What is the CNS, PNS and Autonomic nervous system made up of?
Central Nervous System (CNS)
Brain (in the skull)
Spinal cord (passing through vertebrae)
Peripheral nervous system (PNS):
Cranial nerves (12 pairs)
Spinal nerves (31 pairs)
Autonomic nervous system:
Communicates with internal organs and glands
What is grey and white matter in the CNS?
CNS- the control centre for human behaviour, integrating information for coherent action. All CNS elements contain grey matter (neural cell bodies, dendrites, unmyelinated axons) and white matter (myelinated axons).
Sensory neurons (afferent) enter the spinal cord via the dorsal root. Motor neurons (efferent) exit the spinal cord via the ventral root. The interneurons sit within the CNS.
The brain makes up 2% of total body weight, with 86 billion neurons.
What is the cerebrum?
The largest and most superior structure of the CNS
Includes the cerebral cortex and basal ganglia (and other structures)
Consists of 2 hemispheres connected by the corpus collosum (bundle of fibres)
What is the cerebral cortex?
A folded sheet (2-4mm thick of grey matter), the outer layer covering the cerebral hemispheres: Gyri (crest of folded tissue), Sulci (grooves/fissures that divided gyri). Each hemisphere is divided into 4 lobes- frontal, temporal, parietal and occipital. Each lobe receives input from different sensory systems involved in different processes, however, there is significant cross talk between lobes.
What is the motor cortex, primary motor cortex, rostral CMA, caudal CMA, pre-motor cortex and SMA
Motor cortex- area in the frontal lobe anterior to the central sulcus, fundamental for voluntary motor control and deciding/planning actions.
M1 (primary motor cortex): motor commands to motor neurons, initiation and coordination of voluntary movements, tells muscles to contract
Rostral CMA- motivation, decision to act (should I move?)
Caudal CMA- motor planning and correction (how exactly do I move?)
Pre-motor cortex: organisation of movements is decided before they’re initiated.
Supplementary Motor Area (SMA): preparation and control of sequential movements, makes sure signals are sent in the correct sequence.
What is the frontal eye field, Broca’s area, cingulate motor area, somatotopic organisation and the motor homunculus?
Frontal eye Field- specific for the eyes
Broca’s area: the region of the brain in the frontal left area that contains neurons involved in speech and language.
Cingulate motor area- direction of attention
Somatotopic organisation: relating to the movement capacity of the body.
The Motor Homunculus shows percentages of frontal lobe devoted to body’s motor activities, greater proportion for movement in hands and face (more precise movements), less proportion for lower limbs (great movements from muscle, but less precise)
What is the Basal Ganglia?
Basal Ganglia- a set of subcortical neural nuclei strictly interconnected with the cortex and the brainstem:
Includes the striatum (caudate and putamen), globus pallidus, substantia nigra, subthalamic nucleus and nucleus accumbens.
Important role in the control of voluntary movements, motor learning, cognition and emotion.
Proper functioning of the basal ganglia is required to relay commands to the lower levels.
It helps decide whether to start an action or suppress an action. It does this using the direct pathway and the indirect pathway
Direct pathway- involved in the excitation of a desired motor programme
Indirect pathway- inhibition of competing motor programme
What is Parkinson’s and Huntington’s disease?
Parkinson’s disease- degeneration of neurons in the substantia nigra; symptoms- likelihood of falling, shuffling gait, tremor at rest (fewer voluntary movements), slow voluntary movements (bradykinesia), difficulty in initiating movements (akinesia), inadequate amplitude of movements (hypometria).
Huntington’s disease- selective loss of striatal neurons; symptoms- choreiform movements: involuntary (dyskinesis), continuous movement of the body (extremities and the face- less control), resemble adaptive movements, but involuntary and incoherently.
What is the cerebellum?
Cerebellum- prominent structure situated at the back of the pons (brainstem) and concerned with motor coordination, posture and balance:
Plays a fundamental role in the execution of smooth and accurate movements
Known as the ‘little brain’
Accounts for 10% of the brain’s volume, contains over 50% of the brain’s total neurons
Receives input from the sensory system and from the motor cortex
Motor commands aren’t initiated in the cerebellum, but it modifies the motor commands of the descending pathways to make movements more adaptive and accurate
What are the functions of the cerebellum?
Maintenance of balance and posture- postural adjustments to maintain balance. Input from vestibular system and proprioceptors, it modulates commands to motor neurons to compensate for shifts in body position or changes in load upon muscles.
Coordination of voluntary movements- most movements are composed many different muscle groups acting together in a temporally coordinated fashion. The cerebellum coordinates the timing and force of these different muscle groups to produce fluid limb or body movements.
Motor learning
Cognitive functions
What is the somatosensory system?
The Somatosensory system serves as the conduit between the different sensory modalities within the body, sending information from the periphery to the postcentral gyrus and associated cortices to convey information from the surrounding environment. Somatosensory cortex is located next to the motor cortex, as they communicate with each other.
The planning, execution, and control of voluntary action is, in part, dependent on correct sampling of multiple sensory modalities from body and the world. Without correct processing and translation of sensory input (before and during movement), motor outputs are abnormal and/or inaccurate. There’s a tight link between sensory processing and movement production=sensorimotor processing.
What is the somatosensory cortex?
Somatosensory cortex- somatosensory information converges in the parietal lobe of the cerebral cortex, where it’s processed to provide cohesive perception of your body and your physical environment.
What is the primary somatosensory system?
Primary somatosensory cortex (S1)- located posterior to the central sulcus, on the postcentral gyrus of the parietal lobe. It’s considered the primary somatosensory cortex as it receives direct somatosensory input from the thalamus, relayed from the periphery via the spinothalamic tract.
S1 is somatotopically organised, with the body and face mapped contralateral to the side of the body. The tongue is represented laterally and the feet medially. Activating the left side of muscles, requires the right side of the brain; activating the right side of muscles, requires the left side of the brain.
S1 is principally associated with identification of shape, size and texture. S1 neurons communicate with the secondary somatosensory cortex, the posterior parietal cortex, and the motor cortex. S1 relays somatosensory information to M1, with ongoing input used to refine and update descending motor commands.
“something touched your arm”
What is the thalamus?
The thalamus is like a grand central station in the brain- different signals are directed to different parts of the primary somatosensory cortex based on the information they carry:
Our senses send information into the brain
The thalamus sits in the middle and receives almost all that information first
Then it decides where to send it so the rest of your brain can understand and react
What is the secondary somatosensory cortex?
Secondary somatosensory cortex (S2)- located in the lateral wall of the Sylvian sulcus. It’s important in tactile object recognition, as well as tactile learning and memory. Connections with S1, motor cortex, insular and the Posterior Parietal Cortex. Damage (lesions) to S2 result in deficits in learning through object manipulation.
“this feels like fabric”
What is the posterior parietal cortex?
Posterior Parietal Cortex (PPC)- a multisensory association area that integrates sensory information, including vision, somatosensory and auditory inputs. It’s involved in control and error correction in movement, as well as movement planning to achieve a motor goal. Posterior to S1.
“reach for the fabric over there”
What are phantom limbs?
After amputation, 65% of people experience phantom limbs. Representation of the missing limb in the brain leads to vivid experiences of the limb still being there. Over time this representation in the brain may change or remain the same- ongoing research to understand what drives this experience.
What is a stroke?
Stroke- an event characterised by an alteration in blood flow (either blockage or bleed) in the CNS, resulting in neurological deficit lasting more than 24 hours. Depending on the location of the stroke, both motor and sensory deficits can occur. Cells in the brain don’t receive blood (and oxygen).
Symptoms of a stroke:
Hemiparesis (weakness to one side of the body)
Somatosensory loss, including proprioception and tactile information
Sensorimotor processing is altered and impacts rehabilitation, particularly balance and gait
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Planes, axes and movement7
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Introduction to Bones, Joints and Muscles20
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Introduction to the pelvis girdle, hip and knee17
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Origins and Insertions at the Knee, Hip, Foot and Ankle7
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Foot and ankle14
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Determinants of the muscle force production18
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Structure of the nervous system- The motor unit18
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Neurological consideration for movement- Sensory feedback14
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Neurological considerations for movement- The CNS and Somatosensory system18
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The shoulder and the pelvic girdle11
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The Glenohumeral joint9
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Elbow, wrist and hand13
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The Spine14
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Linear Kinematics12
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Angular kinematics10
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Projectile Motion7
