5 Flashcards
1
Q
What is the gait cycle?
A
The period from heel strike of 1 limb until the next time that heel hits the ground.
2
Q
What is the running pattern?
A
At some point having both feet off the ground simultaneously.
Absorbing and releasing energy stored in tendons biomechanically makes running a series of controlled leaps.
3
Q
Which phase does midstance belong to?
A
Stance phase
4
Q
Which phase does propulsion belong to?
A
Stance phase
5
Q
Which phase does toe-off belong to?
A
Swing phase
6
Q
Which phase does contact belong to?
A
Stance phase
7
Q
Which phase does heel strike belong to?
A
Swing phase
8
Q
What two things make up the locomotor system?
A
Bones and joints
9
Q
What is torque?
A
Rotational force; when most skeletal muscles contract the bones to which they are attached they rotate around a joint.
10
Q
Differentiate between eccentric and concentric muscle action
A
Eccentric – a muscle length increases
Concentric – a muscle length shortens
11
Q
What is an agonist muscle?
A
Agonists cause a movement through their own contraction.
12
Q
What is an antagonist muscle?
A
An antagonist opposes a movement.
13
Q
What is a synergist muscle?
A
Perform/helps to perform the same motion as the agonist.
14
Q
What are tendons?
A
Tough band of connective tissue; attaches muscle to bone
15
Q
Tendons and muscles work together to do what?
A
Pull on a bone
16
Q
How do muscle and joints provide the brain w/ info about body position and movement?
A
They have receptors that send sensory info to the brain.
17
Q
What is the function of the cerebellum?
A
Motor correction – adjusting movement based on sensory and proprioceptive input.
18
Q
Where does the cerebellum receive input from?
A
The spinal cord and other parts of the brain
19
Q
What is motor learning?
A
Improving performance of motor sequence w/ repetition.
20
Q
What term describes a bending movement that decreases the angle between a segment and its proximal segment?
A
Flexion
21
Q
What term describes motion that pulls a structure toward the midline of the body?
A
Adduction
22
Q
What term describes movement in a superior direction?
A
Elevation
23
Q
What term describes toes brought closer to the shin; decreasing the angle between dorsum of the foot and leg?
A
Dorsiflexion
24
Q
What term describes the decreasing angle between the sole of the floor and back of the leg?
A
Plantar flexion
25
What term describes motion that pulls a structure away from the midline of the body?
Abduction
26
What is the main extension muscle at the hip?
Gluteus maximus
27
What is the muscles that abduct the hip?
Gluteus medius and minimus
28
What does the extension at the hip move?
Moves thigh forward and backward.
29
What does abduction of the hip move?
Moves tight sideways.
30
What do quadriceps do?
Extended knee and flex the thigh
31
What does the hamstring do?
Flex the knee and extend the thigh
32
What acts on our centre of mass?
Gravity
33
Where is the centre of mass in humans?
Within the pelvis, in the midline anterior to 2nd sacral vertebra.
34
What is neurulation?
Sides of neural groove come together and form neural tube.
35
What happens to gait due to aging?
Decreased muscle bulk and flexibility --> decreased stride length and increased no. of steps
36
What type of structural damage can alter gait?
Damage to blood vessels, nerves, skeleton, joints, muscles and tendons.
37
What does wearing flip-flops do to the gait cycle?
Wearers take shorter steps and heels hit the floor w/ less vertical force.
Toes are not brought up as much, creating a larger ankle angle and shorter stride length.
38
What does wearing high heels do to the gait cycle?
Shoes are elevated, heel shortens the Achilles tendon, shortening of the calf muscles.
39
Name some inflammatory/degenerative conditions that alter the gait?
Rheumatoid arthritis, infectious arthritis and osteoarthritis, gout, and pseudo-gout.
40
What is an antalgic gait?
Any gait that reduces loading on the affected extremity by decreasing stance phase time or joint forces as to avoid pain on weight-bearing structures.
41
Give examples of an antalgic gait
Diabetic foot, osteoarthritis, gout, ingrown toenail
42
What is an ataxic gait?
Cerebellar gait. Unsteady, uncoordinated walk, a wide base and the feet thrown out, coming down on the heel and then on the toes double tap.
43
What is a parkinsonian gait?
Patient involuntarily moves w/ short, accelerating steps, often on toe tip, w/ the trunk flexed forward and the legs flexed stiffly at the hips and knees.
44
What is a myopathic gait?
Waddling gait
45
What is a neuropathic gait?
High stepping gait
46
What is the neural folds?
Raised edges of the neural plate.
47
What is the neural plate?
A thickening to the ectoderm in (3rd week of gestation)
48
What is the neural groove?
A longitudinal groove formed as the neural plate folds’ inwards.
49
What is the function of the neural folds?
Increase in height and meet to form the neural tube
50
What 3 layers of cells differentiate from the walls that encloses the neural tube?
Marginal layer --> white matter
Mantel layer --> grey matter
Ependymal layer --> lining of the central canal of the spinal cord and ventricles of the brain
51
What is the neural crest?
Tissue between neural tube and skin ectoderm.
52
What does the neural crest differentiate into?
Forms the posterior root ganglia of spinal nerves, spinal nerves, ganglia of cranial nerves, cranial nerves, ganglia of the ANS, adrenal medulla and meninges.
53
What type of cells migrate and differentiate into pharyngeal arches?
Neural crest cells
54
What does the anterior part of the neural tube develop into at 3-4 weeks?
3 enlarged areas – primary brain vesicles
55
Name the 3 primary areas.
Prosencephalon (pros = before) – forebrain
Mesencephalon – midbrain
Rhombencephalon (rhomb = behind) – hindbrain
56
Which primary are of the developing brain develops into the follow secondary vesicles: telencephalon and diencephalon?
Prosencephalon
57
Which primary are of the developing brain develops into the follow secondary vesicles: metencephalon and myelencephalon?
Rhombencephalon
58
What does the metencephalon become?
Pons and cerebellum – houses part of the 4th ventricle
59
What does the myelencephalon become?
Medulla – houses part of the 4th ventricle
60
What does the telencephalon develop into?
2 cerebral hemispheres (including basal nuclei) – houses paired lateral ventricles (1st and 2nd)
61
What does the diencephalon develop into?
Thalamus, hypothalamus, epithalamus – houses 3rd ventricle
62
What does the mesencephalon develop into?
Midbrain which surrounds the cerebral aqueduct
63
What does the area of the neural tube inferior to myelencephalon give rise to?
The spinal cord
64
What is the 4 ventricles of brain associated with?
1st and 2nd in the cerebral hemispheres
3rd – thalamus, hypothalamus, epithalamus
4th – pons and medulla
65
What is the adult ventricular system a remnant of?
The neural tube that has folded up and expanded disproportionally in different regions.
66
What are the important structures associated w/ the C shaped lateral ventricles?
Thalamus, basal ganglia, hippocampus and fornix
67
What is the internal capsule an important site in?
Strokes
68
What is the internal capsule?
Major tract of fibres passing through nuclei of basal ganglia and diencephalon.
69
Which structure forms the most posterior part of the neural tube?
Spinal cord
70
What type of fibres pass in the ventral side of spinal vertebrae?
Motor
71
What type of fibres pass in the dorsal side of spinal vertebrae?
Sensory
72
What neurons are found in the dorsal, ventral, lateral horns?
Dorsal – sensory neurons
Ventral – motor neurons
Lateral – autonomic neurons
73
What are efferent axons?
They are projections of the ventral root that growth toward muscle, glands etc
74
What are afferent fibres?
They have projections that growth into the spinal cord
75
What is spina bifida?
Incomplete closing of the backbone – associated w/ low folic acid levels in first few weeks of development.
76
What is anencephaly?
Absence of the skull and cerebral hemispheres – associated w/ low folate levels in first few weeks of development.
77
Which nerve is CN I?
Olfactory – Sensory (nose)
78
Which nerve is CN X?
Vagus – Both (laryngeal and pharyngeal muscles)
79
Which nerve is CN IV?
Trochlear – Motor (superior oblique muscle eye)
80
Which nerve is CN XII?
Hypoglossal – Motor (tongue, glossal muscles)
81
Which nerve is CN V?
Trigeminal – Both (mastication, face sensations)
82
Which nerve is CN XI?
Accessory – Both (muscles of neck and overlaps functions of vagus nerve)
83
Which nerve is CN IX?
Glossopharyngeal – Both (taste, parotid gland…)
84
Which nerve is CN II?
Optic – Sensory (visual info to brain)
85
Which nerve is CN III?
Oculomotor – Motor (eye movement muscles)
86
What are the 6 functions of the skeletal system?
Support, protection, assistance in movement, mineral homeostasis, blood cell production, triglyceride storage
87
In bones where are triglycerides storage?
Yellow bone marrow
88
In red bone marrow where are developing adipocytes, fibroblasts, macrophages and blood cells found?
A network of reticular fibres
89
When is all bone marrow red?
Newborns
90
Which minerals does bone tissue store?
Calcium, phosphorus, among others
91
What cells does the skeleton develop from?
Neural crest – head
| Mesoderm – body
92
Which part of the skeleton develops in cartilaginous bodies?
All skeleton below the head excluding the clavicles and base of skull.
93
Where are flat bones of the skull, most facial ones, mandible and medial part of clavicles formed?
In the neural crest which later ossifies.
94
When does vertebrae develop from somites?
Day 21-25
95
What does the cerebellum connect to brainstem via?
Cerebellar peduncles
96
When do limb buds develop?
4-5 weeks
97
What is intramembranous ossification?
Bone forms directly within mesenchyme.
98
What is endochondral ossification?
Bone forms within hyaline cartilage the develops from mesenchyme.
99
What happens to cartilage? .
Becomes calcified
100
What is the epiphyseal plate?
Growth plate. Layers of hyaline cartilage that allows the diaphysis to growth in length.
101
What is the periosteum?
Tough connective tissue sheath and associated blood vessels.
Covers bone where the articular cartilage doesn’t.
102
What is the diaphysis?
The bone’s shaft/body. Long, cylindrical main portion.
103
What is the articular cartilage?
Thin layer of hyaline cartilage covering the part of epiphysis where bone forms an articulation w/ another bone.
104
What is the epiphyses?
The proximal and distal ends of the bone.
105
What is the metaphysis?
Regions between the diaphysis and epiphysis
106
What is the function of the periosteum?
Assists in fracture repair; provides attachment point for ligaments and tendons; nourish bone tissue
107
What does the medullary cavity in the diaphysis contain?
Blood vessels, fatty yellow bone marrow
108
What is the endosteum?
Thin membrane that lines the medullary cavity.
109
What does the endosteum contain?
Single layer of bon-forming cells and small amount of connective tissue.
110
Why is damage repair limited in the articular cartilage?
It lacks blood vessels
111
What is the epiphyseal line?
When the cartilage in the epiphyseal plate is replaced by bone it forms a line.
112
Where is spongy bone found in long bones?
Epiphyses
113
Where is compact bond found in long bones?
Diaphysis
114
What are the 5 main types of bone shapes?
Give examples.
```
Long – tibia, fibula, femur
Short – carpal, tarsal
Flat – cranial, sternum, scapulae
Irregular – vertebrae, hipbones
Sesamoid – patellae, many small bones
```
115
What type of bone is cube shaped?
Short bone. Approx. equal length and width
116
What is cortical and cancellous bone tissue?
Cortical – compact bone; cancellous – spongy bone
117
What is the structural units of cortical bone?
Osteons
118
What doe osteons consist of?
Concentric lamellae arranged around a central canal
119
What are lacunae?
Little lakes that contain osteocytes between concentric lamellae
120
What are osteons parallel to?
Length of the diaphysis
121
What is the functions of cancellous bone?
Lighten bone, support and protect the red bone marrow
122
What is the units in cancellous bone tissue?
Trabeculae
123
How are the lamellae of spongy tissue arranged?
An irregular pattern of thin columns called trabeculae.
124
What fills the spaces between the trabeculae?
Red and yellow bone marrow
125
In cancellous bone, what do blood vessels provide nutrients to?
The lacunae and canaliculi that contain osteocytes
126
In bone, what is the extracellular matrix composed if?
15% - water
30% - collagen
55% - crystallised mineral salts
127
What is the most abundant mineral salt?
Calcium phosphate.
128
What the combination of calcium hydroxide and calcium phosphate form?
Hydroxyapatite
129
What are the 4 types of cells in bone tissue?
Osteoprogenitor cells; osteoblasts; osteoclast; osteocytes
130
What is the function of osteoblasts?
Forms bone extracellular matrix
131
What is the function of osteoclasts?
Functions in resorption, the breakdown of bone extracellular matrix
132
What is the function of osteocytes?
Maintains bone tissue; nutrient and waste exchange
133
What is the function of osteoprogenitor cells?
Develops into an osteoblast
134
What are osteocytes a fusion of?
Up to 50 monocytes.
135
Where are osteocytes found?
In the endosteum; on the side of the cell that faces the bone surface
136
How do osteocytes digest the protein and mineral components of bone matrix?
Lysosomal enzymes and acids
137
What are compound fractures?
The broken ends of the bone protrude through the skin.
138
What name is given to a fracture of the distal end of the fibula, w/ serious injury of the distal tibial articulation?
Pott
139
What are greenstick fractures?
A partial fracture in which one side of the bone is broken and other bends. Only occurs in children.
140
Which fracture has splintered, crushed, or bone broken into pieces at the site of impact?
Comminuted
141
What are simple fractures?
The fractured bone doesn’t break the skin.
142
What name is given to a fracture of the distal end of the radius in which the distal fragment is displaced posteriorly?
Colles
143
How are children’s bones different from adult?
They aren’t fully ossified and contain more organic than inorganic material
144
How do osteoblasts build bone?
Synthesise and secrete collagen fibres and initiate calcification
145
What type of cells get trapped in bone tissue?
Osteoblasts; they become osteocytes
146
Name 3 types of joints.
Fibrous, cartilaginous, synovial
147
Which type of joint has a synovial cavity?
Synovial a.k.a. diarthroses
148
Which type of joints have no synovial cavity?
Cartilaginous and fibrous
149
Which type of joints have bones held together by cartilage?
Cartilaginous
150
Which type of joints have bones held together by connective tissue?
Fibrous
151
What holds bones in synovial joints in place?
Accessory ligaments, the connective tissue of articular capsule and socket
152
In which nervous system is grey and white matter found?
CNS
153
Which type of matter makes up the tract?
White
154
Which type of matter makes up the cortex, horns and nuclei?
Grey
155
What are the differences between the nervous system and endocrine system?
N – responds quickly to stimuli by APs and NTs
E – responds to stimuli by secreting hormones into circulation that travels to target tissue
N – short-lived responses (fast)
E – long lasting responses (slow)
N – effects usually reversible
E – effects can be irreversible e.g. growth
156
What are somatic afferents and visceral afferents?
Somatic – external stimuli
| Visceral – internal stimuli
157
What are glial cells?
Provide functional and structural support for neurones.
158
What are nerve cells?
Form the functional basis of the nervous system; responsible for transmitting signals
159
What are the cranial meninges?
Periosteum, dura mater, arachnoid mater, pia mater
160
Name some potential spaces of the skull.
Extradural, subdural, subpial
161
What is subarachnoid space filled w/?
CSF
162
What are brain ventricles filled w/?
CSF
163
Which is more superior: the midbrain or pons?
Midbrain
164
What is pons Latin for?
Bridge
165
What is medulla Latin for?
Marrow
166
What is the cerebellar vermis?
Vermis (L. worm) is in the medial,
Cortico-nuclear zone of the cerebellum
167
What are denticulate ligaments?
Projections of pia mater that anchors the spinal cord in the centre of the vertebral column.
168
In the spinal cord, where is white matter relative to grey matter?
White matter on outside.
Grey matter on inside.
169
Are cranial nerves a part of the CNS or PNS?
PNS
170
Describe the medullary cavity of bone.
Hollow cylindrical space which contains yellow bone marrow in adults. Reduces weight of bone.
171
How many spinal segments are there?
31
| 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal
172
What is a myotome or dermatome?
An area of muscle or skin supplied by a single spinal segment.
173
Name the inorganic and organic components of bone.
Organic – type 1 collagen and non-collagenous proteins
| Inorganic – calcium hydroxyapatite
174
Why do osteoclast have multiple nuclei?
Because they are formed by the fused of monocytes.
175
Which type of bone cells act as mechanoreceptors?
Osteocytes
176
How much calcium is in the body of an adult human body?
1kg
177
What critical roles does calcium have?
Neuromuscular function, blood coagulation, intracellular signalling.
178
Where is most of the phosphate in the adult body stored?
In the skeleton 85%
179
What is cholecalciferol?
Vitamin D3
180
How is cholecalciferol synthesised?
In skin from 7-dehydrocholesterol by UV light.
181
What in the liver produces 1,25 (OH)2 vitamin D3?
1-hydroxylation
182
Why is white matter on the outside in the spinal cord?
The axons have nerves that come off them which doesn’t need to cross the grey matter to leave and enter the spinal cord.
183
What is 1,25 (OH)2 vitamin D3 production regulated by?
PTH – stimulated
| Serum calcium and phosphate – inhibited
184
What is PTH secreted by and in response to what?
The parathyroid gland; in response to low plasma Ca2+¬ levels.
185
What does high levels of PTH stimulate?
Osteoclastic bone resorption
186
What do intermittent-low levels of PTH stimulate?
Osteoblastic bone formation
187
What are the actions of 1,25 (OH)2 vitamin D3?
Ca2+ and PO43- absorptions from intestine.
Mobilises calcium and phosphate from bone.
Induces marrow monocytes to differentiate into osteoclasts to stimulate bone resorption.
188
What is calcitonin?
A 32-aa polypeptide released from the parafollicular cells of the thyroid in response to high plasma calcium levels.
189
How does calcitonin reduce bone resorption?
By activating calcitonin receptors expressed by osteoclasts.
190
How do androgens levels link to the bone marrow density?
Low levels of androgens are linked to lower bone density in men. It’s linked to hypogonadism.
191
What are some causes of hypercalcaemia?
Primary hyperparathyroidism - can be due to malignancy,
Sarcoidosis
Paget's disease
Vitamin D toxicity.
192
How does the cerebellum improve accuracy of movements?
By providing feedback info to cortical motor areas
193
What are some causes of hypocalcaemia?
Renal failure, vitamin D deficiency
194
What are some symptoms of primary hyperparathyroidism?
Kidney stones,
Skull and phalanges most affected,
Periosteal erosions,
Bone pain
195
What is an AP?
Rapid change in electrical potential across the plasma membrane of a cell.
196
What is the purpose of APs?
Intracellular and intercellular communication.
197
What is the membrane potential?
The difference in electric potential between the interior and exterior of a cell, caused by a separation of electric charges. Measured in units of volts/millivolts.
198
What 3 things establish the resting potential?
Low protein-permeability; sodium/potassium pump (active transport); high potassium permeability (passive transport).
199
What are leak channels?
Ion channels that are always open, continually leak ions across the membrane.
200
What are voltage-gated channels?
The open or close in response to voltage change.
201
What are ligand-gated channels?
The open or close in response to a chemical or drug.
202
What can elevated potassium ion levels in the body cause?
The resting potential to be less negative (depolarised); interferes w/ cardiac muscle contraction, stopping the heart.
Used in lethal injections and heart transplant surgery.
203
At what millivolt is the threshold exceeded and an AP (depolarisation) initiated?
-55mV
204
Which channels open at -55mV?
Voltage-gated sodium
205
What happens to voltage-gated sodium channels in the absolute refractory period?
They are inactivated.
206
Which channels open at +40mV?
Voltage-gated potassium channels
207
How does conduction in an unmyelinated and myelinated axon differ?
Myelin sheath insulates axons and prevents ion leakage so sodium and potassium channels concentrate only at the nodes of Ranvier.
Conduction in myelinated axons = saltatory conduction so it’s generally faster
208
What does axon conduction velocity depend on?
Myelination and axon diameter
209
When are unmyelinated fibres faster than myelinated fibres?
When the fibre diameter is small (< 1 micrometre)
210
What are the 4 types of axons?
A-alpha, A-beta, A-gamma, C
211
Which type of axon conducts impulses the fastest?
A-alpha
212
Which fibres are myelinated?
A-alpha, A-beta, A-gamma,
213
Which fibres are unmyelinated?
C
214
Which myelinated fibre has the smallest diameter?
A-gamma
215
What is MS?
An autoimmune disease where T-lymphocytes attack myelin sheaths causing inflammation, lesions and sclerosis (scarring) in axon bundles in the brain, spinal cord, optic nerve.
216
What can be used to either block or increase APs?
Carbamazepine, Tetrodotoxin, local anaesthetics, rDCS (transcranial direct current stimulation)
217
How does carbamazepine work?
Prolongs inactivated state of sodium channel and absolute refractory period. Slows down AP firing rate.
218
How does tetroxotocin work?
Blocks fast-voltage-gated sodium channels --> paralysis
219
What millivolt corresponds to hyperpolarisation and is associated with voltage-gated potassium channels closing?
-80mV
220
Block which channels lead to prevention of APs?
Voltage-gated sodium
221
What is nociception?
The neural processes of detecting, encoding and processing noxious stimuli – physiological response
222
What is pain?
An unpleasant sensory and emotional experience associated w/ actual or potential tissue damage or described in terms of such damage – subjective response.
223
What are charges of the outside of neurons like?
Positively charged due to high sodium ions
224
What are charges of the inside of neurons like?
Negatively charged, high potassium but low sodium
225
What type of nerve cell endings do nociceptors have?
Unspecialised – free nerve endings
226
What sort of afferents does A-alpha, A-beta, A-gamma, C fibres conduct?
A-alpha, A-beta, – low-threshold mechanoreceptor
A-gamma, C nociceptors, thermos-receptors and pain
227
What is 1st pain and 2nd pain?
1st pain – fast; A-gamma fibres; sharp; easily localised
2nd pain – slow; C fibres; dull, arching, slow onset
228
What do voltage gated calcium ion channels trigger release of?
NTs (glutamate, substance P) which activate 2nd order neurons in the spinal cord, sending signals up to brain.
229
What is congenital analgesia?
Inability to feel pain externally or internally.
Otherwise normal sensory responses.
230
What is referred pain caused by?
Convergence of nociceptor inputs from viscera and skin
231
Nociceptive afferents from internal organs (viscera) and the skin enter the spinal cord through the same route. What does this cause?
Cross-talk which gives rise to referred pain. Pain doesn’t originate from the site that hurts.
232
In early stages of appendicitis where is pain referred?
To the umbilical region around the navel
233
What is phantom limb?
The sensation that a missing limb is still attached and moving appropriately.
234
What are some helpful treatments for phantom limb pain?
Mirror therapy, use of myoelectric prosthesis, stump stimulation to reverse remapping of the brain.
235
What is allodynia?
Pain from a stimulus that does not normally provoke pain i.e. light touch.
236
What is hyperalgesia?
Increased sensitivity (reduced threshold) to pain from a stimulus that normally provokes pain.
237
What can induce hyperalgesia and how?
Tissue damage and inflammation triggers release of substances that sensitise peripheral nociceptors.
E.g. substance P, prostaglandins, bradykinin and histamine.
238
What is fibromyalgia?
Chronic and widespread pain and allodynia.
239
What do opioids bind to?
Opioid receptors found in the brain.
There are 3 types: mu, delta and kappa.
240
What are endogenous morphine-like substances?
They are like natural opioids found in the brain which bind to opioid receptors and relieve pain. E.g. endorphins, enkephalins, dynorphins – all peptides
241
What is fentanyl?
An analgesic used during operation and an enhancement of anaesthesia
242
What is pethidine?
Used for mod – severe pain, obstetric analgesia.
243
What are some opioid side effects?
Respiratory depression, constipation, addiction, hypotension, nausea and vomiting, drowsiness
244
Which CN is the only 1 that emerges from dorsal aspect of the brainstem and runs towards the front?
CN IV – trochlear
245
How are cranial nerves ordered?
By their location on the brainstem. Superior to inferior, then media to lateral, and order of their exit from the cranium (anterior to posterior)
246
How many cranial nerves are there?
A set of 12 paired nerves
247
Where do the cranial nerves arise from?
Cerebrum (I, II); midbrain (III, IV), pons (V, VI, VII, VII); medulla (IX, X, XI, XII)
248
How many descending tracts pass through the internal capsule in the brain?
6
249
How are the ascending tracts arranged?
Layered in a very organised structure.
250
How are the descending tracts arranged?
Not ordered very neatly, however the tracts synapse in the anterior horn in a very organised way.
251
Where do nerves that innervate the trunk have cell bodies?
More medial in the anterior horn
252
Where do nerves that innervate most distal parts of the body have cell bodies?
More lateral in the anterior horn.
253
In general, are nerves innervating extensors or flexors of a given region of the body more posterior or anterior in the anterior horn?
Flexors more posterior than extensors in the anterior horn
Extensors more anterior
254
Which motor neurons are somatotrophically arranged?
LMN
255
What does somatotropic mean?
Point-for-point correspondence of an area of the body to a specific point on central nervous system.
256
Name 2 descending tracts.
Ventromedial and dorsolateral
257
What does the ventromedial descending system innervate?
Postural and griddle muscles (proximal limb – arm, thigh, trunk)
258
What does the dorsolateral descending system innervate?
Distal muscles fine movements (forearm/leg and extremities – hands and feet)
259
Is the pontine, tectal, vesicular tracts part of the dorsolateral or ventromedial system?
Ventromedial
260
What would be observed from a ventromedial tract injury?
Collides w/ objects, axial immobility and forward slump, cannot reach out due to lack of ballistic racing, can flex elbow and individual digits.
261
Where is the tectum?
Near part of the midbrain
262
Which descending tract is predominantly ipsilateral?
Ventromedial
263
Which descending tract is predominantly contralateral?
Dorsolateral
264
Where does the dorsolateral tracts originate from?
Cerebral cortex, red nucleus
265
Which ventromedial tracts run contralaterally?
Tectospinal tracts
266
Which tracts play a role in antigravity activity in stance (keeps us upright by extending hip, etc.)?
The vestibulospinal tracts
267
What would be observed from a dorsolateral tract injury?
Arms hang limply, elbow inactive, fingers flex together, normal: axial posture, walking, navigating
268
Which system does corticospinal tracts belong to?
Dorsolateral.
269
What is pyramidal tracts also known as?
Cortical / corticospinal
270
What is anchored at the Z disc?
Actin
271
Which tracts does the ventromedial tract contain?
Pontine, tectal, vestibular
272
Which system does the pontine reticulospinal tracts belong to?
Ventromedial
273
Where do corticospinal tracts decussate?
Medullary pyramids
274
What are the main differences between the dorsolateral and ventromedial tracts?
Dorsolateral – voluntary, distal, flexors
| Ventromedial – postural, proximal, extensors, non-voluntary
275
What is the ventromedial tracts also known as?
Extra-pyramidal
276
Are dorsolateral tracts voluntary or non-voluntary?
Voluntary
277
Where is the primary motor cortex?
Pre-central gyrus (part of frontal lobe)
278
What does the primary motor cortex control?
Force and direction of movement
279
Where are pre-motor and supplementary motor areas found?
Frontal lobe
280
What are the 2 main motor tracts and where to they run from?
Corticospinal – premotor, primary motor and primary sensory cortex --> anterior horn neurons
Rubrospinal – red nucleus --> cervical segments
281
What percentage of the corticospinal tracts decussate at the medullary pyramids?
85-90%; the rest run ipsilaterally until the level of supply to muscles where they decussate and synapse
282
When is Babinski’s sign positive?
When the corticospinal tracts are unmyelinated.
Newborns and people w/ disease.
283
What are the corticospinal tracts involved in?
Voluntary skilled motor activity, independent flexion of single distal joints
284
What does Babinski’s test for?
When the corticospinal tracts are unmyelinated. New borns and people w/ disease.
285
What is the nucleus pulposus?
Inner, soft, pulpy, highly elastic substance in intervertebral disc.
286
What is a positive Babinski result?
Upgoing toe
287
What does the Rubrospinal tracts coordinate?
Movements
288
What does an isolated rubrospinal tract lesion lead to?
Impaired distal arm and hand movement.
Intention tremors.
289
What does the hypothalmospinal tract control?
Sympathetic nervous that control sweat glands of face (secrete) and vessels of face (dilate).
Also dilator muscle of eye and elevation of eyelid.
290
Where do outputs from the cerebellar nuclei go to?
Thalamus --> premotor/primary motor cortex
291
Which tract does Horner’s syndrome affect?
Hypothalamospinal tract (part of dorsolateral tract)
292
What is Horner’s syndrome?
Lazy eyelid, pinpoint pupil, anhydrases
293
How is brainstem death determined?
Criteria: unconscious and unresponsive, heartbeat and ventilation maintained using ventilator, evidence of incurable, serious brain damage, tests carried out by 2 doctors.
294
Which system controls cortical arousal and conscious awareness?
Pontine reticular activating system
295
Where does the spinal cord begin?
Where the medulla ends.
296
Approx. how long the is spinal cord?
42-45cm
297
Where does the spinal cord end?
L1-2
298
Where does a subarachnoid haemorrhage occur?
Between the arachnoid mater and pia mater
299
Which vessels a generally damaged in an subarachnoid haemorrhage?
Arterial bleeding
300
Where does a subdural haemorrhage occur?
Between the dura mater and arachnoid mater
301
Which vessels a generally damaged in an subdural haemorrhage?
Bridge vein tearing – low pressure venous bleed
302
What does a subdural haemorrhage look like on a CT?
Crescent shaped / concave image on CT
303
Where does an extradural haemorrhage occur?
Between the skull and dura mater
304
Which vessels are damaged in an extradural haemorrhage?
Meningeal vessels
305
What does an extradural haemorrage look like on CT?
Egg shaped / convex on CT
306
Where does an intracerebral haemorrhage occur?
Within the brain tissue
307
What does the subarachnoid space contain?
CSF and cerebral arteries
308
Where is the epidural space?
Outside the dura but in the vertebral column.
309
What is the inner (meningeal) dura mater continuous w/?
Spinal cord dura
310
What does pia mean?
Delicate
311
What does the spinal nerve become as it leaves the vertebra?
The anterior and posterior ramus of the spinal nerve
312
What does the cruciform ligament hold?
The odontoid process into the atlas
313
What does compression of the cerebral aqueduct cause?
CSF pressure in ventricles leads to hydrocephalus.
Treatment = shunt
314
Which arteries supply the anterior brain circulation?
Internal carotid – anterior and middle CA
315
Which arteries supply the posterior brain circulation?
Vertebral arteries – posterior CA, basilar and branches
316
How does the white matter change as you go down the spinal cord?
At superior end, there are a lot of axons = lots of white matter.
Inferior end there is less white matter.
317
Where does the central canal go through?
The centre of the grey a matter.
318
How many orders of neurons do ascending tracts have?
3
319
Where are 2nd order neurons found?
In the CNS; spinal cord and brainstem --> thalamus
320
Where do 3rd order neurons travel to?
From the thalamus to primary sensory cortex (somatosensory cortex) via internal capsule.
321
Where do 1st order neurons travel to?
Peripheral receptorsto dorsal roots
322
Where do 2nd order neurons travel to?
Thalamus
323
What sensation does the spinothalamic pathway carry?
Pain, temperature, touch and pressure
324
What sensation does the dorsal column carry?
Proprioception, vibration, 2-point discrimination
325
In the dorsal column pathway, do 1st order neurons ascend ipsilaterally or contralaterally?
Ipsilaterally
326
Where do 1st order dorsal column neurons synapse?
Medulla (ipsilaterally)
327
What sensations foes the spinocerebellar pathway carry?
Proprioception and balance for control of axial muscles.
328
How many neurons are there in the spinocerebellar pathway?
2
329
Which ascending pathway does not decussate at all?
Spinocerebellar
330
Which ascending pathway decussates in the medulla?
Dorsal column
331
Which ascending pathway decussates via white commissure in the spinal cord?
Spinothalamic
332
Which ascending pathway rise ipsilaterally 1-2 spinal segments and decussate at the medial lemniscus and ascended contralaterally?
Spinothalamic
333
Which ascending pathway rise ipsilaterally until it decussates in the nuclei fasciculus and cuneatus?
Dorsal column
334
Where do spinocerebellar pathways eventually synapse on?
Cerebellar hemisphere
335
Where do spinothalamic and dorsal column impulses terminally reach?
Post-central gyrus after getting to the thalamus
336
What does dorsal columns carry?
Proprioception and vibration, fine touch
337
What does spinothalamic tracts carry?
Pain and temperature, crude touch
338
Where do spinothalamic tracts synapse?
In spinal cord
339
Where do ventral corticospinal tracts decussate?
At the level of ventral horn synapse.
340
Where so lateral corticospinal tracts decussate?
In the medullary pyramids.
341
What do brainstem lesions affect?
Pain, temp, touch, position, vibration – contralaterally
342
What do spinal cord lesions affect?
Pain, temp, touch, position, vibration – ipsilaterally
343
What are T-tubules filled w/?
Interstitial fluids
344
What is the function of T-tubules?
To ensure APs excite all parts of the muscle fibre at the same instant.
345
What is sarcolemma?
Fine transparent tubular sheath that envelops the fibres of skeletal muscle
346
What does the sarcoplasm contain?
Glycogen which can be turned to glucose for energy
347
What gives skeletal muscle fibre a striated appearance?
The myofibrils which are composed of filaments.
348
What does sarcoplasmic reticulum contain?
Fluid and calcium ions
349
What is the function of the SR?
Release Ca2+ from the terminal cisterns --> triggers muscle contraction.
350
What are sarcomeres?
Functional units of myofibrils
351
What does the H-band contain?
Myosin
352
What does the I-band contain
Actin
353
What does the A-band contain?
Both actin and myosin
354
Which neurotransmitter is found in neuromuscular junctions?
ACh
355
What does calcium bind to and what does this lead to?
TnC --> TnI shifts to free myosin binding sites for myosin heads to bind
356
What happens to overlap when the muscle fibre is stretched to 170% of its optimal length?
There is no overlap between thin and thick filaments.
357
What is isometric contraction?
Same length, isolated muscle, muscle can develop tension but doesn’t shorten.
358
How does atropine (belladonna) cause dilation of the pupil?
By blocking the parasympathetic outflow to the eye which acts as the constrictor
359
What NT and receptors are found in the sympathetic preganglionic and postganglionic synapses?
PreG – ACh and nicotinic
| PostG – NA and adrenergic
360
Which NT and receptors are found in the sympathetic preG and postG synapses?
PreG – ACh and nicotinic
| PostG – ACh and muscarinic
361
Which receptor is found in all preG synapse in the ANS?
Nicotinic and ACh
362
Where are alpha adrenergic receptors found?
Blood vessels
363
What is the structure of muscarinic and nicotinic receptors?
Muscarinic – GPCRs (7 transmembrane spanning domains)
Nicotinic – ligand-gated ion channels?
364
What is the annulus fibrosus?
Outer fibrous ring of intervertebral disc, made of fibrocartilage
365
Why is suxamethonium used in tracheal intubation?
Because it’s broken down rapidly and is a nicotinic antagonist therefore relaxes the trachea.
366
What causes the myosin head to attach?
Tropomyosin moving aside and exposing myosin binding sites on the actin molecule.
367
What causes the myosin head to detach?
ATP binding to myosin
368
What is isotonic (dynaptic) muscle contraction?
Contraction against natural resistance (no increase in muscle tone – no tension)
369
What is the epimysium?
Sheath of fibrous elastic tissue surrounding a muscle.
370
What is the perimysium?
Sheath of connective tissue surrounding a bundle of muscle fibres.
371
What is the connective tissue surrounding the muscle fibres called?
Perimysium
372
What is dissociated sensory loss?
Neurological damage caused by a lesion to a single tract in the spinal cord which involves selective loss of fine touch and proprioception wo/ loss of pain and temperature, or vice versa
373
Where does the fibres of the spinothalamic pathway cross the midline?
1-2 spinal levels above or below the level they enter
374
Where does the fibres of the dorsal column cross the midline?
Medulla
375
Where is bladder pain referred to?
Lower back, abdomen, groin
376
Where is ureter pain referred to?
Below the ribcage, lower abdo, groin, genital area
377
What is the pterion?
Intersection of frontal, temporal, parietal and sphenoid bones.
378
Where is the primary motor cortex?
Pre-central gyrus
379
Where is the primary sensory area located?
Post-central gyrus
380
Where is the motor speech area?
Broca's area
381
Where is the primary visual area located?
Occipital lobe
382
Name alpha and beta 1 and 2 adrenergic receptor agonist and say what this leads to.
Alpha – NA --> vasoconstriction
Beta 1 – A --> increased HR
Beta 2 – salbutamol, terbutaline --> bronchodilation
383
Where does the postcentral gyrus lie relative to the central sulcus?
POsterior
384
Where is the calcarine fissure/sulcus and what is its function?
Divides the visual (calcarine) cortex into 2.
Central visual field is in posterior portion of calcarine sulcus
Peripheral visual field in the anterior portion.
385
A unilateral spinal cord injury will produce a sensory loss of what on the same side and what on the opposite side?
Ipsilateral – fine touch, vibration, proprioception
| Contralateral – pain and temperature, crude touch
386
Which division of the ANS is a.k.a. thoracolumbar?
Sympathetic
387
Which divisions of the ANS controls the rest-and-digest vs fight-or-flight responses?
Rest and digest = parasympathetic NS
Fight or flight = sympathetic NS
388
Why is the parasympathetic nervous system a.k.a. craniosacral outflow?
Preganglionic neurons emerge from the brainstem (CN III, VII, IX, X) and sacral cord (S2, S3, S4)
389
How does the size of the preG and postG neurons compare in the parasympathetic and sympathetic nervous systems?
Parasympathetic: preG – long, post G – short
Sympathetic: preG – short, post G – long
390
Which division of the ANS has preG neurons from lateral horn that come off at T1-L2?
Sympathetic
391
Where do basal ganglia/nuclei inputs come from?
Cortex and substantia nigra pars compacta --> striatum
392
What is special about the spinous process of the cervical vertebrae C3-6?
It bifurcates into 2 parts so is known as a bifid spinous process
393
What do the transverse foramina conduct?
Vertebral arteries, veins and sympathetic nerves.
394
What shape is the vertebral foramen of the cervical vertebrae?
Triangular
395
What does the occiput articulate w/?
C1 atlas
396
What movement does the atlanto-occipital joint allow?
Flexion/extension
397
What movement does the atlantoaxial joint allow?
Rotation
398
What is the axis?
C2
399
What is the odontoid process?
On the axis (2nd vertebral vertebra)
400
How does odontoid process fractures occur?
From hyperextension/hyperflexion of neck.
401
How many cervical vertebrae are there?
7
402
How many thoracic vertebrae are there?
12
403
How does the size of the thoracic vertebrae changes as you do inferiorly?
Increases
404
How does the thoracic vertebrae articulate with the ribs?
They have ‘demifacets’ on each side of its vertebral body.
These are known as costa facets.
405
How is the spinous processes of the thoracic vertebrae slanted and why?
Inferiorly and anteriorly
Offers increased protection to the spinal cord; preventing sharp objects entering the spinal canal through the intervertebral disks.
406
How does the vertebral foramen of the thoracic vertebrae differ from that of the cervical vertebrae?
Thoracic – circular
| Cervical – triangular
407
How are lumbar vertebrae specialised to support the weight of the upper body?
Very large vertebral bodies
408
What size are the vertebral foramen of lumbar vertebrae?
Kidney shaped
409
What is the sacrum made up of?
What is the sacrum made up of? 5 fused vertebrae
410
What are the facets on the lateral walls of the sacrum for?
Articulation w /the pelvis at sacro-iliac joints
411
What is the coccyx?
Small bone; articulates w/ the apex of the sacrum
412
Which vertebra hasn’t got a body?
C1, Atlas
413
How do you perform a sciatic nerve stretch?
Patient lies on their back; Straight leg raise, dorsiflex foot, knee flexion, knee extension
414
How do you perform a femoral nerve stretch?
Patient lies on their front; Knee flexion (check for back pain), hip extension (pain worse)
415
Name the upper and lower limb dermatomes to test for in a sensory examination.
UL: C4, C5, C6, C7, C8, T1
LL: L1, L2, L3, L4, L5, S1, S2
416
What are somatic and autonomic efferents?
Somatic – skeletal muscles
| Autonomic – smooth and cardiac muscle, glands
417
What does the somatic nervous system include?
Both sensory and motor neurons
418
What do somatic sensory neuron convey input from?
Receptors for somatic senses (tactile, thermal, pain, proprioceptive)
Receptors for special senses (sight, hearing, taste, smell and equilibrium)
419
Which NTs does the somatic motor neurones release?
ACh only
420
Which NTs does the autonomic neurons release?
Sympathetic – NA, ACh (glands)
| Parasympathetic – ACh
421
Where are cell bodies of preganglionic neurons?
In CNS
422
What is the ENS?
Separate from the ANS specialised collection of nerves and ganglia forming a neuronal network within the walls of the GIT, heart, pancreas and gallbladder.
423
What type of motor output does the ANS control?
Involuntary control from hypothalamus, brainstem, limbic system and spinal cord. Limited control from cerebral cortex
424
What do nitroxidergic postG release?
NO (causes vasodilation)
425
What are the 3 types of movement?
| Give examples of each
Reflex – limb withdrawal in response to painful stimulus
Rhythmic – walking, chewing
Voluntary – playing golf
426
What are type Ia sensory fibres?
Primary afferent fibres. It’s the stretch receptor found in the muscle spindle. It monitors the velocity of the stretch.
427
What role does the cerebral hemisphere have in movement?
Executive function; involved in voluntary control; can modify auto movements
428
What role does cerebellum have in movement?
Involved in coordinating movements and earning some fine motor skills
429
What role does the brainstem have in movement?
Involved in automated movements
430
What role does the spinal cord have in movement?
Contains circuitry (motor programs) for coordinating and executing automatic or repetitive movements; gets input from sensory systems and main output (muscles)
431
Do sensory neurons enter or exit the spinal cord and where do they do this?
Enter at the dorsal horn
| motor neurons exit at ventral horn
432
Where are sensory and motor cell bodies found?
Sensory – dorsal root ganglion
| Motor – ventral horn
433
Why is there no ventral root ganglion?
Because a ganglion is a bundle of nerve fibre cell bodies outside the spinal cord/CNS.
Motor neurons originate in the ventral horn of the spinal cord.
434
Describe the diameter of the spinal cord.
Not uniform; has enlargements which have large ventral horns thus large no. of motor neurons.
435
Where are spinal enlargements found?
Cervical enlargement: C3-T1 (arms)
| Lumbar enlargements: L1-S3 (legs)
436
How are motor neurons arranged in the spinal cord?
Topographically
Motor neurons controlling axial body parts (trunk) and proximal limbs are in the medial part of the spinal cord. Those controlling the distal parts (hands/feet) are in the lateral parts.
437
What do the axial muscles control?
Trunk – posture
438
What do the proximal muscles control?
Upper limbs – locomotion
439
What do the distal muscles control?
Hands/feet – object manipulation
440
After a command has been sent from the brain/brainstem which neurons do they travel down in the spinal cord?
Alpha motor neuron; myelinated; large axons
441
What are the differences between UMNs and LMNs?
UMNs – axons remain in CNS and synapse on LMNs directly/indirectly
LMNs – axons leave CNS and synapse on muscle fibres
442
What are muscle fibres a type of?
Proprioceptor
443
From what 5 places does alpha motor neurons receive and integrate inputs from?
```
Muscle spindles (Ia afferents)
Golgi tendon organs (Ib afferents)
Cutaneous receptors
Spinal interneurons
UMNs
```
444
What are Golgi tendon organs?
A proprioceptive sensory receptor organ that senses changes in muscle tension.
445
What does ALS do?
Progressive degeneration of alpha motor neurons (upper – from brain and lower – from spinal cord)
446
What are symptoms of ALS?
Muscle weakness, atrophy, twitching, abnormal reflexes, difficulty breathing and swallowing
447
What is the aetiology (cause) of ALS?
Unknown; theory: too much glutamate
448
Describe the Ia fibres.
Largest and fastest fibres; the fire when the muscle is stretching.
Characterised by their rapid adaptation.
449
What is a reflex?
Involuntary movements that occurs because of sensory stimulation and involves impulses travelling through a reflex arc.
450
What is a reflex arc?
Composed of: a sensory neuron, interneurons (0 to many) and a motor neuron
451
How does no. of synapses and speed of conduction of APs correlate?
More synapses = slow conduction
452
What are extrafusal muscles?
Muscles that moves the bone (motor) – controlled by alpha motor neurons
453
What are intrafusal muscles?
In the muscle spindle; part of the proprioception system (sensory); detect amount and rate of change of muscle length – controlled by gamma motor neurons
454
Where are intrafusal muscles imbedded?
Imbedded in the muscle spindle (parallel to extrafusal fibres)
455
Why do gamma motor neurons adjust the intrafusal muscle length?
To allow the muscle spindle to be maximally sensitive at any given limb position
456
When the extrafusal muscle is short (flexed) what is the length of the intrafusal muscle fibres?
Shorter
457
When the extrafusal muscle is extended, what is the length of the intrafusal muscle fibres?
Longer
458
What does stretching the muscle spindle increase?
Ia afferent activity
459
What happens when the load on a limb increases?
It’s detected and arm automatically contracts to keep the arm upright.
460
There is a single synapse between muscle sensory fibre and alpha motor neuron. What is the purpose of this?
Monosynaptic – makes it fast
461
What is reciprocal inhibition?
When the antagonist muscle relaxes for the agonist muscle to contract.
462
What is the inverse stretch reflex a.k.a and what does this do?
Golgi tendon; prevents muscle overloading by forcing it to relax and drop load when lifting/carrying heavy loads.
463
Activation of the Ib afferents do what to the activity of the alpha motor neurons?
Decreases alpha motor neuron activity.
464
What do the Ib afferents from the Golgi tendon organs synapse w/?
Inhibitory interneurons in spinal cord
465
What is the function of the inverse stretch reflex?
Prevent muscle and tendon damage from very high muscle tension.
466
What is the flexor withdrawal reflex?
Polysynaptic flexion of one limb and extension of the other (opposite of the other limb). This is so that the affected limb is flexed (withdrawal) whilst the other is extended to provide compensatory postural support.
467
What does the spinal cord circuitry use to produce complex rhythmic movements such as running?
Spinal central pattern generators (CPGs)
468
What does CPGs do?
Produce rhythmic outputs wo/ sensory feedback.
469
Give examples of rhythmic movements.
Locomotion, chewing, sucking, swallowing, respiration, swimming in animals
470
What is the area directly adjacent to the neural tube called?
The paraxial mesoderm
471
What does the paraxial mesoderm differentiate into?
Segments (somites)
472
How many pairs of somites are formed?
44 but they regress until 31 pairs remain
473
What do the somites correspond to in the adult?
31 pairs of spinal nerves
474
What are somites composed of?
Dorsal and ventral portion
475
What does the ventral portion of somites form?
Sclerotome (precursor of ribs and vertebral column)
476
What does the dorsal portion of somites consist of?
Dermomyotomes --> myotome proliferates --> muscle
477
What is the C7 myotome associated w/?
Elbow extension
478
What is the C5 myotome associated w/?
Elbow flexion
479
What is the L5 myotome associated w/?
Great toe extension
480
What is the L3 myotome associated w/?
Knee extension
481
What is the S1 myotome associated w/?
Ankle plantar flexion
482
What is the C6 myotome associated w/?
Wrist extension
483
What is the T1 myotome associated w/?
Finger abduction
484
What is contained in the dorsal root ganglion?
Cell bodies of 1st order afferents
485
Where do basal ganglia/nuclei outcomes go to?
Globus pallidus and substantia nigra pars reticulata
486
In which sensory pathway is the 1st synapse at the level of the medulla?
Dorsal column
487
In the dorsal column pathway where is the tertiary neuron located?
Thalamus
488
Is the tectospinal tract sensory or motor?
Motor
489
Where does the spinothalamic and spinocerebellar synapse?
Spinal cord
490
Which fibres convey proprioceptive info?
A-beta
491
How does a receptor potential differ from an AP?
It is gated to stimulus intensity by frequency.
492
What is the structure of neurons that convey only somatic pain?
Small diameter, unmyelinated; C-fibres
493
What can A-delta fibres be activated by?
Innocuous, non-painful pressure and pain
494
What can A-delta fibres be activated by?
Innocuous, non-painful pressure and pain
495
Which ascending pathway carries vibration sense?
Dorsal columns
496
Which ascending pathway carries proprioception sense?
Dorsal columns
497
Which ascending pathway carries temperature sense?
Spinothalamic
498
Which ascending pathway carries 2-point discrimination?
Dorsal columns
499
In a right-sided, thoracic hemisection of the cord, which sensory modality will be lost from the left leg but not the right?
Pain; cord hemisection causes a Brown-Sequard syndrome where below the level of the lesion there is; ipsilateral loss of dorsal column function and UMN innervation + contralateral loss of spinothalamic function.
Due to position of the pathway decussation.
500
What are muscle spindles comprised of?
What is the role of the substantia gelatinosa? Location of synapse for spinothalamic primary neurons (pain and temp)
501
High threshold, mechanical nociceptors signal through which afferent fibre type?
A-delta fibres
502
What is the role of the substantia gelatinosa?
Location of synapse for spinothalamic primary neurons (pain and temp)
503
What is the substantia gelatinosa?
A collection of cells in the dorsal horns of the spinal cord found at every level. It’s the location of the cell bodies of second order spinothalamic neurons
504
What does the following describe: pain is influenced by ascending and descending influences, controlled at the spinal cord?
Gate control theory of pain.
Pain is a multifaceted experience that is controlled at the spinal cord level. A-beta fibres inhibit pain sensation. A-delta and C fibres carry perception of pain.
505
What effects do opioid have outside the CNS?
Reduced GI motility, pupil constriction, analgesia, sedation, reduced CO2 sensitivity, euphoria.
506
How do opioids cause euphoria?
Disinhibition of nucleus accumbens.
By reducing GABAergic transmission from interneurons from the ventral tegmental area to the nucleus accumbens --> increasing dopaminergic neuron activation in the limbic system --> euphoria
507
Where are gustatory sensory cells located?
Lateral walls of tongue papillae.
508
What is a central pattern generator?
Spinal cord circuits for repetitive movements
509
Which motor pathways is most important in supply of distal limb flexors?
Corticospinal
510
What pathways are needed for postural control and head/eye movements?
Ventromedial pathways
511
Where does the tectospinal tract originate?
Superior colliculus in the midbrain
512
What collection of clinical features are found in an upper motor neuron lesions?
Hypertonia, hyperreflexia, muscle weakness, up-going plantars (extensor plantar response – +ve Babinski sign)
513
What causes UMN lesions?
Stroke, MS, cerebral palsy, trauma
514
What causes LMN lesions?
Bell’s Palsy, Guillen-barre syndrome
515
What collection of clinical features are found in a LMN lesion?
Hypotonia, hyperreflexia, muscle atrophy, muscle weakness, down-going plantars, muscle fasciculation
516
Which part of the brain is most important for sequencing of movements?
2 hemispheres, vermis + deep nuclei
517
What is the main role of the cerebellar vermis?
Maintain posture and head position
518
What can the cerebellum be divided into anatomically?
2 hemispheres, vermis + deep nuclei
519
What can the cerebellum be divided into functionally?
Spinocerebellum, vestibulo-cerebellum and cerebro-ponto-cerebellum.
520
What does the cerebellar hemispheres control?
Force and timing of movement
521
What does the basal ganglia influence?
Speed and movement initiation.
522
What controls fine flexor movements?
The cortex
523
What is the collective term given to the caudate nucleus and putamen?
Striatum
524
What is the globus pallidus anatomically and functionally divided into?
The globus pallidus interna and externa.
525
What is the limbic system comprised of?
Amygdala, nucleus accumbens, hippocampus, mammillary bodies and parts of the hypothalamus
526
What is the substantia nigra divided into?
Pars compacts and pars recularis.
527
What is dysarthria?
Inability to form words properly.
528
What is dysdiadochokinesis?
Reduction in ability to perform rapidly alternating movements
529
How do you differentiate between a LMN or UMN lesion of CN VII?
UMN – facial dropping, eyes are NOT affected
| LMN – (a.k.a Bell’s Palsy) facial dropping and eyes affected
530
What is Brown-Sequard syndrome?
Damage to one half of the spinal cord. It’s rare.
531
What does Brown-Sequard syndrome cause?
Ipsilateral loss of find-touch and proprioception
| Contralateral loss of pain and temperature sense
532
What is anterior cord syndrome?
Where the anterior spinal artery is interrupted causing ischaemia or infarction of the spinal cord.
533
What is anterior cord syndrome characterised by?
Loss of pain/temp sensation below the level of injury and preservation of sensations carried by the posterior columns (fine touch, vibration and proprioception)
534
What is central cord syndrome?
Cervical spinal cord injury. Variable sensory loss
535
What is central cord syndrome characterised by?
Motor deficits greater in UL than LL. Loss of motion and sensation in arms and hands
536
Where does pain and temp pathways decussate?
At the spinal level, itself unlike fine touch and proprioception.
537
Wo/ ATP but in the presence of calcium ions what happens to myosin and actin?
Myosin heads remain bound to actin
538
What does the precentral gyrus form?
Primary motor cortex
539
Where is the primary somatosensory area?
Postcentral gyrus.
540
What is the cerebral cortex?
A region of grey matter that forms the outer rim of the cerebrum.
541
What are gyri, fissures and sulci?
Gyri – the folds
Fissures – deepest grooves between folds
Sulci – shallow grooves between folds
542
What is the falx cerebri?
The longitudinal fissure that separates the cerebrum in L and R hemispheres.
543
What is the corpus callosum?
Broad band of white matter that connects the L and R hemispheres together.
544
What does the central sulcus separate?
Frontal lobe from parietal lobe
545
Where is the primary visual area?
Posterior tip of occipital lobe.
546
Where is the primary auditory area?
Superior part of the temporal lobe, near lateral cerebral sulcus
547
Where is the primary gustatory area?
Base of postcentral gyrus.
548
Where is the primary olfactory area?
Temporal lobe
549
Where is Broca’s area?
L frontal lobe in 97% of population. R in 3%
550
Where is Wernicke’s area?
Post section of the superior temporal gyrus in L hemisphere.
551
In the somatotropic arrangement where are nerve endings for the LL and trunk relative to head and UL?
More medial
552
Why isn’t the face usually paralysed when there is a UMN lesion of the facial nerve?
Because face is supplied by 2 UMN pathways so damage to 1 doesn’t affect other.
553
A lesion that isn’t purely motor might me located there in the brain and why?
UMN
554
How does dopamine influence the direct pathway of the basal ganglia?
Increase pathway activity to promote movement.
555
What does lemniscus mean?
Greek for ribbon or band
556
Where is the lemniscus found and what is it?
A bundle of secondary sensory fibres in the brainstem
557
Which half of the body is the R hemisphere of the cerebellum concerned w/?
The right side
558
Where does the cerebellum receive input from?
The entire body
559
Where does the cerebellum output info?
Up the cerebral cortex
560
What do clinicians mean when they say pyramidal lesion?
Internal capsule lesion
561
Which motor pathways are distal in the spinal cord?
Dorsolateral
562
What are compensatory movements?
Anticipatory postural reflexes
563
What is the role of the basal ganglia?
Selection/inhibition of voluntary movements.
564
What info does the cerebellum need to coordinate muscle contraction?
How contracted the muscle is and where it is
565
What percentage does the cerebellum constitute of the total volume of the brain?
10%
566
Relative to the putamen where is the globus pallidus?
Medial
567
How does movements like riding a bike become unconscious?
Once the cerebellum stores it.
568
What does damage to the cerebellum cause?
Jerky, uncoordinated, inaccurate (ataxia) movements
569
Where does the cerebrocerebellum receive input from?
From cerebral cortex
570
Where do spinocerebellar outputs from the cerebellum enter?
Interposed + fastigial nucleus
571
What is a core feature of idiopathic Parkinson’s?
Bradykinesia, postural instability, rigidity, tremor.
572
What molecule is dopamine synthesised from?
Tyrosine --> DOPA --> DA
573
What is the mechanism of action of naloxone?
Competitive antagonist at mu-receptors
574
Which structure passes through the foramen ovale?
Mandibular division of trigeminal nerve
575
What structures pass through the foramen magnum?
Accessory nerve, medulla oblongata, anterior spinal artery,
576
Which ligament is most important in preventing posterior subluxation of the odontoid process?
Transverse ligament
577
What is the falx cerebri composed of?
Double-layer meningeal dura mater
578
What vessels are most commonly the origin of bleeding in atraumatic subdural haemorrhages?
Bridging veins
579
Does the direct or indirect pathway suppress movement?
Indirect
580
Which part of the ventricular system connects the 3rd and 4th ventricles, passing through the midbrain?
Cerebral aqueduct
581
Where is most CSF re-absorbed into the vascular system?
Sagittal sinus arachnoid granulations
582
Which structure lies immediately to the 3rd ventricle?
Thalamus and hypothalamus
583
At what level does the common carotid artery bifurcate?
C3/4
584
Which arteries are formed from the bifurcation of the internal carotid artery?
Anterior and middle cerebral
585
Where is Wernicke’s area located?
Supero-posterior temporal lobe
586
What is contained within the epidural space of the spinal canal?
Fat
587
What is contained within the subarachnoid space?
CSF
588
What is the role of the filum terminale?
Attachment of the conus medullaris
589
What is the filum terminale?
Thickened extension of the pia mater that attaches the conus medullaris to posterior wall of the sacrum.
590
What is the main consequence of interruption to the anterior spinal artery?
Loss of motor function
591
What is the output zone of the basal ganglia?
Globus pallidus and substantia nigra (par reticulate)
592
What is the basal ganglia made up of?
What is the basal ganglia made up of? Collection of functionally distinct nuclei.
593
How can chronic alcohol misuse affect the gait?
Degeneration of the anterior cerebellum --> wide and staggering gait but little impairment of arm/hand movements.
594
What fibres are the main cell types that input into to cerebellar cortex?
```
Climbing fibres (originate from inferior olive)
Mossy fibres (all other inputs
```
595
What do climbing fibres twist around?
Densrites of Purkinje cells
596
Which fibres carry the output from the cerebellum?
Purkinje cell
597
How are sensory and motor info represented on the cerebellum?
Ipsilaterally
598
What does damage of the cerebrocerebellum cause?
Highly skilled sequences of learned movements disturbances
599
What does damage of the vestibulocerebellum impair?
Balance and eye movement disturbances.
600
What does damage to the spinocerebellum impair?
Gait
601
Name 3 inpus to the basal ganglia
Corticostriatal pathway
Nigrostriatal pathway
Medium spiny neurons
602
Where do most inputs to. the basal ganglia come to?
Stratum
603
Which 2 pathways does the stratum send most of its info out through?
Substantia nigra par reticulata
| Globus pallidus internus
604
What is the direct and indirect corticostratial loops?
Info in the corticostraiatal sstem is transmitted to basal ganglia via the direct and indirect pathways
605
What is Parkinson’s caused by?
Death of cells in substantia nigra reduces dopaminergic effects of both D1 and D2 receptors --> reduced excitation of the direct pathway (D1) and reduced inhibition of the indirect pathway (D2) --> increased inhibition of thalamus and decreased excitation of motor cortex --> reduction of movement
606
How is the indirect pathway affected in Parkinson’s?
Increased stimulation leads to reduction of movement
607
Does Huntington’s cause increased or decreased movement and how?
Increased movement by death of. stratal inputs to globus pallidus externa which reduces inhibition of subthalamic nucleus which reduces excitation of globus pallidus interna meaning less tonic inhibition of thalamus occurs
608
What is the inferior olivary nucleus?
Provides instructions for the cerebellum to adjust muscle activity as you learn new motor skills
609
WHat is the pineal gland?
Endorine gland behind 3rd ventricle
Secretes melatonin
610
What is the tectum made up of?
The inferior and superior colliculi (2 of both).
| It’s responsible for auditory (inferior) and visual (superior) reflexes.
611
What is the choroid plexus?
Ependymal cells of the choroid plexus = where CSF is produced.
612
What is raloxifene?
Selective oestrogen receptor modulator; prevents osteoclast activation
613
Calciferol
Vitamin D; essential of calcium and phosphorus absorption.
614
Alendronic acid
Inhibits osteoclast bone resorption; can be used w/ vitamin D.
615
HRT
HRT replaces lowered oestrogen and progesterone post-menopause; oestrogen prevents osteoclast activity.
616
What is osteomalacia and rickets?
Softening of bones; can be caused by vitamin D deficiency.
617
What are the 2 types of alpha receptors?
α1 - Vasoconstriction
| α2 - Glucose metabolism
618
What are the risk factors for osteoporosis?
Age – low oestrogen levels; vitamin D or calcium deficiency; inactive lifestyle; tobacco smoking; drinking excessively
619
What are the 3 types of beta receptors?
β1 – Targets ♥ ( HR, conduction, contraction), vasoconstrictor
β2 – Bronchodilator
β3 – Thermogenesis (heat production) in brown adipose tissue
620
Give examples of beta agonists.
Dobutamine (β1) - Increase CO, treatment for HF
Isoprenaline (non-selective) - Bradycardia treatment
Salbutamol (β2) - Bronchodilation, treatment for asthma
Malmeterol (β2) - Long acting, maintenance/prevention of
asthma and COPD
621
Give examples of alpha agonists.
NA (non-selective) - Causes vasoconstriction, treats hypotension
622
What do NSAIDs inhibit synthesis of?
Prostaglandins and thromboxanes
| by binding to COX enzyme
623
What is Huntington’s diseas
Loss of output neurons of striatum that provide input to indirect pathway.
Causes greater excitation of motor cortex, increase of movement due to less inhibition of thalamus.
624
What is Hemiballismus?
Damage to the subthalamic nucleus.
Causes rapid, flinging, and violent movements of limbs on 1 side of the body (contralateral)
625
What is Parkinson’s disease?
Lesion to substantia nigra pars compacta.
Decrease in dopaminergic neurons.
Excited indirect pathway, inhibited direct pathway (less motor function).
Result = tremor, muscular rigidity, slow imprecise movements.
626
What are the 2 types of peripheral fibres of the ANS?
PreG – Myelinated B fibres (small diameter)
| PostG – Unmyelinated C fibres (smaller diameter)
627
In what structure in brain do pain fibres synapse?
Thalamus
628
Which 3 nuclei does the basal ganglia consist of?
Caudate nucleus, putamen, globus pallidus
629
Where is the primary visual area?
Calcarine fissure.
630
What are gyri?
Folds
631
What are sulci?
Grooves
632
Describe the corticospinal pathway.
- Voluntary skilled motor activity (pyramidal)
- Contralateral - 90% decussate in medulla (lateral), 10% decussate in spinal cord (anterior)
- Dorsolateral
- Lateral controls distal movement, anterior controls proximal movemen
633
Describe the spinocerebellar pathway.
- Proprioception to cerebellum
- Ipsilateral – Posterior stay ipsilateral, anterior decussate x2
- Synapse in Clarke’s nucleus (posterior grey horn)
- Travel to cerebellum
634
Describe the dorsal column-medial lemniscus pathway.
- Fine touch, pressure, vibration, conscious proprioception
- Contralateral – Decussate in medulla
- Synapse in medulla and thalamus
- Travel to primary sensory cortex
635
Describe the spinothalamic pathway.
- Pain, temperature, itch, tickle, crude touch
- Contralateral – Decussate in spinal cord (2-3 levels above entry)
- Synapse in posterior horn and thalamus
- Travel to primary sensory cortex
636
What is the functions of compact bone?
Protection, support, stress resistance, movement
