3. musculoskeletal system Flashcards
1
Q
what are the three types of muscle tissue?
A
- skeletal
- cardiac
- smooth
2
Q
characteristics of skeletal muscle
A
long cylindrical cells
many nuclei per cell
striated
voluntary
rapid contraction
3
Q
what muscle tissue is striated?
A
skeletal and cardiac
4
Q
what gives skeletal and cardiac muscle striations?
A
Myofibrils are composed of actin (thin filaments), myosin (thick filaments), and support proteins. The arrangement of actin and myosin gives skeletal muscle its microscopic striated appearance and creates functional units called sarcomeres
Striated muscle tissue is a muscle tissue that features repeating functional units called sarcomeres. The presence of sarcomeres manifests as a series of bands visible along the muscle fibres, which is responsible for the striated appearance observed in microscopic images of this tissue.
5
Q
characteristics of cardiac tissue?
A
branching cells
one or two nuclei/cell
striated
involuntary
medium speed contractions
6
Q
list the muscle tissue in order of increasing contraction speed
A
smooth = slow wave-like contraction
cardiac = medium speed contractions
skeletal = rapid contractions
7
Q
smooth muscle characteristics
A
fusiform cells
one nucleus/cell
nonstriated
involuntary
slow, wave-like contractions
8
Q
which muscle tissue has involuntary control?
A
cardiac and smooth
9
Q
list the muscle tissues in order of number of nuclei in cells?
A
smooth= 1/cell
cardiac= 1 or 2/cell
skeletal= many/cell
10
Q
shapes of the different muscle tissues
A
skeletal= long cylindrical cells
cardiac= branching cells
smooth= fusiform cells
11
Q
microanatomy of skeletal muscle
A
thin (actin) filament and thick (myosin) filament. elastic (titin) filament
Skeletal muscle fibres are long, multinucleated cells. The membrane of the cell is the sarcolemma; the cytoplasm of the cell is the sarcoplasm. The sarcoplasmic reticulum (SR) is a form of endoplasmic reticulum. Muscle fibres are composed of myofibrils which are composed of sarcomeres linked in series.
Each skeletal muscle consists of thousands of muscle fibres wrapped together by connective tissue sheaths. The individual bundles of muscle fibres in a skeletal muscle are known as fasciculi. The outermost connective tissue sheath surrounding the entire muscle is known as epimysium.
12
Q
tropomyosin
A
Tropomyosin is a protein involved in skeletal muscle contraction and that wraps around actin and prevents myosin from grabbing it. This prevents muscle contractions until the proper signal arrives. When the nervous system tells the muscle cell to contract, calcium is released.
13
Q
contraction of skeletal muscle
A
When signalled by a motor neuron, a skeletal muscle fibre contracts as the thin filaments are pulled and then slide past the thick filaments within the fibre’s sarcomeres. This process is known as the sliding filament model of muscle contraction
Skeletal muscle contraction begins first at the neuromuscular junction, which is the synapse between a motoneuron and a muscle fibre. Propagation of action potentials to the motoneuron and subsequent depolarization results in the opening of voltage-gated calcium (Ca2+) channels of the presynaptic membrane.
Tropomyosin is one of many protein filaments used in the process of contracting the skeletal muscles. Its main function is to prevent the muscle from contracting at the wrong time and it accomplishes this role by preventing actin and myosin filaments from making contact with each other.
14
Q
H band
A
H-band is the zone of the thick filaments that has no actin
appears in the middle of the sarcomere formed of cross-connecting elements of the cytoskeleton.
15
Q
NMJ
A
The neuromuscular junction (NMJ) is a synaptic connection between the terminal end of a motor nerve and a muscle (skeletal/ smooth/ cardiac). It is the site for the transmission of action potential from nerve to the muscle. It is also a site for many diseases and a site of action for many pharmacological drugs.
16
Q
sarcolemma skeletal muscle
A
the cell membrane surrounding a skeletal muscle fibre or a cardiomyocyte
The sarcolemma is a tubular sheath that encases and defines each muscle fibre, forming a barrier between extracellular and intracellular compartments. The sarcolemma is comprised of a plasma membrane and a polysaccharide coating that fuses with tendon fibres.
17
Q
acetylcholine and voluntary muscle contractions
A
Acetylcholine opens Na+ channel
Acetylcholine is involved in many important functions in your body. It plays a major role in voluntary muscle movement all over your body. This is muscle movement you control. Nerve cells stimulate muscle nerve cells, causing muscles to contract.
The activation of muscle function involves: a nerve impulse arriving at the terminal of a motor neuron; ACh is released into the neuromuscular junction; it combines with a receptor molecule in the postsynaptic membrane of a muscle fibre, changing the permeability of the membrane, causing channels to open that allow positively charged sodium ions to flow into the muscle cell; if successive nerve impulses accumulate at a sufficiently high frequency, sodium channels along the end-plate membrane become fully activated, resulting in muscle cell contraction
18
Q
isometric vs isotonic contraction
A
Isometric contractions are contractions in which there is no change in the length of the muscle. No joint or limb motion occurs. Isotonic contractions occur when the muscle changes length, producing limb motion.
19
Q
isometric contraction
A
produces no movements
e.g. standing, sitting, posture
20
Q
isotonic contraction
A
produces movement
e.g. walking, moving body
21
Q
isokinetic contraction
A
Isokinetic contraction is the muscular contraction that accompanies constant velocity limb movements around a joint. The velocity of movement is maintained constant by a special dynamometer. The resistance of the dynamometer is equal to the muscular forces applied throughout the range of movement.
22
Q
what are 4 parts of the skeletal system?
A
- bones (skeleton)
- joints
- cartilages
- ligaments (bone-bone)
23
Q
what two divisions is the skeletal system divided into?
A
- axial skeleton
skull, spinal column - appendicular skeleton
limbs and girdle
24
Q
functions of bone
A
support
protection
assistance in movement
storage of minerals
production of blood cells
storage of chemical energy
25
support of bone
the skeleton is the body framework, it supports the soft tissue and provides attachment points for most skeletal muscle
26
protection of bone
protect delicate organs
e.g. ribs protecting lungs and heart and skull protecting brain
27
movement of bone
muscles contract and pull the bones which give rise to the movement
28
agonist vs antagonist
In an antagonistic muscle pair, as one muscle contracts, the other muscle relaxes or lengthens. The muscle that is contracting is called the agonist and the muscle that is relaxing or lengthening is called the antagonist.
29
what connective tissue connects bone to muscle?
A tendon is a fibrous connective tissue that attaches muscle to bone. Tendons may also attach muscles to structures such as the eyeball. A tendon serves to move the bone or structure.
30
mineral storage of bone
outer layers of body tissues are used for the storage of minerals (primarily calcium and phosphorus)
31
blood cell production of bone
red and white blood cells and platelets are made in the bones.
the ends of the long bones and some other bones including the ribs, humorous, femur and even vertebrae bones contain RED BONE MARROW (embedded in spongy bone)
this is where the blood cells are produced.
the shaft of long bones is filled with yellow bone marrow which does not produce blood cells.
32
red vs yellow bone marrow
There are two types of bone marrow: red and yellow. Red bone marrow contains blood stem cells that can become red blood cells, white blood cells, or platelets. Yellow bone marrow is made mostly of fat and contains stem cells that can become cartilage, fat, or bone cells.
red marrow embedded in spongy bone at ends of long bones and some other bones and yellow bone marrow in the shaft.
33
fat storage of bones
The soft spongy area inside most bones, called the bone marrow, produces blood cells and stores energy in the form of fat and therefore plays an important role in bone health. The fat cells found in the bone marrow (bone marrow adipocytes) are very different from fat cells found in other parts of the body.
34
how many bones form the skeleton?
206
35
what are the 2 basic types of bone tissue?
compact bone
- homogeneous
spongy bone
- small needle-like pieces of bone
- many open spaces
36
what are the 4 main types of bone shape?
(bones tend to be classified by shape)
1. long:
longer than they are wide (arms, legs)
2. short:
usually square, cube like (wrist, ankle)
3. flat:
flat, curves (skull, sternum)
4. irregular
odd shapes (vertebrae, pelvis)
37
where is short bone found?
wrist, ankle
(usually square, cube like)
38
what are the three types of bone cells?
1. osteocytes
- mature bone cells
2. osteoblasts
- bone-forming cells (building)
3. osteoclasts
- bone-destroying cells (clear-breakdown bone matrix for re-modelling and release of calcium)
39
what cells are involved in bone re-modelling?
osteoblasts (forming) and osteoclasts (destroying)
40
what are mature bone cells called?
osteocytes
41
what are bone-forming cells called?
osteoblasts
42
what are bone-destroying cells called?
osteoclasts
*break down bone matrix for re-modelling and release of calcium
43
hyaline cartilage
Hyaline cartilage at the ends of your bones is sometimes referred to as articular cartilage. Hyaline cartilage is slippery and smooth which helps your bones move smoothly past each other in your joints. It's flexible but strong enough to help your joints hold their shape.
44
in embryos what primarily makes up the skeleton?
hyaline cartilage
45
comment on the change in human skeleton during development
in embryos, the skeleton is primarily hyaline cartilage
during development, much of this cartilage is replaced by bone
cartilage remains in isolates areas e.g. bridge of node, parts of ribs, joints
46
where in the body does cartilage remain from early embryonic development?
bridge of nose
parts of ribs
joints
47
what are the three types of cartilage?
hyaline, fibrous, and elastic cartilage
*In the embryo, bone begins as hyaline cartilage and later ossifies
48
what are the 3 divisions of the axial skeleton?
1. skull
2. vertebral column
3. rib cage
*forms the longitudinal part of the body
49
axial vs appendicular skeleton
Your axial skeleton is made up of the bones in your head, neck, back and chest. Your appendicular skeleton is made up of everything else — the bones that attach (append) to your axial skeleton.
50
the hyoid bone
the only bone that does not articulate with another bone
serves as a moveable base for the tongue and other muscle attachments
51
what is the only bone that does not articulate with another bone?
the hyoid bone
*serves as a moveable base for the tongue and other muscle attachments
52
joints
a joins/articulations is the place where two bones come together
fibrous-immovable:
connect bones, no movements (skull and pelvis)
cartilaginous- slightly moveable:
bones are attached by cartilage (spine and ribs)
synovial- freely moveable:
cavities between bones filled with synovial fluid (to lubricate and protect)
53
what are the three types of joins/articulations?
1. fibrous- immovable:
connect bones, no movement (skull and pelvis)
2. cartilaginous- slightly movable:
bones are attached by cartilage (spine and ribs)
3. synovial- freely moveable:
cavities between bones filled with synovial fluid (to lubricate and protect)
54
joint vs articulation
Joints, also known as articulations, are a form of connection between bones. They provide stability to the skeletal system as well as allowing for specialized movement.
55
synovial joint
In a Synovial joint, the ends of bones are encased in smooth cartilage. Together, they are protected by a joint capsule lined with a synovial membrane that produces synovial fluid. The capsule and fluid protect the cartilage, muscles, and connective tissues.
56
cartilaginous joint
the adjacent bones are united by cartilage, a tough but somewhat flexible type of connective tissue. These types of joints lack a joint cavity and involve bones that are joined together by either hyaline cartilage or fibrocartilage
57
skeletal levers
Bones, ligaments, and muscles are the structures that form levers in the body to create human movement. In simple terms, a joint (where two or more bones join together) forms the axis (or fulcrum), and the muscles crossing the joint apply the force to move a weight or resistance.
Lever: Levers, also known as anatomical levers, in the human body refer to a bone. Pivot/fulcrum: A pivot, also known as a fulcrum, refers to the joint that is formed by the connection between two or more bones. Effort: The effort refers to the force generated by the contraction of the muscles in the lever system.
57
6. types of synovial joints
Synovial joints are often further classified by the type of movements they permit. There are six such classifications:
1. hinge (elbow),
2. saddle (carpometacarpal joint),
3. planar (acromioclavicular joint),
4. pivot (atlantoaxial joint),
5. condyloid (metacarpophalangeal joint),
6. ball and socket (hip joint).
58
classification of the levers
First Class Lever: The fulcrum is between the force and the weight (resistance) .
Second Class Lever: The weight (resistance) is between the fulcrum and the force.
Third Class Lever: The force is located between the fulcrum and the weight (resistance). F Most of the movements of the body are produced by third class levers.
FWF= 1st,2nd,3rd
*Lever: Levers, also known as anatomical levers, in the human body refer to a bone. Pivot/fulcrum: A pivot, also known as a fulcrum, refers to the joint that is formed by the connection between two or more bones. Effort: The effort refers to the force generated by the contraction of the muscles in the lever system.
59
sensorimotor system
sensory info used by all levels of the motor system
60
hierarchy of controls
highest level = strategy
middle level= tactics
lowest level= execution
Strategy: is thinking about what you're going to do.
Tactics: are things you can do.
Execution: is doing things in a thoughtful way.
61
descending spinal tracts: two major descending pathways
axons from brain descend along two major pathways
1. lateral
2. ventromedial
lateral tracts travel in the lateral columns of the spinal cord. They synapse on more laterally located motor neurons, in the ventral horn of the spinal cord. Medial motor systems descend in the anteromedial aspect of the spinal cord. They synapse on medial ventral horn neurons.
The lateral pathways control the fine movements of arms and fingers. The ventromedial pathways control the posture of the head and neck.
[ lateral vs medial= away from midline vs towards ]
The lateral tracts are responsible for carrying information about voluntary movement of the arms and legs. The ventromedial pathways are responsible for carrying information about posture and balance.
62
is the lateral descending spinal tract pathway voluntary or involuntary movement?
voluntary movement (originates in cortex)
63
components of lateral pathway
1. corticospinal tract (pyramidal tract)
2. rubrospinal tract
The lateral motor system includes the following tracts: Lateral corticospinal tract; responsible for voluntary movement of the limbs. Rubrospinal tract; augments the activity of the flexor muscles and inhibits the action of the extensor (antigravity) muscles.
The Lateral Corticospinal Tract is a pathway that originates in the cerebral cortex and descends to the lower motor neurons in the spine, controlling the motor neurons for the muscles of the distal extremities.
64
effects of corticospinal lesions of lateral pathway
- deficit in fractionated movement of arms and hands
- paralysis on contralateral side
- recovery if rubrospinal tract intact
- subsequent rubrospinal lesion reverses recovery
65
what are the 4 major ventromedial pathways?
vestibulospinal tract:
head balance, head turning
tectospinal tract:
orientating
descending motor pathways that originate in the brainstem and control posture, balance, and movements along the midline
Anterior (or Ventral) Corticospinal Tract:
This tract originates in the motor cortex and descends directly to the anterior horn of the spinal cord, controlling voluntary movements of the trunk and proximal limbs.
Vestibulospinal Tract:
This tract originates from the vestibular nuclei in the brainstem and carries information related to balance and equilibrium, controlling reflexive postural adjustments.
Tectospinal Tract:
This tract originates in the midbrain and controls reflexive head and eye movements in response to visual and auditory stimuli.
Reticulospinal Tract:
This tract originates in the brainstem reticular formation and influences muscle tone and posture, helping to maintain balance and coordination.
66
what do the ventromedial pathways allow?
posture and locomotion
*originates in brain stem
The ventromedial pathways are responsible for carrying information about posture and balance.;; The lateral tracts are responsible for carrying information about voluntary movement of the arms and legs
67
pontine and medullary reticulospinal tract (ventromedial pathways)
pontine: enhances postural reflex
medullary: liberates postural muscles from reflex
Medullary Reticulospinal Tract, arises from the nuclei of reticular formation located in the medulla of the brainstem. Pontine Reticulospinal Tract, arises from those nuclei of reticular formation which are present in pons.
68
pontine vs medullary reticulospinal tract (ventromedial pathways)
pontine= enhances postural reflex
medullary= liberates postural muscles from reflex
69
summarise the descending spinal tracts
1. corticospinal pathway
-CORTICOBULBAR TRACTS: upper motor neurons located at primary motor cortex (cerebral hemisphere); terminations at lower motor neurons of cranial nuclei in brainstem; crossover at brainstem; function is the conscious motor control of skeletal muscle
- LATERAL CORTICOSPINAL TRACT: upper motor neurons located at primary motor cortex (cerebral hemisphere); termination at lower motor neurons of anterior grey horns of the spinal cord; crossover at pyramids of medulla oblongata
- ANTERIOR CORTICOSPINAL TRACT: upper motor neurons located at primary motor cortex (cerebral hemisphere); termination at lower motor neurons of anterior grey horns of the spinal cord; crossover at level of lower motor neuron; crossover at pyramids of medulla oblongata
2. medial pathway
-VESTIBULOSPINAL TRACTS: upper motor neurones located at vestibular nuclei (at border of pons and medulla oblongata); termination at lower motor neurons of anterior grey horns of the spinal cord; uncrossed; function is subconscious regulation of balance and muscle tone
-TECTOSPINALSTRACT: upper motor neurones located at tectum (mesencephalon superior and inferior colliculi); termination in lower motor neurons of anterior grey horns (cervical spine only); crossover at brain stem (mesencephalon); function of subconscious regulation of eye, head, neck, and upper limb position in response to visual and auditory stimuli
-RETICULOSPINAL TRACTS: upper motor neurons at reticular formation (network of nuclei in brainstem); termination at lower motor neurons of anterior grey hons of spinal cord; uncrossed; function in subconscious regulation of reflex activity
3. lateral pathways
-RUBROSPINAL TRACTS: upper motor neurons located in red nuclei of mesencephalon; termination at lower motor neurons of anterior grey hons of spinal cord; crossover at brain stem (mesencephalon); function in subconscious regulation of upper limb muscle tone and movement
70
decussation
: the action of crossing (as of nerve fibers) especially in the form of an X. 2. : a crossed tract of nerve fibers passing between centers on opposite sides of the nervous system
71
which descending spinal tracts are uncrossed?
1. vestibulospinal tracts (medial pathway)
2. reticulospinal tracts (medical pathway)
72
pons
Your pons is a part of your brainstem, which links your brain to your spinal cord. That makes your pons a vital section of your nervous system, providing a route for signals to travel to and from your brain. Several neurotransmitters in your pons facilitate brain function, particularly sleep.
73
pons and medulla oblongata
Pons: The middle portion of your brainstem that coordinates face and eye movements, facial sensations, hearing and balance. Medulla oblongata: The bottom part of your brainstem that regulates your breathing, heartbeat, blood pressure and swallowing.
The medulla oblongata is the connection between the brainstem and the spinal cord, carrying multiple important functional centres. It is comprised of the cardiovascular-respiratory regulation system, descending motor tracts, ascending sensory tracts, and origin of cranial nerves IX, X, XI, and XII.
Your pons is a part of your brainstem, which links your brain to your spinal cord. That makes your pons a vital section of your nervous system, providing a route for signals to travel to and from your brain. Several neurotransmitters in your pons facilitate brain function, particularly sleep.
74
motor cortex - function and areas of frontal lobe
The primary function of the motor cortex is to send signals to direct the body's movement.
areas 4 and 6 of the frontal lobe
The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately anterior to the central sulcus.
75
cerebral cortex
Your cerebral cortex is the outermost layer of your brain. Its surface has many folds, giving it a wrinkled appearance. The folds consist of many deep grooves called sulci and raised areas called gyri.
76
4 brain lobes
frontal lobe,
parietal lobe,
temporal lobe,
occipital lobe
77
area 4 of motor cortex
primary motor cortex (M1)
78
area 6 of motor cortex
higher motor area
79
PMA and SMA
PMA= premotor area (lateral region)
sensory guidance of movement
SMA= supplementary motor area (medial regions)
intentional preparation for movement
* similar function; different groups of muscles innervated (motor cortex and the planning of movement by cerebral cortex)
80
where do areas 5 and 7 in cerebral cortex receive inputs from?
area 5: inputs from areas 3, 1 and 2
area 7: inputs from higher-order visual cortical areas such as MT
MT= (Middle Temporal Area)
Area 5 is part of the posterior parietal cortex and is involved in integrating sensory information from multiple modalities (such as somatosensory and proprioceptive inputs).
Inputs from Areas 3, 1, and 2: These areas are part of the somatosensory cortex and represent the primary sensory processing regions that receive information about touch, proprioception (body position), and other somatosensory information.
MT (Middle Temporal Area), also known as V5, is an area in the visual cortex that is crucial for motion perception. It's involved in processing dynamic visual information, particularly the detection of motion and motion direction.
81
anterior frontal lobes
abstract thought, decision making and anticipating consequences of action
82
area 6 of cerebral cortex
actions converted into signals specifying how actions will be performed
83
per Roland
monitored cortical activation accompanying voluntary movement (PET)
*results support view of high order motor planning
84
neuronal correlates of motor planning
evarts:
demonstrated importance of area 6 in planning movement
'ready'
parietal an frontal lobes
'set'
supplementary and premotor areas
'go'
area 6
85
primary structures within limbic system
1. amygdala
2. hippocampus
3. thalamus
4. hypothalamus
5. basal ganglia
6. cingulate gyrus
86
what is the emotion centre of the brain?
amygdala
87
what plays an essential role in the formation of memories on past past experience?
hippocampus
88
limbic system
The limbic system is a group of structures in your brain that regulate your emotions, behaviour, motivation and memory.
89
basal ganglia
a group of structures linked to the thalamus in the base of the brain and involved in coordination of movement.
selection and initiation of willed movements
90
what part of brain plays a role in the selection and initiation of willed movements?
Basal Ganglia
91
where does basal ganglia project to and give major input to?
- project to the ventral lateral (VLo) nucleus
- provides major input to area 6
*cortex- projects back to basal ganglia; forms a 'loop'
92
the motor loop of basal ganglia
The Motor Loop: excitatory connection from cortex to putamen
- cortical activation
- excited putamen
- inhibits globus pallidus
- release VLo from inhibition
so activity in VLo (ventral lateral) influences activity in SMA
SMA- supplementary motor area (medial region); intentional preparation for movement
93
what does activity in VLo influence?
activity in VLo influences activity in SMA
SMA= supplementary motor area (medial region); intentional preparation for movement
VLo= ventral lateral
94
basal ganglia disorders
Parkinson's disease:
trouble initiating willed movements due to increased inhibition of the thalamus by basal ganglia
symptoms= bradykinesia, akinesia, rigidity, tremors of hand and jaw
organic basis= degeneration of dopaminergic substantia nigra input to striatum
dopa treatment= facilitates production of dopamine to increase SMA activity
Huntington's disease:
symptoms= hyperkinesia, dyskinesia, dementia, impaired cognitive ability, personality disorder
hemiballismus= violent, flinging movement on one side of the body
loss of inhibition with loss of neurons in caudate, putamen, globus pallidus
95
parkinsons disease
Parkinson's disease:
trouble initiating willed movements due to increased inhibition of the thalamus by basal ganglia
symptoms= bradykinesia, akinesia, rigidity, tremors of hand and jaw
organic basis= degeneration of dopaminergic substantia nigra input to striatum
dopa treatment= facilitates production of dopamine to increase SMA activity
*ganglia disorder
96
huntingtons disease
Huntington's disease:
symptoms= hyperkinesia, dyskinesia, dementia, impaired cognitive ability, personality disorder
hemiballismus= violent, flinging movement on one side of the body
loss of inhibition with loss of neurons in caudate, putamen, globus pallidus
*ganglia disorder
97
initiation of movement by the primary motor cortex
electrical stimulation of area 4
- contraction of small group of muscles
input-output organisation of M1
- Betz cells: pyramidal cells in cortical layer 5
- two sources of input to Betz cells (cortical areas and thalamus)
coding movement in M1
- activity from several neurons in M1 encodes force and direction of movement (direction vector)
98
two sources of input to Betz cells
cortical areas
thalamus
99
movement of direction encoded by collective activity of neurons
motor cortex: many cells active for every movement
activity of each cell: represents a single 'vote'
direction of movement: determined by a tally (and averaging)
100
control of saccadic eye movements by the superior colliculus
computational map of motor 'error' in fast movements
motor error: desired eye position- current eye position
for control of eye movements: pathway to midbrain. Superior colliculus inputs in voluntary control of saccades (REMs to salient stimuli) and in coordinating movements of head in concert with this. Pretectal nuclei participate in pupillary reflexes.
101
cerebellum
The cerebellum is a vital component in the human brain as it plays a role in motor movement regulation and balance control. The cerebellum coordinates gait and maintains posture, controls muscle tone and voluntary muscle activity but is unable to initiate muscle contraction
sequence of muscle contractions; calibration and coordination
cerebellar lesions
- ataxia; uncoordinated and inaccurate movements
-dyssynergia: decomposition of synergistic multijoint movements
-dysmetria: overshoot or undershoot target
102
ataxia
uncoordinated and inaccurate movements (cerebellar lesions)
103
dyssynergia
decomposition of synergistic multijoint movements (cerebellar lesion)
104
dysmetria
overshoot or undershoot target (cerebellar lesion)
105
motor loop through lateral cerebellum
calibrated execution of planned, voluntary, multi-joint movements
106
pontine nuclei
axons from layer V pyramidal cells in the sensorimotor cortex from massive projections to pons.
The pontine nuclei (or griseum pontis) are all the neurons of the ventral pons. Corticopontine fibres project from the primary motor cortex to the ipsilateral pontine nucleus; pontocerebellar fibres then relay the information to the contralateral cerebellum via the middle cerebellar peduncle.
107
how much larger are corticopontocerebellar projection than pyramidal tract?
20x
corticopontocerebellar projection
- 20 times larger than pyramidal tract
108
control of force
the CNS plays a role in controlling muscle force (in addition to muscle protein expression and architecture)
109
motor unit
all the muscle fibres controlled by one nerve fibre
110
motor unit ratios
back muscles = 1:100
finger muscles = 1:10
eye muscles = 1:1
111
nature of activation
amplitude and frequency can change to develop more force
recruitment order-same fibres used more often leading to the concept of fibre type
112
controlling movement
- the efferent pathways conduction nerve impulse from the CNS need information to regulate their function
- the muscle shortening produces force or speed movements depending on the type of muscle and its 'architecture' (both internally and in attachments to the skeleton)
- the amount (number of 'cells') and area of the motor cortex activated will determine what we move and, therefore, 'direction of travel'
113
cortical output
The cortical output that most directly controls bodily movement arises from neurons in layer V of a specialized region, the primary motor cortex (M1).
114
motor units
the fundamental functional unit of skeletal muscle, consisting of a motor neuron and all the muscle fibers it innervates
Motor units, defined as a motoneuron and all of its associated muscle fibres, are the basic functional units of skeletal muscle. Their activity represents the final output of the central nervous system
This 'regulated' motor cortical output will determine the amount of muscle mass being activated (giving a refinement to muscle activity)
- motor units are recruited in a precise order
- small units are recruited first (i.e. task-appropriate recruitment to minimise fatigue- Henneman's size principle)
115
how do we provide info to the CNS?
afferent pathways
116
Henneman's suze principle
motor units are recruited in a precise order; small units are recruited first (task-appropriate recruitment to minimise fatigue)
*this 'regulates' motor cortical output will determine the amount of muscle mass being activated (giving a refinement to muscle activity)
117
proprioception
Proprioception is a sense that lets us perceive the location and movements of our body parts. It is mediated by specialized sense organs (proprioceptors) located within the muscles and tendons. The two classical proprioceptors are the muscle spindles and the Golgi tendon organs.
118
proprioceptors
in the limbs, the proprioceptors are sensors that provide information about joint angle, muscle length, and muscle tension, which is integrated to give info about the position of the limb in space.
the muscle spindle: provides info about changes in muscle length
the golgi tendon: provides info about changes in muscle tension
119
what are the two main proprioceptors and their function?
muscle spindle:
provides info about changes in muscle length
golgi tendon organ:
provides info about changes in muscle tension
120
the muscle spindle
(proprioceptor)
small sensory organs enclosed within a capsule.
found throughout the body of a muscle, in parallel with extrafusal fibres (typical muscle fibres)
within a muscle spindle, there are several small, specialised muscle fibres known as intrafusal fibres.
intrafusal fibres have contractile proteins (thick and thin filaments) at either end with a central region that is devoid of contractile proteins.
the central region is wrapped by the sensory dendrites of the muscle spindle afferent.
when the muscle lengthens:
the muscle spindle is stretched; opens ion channels; triggers action potentials in muscle spindle afferents
intrafusal fibres are innervated by an efferent neuron known as the gamma motor neuron (MN)
efferents that innervate extrafusal fibres are known as alpha MN
the gamma MN operates to maintain muscle spindle sensitivity, regardless of muscle length
when extrafusal fibres are stimulated to contract by alpha MN activation, the gamma MN is simultaneously excited (alpha-gamma coactivation)
the gamma MN stimulates contraction in the two ends of the intrafusal fibre, readjusting its length and keeping the central region of the intrafusal fibre taut (necessary to keep muscle spindle afferents responsive)
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MN
motor neuron
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in parallel with what typical muscle fibres are the muscle spindle fibres found throughout the body?
EXTRAFUSAL FIBRES
found throughout the body of a muscle in parallel with extrafusal fibres (typical muscle fibres)
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what are the specialised muscle fibres known as found inside a muscle spindle?
INTRAFUSAL FIBRES
within a muscle spindle, there are several small specialised muscle fibres known as intrafusal fibres.
*intrafusal fibres have contractile proteins (thick and thin filaments) at either end, with a central region that is devoid of contractile proteins- the central region is wrapped by the sensory dendrites of the muscle spindle afferent
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structure of intrafusal fibres
within a muscle spindle, there are several small, specialised muscle fibres known as intrafusal fibres.
intrafusal fibres have contractile proteins (thick and thin filaments) at either end, with a central region that is devoid of contractile proteins- the central region is wrapped by the sensory dendrites of the muscle spindle afferent
*when the muscle lengthens, the muscle spindle is stretched, opens ion channels, triggers action potentials in muscle spindle afferents
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by which neuron are intrafusal fibres of muscle spindle innervated?
by an efferent neuron known as the gamma motor neuron
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what are the efferent that innervate extrafusal fibres of the muscle spindle known as?
alpha motor neuron (MN)
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what does the gamma MN operate to maintain?
the gamma MN operates to maintain muscle spindle sensitivity, regardless of muscle length
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what is alpha-gamma coactivation?
when extrafusal fibres are stimulated to contract by alpha MN activation, the gamma MN is simultaneously excited.
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where on the intrafusal fibre does the gamma MN stimulate contraction?
the gamma MN stimulates contraction in the two ends of the intrafusal fibre, readjusting its length and keeping the central region of the intrafusal fibre taut (necessary to keep muscle spindle afferents responsive)
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Golgi tendon organ
The Golgi tendon organ is a sensory receptor located near the junction of a muscle and tendon, responding to muscle tension rather than muscle stretch, and playing a role in transmitting the magnitude of contractile force during movement.
in series with muscle fibres (located in the tendons)
the sensory dendrites of the Golgi tendon organ afferent are interwoven with collagen fibrils in the tendon
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with what are the sensory dendrites of the Golgi tendon organ afferent interwoven in the tendon?
collagen fibrils
the sensory dendrites of the Golgi tendon organ afferent are interwoven with collagen fibrils in the tendon
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afferent vs efferent
Afferent neurons carry information from sensory receptors of the skin and other organs to the central nervous system (i.e., brain and spinal cord), whereas efferent neurons carry motor information away from the central nervous system to the muscles and glands of the body.
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what activates the Golgi tendon organ?
when the muscle contracts, the collagen fibrils are pulled tight, and this activates the Golgi tendon organ afferent
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how can the Golgi tendon organ provide info about muscle tension?
changes in muscle tension will provide different degrees of pull on the tendon (so the golgi tendon organ provides info about muscle tension)
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why doesn't muscle stretch activate the Golgi tendon?
you might think that muscle stretch would also pull on the tendons and stimulate the Golgi tendon organ afferent
however, most of the force of a stretch is absorbed by the muscle itself, so a muscle contraction is a much better stimulus for the Golgi tendon organ.
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is a muscle stretch or muscle contraction a better stimulus for the golgi tendon organ?
muscle contraction
*you might think that muscle stretch would also pull on the tendons and stimulate the Golgi tendon organ afferent
however, most of the force of a stretch is absorbed by the muscle itself, so a muscle contraction is a much better stimulus for the Golgi tendon organ.
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what are mechanoreceptors?
other proprioceptors.
Mechanoreceptors detect stimuli such as touch, pressure, vibration, and sound from the external and internal environments. They contain primary sensory neurons that respond to changes in mechanical displacement, usually in a localized region at the tip of a sensory dendrite.
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tactile receptors and baroreceptors
types of mechanoreceptors (proprioceptors)
tactile: provide the sensations of touch pressure and vibration
baroreceptors: detect pressure changes
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4 types of mechanoreceptors?
1. merkel receptors
2. meissner corpuscles
3. ruffini cylinders
4. pacinian corpuscles
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how do the 4 types of mechanoreceptors differ?
(merkel receptors, meissner corpuscles, ruffini cylinders, pacinian corpuscles)
these receptors differ in regard to:
- their location in the skin
- their physical features
- their speed of adaptation to stimulation
- the size of their receptive fields
- the type of mechanical stimulation to which they respond
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touch receptors- how is data on mechanoreceptors gathered?
(mechanoreceptors)
- most of out knowledge about mechanoreceptors comes from recording from nerve fibres in the skin
- in humans, microneurography records from a single nerve fibre under the skin via a very fine electrode
- balanowski and his co-workers found that each type of mechanoreceptor response to a range of frequencies of mechanical stimulation
- they respond to a range from 0.3Hz (e.g. slowly pushing and releasing your skin once every three seconds) to 500Hz (extremely rapid vibration created by machinery)
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what mechanoreceptors are associated with slowly adapting (SA) fibres?
merkel disks and ruffini cylinders
*responding while the stimulus is present
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what mechanoreceptors are associated with rapidly adapting fibres?
meissner corpuscles and pacinian corpuscles.
*repsond to stimulation with a burst of firing at the beginning and end of stimulation
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how do meissner corpuscles and pacinian corpuscles mechanoreceptors respond to stimualtion?
rapidly adapting fibres* respond to stimulation with a burst of firing at the beginning and end of stimulation
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location of mechanoreceptor receptive fields
the receptors with small receptive fields are located close to the surface of the skin while those with large receptive fields are located deeper in the skin
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simple reflexes
Simple reflexes are rapid, brief, automatic, and involve only a small portion of the body in a two-neuron arc. Simple reflexes include the contraction of a muscle in reaction to stretching, salivation at the view of food, and blinking of eyes when the cornea is touched.
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complex reflexes
interneurons are in the spinal cord. So, when an interneuron participates in a reflex, there is more than one synapse, and these reflexes are then called complex reflexes.
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dizziness and motion sickness
dizziness is a result of the vestibulo-ocular reflex gone wrong.
- normally inputs from out balance organs direct compensating movements of out eye
- spinning causes sensory cells to keep signalling even after we stop
- put eyes track back and forth (nystagmus)
- and for a while, we can't tell which way is up
motion sickness is a similar mismatch in the vestibulo-ocular system
- reading in a moving car
- the eyes gove the impression you-re sitting still
- inner ear signals that you're moving
- for some, this sensory disagreement triggers nausea and vomiting
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what system in particular is affected in dizziness and motion sickness?
vestibulo-ocular system
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nystagmus
a rhythmical, repetitive and involuntary movement of the eyes.
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tissue regeneration
growth of cells and tissues to replace lost structures
*required an intact connective tissue scaffold
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what does regeneration require?
requires an intact connective scaffold
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3 cell types in terms of ability to divide?
1. labile: undergo mitosis continually
2. stable: can be stimulated to divide
3. permanent: never undergo cell division
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labile cells
have a high rate of loss and replacement and therefore high capacity for regeneration
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examples of labile cells
squamous and glandular epithelia
haemopoietic cells in bone marrow
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stable cells
normally non-poliferative but can be stimulated to after damage
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examples of stable cells
renal tubular cells
hepatocytes
osteoblasts
endothelial cells
fibroblasts
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permanent cells
unable to divide after initial development and cannot regenerate when damaged
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examples of permanent cells
neurons
cardiac and skeletal muslce
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therapeutic cloning
Therapeutic cloning, also called somatic cell nuclear transfer, is a way to create versatile stem cells independent of fertilized eggs. In this technique, the nucleus is removed from an unfertilized egg. This nucleus contains the genetic material. The nucleus also is removed from the cell of a donor.
Therapeutic cloning is a process that produces an embryo with genes that are identical to the patient's. Stem cells taken from this embryo will have the same DNA as the patient. This means that the patient's body will not reject the stem cells or body cells made from the embryo's stem cells.
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signalling mechanisms in cell growth
Cell signalling pathways play a major role in cell division. Cells do not normally divide unless they are stimulated by signals from other cells. The ligands that promote cell growth are called growth factors. Most growth factors bind to cell-surface receptors that are linked to tyrosine kinases
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signal transduction pathway
A signal transduction pathway is a series of molecular interactions triggered by the binding of a signalling molecule to its receptor, leading to the activation of various intracellular pathways involved in cell signalling.
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what are different pathways in which transcription factors can be activated in cell growth/regeneration? [signal transduction pathways]
[signal transduction pathways]
PI3 kinase pathway
MAP-kinase pathway
IP3 pathway
(growth factor; receptor with intrinsic tyrosine kinase activity)
cAMP pathway
(seven transmembrane G-protein-coupled receptors)
JAK/STAT pathway
(cytokine; receptors without intrinsic tyrosine kinase activity)
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what signal transduction pathways are stimulated by growth factor binding to receptors with intrinsic tyrosine kinase activity?
PI3 kinase pathway
MAP-kinase pathway
IP3 pathway
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variables that influence healing
injury:
type, intensity, duration
patient:
age, comorbidity, medication
treatment:
apposition, stabilisation, loading + motion
trauma-> cell + matrix damage-> healing [inflammation-> repair-> remodelling]
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4 possible outcomes of healing
[inflammation-> repair-> remodelling]
1. restoration of original tissue
2. scar
3. excessive repair
4. failure of healing
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inflammation
(0-7 days)
inflammatory cells migrate from:
- epitendinous tissues (sheath, periosteum, soft tissues)
- epitendon and endotendon
defect rapidly filled with gransulation tissue, haematoma and tissue debris
fibronectin laid down as scaffolding for collagen synthesis
extrinsic response outweighs intrinsic response
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where do inflammatory cells migrate from?
-epitendinous tissues (sheath, periosteum, soft tissues)
- epitendon and endotendon
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what is the 3 things is the trauma site rapidly filled during inflammation?
defect rapidly filled with:
1. granulation tissue
2. haematoma
3. tissue debris
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what is laid down during inflammation for collagen synthesis?
fibronectin
- fibronectin laid down as scaffolding for collagen synthesis
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relationship between extrinsic and intrinsic response during inflammation?
extrinsic response outweighs intrinsic response
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how many days following trauma does inflammation occurs?
0-7 days
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repair
[3-60days]
fibroblast migrate to zone of injury and begin to synthesise collagen by day 5
initially collagen type 3 produced which is laid down in a random orientation
during 4th week intrinsic fibroblasts proliferate and these cells take over the healing process both synthesising and reabsorbing collagen
- tendon callus
switch to production of type 1 collagen which is increasingly orientated along line of force
vascular ingrowth via collagen/fibronectin scaffolding
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fibroblast
A fibroblast is a type of cell that contributes to the formation of connective tissue, a fibrous cellular material that supports and connects other tissues or organs in the body. Fibroblasts secrete collagen proteins that help maintain the structural framework of tissues.
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what is the time frame of repair in healing after trauma?
3-60 days
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what type of cells migrate to the injury zone to begin collagen synthesis during repair?
fibroblasts.
fibroblast migrate to zone of unjust and begin to synthesis collagen by day 5.
*A fibroblast is a type of cell that contributes to the formation of connective tissue, a fibrous cellular material that supports and connects other tissues or organs in the body. Fibroblasts secrete collagen proteins that help maintain the structural framework of tissues.
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by what day do fibroblasts migrate to injury zone to begin collagen synthesis?
by day 5
repair [days 3-60]
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what type of collagen is synthesised at which stages of repair? *healing
initially collagen type 3 is produced which is laid down in a random orientation
during 4th week intrinsic fibroblasts proliferate and these cells take over the healing process both synthesising and reabsorbing collagen
switch to production of type 1 collagen which is increasingly oriented along line of force
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organisation
28-180 days
final stability acquired during this phase by the normal physiological use of the tendon
accompanied by cross linking between fibrils further increasing tendon tensile strength
complete regeneration never achieves
- defect remains hypercellular
- thinner collagen fibrils
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can complete regeneration of a tissue be achieved
complete regeneration never achieved
- defect remains hypercellular
- thinner collagen fibrils
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at what time frame does organisation occur post trauma?
28-180 days
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what are the three main divisions of tendon healing?
1. inflammation
2. repair
3. organisation
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what is acquired during the organisation phase of tendon healing?
final stability.
- final stability acquired during this phase by the normal physiological use of the tendon
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what is accompanied with final stability during the organisation phase of tendon healing?
by cross linking between fibrils
final stability acquired during organisation phase by the normal physiological use of the tendon; accompanied by cross linking between fibrils further increasing tendon tensile strength
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comment on early mobilisation in terms on tendon healing
early mobilisation:
- increases ROM (range of motion?) but can decrease repair strength is excessive stress placed on repair
- immobilisation leads to increase tendon substance strength at expense of ROM
*Early mobilization is the application of physical activity as early as the 2nd to 5th day after the onset of critical illness or injury.
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early mobilisation
Early mobilization is the application of physical activity as early as the 2nd to 5th day after the onset of critical illness or injury.
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time frame of tendon healing in terms of strength
weakest: 7-10 days
regain most of original strength: 21-28 days
achieve max. strength by about 6 months
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3 novel therapeutics to introduce better regeneration
1. micro-fracture for cartilage
2. calf serum for ligaments
3. stem cells for the heart
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what are the disparities in tissue healing?
healing much faster in tissues with better regeneration potential (better signalling= better blood supply?)
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in what stage of development are fractures common?
fractures common only in immature skeleton
- physeal injuries 'weak link' = physis
- buckle or torus fracture
- plastic deformation
- greenstick fracture
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analgesia vs anti-inflammatory; discuss NSAIDs in healing of musculoskeletal injuries
- rationale for using NSAIDs musculoskeletal injuries is that healthy tissue is not inflamed; therefore, if we stop the inflammation in an injured tissue, the tissue will be healthy
- the problem with this viewpoint is that in addition to being a sign of injury, inflammation is a necessary component of the healing process 'inflammation can occur without healing, but healing cannot occur without inflammation'
- whether the injured tissue is a ligament, tendon, or muscle, the body responds to injury with a sequence of events that begins with an influx of inflammatory cells and blood
- inflammatory cells remove debris and recruit cytokines and other growth factors toward the injury site
- this inflammatory phase is partly mediated by the same prostaglandins that are blocked by NSAIDs
- in healing, the proliferative phase consisting of a mixture of inflammatory cells and fibroblasts naturally follows the inflammatory phase
- fibroblasts build a new extracellular matric and persist into the final phase of repair, the maturation phase, where, if all goes well, functional tissue is laid down
- the key point is that each phase of repair is necessary for the subsequent phase and by blocking the inflammatory phase, NSAIDs can, at least theoretically delay the healing of musculoskeletal injuries.
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what is the rationale for using NSAIDs to treat musculoskeletal injuries?
healthy tissue is not inflamed; therefore if we stop the inflammation in an injured tissue, the tissue will be healthy
*Nonsteroidal anti-inflammatory drugs (NSAIDs) are a drug class FDA-approved for use as antipyretic, anti-inflammatory, and analgesic agents
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analgesia
An analgesic drug, also called simply an analgesic, antalgic, pain reliever, or painkiller, is any member of the group of drugs used for pain management
Anti-inflammatory analgesics reduce inflammation
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what is the problem with the viewpoint that is we stop the inflammation in an injured tissue the tissue will be healthy because healthy tissue is not inflamed?
in addition to being a sign of injury, inflammation is a necessary component of the healing process
'inflammation can occur without healing but healing cannot occur without inflammation'
each phase of repair is necessary for the subsequent phase and by blocking the inflammatory phase, NSAIDs can, at least theoretically, delay the healing of musculoskeletal injuries
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what stages occur during the inflammatory phase of healing?
whether the injured tissue is a ligament/tendon/muscle, the body responds to injury with a sequence of events that begins with an influx of inflammatory cells and blood.
inflammatory cells remove debris and recruit cytokines and other growth factors toward the injury site.
this inflammatory phase is partly mediated by the same prostaglandins that are blocked by NSAIDs.
in healing, the proliferative phase consisting of a mixture of inflammatory cells and fibroblasts naturally follows the inflammatory phase.
fibroblasts build a new extracellular matrix and persist into the final phase of repair, the maturation phase, where if all goes well, functional tissue is laid down
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muscles vs ligaments vs tendons
Muscles allow for movement, ligaments attach bones, and tendons connect muscle to bone
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cytokines
Cytokines are small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells. When released, they signal the immune system to do its job. Cytokines affect the growth of all blood cells and other cells that help the body's immune and inflammation responses
Cytokines are signalling proteins that help control inflammation in your body. They allow your immune system to mount a defence if germs or other substances that can make you sick enter your body. Too many cytokines can lead to excess inflammation and conditions like autoimmune diseases.
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soft tissue
Soft tissues connect, support, and surround the different body organs. They can be found in most parts of the body. Soft tissues include fat, muscle, nerves, blood vessels, ligaments, tendons, and other fibrous tissues
*Bone, cartilage, and teeth are examples of hard tissue
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treatment for soft tissue injuries
RICE; rest, ice, compression, elevation
e.g.
HI-RICE; hydration, ibuprofen, rest, compression, elevation
PRICE; protection, rest, ice, compression, elevation
PRICES; protection, rest, ice, compression, elevation, support
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examples of isokinetic, isotonic and isometric contractions
Riding a stationary bike, raising a dumbbell with a bicep curl, and holding a weight at a constant height are examples of isokinetic, isotonic, and isometric contractions, respectively.
201
joints
A joint is the part of the body where two or more bones meet to allow movement.
202
corticospinal tract
upper motor neurons located at primary motor cortex (cerebral hemisphere); terminations at lower motor neurons of cranial nuclei in brainstem; crossover at brainstem; function is the conscious motor control of skeletal muscle
203
lateral corticospinal tract
upper motor neurons located at primary motor cortex (cerebral hemisphere); termination at lower motor neurons of anterior grey horns of the spinal cord; crossover at pyramids of medulla oblongata
204
anterior corticospinal tract
upper motor neurons located at primary motor cortex (cerebral hemisphere); termination at lower motor neurons of anterior grey horns of the spinal cord; crossover at level of lower motor neuron; crossover at pyramids of medulla oblongata
205
vestibulospinal tract
upper motor neurones located at vestibular nuclei (at border of pons and medulla oblongata); termination at lower motor neurons of anterior grey horns of the spinal cord; uncrossed; function is subconscious regulation of balance and muscle tone
(medial pathway)
206
tectospinal tract
upper motor neurones located at tectum (mesencephalon superior and inferior colliculi); termination in lower motor neurons of anterior grey horns (cervical spine only); crossover at brain stem (mesencephalon); function of subconscious regulation of eye, head, neck, and upper limb position in response to visual and auditory stimuli
(medial pathway)
207
reticulospinal tract
upper motor neurons at reticular formation (network of nuclei in brainstem); termination at lower motor neurons of anterior grey hons of spinal cord; uncrossed; function in subconscious regulation of reflex activity
(medial pathway)
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rubrospinal tract
upper motor neurons located in red nuclei of mesencephalon; termination at lower motor neurons of anterior grey hons of spinal cord; crossover at brain stem (mesencephalon); function in subconscious regulation of upper limb muscle tone and movement
(lateral pathway)
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What is the motor cortex and where is it located in the brain?
The motor cortex is located in the frontal lobe, just in front of the central sulcus. It controls voluntary movements.
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What is the role of the lateral pathway in motor control?
The lateral pathway controls voluntary movements, especially those involving distal muscles (e.g., hand and finger movements).
211
What is the lateral corticospinal tract and how does it function?
The lateral corticospinal tract controls distal muscles. It originates in the motor cortex, passes through the thalamus, midbrain, and medulla, and crosses over at the pyramids of the medulla before synapsing in the spinal cord to target the muscle.
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What is the role of the rubrospinal tract?
The rubrospinal tract originates from the red nucleus in the midbrain and is involved in controlling large muscles and posture.
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What are the functions of the anterior corticospinal tract?
The anterior corticospinal tract controls proximal muscles (e.g., muscles of the arm). It does not cross over at the pyramids like the lateral corticospinal tract.
214
How does the vestibulospinal tract contribute to motor control?
The vestibulospinal tract, originating from the vestibular nuclei in the medulla, is responsible for controlling head balance and orientation of the head.
215
What does the reticulospinal tract control?
The reticulospinal tract controls posture and balance, particularly involving axial muscles.
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What is the tectospinal tract and its function?
The tectospinal tract, originating from the superior colliculus in the midbrain, coordinates the orientation response and movement related to visual stimuli, such as turning the head in response to sight.
217
What are the differences between the lateral and anterior medial pathways?
he lateral pathway controls voluntary, fine movements of distal muscles (e.g., fingers), while the anterior medial pathway controls coarse movements of axial muscles (e.g., posture and balance).
218
What happens if there is damage to the corticospinal tract?
Damage to the corticospinal tract can lead to paralysis on the opposite side of the body (contralateral paralysis) because the tract crosses over at the medulla.
219
which descending spinal pathways remain uncrossed?
vestibulospinal tracts and the pontine reticulospinal tract
220
which spinal tracts are voluntary/involuntary
Voluntary movements are controlled by the pyramidal tracts, specifically the corticospinal tract, which originate in the cerebral cortex and descend to the spinal cord.
Involuntary movements, including reflexes and postural adjustments, are mediated by the extrapyramidal tracts, which originate in the brainstem and connect to the spinal cord
