chapter 11 Flashcards
- Continue to be comfortable with afferent vs. efferent.
Afferent: Arriving; into CNS
Efferent: Exiting; leaving CNS
Afferent somatosensory information travels from the sensory organs inward via the somatic nervous system
Movement information travels out of the central nervous system via a parallel efferent motor system
- What side of the spinal cord do efferent signals come out? What side do afferent signals come in?
Efferent signals (fibers) come out of the spinal cord’s VENTRAL side (anterior) carrying information from the spinal cord to the muscles
Afferent Signals come in: Information coming from sensory receptors enters the CNS via DORSAL (posterior) root fibers
- What is a dermatome?
Dermatomes are areas of skin that send signals to the brain through the spinal nerves
-Each spinal segment corresponds to a region of body surface called a dermatome
- Which part of the brain produces movement? Which part organizes movement? Which part plans movement?
- Prefrontal Cortex: plans movement (PLANS)
- Premotor Cortex: organizes movement sequences (ORGANIZES/SEQUENCES)
- Motor Cortex: produces specific movements (EXECUTES ACTIONS)
- What is the role of the brainstem in creating movement?
It connects your brain to your spinal cord and regulates involuntary actions, including balance, breathing, eye movements, and heart rate. Additionally, nerve tracts within the brainstem relay signals from the cerebellum to areas of the cerebral cortex involved in motor control, allowing for the coordination of fine motor movements needed for activities like walking or playing video games
- What is a movement category? What area(s) of the brain would you stimulate to create a movement category?
Fundamental movements.
Primary motor cortex- hand control in lower body space, hand control in central body space, masticate/lick
Premotor motor cortex- bring hand toward mouth, defensive posture/expression
- Do we create new neurons in the motor cortex after brain damage?
No: After brain damage, neurons in the primary motor cortex do not regrow or repair. However, the brain can regain some lost function through neuroplasticity
example: Damged part of the motor cortex that controlled the hand in monkeys
-Without rehabilitation:
–>The hand area of the motor cortex became smaller, whereas the elbow and shoulder area became larger
–>Monkeys lost most ability to move their hand
-With rehabilitation:
–>The hand area of the motor cortex retained its size
–>Monkeys retained some ability to move their hand
- What information is carried along the corticospinal tract?
(“cortico” –> “spinal”)
-Main efferent pathways from the motor cortex to the brainstem to the spinal cord
- is a collection of axons that carry movement-related information from the cerebral cortex to the spinal cord.
- What kinds of neurons do we expect to find on the ventral (aka anterior) side of the spine?
-interneurons and motor neurons
——muscles are arranged in pairs
-extensor: moves (extends) the limb away from the trunk
-flexor: moves the limb toward the trunk
The connection between interneurons and motor neurons ensures that the muscles work together so that when one muscle contracts, the other relaxes.
- What structures make up the basal ganglia?
- Caudate nucleus and putamen: Together they form the striatum (meaning striped body, named for the fibers, including corticospinal fibers, running through it)
- Subthalamic nucleus
- Globus pallidus
Basal Ganglia:
-Project to the motor cortex and substantia nigra
-Serve a wide range of functions, including association or habit learning, motivation, emotion, and motor control
- Compare and contrast hyperkinesia and hypokinesia?
Damage to the basal ganglia can produce two main types of motor symptoms.
- Hyperkinetic symptom: Damage to the caudate putamen may cause unwanted writhing and twitching movements called dyskinesias; seen in Huntington disease and Tourette syndrome
- Hypokintic symptom: Damage to the basal ganglia may result in a loss of motor ability, leading to rigidity and difficulty initiating and producing movement; seen in Parkinson diesease
- What is the role of the cerebellum in movement? How does it accomplish this role?
Two main motor functions:
1. Timing: movements and perceptions
2. Mainting movement accuracy: error correction—-compares intended movement with actual movement and makes the necessary adjustments accordingly
-Cortex sends motor instructions to the spinal cord.
-Copy of same instructions sent to the cerebellum.
-Sensory receptors code actual movement and report to the cerebellum.
-Cerebellum has information about both versions of the movement—what you intended to do and what you actually did—and can calculate the error and tell the cortex how to correct the movement.
- What is the difference between hairy and glabrous skin?
-Areas with larger numbers of receptors are more sensitive to stimulation than areas with relatively fewer receptors.
-Sensitivity to different somatosensory stimuli is a function of the kinds of receptors.
-Humans have two kinds of skin.
1.Hairy skin
2. Glabrous skin: Skin that does not have hair follicles but contains larger numbers of sensory receptors than do other skin areas. (ex. palms)
-Hairy cells have less sensory receptors than glabrous cells which don’t grow hair follicles
- What are the three categories of somatosensory receptors? (DO NOT MEMORIZE ALL THE SPECIFIC TYPES OF RECEPTORS, just the three main categories
1.Nociception (pain, temperature, itch)
2.Hapsis (fine touch and pressure)
3.Proprioception (body awareness)
- What is the benefit of having both fast and slow adapting receptors? Why is this specifically beneficial for nociception?
it’s important to adapt slowly because we don’t want a signal to stop if something is hurting (nociception), rapidly is good so we don’t clog up the brain with unnecessary info
- Rapidly adapting receptor: Body sensory receptor that responds briefly to the beginning and end of a stimulus on the body
-These receptors respond rapidly to changes in a stimulus but quickly adapt and reduce their firing rate if the stimulus remains constant.
-They are crucial for detecting sudden changes, such as touch, pressure, or vibration.
-For example, when you touch a hot surface, fast adapting receptors signal the initial heat sensation.
-In nociception, fast adapting receptors help detect acute pain (e.g., a sharp pinprick).
Slowly adapting receptor: Body sensory receptor that responds as long as a sensory stimulus is on the body
-Slowly adapting receptors keep firing as long as the stimulus is present.
-They provide continuous information about the ongoing state of the stimulus.
-Tonic receptors are essential for maintaining posture, muscle tone, and overall awareness of the body’s position in space.
-In nociception, slow adapting receptors contribute to the perception of persistent or chronic pain (e.g., dull, throbbing pain).
