Week 4 Flashcards
1
Q
What is the superior boundary of the neck?
A
Base of skull & inferior border of mandible
2
Q
What is the inferior boundary of the neck?
A
Top of sternum, clavicle, acromion (anterior) & C7 (posterior)
3
Q
What are the boundaries of the anterior triangle in the neck?
A
Inferior border of mandible, anterior border of sternocleidomastoid & midline of neck
4
Q
What are the boundaries of the posterior triangle of the neck?
A
Posterior border of sternocleidomastoid muscle, middle 3rd of clavicle & anterior border of trapezius
5
Q
What 3 vessels lie in the sternocleidomastoid region?
A
- Great auricular nerve
- Transverse cervical nerve
- External jugular vein
6
Q
What nerves lie in the posterior cervical region (near the trapezius)?
A
Cutaneous branches of posterior rami cervical spinal nerves
7
Q
Describe the 2 midline neck compartments?
A
- VISCERAL compartment: parts of respiratory system, digestive system & endocrine glands
- VERTEBRAL compartment: cervical vertebrae, spinal cord, muscles & cervical nerves
8
Q
Describe the lateral neck compartments?
A
2 VASCULAR compartments: blood vessels & nerves (CN X)
9
Q
Describe the purpose of neck fascia?
A
- Containment of muscles & viscera
- Slipperiness, allows structures to slide over each other (expansion/contraction, up/down)
- Conduit passage of neurovascular structures
10
Q
What does the superficial fascia of the neck contain?
A
- Cervical subcutaneous tissue
- Platysma
11
Q
Describe the deep fascia of the neck?
A
- Connective tissue which gives protective & is strong enough to suture
- It has different layers (investing, pretracheal, preverterbal, carotid sheath)
12
Q
What is the purpose of the superficial neck fascia & what does it contain?
A
- Continuous with superficial fascia of thorax
- Connects to mandible & facial muscles
- Contains cutaneous nerves, vessels, superficial lymph nodes & fat
13
Q
What is the purpose of the deep investing neck fascia?
Musculofascial Collar
A
- Surrounds neck completely except for superficial layer
- Encloses SCM, trapezius & infrahyoid muscles, parotid & submandibular glands
- Pierced by external & anterior jugular veins & nerves including cervical plexus
14
Q
What does the deep Investing fascia of the neck attach to posteriorly?
(Musculofascial Collar)
A
Ligamentum nuchae & C7 spinous process, surrounds trapezius
15
Q
What does the deep Investing fascia of the neck attach to anteriorly?
(Musculofascial Collar)
A
Hyoid bone, surrounds infrahyoid & SCM
16
Q
What does the deep Investing fascia of the neck attach to superiorly?
(Musculofascial Collar)
A
External occipital protuberance & superior nuchal line
17
Q
What does the deep Investing fascia of the neck attach to inferiorly?
(Musculofascial Collar)
A
Spine of scapula, acromion, clavicle, manubrium
18
Q
What does the deep Investing fascia of the neck attach to laterally?
(Musculofascial Collar)
A
Mastoid process & zygomatic arch
19
Q
What does the pretracheal deep fascia of the neck surround?
A
Viscera as visceral part (trachea, oesophagus & thyroid gland)
20
Q
Where is the pretracheal deep fascia of the neck?
A
Extends from hyoid bone to upper thoracic cavity (blends with fibrous pericardium & aortic arch)
21
Q
What is the pretracheal deep fascia of the neck posteriorly called?
A
Buccopharyngeal fascia (runs from base of skull to thoracic cavity)
22
Q
What does the pretracheal deep fascia of the neck laterally fuse with?
A
Carotid sheath (extends to C7)
23
Q
What does the pretracheal deep fascia of the neck anteriorly separate?
A
Infrahyoid muscles from the trachea & thyroid glands (muscular part)
24
Q
What pierces the pretracheal deep fascia of the neck?
A
Thyroid vessels
25
What does the prevertebral deep fascia of the neck surround?
Vertebral column (including cervical nerves), pre- & post-vertebral muscles (scalenes, longus colli, longus capitus, deep cervical muscles)
26
What pierces the prevertebral deep fascia of the neck?
Cutaneous branches of cervical plexus
27
Where is the prevertebral deep fascia of the neck?
- Fixed to cranial base (superior), blends with endothoracic fascia (inferior), blends with anterior longitudinal ligament at T3/4 (posterior)
- Laterally over 1st rib to surround axillary vessels & brachial plexus as the axillary sheath
28
How does the prevertebral deep fascia of the neck extend posteriorly?
```
Along superior nuchal line to external
occipital protuberance (eventually to superior mediastinum)
```
29
How does the prevertebral deep fascia of the neck extend anteriorly?
Attaches to basilar part of occipital
| bone, area of jugular foramen & carotid canal
30
Where does the prevertebral deep fascia of the neck extend laterally?
Mastoid process
31
What does the carotid sheath surround?
Major vasculature (CCA, int CA, part ext CA, int JV) & CN X), other nerves, some cervical lymph nodes
32
Where does the carotid sheath extend to and from?
Runs from foramen of carotid canal to aortic arch
33
Describe the location of the pretracheal space?
Between investing layer & pretracheal fascia, extends between neck & superior mediastinum
34
Describe the location of the "true" retropharyngeal space?
Between buccopharyngeal fascia & superficial prevertebral fascia (alar fascia), extends between base of skull & superior mediastinum
35
Describe the location of the danger (alar) space/fascial space within prevertebral layer?
- Within prevertebral layer (alar fascia & deep prevertebral layer)
- Extends from base of skull through posterior mediastinum to diaphragm
36
What is the case of fascial spaces in healthy individuals?
Danger (alar) space is indistinguishable for the ‘true’ retropharyngeal space
37
How can infections from the pharynx spread?
Via the ‘true’ retropharyngeal (e.g. retropharyngeal abscess) & danger (alar) spaces into the posterior mediastinum
38
What structures are at risk during infection spread from fascial spaces?
Thoracic structures since many of the compartments & spaces extend into thorax
39
What vertebral level is the hyoid bone located?
C3 in anterior neck
40
Describe the hyoid bone?
- Suspended by muscles & ligaments
- Connected to mandible, styloid process, thyroid cartilage, manubrium & scapulae
- Doesn't articulate with skeletal elements in head & neck
41
What 2 things does the hyoid bone connect?
Connects oral cavity with pharynx posteriorly & larynx inferiorly
42
What movements does the cervical spine allow for?
Lateral flexion & rotation
43
What does the ligament nuchae attach to?
External occipital protuberance & foraman magnum to spinous processes of the cervical vertebrae
44
What is the ligament nuchae continuous with?
Supraspinous ligament
45
Describe the "atypical" C7 vertebrae?
Non-bifid spinous process is attachment of ligamentum nuchae
46
What special feature do only the cervical vertebrae have?
Foramen transversarium (vertebral artery)
47
Describe the "atypical" C1 Atlas vertebrae?
- Anterior & posterior arches
- No body
- Spinous process= tubercle
48
Describe the main feature of the C2 Axis vertebrae that makes it "atypical"?
It has a DENS
49
Describe the lateral atlanto-axial joint & pivot joint of the dens?
- Allows rotation of head (side- to-side)
| - Assisted by transverse ligament of atlas holding dens in position
50
Describe the atlanto-occipital joint?
- Allows flexion & extension (nodding)
| - Condyloid joint
51
What is the purpose of the alar ligaments?
- Prevent excessive rotation of head & neck
| - Connect dens to occipital condyles
52
Where in the vertebral column is there no intervertebral disc?
Between C1 & C2
53
Describe the result of whiplash injurys/hyperextension of the neck?
- Major area of damage for anterior longitudinal ligament
| - Vertebrae can also become dislocated &/or fractured
54
What are the surface anatomy landmarks for the C3/4 spinal level?
- Bifurcation of common carotid artery
- Top of thyroid cartilage of larynx (palpable)
- Hyoid bone
55
What are the surface anatomy landmarks for the C6 spinal level?
- Lower border of pharynx & larynx (cricoid cartilage palpable)
- Upper border of oesophagus & trachea
56
Where is the apex of lung & cervical portion of parietal pleura located?
In the NECK NOT THORAX!
57
What are the 4 triangular subdivisions of the anterior triangle?
1. Submandibular
2. Submental
3. Carotid
4. Muscular
58
What does the submandibular (digastric) division of the anterior triangle contain?
- Submandibular gland
- Lymph nodes
- (parts of) CN XII
- Mylohyoid nerve
- (parts of) Facial artery & vein
59
What does the submental division of the anterior triangle contain?
- Submental lymph
| - Small veins
60
What does the carotid division of the anterior triangle contain?
- Thyroid gland
- Larynx
- Pharynx
- Carotid sheath (& its contents)
- Branches of cervical plexus
- Superior root of the ansa cervicalis
- Deep cervical lymph nodes & (parts of) CN XI & XII
61
What does the muscular (omotracheal) division of the anterior triangle contain?
- Sternohyoid muscle
- Sternothryoid muscle
- Thyroid gland
- Parathyroid gland
62
What are the 4 suprahyoid muscles?
1. Mylohyoid
2. Digastric
3. Stylohyoid
4. Geniohyoid
63
What are the 4 infrahyoid muscles?
1. Sternohyoid
2. Omohyoid
3. Thyrohyoid
4. Sternothyroid
64
What is the location & attachments of the mylohyoid muscle (suprahyoid)?
From mylohyoid line on mandible, inserts into body of hyoid & fibres of opposite mylohyoid
65
What are the actions of the mylohyoid muscle?
- Elevates the hyoid & the floor of the mouth
| - Supports floor of mouth
66
What is the location & attachments of the digastric muscle (suprahyoid)?
- Anterior belly from digastric fossa on lower medial aspect of mandible
- Posterior belly from mastoid notch on medial side of mastoid process
- Both insert at attachment of their intermediate tendon at hyoid
67
What are the actions of the digastric muscle?
- Anterior belly raises hyoid & opens mouth by lowering mandible
- Posterior belly elevates & retracts hyoid bone
68
What is the innervation of the mylohyoid muscle?
CN V3 inferior alveolar branch
69
What is the innervation of the digastric muscle?
- Anterior belly: nerve to mylohyoid (CN V3)
- Posterior belly: digastric branch of
CN VII
70
What is the location & attachments of the stylohyoid muscle (suprahyoid)?
From the styloid process & inserts into body of hyoid (laterally)
71
What are the actions of the Stylohyoid muscle?
Pulls hyoid bone upward (posterosuperior)
72
What is the innervation of the Stylohyoid muscle?
CN VII (facial)
73
What is the location & attachments of the Geniohyoid muscle (suprahyoid)?
From the mandible (mental spine) & inserts at body of hyoid (located superior to mylohyoid)
74
What are the actions of the Geniohyoid muscle?
- Fixed mandible: elevates & pulls hyoid forward
| - Fixed hyoid: pulls mandible downward & inward
75
What is the innervation of the Geniohyoid muscle?
Anterior ramus of C1 (travels with CN XII)
76
What is the location & attachments of the Sternohyoid muscle (infrahyoid)?
From the posterior surface of sternoclavicular joint & manubrium, inserts into body of hyoid medially
77
What are the actions of the Sternohyoid muscle?
Depresses hyoid after elevation during swallowing
78
What is the location & attachment of the Omohyoid muscle (infrahyoid)?
- Superior belly from its intermediate tendon & inserts into body of hyoid laterally (has superior & inferior bellies)
- Tendon attaches to clavicle with fascial sling
79
What are the actions of the Omohyoid muscle?
Depresses & fixes the hyoid
80
What is the location & attachment of the Thyrohyoid muscle (infrahyoid)?
From oblique line on thyroid cartilage, inserts into greater horn & adjacent body of hyoid
81
What are the actions of the Thyrohyoid muscle?
- Depresses the hyoid
| - Raise larynx when hyoid is fixed
82
What is the location & attachment of the Sternothyroid muscle (infrahyoid)?
From posterior surface of manubrium, inserts into oblique line on thyroid cartilage
83
What are the actions of the Sternothyroid muscle?
Draws the larynx downward
84
What is the innervation of the Sternohyoid, Omohyoid & Sternothyroid muscles?
Anterior rami of C1-C3 (via the ansa cervicalis)
85
What is the innervation of the Thyrohyoid muscle?
Anterior rami of C1, fibres run with CN XII
86
Where is the thyroid gland located?
- Within visceral compartment of neck
| - From thyroid cartilage to 5th tracheal ring
87
What is the thyroid gland composed of?
- 2 lateral lobes (right & left)
- Midline isthmus (level of 3rd tracheal ring)
- Midline pyramidal lobe (remnant of thyroglossal duct)
88
What are the 2 arterial supplies of the thyroid gland?
1. Superior thyroid artery (1st branch of external CA)
| 2. Inferior thyroid artery (off thyrocervical trunk from subclavian)
89
What is the venous drainage of the thyroid gland?
1. Superior thyroid vein (into IJV)
2. Middle thyroid vein (into IJV)
3. Inferior thyroid vein (into bracheocephalic)
90
What are the parathyroid glands?
2 pairs (superior & inferior) of small glands on posterior surface of thyroid, position varies
91
Describe the vascular supply of the parathyroid glands?
- ARTERY: Inferior thyroid arteries (off thyrocervical trunk from subclavian)
- VEIN: thyroid venous plexus
92
What is the innervation of the thyroid & parathyroid glands?
Thyroid branches from the cervical (sympathetic) ganglia
93
What nerves lie close to the thyroid & parathyroid glands & are commonly injured during neck surgery?
Recurrent laryngeal nerves (from CN X)
94
What makes up the roof of the posterior triangle in the neck?
Deep Investing fascia surrounding SCM & trapezius (CN XI)
95
What makes up the floor of the posterior triangle in the neck?
Prevertebral fascia surrounding splenius capitus, levator scapulae & posterior, middle, anterior scalene muscles (cervical nerves)
96
What is the location & attachment of the Sternocleidomastoid muscle (SCM)?
- Sternal head from
manubrium of sternum & inserts lateral 1/2 of superior nuchal line
- Clavicular head from medial 3rd of clavicle & inserts into lateral surface of mastoid process
97
What are the actions of the Sternocleidomastoid muscle?
- Draws head forward (both SCMs)
| - Tilts head toward ipsilateral shoulder while turning face contralaterally (1 SCM)
98
What is the innervation of the Sternocleidomastoid & Trapezius muscle?
Spinal accessory nerve (CN XI)
99
What is the location & attachment of the Trapezius muscle?
From superior nuchal line, external occipital protuberance, ligamentum nuchae & spinous processes (C7-T12), inserts into lateral 3rd of clavicle,acromion & spine of scapula
100
What are the actions of the Trapezius muscle?
- Assists in rotating scapula during abduction of humerus
- Upper fibres elevate
- Middle fibres adduct
- Lower depress scapula
101
What is the location & attachment of the Levator Scapulae muscle?
From C1-C4 (transverse processes), inserts into scapula (upper medial border)
102
What are the actions of the Levator Scapulae muscle?
Elevates scapula
103
What is the innervation of the Levator Scapulae muscle?
C3, C4, & dorsal scapular nerve (C4, C5)
104
What is the location & attachment of the Anterior Scalene muscle?
From C3-C6 (anterior tubercle of transverse processes), inserts into upper surface of rib 1 & scalene tubercle
105
What is the location & attachment of the Middle Scalene muscle?
From C4-C7 (transverse processes), inserts into upper surface of rib 1, posterior to groove for SCA
106
What are the actions of the Anterior & Middle Scalene muscles?
Elevates 1st rib
107
What is the innervation of the Anterior & Middle Scalene muscles?
Anterior rami of C4-C7 (both anterior & middle), C3 (also for anterior)
108
What makes up the cervical plexus?
Anterior rami of C1, C2-C4
109
What are the muscular branches of the cervical plexus?
- Phrenic nerve (C3, C4, C5)
| - Ansa cervicalis (C1, C2, C3) branches to prevertebral & vertebral muscles
110
What are the cutaneous branches of the cervical plexus?
- C2: lesser occipital nerves
- C2, C3: great auricular & transverse cervical nerves
- C3, C4: supraclavicular nerves
111
What do the superior & inferior roots of the ansa cervicalis (anterior rami of C1-C3) innervate?
Infrahyoid muscles
112
What does the external jugular vein drain into?
Subclavian vein
113
What does the anterior jugular vein drain into?
External jugular vein
114
What is the definition of learning & memory?
Mechanism by which past experience alters present experiences or behaviours
115
What is termed engrams?
Link between memory's & remembering is presumed biochemical in nature
116
Where do we currently think engrams are located?
All over the brain, but in places related to processing the learning (amygdala for fearful memories etc)
117
What is associative learning?
- As cells fire simultaneously they increase the synaptic associations
- Results in networks of cells which are synaptically linked
118
Who pioneered habituation & sensitisation?
Eric Kandel (Columbia) using Aplysia californica creature
119
What is habituation?
Decrease in response (& NT release ) with repeated stimulus
120
What is sensitisation?
Increase in response with repeated stimulation, mediated by interneuron
121
What does repeated Siphon stroke cause?
Habituation as the sensory neuron EPSP reduces
122
What does concurrent tail stimulation cause & why?
Sensitisation because it causes release of 5HT onto pre-synaptic membrane of siphon skin sensory neurons from interneurons. This prolongs the NT release & causes sensitisation
123
What do long term synaptic changes require?
Genetic involvement
124
What was long term potentiation (LTP) 1st shown in?
Rabbit hippocampus (1970s)
125
What prevents "whole brain potentiation"?
Reverse effect- habituation
126
What is long term depression (LTD) initiated by?
Slower train of stimulatory impulses over a longer period
127
What effect can long term depression (LTD) have on long term potentiation (LTP)?
LTD can modulate LTP or even reverse it
128
Describe what a short term memory is?
- Brief memory (sec) from external stimulus/long term memory
- Easily displaced by another stimulus
- Turns into working memory by a) repetition in phonic loop (temporal extension) b) chunking, which links familiar chunks together to extend the size
129
What is the most commonly used clinical test for short term memory chunks?
Digit span (read & repeat increasing series of numbers, usually 6-7norm)
130
Describe what working memory is?
- Maintenance & integration of info in active state for a brief time in order to achieve short term task/goal
- Mix of short &/or retrieved long term memory
131
How are short term & working memory linked?
Short term memory only lasts a few secs, it must be repeatedly re-activated, its reactivation & subsequent duration is working memory (this is known as an executive function)
132
What happens to working memory when the task is over?
1. Encoded into long term memory
| 2. Left to lapse
133
How can long term memory be formed directly from sensory input?
Under control of executive functions (pre-frontal cortex)
134
What can long term memory be sub-divided into?
1. Declarative memory
| 2. Non-declarative memory
135
What is long term memory?
Acquisition & retrieval of information over long periods
136
Describe the different parts of the Declarative/explicit long term memory?
- Conscious
- Semantics (language/facts)
- Episodic (events/experiences)
- Medial temporal lobe structures/association areas
137
Describe the different parts of the Non-declarative/implicit long term memory?
- Not requiring conscious effort to from or access
- Procedural (habits & skills)
- Associative learning (classical conditioning, emotional responses)
- Priming (habituation / sensitisation)
138
Describe the 4 parts of the process of learning (storing memory)?
1. Encoding (memory creation)
2. Storage (persistence of memory traces)
3. Retrieval (memory recovery)
4. Consolidation (strengthening of memory traces)
139
Describe the 3 parts of memory formation?
1. Series of events are encoded by hippocampus & reference is made to their memory location- hippocampal index
2. If this info is recalled prior to consolidation, the hippocampus performs the retrieval from its index of the events
3. After consolidation of the memory retrieval can be initiated directly from the sensory cortices
140
What is plasticity in long term memory used for clinically?
- Counselling for post traumatic stress disorder
- Patients asked to re-live events leading to PTSD & given adrenergic beta receptor blocker (propranolol) which blocks re-consolidation of memory
141
What is consolidation a result of?
Physical changes at the synapse
142
What 4 changes in morphology on dendritic spines have been associated with long term potentiation?
1. Increase no. of presynaptic vesicles, postsynaptic receptors & ribosomes
2. Develop separate synaptic zones divided by wall/cleft in spine
3. Single spine may divide in 2
4. New dendritic spines appear ~1hr after stimulus that induces LTP
143
What are the 4 structures involved in non-declarative memory?
1. Amygdala
2. Caudate nucleus
3. Putamen
4. Cerebellum
144
How is the corpus striatum (basal ganglia) involved in non-declarative memory?
Influence memories involving movement & procedural memory e.g. Olympic diving
145
How is the cerebellum involved in non-declarative memory?
Influences fine motor learning including speech movements
146
What is dissociated amnesia?
Amnesia occurring without any other deficits
147
Are declarative, non-declarative, short term & long term memory processed in the same place/by the same mechanisms?
NO
148
What (other than temporal lobe) can cause anterograde amnesia when damaged?
Anterior/Dorsomedial nuclei of the Thalamus, or in the Mammillary bodies
149
What does the Dorsomedial nucleus of the thalamus receive?
Input from temporal lobe structures which is then relayed almost exclusively to the frontal cortex (executive function)
150
What functional link is there in memory consolidation?
Dorsomedial thalamus & the medial temporal lobe
151
What can damage to the striatum of basal nuclei (huntington's disease) cause?
Loss of non-declarative memory
152
What did Lashleys experiments on rats in 1890-1958 show?
Large areas of cerebral cortex had to be removed to prevent learning & memory of complex tasks & lesions had little effect on simple tasks
153
If synapses were only capable of long term potentiation (LTP) what would eventually happen?
Whole brain potentiation
154
What do episodic & semantic memories in declarative long term memory join to form?
Autobiographical memory- makes you YOU!
155
What is retrograde amnesia?
Patient doesn't have trouble producing new memory, but they will have a period in the past where they don’t remember anything because those memories haven’t been consolidated!
156
What is anterograde amnesia?
Patient is fine remembering things from the past, but struggle to make new memories!
157
What does the vascular compartment of the neck contain medially, laterally & posteriorly?
- MEDIAL: common, internal & external carotid arteries
- LATERAL: internal jugular vein
- POSTERIOR: CN X
158
Where does the left common carotid artery come from?
Arch of aorta
159
Where does the right common carotid artery come from?
Brachiocephalic trunk
160
Describe the distribution of Internal carotid artery & what it supplies?
- No branches in the neck
- Ascends to enter carotid canal
- Supplies the anterior brain
161
Describe the carotid sinus?
Enlargement at bifurcation of common carotid artery containing baroreceptors/ pressoreceptors in wall of internal carotid artery
162
What is the purpose of the carotid sinus?
- Monitors blood pressure
- Baroreceptors sensitive to stretch
- Helps keep BP within
homeostatic values
163
Describe the innervate of the carotid sinus?
CN IX via carotid
| sinus nerve & CN X (back to the tractus solitarius)
164
Describe the passage of action potentials from the carotid sinus baroreceptors?
From baroreceptors through CN IX to cardioregulatory & vasomotor centres in medulla
165
Describe the carotid body?
Small organ, houses chemoreceptors at bifurcation of CCA near carotid sinus
166
What is the purpose of the carotid body?
- Monitors blood O2, CO2, & pH & temp
| - In emergency situations it increases respiration, blood pressure & cardiac rate
167
Describe the innervate of the carotid body?
CN IX via carotid sinus nerve & CN X (back to the tractus solitarius)
168
Describe the passage of afferent fibres from the carotid body?
Travel to cardioregulatory & vasomotor centres in the medulla
169
List the 8 branches of the external carotid artery?
1. Superior thyroid
2. Ascending pharyngeal
3. Lingual
4. Facial
5. Occipital
6. Posterior auricular
7. Superficial temporal
8. Maxillary
170
What branch does the superficial temporal artery (from external carotid artery) give off?
Transverse facial artery
171
What are the 2 terminal branches of the external carotid artery?
1. Superficial temporal
| 2. Maxillary
172
Describe the location of the Internal Jugular Vein?
- Continuation of sigmoid sinus
- Exits skull via jugular foramen & enters carotid sheath
- Lateral to CCA
173
List the 7 veins which drain into the internal jugular vein?
| drains blood from brain, skull, face & parts of neck
1. Inferior petrosal sinus
2. Pharyngeal
3. Occipital
4. Facial
5. Lingual
6. Superior thyroid
7. Middle thyroid
174
What does the Internal jugular vein join?
Subclavian vein to become brachiocephalic vein (left & right)
175
What muscle runs across the internal jugular vein in the neck?
Omohyoid muscle
176
Describe the passage & location of the external jugular vein?
- Begins at angle of mandible
- Crosses over SCM, pierces investing fascia & drains into subclavian
- Joining retromandibular (superficial temporal & maxillary) & posterior auricular veins
177
List the 3 veins draining into the external jugular vein?
1. Posterior external jugular
2. Transverse cervical
3. Suprascapular
178
Describe the location & passage of the anterior jugular vein?
Arise near hyoid bone & run either side of midline through subcutaneous tissue communicating via the jugular venous arch
179
Where does the anterior jugular vein drain?
Into EJV, in some instances, directly into subclavian vein
180
What neck muscles does the cranial nerve VII supply?
- Platysma muscle
- Digastric muscle
- Stylohyoid muscle
181
Describe the passage of the CN IX in the neck?
- Jugular foramen & travels downward between the IJV & ICA
- Most travels to oral cavity, some downward to carotid sinus (& body), pharynx (sensory) & stylopharyngeus (motor)
182
Describe the passage of the CN X in the neck?
- Jugular foramen & travels within carotid sheath with IJV & CCA
- Motor branch to pharynx & branch to carotid body, the superior laryngeal nerve & cardiac branch
183
Describe the passage of the CN XI (spinal) in the neck?
- Jugular foramen & travels between IJV & ICA
- Crosses lateral surface of IJV to descend to posterior triangle
- It innervates SCM & trapezius
184
Describe the passage of the CN XII in the neck?
- Hypoglossal canal & between IJV & ICA
- Crosses ICA & ECA laterally on way to oral cavity
- No branches to anterior triangle
185
What does the transverse cervical nerve supply?
| anterior rami of C2, C3
Cutaneous innervation over SCM & anterior triangle
186
What is the cervical part of sympathetic trunk?
Superior, middle & inferior cervical ganglia
187
What are the spinal levels of the brachial plexus?
C5-T1
188
What, physically, is the limbic system?
Interconnected discrete structures within the brain & brainstem largely forming a ring around corpus callosum
189
What are the 4 general functions of the limbic system?
1. Emotion & motivation (puts a value on things)
2. Appetitive behaviour
3. Endocrine function
4. Autonomic nervous system control
190
What are the 8 functional factors of the limbic system?
1. Eating / Drinking
2. Fighting/killing
3. Sex drive
4. Enjoyment
5. Fear / anxiety
6. Autonomic preparation
7. Memory formation and recall
8. Expression of emotion
191
What does is the philosophical meaning of the limbic system?
Relates person to their environment
| with reference to past experience, current requirements & present situation
192
What are the 4 functional categories of the limbic system?
1. Emotions & drives via amygdala
2. Homeostasis & motivation (autonomic & neuroendocrine) via hypothalamus
3. Olfaction via olfactory cortex
4. Memory via hippocampus
193
Where can your find the Amygdala?
Anterior tip of hippocampus
194
What does the Amygdala provide?
- Emotional component to experiences & memory
- Appreciation of innate & learned fear & connections with all cortical association areas allowing integrative function
195
Where are the most significant afferents to the Amygdala from?
Frontal temporal & parietal lobes receiving cognitive information
196
Where do the most significant efferents from the Amygdala go to?
Hypothalamus & limbic cortex providing emotional cognisance & visceral/homeostatic information
197
What is the significance of the Amygdala in the Macaque Monkeys?
- Lack of fear so they no longer function within the group
- Constantly attacked for taking food, mating with inappropriate partners.
- Unable to learn
- Display unusual tameness
198
What are Ekman's 6 types of universal facial expressions?
1. Anger
2. Fear
3. Disgust
4. Surprise
5. Happiness
6. Sadness
199
What can happen due to lesions in the human Amygdala?
Loss recognition of fear & anger in other peoples faces, however can usually recognise the other 4 Ekman emotion types (sad, happy, disgust, surprise & anger)
200
What can electrical stimulation of the Amygdala (& anterior hypothalamus & PAG) cause?
Anxiety, agitation & aggression
201
What does the FMRI show regarding he Amygdala?
Increased activity in amygdala when fearful faces are shown as compared to other emotions
202
Describe the range of symptoms (Kluver-Bucy syndrome) produced due to bilateral temporal lobe lesions in all mammals?
- Visual recognition impairments (visual agnosia)
- Heightened sexual appetite(Hypersexuality)
- Loss of fear & conditioning
- Oral tendencies
(Hyperorality)
- Flattened emotions
203
What do Arachnophobics & Ophidophobics show?
| unconscious reactions in the Amygdala
Skin conductivity reaction to seeing camouflaged spiders/snakes, before they are aware they are there
204
What does the unconscious reactions in the Amygdala show?
Fast sub-cortical route for visual information which connects to thalamus to the amygdala & to the hypothalamus
205
What is the main effector of the limbic system?
HYPOTHALAMUS
206
Describe the Hypothalamic circuitry (efferents)?
- All efferent targets feed back to limbic system to provide info about internal/ external environments
- Prepares body for fight/flight by systemic arousal (triggered by emotion derived from situation)
207
What are the 3 different effects exerted by the hypothalamus?
```
1. Vegetative
functions
2. Endocrine
functions
3. Behavioural
functions
```
208
Describe the Vegetative function of the hypothalamus?
Cardiovascular regulation, Thirst, Appetites, Temp, blushing, pallor, Sexual excitement
209
Describe the Endocrine functions of the hypothalamus?
Control over anterior pituitary gland hormone release through connecting blood supply
210
Describe the Behavioural functions of the hypothalamus?
- General level of activity up to & including ‘rage’ for food, water, sex etc
- Ingestion/ disinterest of food, Fear & punishment behaviour, Increased sexual drive
211
Describe the location of the mesolimbic dopamine system (reward system)?
Originates in ventral tegmental area of midbrain, & projects to medial prefrontal cortex (mPFC), amygdala, hippocampus, nucleus accumbens & ventral pallidum
212
What are drugs of abuse (cocaine, heroin, ethanol etc) thought to all have?
Final common dopaminergic pathway feeding into the limbic system
213
What does the anterior insular cortex provide?
Introspection which allows interpretation of sensation as joy or disgust
214
What do patients with Huntington's disease (progressive frontal cortex degenerative disease) show?
- Impairment of visual characteristics associated with disgust
- Extent of impairment dependent on amount of damage to insular
215
What can the PAD (Periaqueductal grey) do?
Reduce activity in ascending pain pathway, its effects are agonised by endorphins & so opiates
216
What can electrical stimulation of PAG (Periaqueductal grey) produce?
- Analgesia which can be blocked by nalaxone (Opioid receptor blocker)
- Aggression
217
What type of pain hurts more than an another?
Sadistically inflicted pain stimuli hurts more than accidentally inflicted pain stimuli from a friend
218
What 2 limbic structures are involved in depression?
1. Ventromedial portion of the prefrontal cortex (goal setting, forward planning, ascribing meaning to perceptions)
2. Cingulate gyrus
219
How is the Ventromedial portion of the prefrontal cortex associated with depression?
- It has reduced mass in individuals with familial depression (from loss of glial cells)
- Modulated by neurotransmitters with dysfunctions commonly associated with depression
220
Describe the Ventromedial portion of the prefrontal cortex in Bipolar sufferers?
Virtually inactive during depression (no meaning to life) & hyperactive during manic phases
221
How is the cingulate gyrus associated with depression?
Activity becomes reduced during depression, usually functions as straddle between emotion & cognition
222
Describe the cingulate gyrus in Bipolar patents?
Anterior portion more active during depression & less active during manic periods (opposite to ventromedial cortex)
223
How are neurotransmitters & glucocorticoids in limbic system associated with depression?
- Imbalances in neurotransmitters such as serotonin, dopamine & norepinephrine
- True imbalances maybe lie in other receptor expression as well as different neurotransmitter release
224
What drugs are said to correct perceived imbalances in serotonin levels & thus directly reduce depression?
Antidepressants such as Prozac (fluoxetine)
225
What is the bodies response to exposure of prolonged stressors?
Elevated blood glucocorticoid levels
226
Describe how the body elevates blood glucocorticoid levels in times of prolonged exposure to stressors?
- Pituitary releases ACTH, signals adrenal glands to release glucocorticoid
- Glucocorticoid detected by hippocampus, activates hypothalamus releasing CRH
- CRH causes release of ACTH which releases more glucocorticoids
227
What does increased glucocorticoids affect?
Expression of serotonin receptors leading to depression & possible suicide
228
What does Egas Moniz (frontal lobotomy) psychosurgery involve?
- Separate the limbic cortex at level of frontal lobes under local anesthesia with a "leukotome"
- Resulted in disinhibition, lack of forward planning, lowered executive function & multitasking abilities
229
What did Walter Freeman refine the Egas Moniz frontal lobotomy into?
Transorbital leucotomy
230
What is the anterior boundary of the neck?
Top of manubrium & superior border of clavicle
231
What is the posterior boundary of the neck?
T1 & superior margin of scapula to coracoid process
232
What is the lateral boundary of the neck?
1st pair of ribs
233
What is the inferior boundary of the neck?
Superior thoracic aperture (thoracic inlet) & axillary inlets
234
Where is the apex of the lung (summit) located?
~2.5 cm above middle 1/3 of clavicle, in the root of the neck
235
Where/What is the cervical pleura?
Superior continuation of costal & mediastinal parts of the parietal pleura, superiorly forms a cup-like dome called PLEURAL CUPOLA
236
Why is the cervical pleura in children & infants more susceptible to injury?
Since it extends
| higher due to relatively short length of neck
237
What can injures at the root/base of the neck compromise?
Lungs & pleural sacs (pneumothorax, haemothorax, chylothorax)
238
What is the cervical pleural reinforced with?
Suprapleural membrane (Sibson’s fascia)
239
Describe the supra pleural membrane (Sibson's fascia)?
- Strong fibrous connective tissue that's an extension of endothoracic fascia
- Attaches to internal surface of rib 1 & C7 transverse processes
240
What does the suprapleural membrane (Sibson's fascia) act as?
Anchors the lung & barrier preventing changes in intrathoracic pressure drawing upon contents in the neck
241
What are the 3 branches that come off the aortic arch?
1. Brachiocephalic trunk ( o right CCA & right subclavian)
2. Left common carotid artery
3. Left subclavian artery
242
Describe the subclavian arteries?
- Posterior to sternoclavicular joints, ascend through superior thoracic aperture to enter root of neck
- Becomes axillary arteries after passing over lateral border rib 1
243
What are the 3 parts of the subclavian artery (relative to the anterior scalene muscle- ASM)?
- 1st part: Medial to ASM
- 2nd part: Posterior to ASM
- 3rd part: Lateral to ASM (until lateral border of 1st rib)
244
What makes the 3rd part of the subclavian artery different?
Lies anterior to trunks of brachial plexus, also longest & most superficial
245
What are the 3 branches off the 1st part of the subclavian artery?
1. Vertebral artery
2. Thyrocervical trunk
3. Internal thoracic artery
246
What does the Thyrocervical trunk ascend to give off?
1. Inferior thyroid artery
2. Transverse cervical artery
3. Suprascapular artery
247
Describe the inferior thyroid artery?
- Largest
- To thyroid
- Gives off ascending cervical artery to prevertebral muscles & spinal cord
- Supplies larynx, trachea, oesophagus, thyroid, parathyroid glands
248
Describe the transverse cervical artery?
- Anterior to anterior scalene muscle
| - Gives superficial branch to trapezius & deep branch to rhomboids & scapula
249
Describe the suprascapular artery?
- Anterior to anterior scalene muscle
| - Supplies supraspinatus fossa
250
What are the 2 terminal branches of the thyrocervical trunk?
1. Inferior thyroid artery
| 2. Ascending cervical artery
251
Describe the internal thoracic artery (branch off the 1st part of subclavian)?
- DESCENDS inferomedially posterior to clavicle into thoracic cavity to 6th intercostal space
- Gives rise to anterior intercostal arteries that supply intercostal spaces
252
What is the branch off the 2nd part of the subclavian artery?
Costocervical trunk
253
What 2 branches does the Costocervical trunk divide into when ascending posteromedially?
1. Supreme intercostal artery
| 2. Deep cervical artery
254
Describe the location of the supreme intercostal artery?
To rib 1 as posterior intercostal arteries to 1st & 2nd intercostal spaces
255
Describe the deep cervical artery?
- Ascends superiorly to back of neck, supplies deep cervical muscles
- Anastomose with occipital artery from ECA
256
Where is the nucleus accumbens located?
Head of caudate nucleus
257
What is the branch off the 3rd part of the subclavian artery?
Dorsal Scapular artery (HIGHLY VARIABLE ORIGIN)
258
Describe the subclavian vein?
- Continuation of axillary at lat border of 1st rib
- Drains upper limb
- Parallel & ant to artery
- Anterior to anterior scalene muscle
259
What makes up the brachiocephalic vein?
Internal jugular vein + Subclavian vein
260
Where do the inferior thyroid veins in anterior triangle drain?
Directly into brachiocephalic vein
261
What is the thoracic duct?
Major lymphatic drainage channel that begins in abdomen ascending through thoracic cavity & into the neck
262
Where does the thoracic duct enter the venous system in the neck?
Between left internal jugular vein & left subclavian vein
263
Where do preganglionic sympathetic neurons arise from?
Lateral horns of T1-L2
264
Where do postganglionic sympathetic fibres leave?
Via gray rami towards anterior rami (no white rami in cervical region)
265
Describe the location of the cervical part of the sympathetic trunk?
- Anterior to longus capitus & longus colli muscles
| - Posterior to internal & common carotid arteries
266
Where is the spinal roots of the superior cervical sympathetic ganglion?
C1/C2
267
Where is the spinal roots of the middle cervical sympathetic ganglion?
C6
268
Where is the spinal roots of the inferior cervical sympathetic ganglion?
C7
269
What does the inferior cervical ganglion fuse with?
1st thoracic ganglion to form Cervicothoracic ganglion (stellate ganglion) in 80% of people
270
The superior cervical sympathetic ganglion supplies branches via what structures?
- ICA & ECA (forming plexuses)
- Cervical spinal nerves (C1-C4, cervical plexus)
- Pharynx
- Superior cardiac nerves
271
The middle cervical sympathetic ganglion supplies branches via what structures?
- Cervical spinal nerves (C5, C6)
| - Middle cardiac nerves
272
The inferior cervical sympathetic ganglion supplies branches via what structures?
- Vertebral artery (forming a plexus)
- Cervical spinal nerves (C7-T1; C7 & C8 to brachial plexus)
- Inferior cardiac nerves
273
What does the parotid gland secrete?
Serous fluid
274
What does the submandibular gland secrete?
Serous & mucous fluid
275
What does the sublingual gland secrete?
Mostly Mucous & some serous fluid
276
Describe the serous salivary secretory unit?
- Amylase, lysozyme
| - Protein secreting
277
Describe the mucous salivary secretory unit?
- Sialomucins
| - Mucin secreting
278
Describe the mixed salivary secretory unit?
Serous secretion &
| sialomucins
279
Describe the location of the Parotid gland?
Outside oral cavity between zygomatic arch & lower border of mandible between SCM, external acoustic meatus & masseter
280
What is the parotid gland enclosed in?
Parotid sheath (capsule): part of deep investing cervical fascia
281
What does the fatty tissue between loves of the parotid gland allow?
Flexibility around mandible
282
Describe the passage of the Parotid duct (Stensen's duct)?
Anteriorly & horizontally before piercing buccinator to enter oral cavity near the upper 2nd molar tooth
283
What 4 structures are embedded in the Parotid gland?
1. Retromandibular vein
2. External carotid artery
3. CN VII (does not innervate the parotid gland)
4. Parotid lymph nodes
284
Describe the location of the CN VII?
- Enters internal acoustic meatus
- Exits stylomastoid foramen
- 2 branches (post. auricular & digastric)
- Main nerve enters the Parotid gland
285
What is the parasympathetic innervation (secretomotor) of the Parotid gland?
- Preganglionic: CN IX travel to otic ganglion in tympanic nerve & lesser petrosal nerve
- Postganglionic: otic ganglion pass to auriculotemporal nerve (CN V3), branches to parotid gland
286
What is the sympathetic innervation (vasoconstriction/ reduced saliva volume) of the Parotid gland?
From superior cervical ganglion & nerve plexus on external carotid artery
287
What are the 2 different cutaneous innervations over the Parotid gland?
1. CN V3- Auriculotemporal
| 2. Cervical nerve C2 & C3- great auricular
288
Describe the location of the Submandibular gland?
- Mandible, partly superficial (below) & partly deep (above) to the mylohyoid
- Gland wraps around mylohyoid - Deep part lies in floor of oral cavity, lateral to root of tongue
289
Describe the location of submandibular ducts?
- Begin in submandibular gland between mylohyoid & hypoglossus
- Open into 3 orifices in oral cavity beside base of frenulum (small sublingual papilla/caruncles)
290
What is the relation of the lingual nerve (CN V3) to the submandibular duct?
Loops under duct before it opens into oral cavity
291
What is the submandibular gland covered in?
Fascial capsule that is continuous with deep investing cervical fascia
292
What is the vascular supply of the submandibular duct?
- ARTERY: submental (branches of facial)
| - VEIN: submental (to lingual & facial)
293
Describe the location of the sublingual gland?
- Floor of mouth between mandible & hyoglossus, lateral to submandibular duct & lingual nerve (CN V3)
- Sits in sublingual fossa of mandible, superior to anterior part of mylohyoid line
294
What do sublingual folds overlay?
Sublingual glands that extend to frenulum of tongue
295
How do sublingual ducts drain into the oral cavity?
Via openings into crest of sublingual fold (sometimes empty with submandibular duct at sublingual papilla/caruncles)
296
What is the vascular supply of the sublingual ducts?
- ARTERY: submental & sublingual (branch of facial & lingual)
- VEIN: submental (lingual & facial veins)
297
What is the covering of the sublingual gland?
Has NO true fascial/fibrous capsule
298
What is the parasympathetic (secretomotor) innervation of the sublingual & submandibular glands?
- Preganglionic: to submandibular ganglion from chorda tympani (CN VII nervus intermedius) via lingual nerve (CN V3)
- Postganglionic: in lingual nerve (CN V3) to sublingual gland OR directly to sublingual & submandibular glands not in nerve
299
What is the sympathetic (vasoconstriction/reduced volume) innervation of the sublingual & submandibular glands?
Superior cervical ganglia & nerve plexus on external carotid artery
300
Where are minor salivary glands found?
Diffusely embedded throughout submucosa of oral cavity:
- Buccal
- Palatine
- Lingual
- Labial
301
What are the minor salivary glands innervated by?
CN VII & CN V
302
What is the clinical significance of minor salivary glands?
Susceptible to mucoceles (swelling due to blockage of associated ducts)
303
What is the parasympathetic (secretomotor) innervation of the minor salivary glands ABOVE the oral fissure?
- Preganglionic: to pterygopalatine ganglion in greater petrosal nerve (CN VII nervus intermedius)
- Postganglionic: to palate via palatine nerves
304
What is the parasympathetic (secretomotor) innervation of the minor salivary glands BELOW the oral fissure?
- Preganglionic: to submandibular ganglion from chorda tympani (CN VII nervus intermedius) & via lingual nerve (CN V3)
- Postganglionic: in lingual nerve (CN V3) to glands OR directly not in nerve
305
Describe Mumps of salivary glands/ducts?
- Viral infection presents in children as painful swellings over the salivary glands
- Common in parotid glands
- Spread to other parts of the body (viral meningitis)
306
Describe Salivary stones/calculi (sialolithiasis)?
- Pain, swelling & lack of salivation
- Common in submandibular duct due to upward course into oral cavity
- Treated with surgical resection (watch surrounding nerves- lingual nerve esp. for submandibular duct)
307
Describe excessive salivation (ptyalism)?
Commonly occurs prior to vomiting, but can also be associated with several disease processes/pathologies
308
What % of salivary gland tumours are benign?
~80%
309
What is the most common salivary gland tumour?
Pleomorphic adenoma (visible nodules of ECM of cartilage, produced by myoepithelial cells)
310
Describe the symptoms associated with tumours in salivary glands?
Painless swelling near gland, but some numbness/ weakness in surrounding muscles
311
What is the usual treatment for parotid gland tumours?
Total parotidectomy (can lead to CN VII dysfunction)
312
What is the definition of sleep?
Easily reversible state of inactivity with a lack of interaction with environment
313
What 2 things can unconsciousness be?
1. Coma (depressed state of neural activity)
| 2. Sleep (variation in neural activity)
314
What 3 states can consciousness be described as?
1. Wakefulness
2. Core consciousness
3. Extended consciousness
315
What is core consciousness?
Wakefulness + emotional responses & simple
| memory
316
What is extended consciousness?
Same as wakefulness & core consciousness + self awareness, autobiographical memory, language & creativity
317
What is the suggested functions of sleep?
Processing & storage of memories, recuperation of bodies immune system & conserve energy
318
What happens to the brain during sleep?
- Neurons are active
| - Consumes as much O2 as wakeful brain, or more
319
What are the 2 main forms of externally discernible sleep?
1) Eyes move rapidly from side to side (REM sleep)
| 2) When they do not (non REM, slow wave or deep sleep)
320
What does EEG stand for?
Electroencephalogram
321
Can post synaptic activity of individual neurons be picked up by EEG?
NO
322
Can post synaptic activity of synchronised dendritic activity be picked up by EEG?
YES (more neurons synchronised, the bigger the peaks on EEG)
323
How can synchronisation occur?
Either by neuronal interconnections or pacemaker
324
How are the EEG electrodes arranged?
19 pairs (or more) at internationally agreed points on surface of the head
325
What do EEG recordings allow for?
Separation of REM & non-REM sleep & for latter to be subdivided into a further 4 stages of sleep, each with its own characteristic brain wave patterns
326
How long does it take from drowsy to deep sleep?
About 1hr
327
How many REM sleeps do we have on average per night?
5 REM sleeps
328
What is the minimum time between REM sleeps?
30mins
329
What do the waves in an EEG look like when a patients is awake with eyes closed?
Alpha High frequency (8- 13Hz), & low amplitude (50-μV)
330
What do the waves in an EEG look like when a patient is awake with eyes open?
Beta waves (14-60Hz) waves of activity
331
What do the waves in an EEG look like when a patient is in Stage 1 non-REM sleep?
- Easily roused
- Slow rolling eye movements
- Some theta waves (slower frequency (4-7Hz) & higher amplitude) waves
- 1-5min duration
332
What do the waves in an EEG look like when a patient is in Stage 2 non-REM sleep?
- K complexes & sleep spindles (8- 14Hz bursts)
- No eye movement but body movement remains possible
- 10-15min duration
333
What do the waves in an EEG look like when a patient is in Stage 3 non-REM sleep?
```
- Has slower frequency
delta waves (inc amplitude) appear
- Harder to rouse
- Few spindles
- Few min duration
```
334
What do the waves in an EEG look like when a patent is in Stage 4 non-REM sleep?
- Deepest sleep, hardest to rouse
- >50% EEG waves at 2Hz & high amplitude (>200μV) called delta waves
- Heart rate & BP lower, movement
- 15-30min duration
335
What do the waves in an EEG look like when a patients is in REM sleep?
- Fast beta waves & REM
- Subject easier to rouse than in stage 4
- Dreaming, recalled, plus low muscle tone
336
When is stage 4 non-REM sleep reached?
In initial sleep cycles, thereafter the deepest sleep attained is Stage 3
337
What is the difference in eye movements between 1st stage & REM?
- 1ST STAGE: slow & rolling
| - REM: rapid
338
What is characterised by REM?
Increase in heart rate, neural activity, respiration, oxygen consumption & penile erection
339
Describe the 3 characteristics of EEG slow waves in non-REM sleep?
1. Deeper into non-REM sleep, movement & breathing depressed
2. Stage 4 brain slow waves synchronised firing of large groups of neurones
3. More than 1 alpha wave subtype (visual cortex (classic type), sensory motor cortex (mu type) & auditory (kappa type)
340
Describe the 3 characteristics of EEG waves in REM sleep?
1. Brain very active & dreaming, but body is effectively paralysed
2. 1 source of activity concerned with inhibiting motor output (except breathing & eye movement)
3. Body temp drops as metabolism is inhibited
341
How is the reticular formation involved in sleep?
Arousal centers in brainstem project fibres to structures in brain including thalamus (norepinephrine, serotonin, acetylcholine)
342
What does lesions in any one of the neuronal systems in control of sleep via reticular formation result in?
Either coma or stupor. ie. NT from neurons of reticular formation are required for consciousness
343
What can control the general excitability of the thalamus?
Reticular formation
344
What does lesioning in the thalamus cause?
Abolishes (most) synchronous EEG waves
345
What does rhythmic stimulation of the thalamus induce?
Stage 4 deep sleep (high amplitude, low frequency waves)
346
What certain EEG wave types can be changed & how?
Alpha --> Beta (increasing alertness), by activation of reticular formation & so thalamus
347
What 3 things is wakefulness interconnected with?
1. Reticular formation of the brainstem
2. Thalamus
3. Cerebral cortex
348
What does excitation of the reticular formation do to EEG waves?
Depolarisation (excitation) of thalamus --> Non-rhythmic output --> Increased arousal (alpha waves to beta)
349
What does inhibition of the reticular formation do to EEG waves?
Hyperpolarisation (less excited) of thalamus --> Rhythmic output --> Slow, synchronised EEG waves in cerebral cortex
350
What causes sleep spindles & K complexes?
Inherent rhythmicity of thalamic neurons as they hyperpolarise due to reduced ascending reticular formation input (seen in non-REM stage 2 sleep)
351
What is blocked during REM?
High descending motor output blocked by brainstem (locus coeruleus)
352
What 3 motor systems are exceptions to blocked descending motor output in REM sleep?
1. Eye centre
2. Middle ear centre
3. Respiratory centre
353
Describe the arousal pathway 1?
- Midbrain reticulum projects cholinergic excitation to thalamus
- Only strong signals pass through
- Nearly always ON
- Only inactive in NREM sleep
- Inputs facilitate thalamo- cortical transmission when awake
354
Describe the arousal pathway 2?
- Direct cortical excitation
- Inactive during REM
- Some firing during NREM & most when awake
355
What inputs does arousal pathway 2 receive?
- Lateral hypothalamus orexin
| - Basal forebrain neurons containing GABA/Ach
356
Describe the ventrolateral pre-optic nucleus (VLPO) & its function?
- Centre of non-REM sleep promotion
- Inhibitory projections to major direct arousal centres, & active during sleep
- Innervates lateral hypothalamus neurons
357
What does the extended VLPO (eVLPO) promote?
REM sleep
358
What does the VLPO cluster promote?
non-REM sleep
359
What is VLPO reciprocally inhibited by?
Projections (NA, GABA & 5-HT) from arousal centres
360
What is switching between arousal & sleep informally called?
"Flip-Flop" as its fast!
361
When are Orexinergic neurons normally active?
During wakefulness (lateral hypothalamus)
362
Where do the Orexinergic neurons project?
Cerebra, arousal nuclei & VLPO, however VLPO has no orexin receptors
363
What happens when Orexin is released in the flip-flop switch?
- Stimulates arousal centres & causes inhibition of VPLO
| - As long as Orexin is released the balance is shifted towards wakefulness
364
What happens when the VPLO begins to fire in the flip-flop switch?
Inhibits both orexinergic neurons & arousal centres:
1. Removes inhibition of VLPO by arousal centre
2. Cuts off excitation from orexinergic neurons thus pushing the balance quickly towards sleep
365
Where is the suprachiasmatic nucleus (SCN) located?
Hypothalamus
366
What 2 things does the suprachiasmatic nucleus (SCN) control?
1. Circadian cycles
2. Influences many physiological & behavioural rhythms
occurring over 24hr period, including sleep/wake cycle
367
How is the cycle controlled by the suprachiasmatic nucleus (SCN) reset each day?
By a variety of zeitgebers
368
What is the most dominant cycle controlled by the suprachiasmatic nucleus (SCN)?
Light dark cycle (retina receptors containing melanopsin react to light & synapse onto SCN resetting clock gene)
369
What are the 2 forms of permanent Insomnia?
1. Rare inherited neurodegenerative process affecting thalamus & rostral hypnogenic centres
2. Stroke resulting in blockade of basilar artery (loss of pontine hypogenic centre=insomnia)
370
How can narcolepsy occur?
- Specific loss of Orexin containing neurons in Lateral Hypothalamus
- Inherited auto immune condition linked to chromosome 6
371
What is the tetrad of symptoms associated with narcolepsy?
1. Repeatedly falling asleep during day, regardless of current activity
2. Limb weakness during emotional episodes (cataplexy)
3. Night time or morning wakening + muscular paralysis (sleep paralysis)
4. Vivid dream recollection
372
How does REM sleep behaviour disorder occur & what is it characterised by?
- During REM sleep & when descending pontine reticular formation fails to properly immobilise body
- Rapid/violent movement & behaviour
373
How does Somnambulance occur & what is it characterised by?
- During non-REM sleep
- Same as REM sleep behaviour disorder but no memory of dreams enacted
- Midbrain reticular formation fails to paralyse body
