblongata in the medullary pyramids (pyramidal tract = tracts in brainstem)
- UMNs travel down spinal chord and terminate on LMNs on contalateral side
- In spinal chord, they mainly travel in the lateral corticospinal tract
- UMNs from one side of the brain control movement on the opposite side of the body
What happens when UMNs are damaged?
- Damage to UMNs and tracts up and until medullary decussation cause weakness on the contralateral side and damage to tracts in the spinal chord cause weakness on the ipsilateral side
- UMNs are very _____
- They have long axons
- Their cell bodies are located in the ____ _____
- Axons —-> Motor cortex —-> Internal capsule —-> _____.
long
motor cortex
Brainstem
Where are upper motor neurons to the limbs and trunk found?
What are pyramidal pathways called?
Through brainstem via _____ ______.
Through spinal cord via ____ ________.
pyramidal tract
corticospinal tract
Details of upper motor neuron pathways to limbs and trunk: (6)
LMNs to limbs & trunk:
Where are the LMNs found? (2)
- LMNs to the limbs and trunk are found int the anterior/ventral horn of the spinal chord gray matter
- Axons exit the spinal chord via the ventral root where they meet with the dorsal root of the spinal chord containing sensory neurons to form the common nerve before exiting the vertebrae
What do UMNs in the spinal cord supply?
- Dorsal root =
- Ventral root =
purely sensory
purely motor
- LMNs target ______ muscle and presynaptic terminal of LMNs is part of the neuromuscular junction.
- LMNs are activated by _____ to produce movement but can also be controlled by sensory neurones
skeletal
UMNs
- Only two neurones are required to produce contraction of muscle =
LMNs and UMNs
Where do the LMNs exit? (2)
- They exit the spinal chord to form the ventral root and then join the dorsal root (sensory nerves) to form a common nerve
- Common nerve then passes through the foramina to exit the vertebral column
Where do the LMNs exit? (2)
- They exit the spinal chord to form the ventral root and then join the dorsal root (sensory nerves) to form a common nerve
- Common nerve then passes through the foramina to exit the vertebral column
- Vertebral disc ______ would damage the common nerves
lesions
LMNs & muscle tone:
True or False,
* While power may be reduced, tone may be increased.
True,
* While power may be reduced, tone may be increased.
* e.g power of the biceps is tested by flexing the arm against resistance (person examining will try and extend the arm while the patient flexes)
How can we assess tone?
- To asses tone, the patient will be asked to relax the arm and the examiner will passively flex and extend the arm while feeling the biceps muscle tone.
How can we assess tone?
- To asses tone, the patient will be asked to relax the arm and the examiner will passively flex and extend the arm while feeling the biceps muscle tone.
- Muscle tone comes from a level of muscle contraction at rest —->
- Muscle spindles fire at all times to provide position ______
- Stimulus for contraction at rest is from muscle spindles constantly firing at rest
- sensation