block 3- the musuloskeletal system Flashcards

Question

describe the lateral descending motor pathway | spinal tracts

Answer 1

1. Lateral pathway - voluntary movement, originates in cortex - components: -1. Corticospinal tract (pyramidal tract): -Direct motor cortex to spinal cord -involved in fine motor control such as finger movement -main pathway for voluntary movement - crosses over at the medulla so right brain controls left side and vise versa 2. Rubrospinal tract: Aids movement if corticospinal tract is damaged. - originates in midbrain - part of extra-pyramidal system Lesions: - Affects contralateral motor function- - recover possible if the rubrospinal tract is still intact but recovery is harder with age - can cause paralysis on opposite side of body - deficits in movements of hands and arms

Answer 2

- involved in posture, balance and movement - originates in brain stem - automatic movements components: 1. vestibulospinal tract - head balance and turning (automatic actions) 2. Tectospinal tract - reflexive orientation to stimuli (turning head to stimuli) 3. Reticulospinal tract - pontine -> enhances postural reflexes (keeping posture stable) - medullary -> suppresses postural reflexes (relaxing muscles involved on posture)

Answer 3

= carry motor information from brain to body = carry motor information from upper motor neurons in the brain to lower motor neurons in the spinal cord. The lower motor neurons then send the information to muscles.

Answer 4

1. Motor Cortex (Where Movement Starts) Located in the frontal lobe. Divided into two key areas: Primary Motor Cortex (M1, Area 4) – Sends direct movement commands to muscles. Higher Motor Areas (Area 6) – Plans movement before it happens. - premotor area (PMA) -> uses sensory info to guide movement in the lateral region - supplamentary area (SMA) -> plans internally driven movements in the medial region (intention before the action occurs) - both these areas control different muscle groups, but both help to co-ordinate movement

Answer 5

Ready → Parietal & Prefrontal Cortex (Decision made). Set → SMA & PMA (Movement is planned). Go → Motor Cortex (M1, Area 4) (Movement is executed).

Answer 6

Prefrontal Cortex: Decides what action to take based on goals. Parietal Cortex: Processes sensory info (where your body is in space). Together, they make high-level movement decisions before sending instructions to Area 6. Prefrontal = Thinks about action, Parietal = Knows body position.

Answer 7

- involved in regulating emotion and behaviour key structures: amygdala -> emotion centre hippocampus -> memory formation basal ganglia thalamus cingulate gyrus hypothalamus

Answer 8

= involved in the selection and initiation of willed movements The motor loop is a pathway that connects the cortex, basal ganglia, and thalamus to help control movement. steps: 1. Cortex sends an excitatory signal (wants to move). 2. Striatum (Putamen) receives the signal and processes it. 3. Globus Pallidus (brake) is inhibited, so movement is allowed. 4.. Thalamus sends a "GO" signal back to the Motor Cortex (M1). 5. Motor Cortex activates muscles, and movement happens! 👉 Key Idea: The Basal Ganglia acts like a traffic light. It decides whether to allow or stop movement signals from reaching the muscles.

Answer 9

Parkinson’s Disease: Dopamine deficiency → bradykinesia, tremors, rigidity. - trouble initiating willed movements due to increased inhibition of thalamus by basal ganglia Huntington’s Disease: Loss of inhibition → hyperkinesia, involuntary movements. Hemiballismus: Violent flinging movements on one side of body due to basal ganglia damage.

Answer 10

Neurons in M1 encode movement, direction & force. Activity of multiple neurons collectively determines movement. Superior Colliculus: Controls rapid eye movements (saccades). - saccadic = small, rapid movement of eye as it moves from one fixation point to another

Answer 11

- ensures smooth, co-ordianted movements - can create new motor programmes Motor Learning: Adjusts movements via feedback from sensorimotor cortex. lesions cause: ataxia -> poor co-ordiantion dysmetria -> overshooting/undershooting movements dysynergia -> abrupt movements/ abnomal co-ordiantion

Answer 12

= all the muscle cells controlled by one nerve cell - when the nerve sends a message, causes the associated muscle cells to contract

Answer 13

Back muscles (1:100) – large force, less precision. Finger muscles (1:10) – moderate precision. Eye muscles (1:1) – high precision. the ratio means for every 1 nerve cell, there are .... associated mucle cells Recruitment Order: Small motor units are recruited first, followed by larger ones as more force/intensity is needed (Henneman's size principle). Force Control: Adjusted by varying recruitment and firing frequency. - amplitude and frequency can change to develop more force

Answer 14

= head and face regions are innervated by the inferior portion of the precentral gyrus. Conversely, the lower limbs are innervated by the superior portion -> the point-for-point correspondence of an area of the body to a specific point on the central nervous system. Typically, the area of the body corresponds to a point on the primary somatosensory cortex (postcentral gyrus).

Answer 15

large pyramidal neurons in the primary motor cortex of the brain input to these cells: - thalamus - cortical areas

Answer 16

= refers to the body’s ability to perceive its own position, movement, and the amount of strength exerted in any activity. - the brain receives and interprets information from multiple inputs such as eyes, stretch receptors and vestibular organs - (info from the body to tell the brain what to do)

Answer 17

- the regulated motor cortical output determines the amount of muscle mass being activated - small motor units are recruited first (Hennemans size principle) the number of cells and the area of the motor cortex that's been activated will determine what we move and the direction of travel

Answer 18

= sensory nerve endings in the limbs that provide information about bodys position and movement -> joint angle (is limb bent or straight) muscle length (stretched or cntracted) tension (force produced)

Answer 19

= are sensory nerves that wrap around every muscle fibre - lie within an independent capsule parrallel to main muscle fibres (extrafusal fibers->muscle contraction). - Within a muscle spindle, there are several small, specialized muscle fibres known as intrafusal fibres which contain contractile units - Detect changes in muscle length and rate of stretch. - -Send signals to the CNS via sensory (afferent) nerve fibers; the faster they fire, the more the muscle is being stretched. - Muscle shortens, sensory nerves compressed, opening frequency of channels decreases, nerve firing rate decreases (relaxed state) - When the muscle lengthens the muscle spindle is stretched, opens ion channels triggers action potentials in muscle spindle afferents -Gamma motor neurons adjust spindle sensitivity so the muscle spindle can detect changes in length at all times, even when the muscle is partially contracted.(alpha-gamma co-activation)

Answer 20

- Located in the tendons, in series with muscle fibers. - Detect changes in muscle tension (pulling force). - Fire more rapidly when tension increases (as in active muscle contraction). - consists of sensory nerve endings interwoven among collagen fibres -When the muscle contracts, the collagen fibrils are pulled tight, and this activates the Golgi tendon organ afferent

Answer 21

4 types: 1. Merkel receptors - pressure 2. Meissner capsules- flutter 3. Ruffini cylinders -stretch 4. Pacinian Corpuscles - vibration - these differ in regards to: location, physical features, speed of adaptation to stimuli, size of receptive fields, type of mechanical signal to which they respond to Provide information about touch, pressure, and stretching of the skin, helping the brain interpret contact with external objects and movement across surfaces. - each type responds to a range of frequencies of mechanical stimulation

Answer 22

- Merkel discs and Ruffini cylinders - they respond when a stimuli is present - sensitivity can chnage over time when stimuli becomes common

Answer 23

- Meissner corpuscles and Pacinian corpuscles respond to stimuli with a firing at the start when stimulus is on, then at end when stimulus is off - second trigger present to turn off

Answer 24

- receptors with small receptive fields = close to surface of skin - large receptive fields = deeper in skin

Answer 25

The afferent pathways carry proprioceptive and mechanoreceptive information to the spinal cord and brain. The motor cortex and spinal cord use this feedback to refine motor output, adjusting how many motor units are recruited and how strongly muscles contract. The limbic system also plays a role in habitual movements—repetitive actions become more automatic and need less conscious thought over time.

Answer 26

Movement Control: Motor commands (efferent signals) originate in the motor cortex, travel down the spinal cord, and activate specific muscles (via alpha motor neurons). Continuous feedback from muscle spindles, Golgi tendon organs, skin/joint mechanoreceptors, and the vestibular-ocular system informs the CNS about the current state of the body. This feedback loop allows for fine-tuning of muscle force and position, ensuring coordinated, purposeful movement. Reflexes and Higher Processing: Simple (spinal) reflexes occur at the level of the spinal cord (e.g., knee-jerk reflex) and are very fast. Complex reflexes and voluntary movements involve additional processing in the brain (e.g., motor cortex, cerebellum, limbic system) and can be modified or overridden by conscious decisions.

Answer 27

Often related to a mismatch between signals from the vestibular system, visual input, and proprioceptive feedback. When these systems provide conflicting information (e.g., reading in a moving car), it can lead to dizziness or nausea.

Answer 28

=sensory system located in the inner ear that helps the body maintain balance, spatial orientation, and coordination of head and eye movements. It provides critical information about the position and movement of the head, allowing the brain to adjust the body's posture and respond to changes in the environment.

Answer 29

first order neuron = sensory, delivers sensations to CNS second order neuron = may be located in spinal cord or brain stem , axon of first order synpases here third order = second order synpases on third order in the thalamus, axon carries sensory info from thalamus to appropriate sensory area of cerebral cortex

Answer 30

1. Labile cells - High rate of loss and replacement, capable of rapid regeneration. Examples include squamous and glandular epithelia, and hematopoietic cells in bone marrow. 2. Stable cells - Normally non-proliferative but can regenerate when stimulated after damage. - Examples that have some capacity to grow include renal tubular cells, hepatocytes, osteoblasts, endothelial cells, and fibroblasts. 3. Permanent cells - Unable to divide post-development, thus cannot regenerate. Examples include neurons and cardiac/skeletal muscle cells.

Answer 31

= growth of cells and tissues to replace loss structures - requires an intact connective tissue scaffold if there is damage to the connective tissue and cells -> when cells try to regenerate they don't know how to align -> scarring if there is damage to cell WITHOUT damaging connective tissues -> regeneration can occur as scaffolding is there to organise the cell growth

Answer 32

1. autocrine signalling -> cell releases a chemical messenger that binds to receptors on the same cell 2. paracrine signalling -> a cell releases a signal to change the behavior of nearby cells. 3. endocrine signalling -> hormones are released into the bloodstream and carried to target cells in other parts of the body.

Answer 33

1. Inflammation (0-7 days) - Inflammatory cells migrate from surrounding tissues, filling the defect with granulation tissue and debris. Fibronectin provides a scaffold for collagen synthesis. Tissue becomes swollen 2. Repair (3-60days) - Fibroblasts synthesize collagen, initially type 3, which is laid down randomly. By week 4, intrinsic fibroblasts take over, producing type 1 collagen aligned with the line of force. 3. Organisation (28-180 days) - Final stability achieved through physiological use of the tendon, with cross-linking of fibrils enhancing tensile strength. Complete regeneration is rare, often leaving a hypercellular defect.(scar)

Answer 34

- Weakest point occurs at 7-10 days post-injury. - Most original strength regained by 21-28 days, with maximum strength typically achieved by 6 months. - Early mobilization can enhance range of motion (ROM) but may compromise repair strength if excessive stress is applied. - Immobilization can strengthen tendon substance but may reduce ROM.

Answer 35

- Healing rates vary significantly among tissues, with better regeneration potential linked to improved signaling and blood supply. - Examples of novel therapeutics include micro-fracture techniques for cartilage, calf serum for ligaments, and stem cell applications for heart tissue.

Answer 36

Fractures are more common in immature skeletons due to weaker physeal regions. Types of fractures include: Buckle or Torus Fracture: A compression fracture common in children. Plastic Deformation: Permanent bending of bone without fracture. Greenstick Fracture: Incomplete fracture, typical in children. - tissue injuries in adults less likely to regain proper function than in children

Answer 37

- NSAIDs are used to treat musculoskeletal injuries by reducing inflammation, which is often seen as detrimental to healing. - However, inflammation is a necessary component of the healing process; blocking it can theoretically delay recovery. - The inflammatory phase is crucial for debris removal and recruitment of growth factors to the injury site.

Answer 38

RICE: Rest, Ice, Compression, Elevation - a foundational treatment approach. Variations include: HI-RICE: Hydration, Ibuprofen, Rest, Ice, Compression, Elevation. PRICE: Protection, Rest, Ice, Compression, Elevation. PRINCE: Protection, Rest, Ice, NSAIDs, Compression, Elevation. RICER: Rest, Ice, Compression, Elevation, Referral. POLICE: Protection, Optimal Loading, Ice, Compression, Elevation.

block 3- the musuloskeletal system Flashcards

(62 cards)