Term
| What are the 2 main pathways of the somatosensory system? |
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Definition
DCML - dorsal column medial lemniscus spinothalamic tract |
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Term
| Somatosensory information goes to what part of the thalamus? |
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Definition
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Term
| What are the receptors of the spinothalamic system? |
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Definition
nocioceptors - pain thermoreceptors - temperature mechanoreceptors - crude touch |
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Term
what is the periaqueductoral grey? |
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Definition
Periaqueductal gray (PAG; also called the "central gray") is the midbrain grey matter that is located around the cerebral aqueduct within the midbrain. It plays a role in the descending modulation of pain and in defensive behaviour. From Wikipedia. |
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Term
| What three types of interneurons provide inhibitory mechanisms for pain? |
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Definition
substantia gelatinosa periaqueductal grey-raphe nuclei pathway spinomesencephalic fibers, hypothalamus or cortex |
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Term
| which pathway is refered to as the tactile pathway? |
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Definition
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Term
what receptors are part of the DCML? |
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Definition
cutaneous mechanoreceptors: touch - Meissner, Merkel, hair vibration - Pacinian pressure - Ruffini muscle spindles: muscles spindle (Ia) golgi tendon (Ib) |
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Term
| What are the primary somatic sensory afferents of the head? |
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Definition
from cranial nerve: V trigemincal (gasserian) ganglion mesencephalic nucleus VII facial (geniculate) ganglion IX superior ganglion of IX X superios of X |
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Term
| What are the primary visceral sensory afferents of the head? |
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Definition
from cranial nerve: VII geniculate ganglion IX inferior ganglion of IX X inferior ganglion of X |
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Term
| What is the spinal trigeminal nucleus? |
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Definition
The spinal trigeminal nucleus is a nucleus in the medulla that receives information about deep/crude touch, pain, and temperature from the ipsilateral face. From Wikipedia spinothalamic homologue. |
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Term
| What are the three distinct regions of the spinal nucleus? |
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Definition
1. oral nucleus 2. interpolar nucleus 3. caudal nucleus |
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Term
| What is the pathway for pain and temperature from the face? |
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Definition
| primary afferent neurons from face --> synapse of spinal nucleus (e.g. caudal nucleus) --> secondary neurons cross midline --> joins spinothalamic tract --> VPM --> tertiary neurons goto IC --> post central gyrus |
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Term
| What are the two ascending pathways of the trigeminal tract? |
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Definition
1. medial lemniscus (ventral trigeminothalamic) tract Major crosses then joins medial lemniscus 2. dorsal trigeminothalamic) tract Minor does not cross ascends to ipsilateral VPM and post-central gyrus |
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Term
| What are the 4 main connections of the trigeminal nerve? |
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Definition
1. peripheral branches of the mesecephalic neurons - connect to mesencephalic nucleus 2. tactile afferents - either join the medial lemniscus (ventral trigeminothalamic) or the dorsal trigeminal tract 3. axons of trigeminal motor connect with motor nucleus 4. pain-temperature afferents connect to spinal nucleus (e.g. caudate) |
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Term
| What are the 2 main pathways for the motor sytem? |
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Definition
lateral corticospinal tract corticobulbar tract |
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Term
| What are the 4 extrapyramidal tracts? |
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Definition
vestibulospinal tract - mediate postural adjustments and head movements reticulospinal tract - major alternate route to spinal cord in humans rubrospinal tract - minor alternate route to spinal cord in humans tectospinal tract - eye movements |
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Term
| What are the effects of a lesion in lower motor neurons (alpha motor neurons innervating striated muscle)? |
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Definition
| paralysis, eventually muscle atrophy |
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Term
| What are the effects of a lesion in upper motor neurons (alpha motor neurons innervating striated muscle)? |
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Definition
| hyperactive reflex, paralysis or weakness (paresis) |
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Term
| What would result from unilateral corticobulbar damage? |
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Definition
1. Inability to contract muscle (e.g., contralateral lower face) 2. may have some transient contralateral weakness 3. no asymmetry at all |
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Term
| Trace the rubrospinal tract. |
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Definition
| secondary neurons originate in red nucleus --> crosses at same level --> descends lateral part of brainstem tegmentum --> runs down SC along with CST --> synapse in cervical SC |
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Term
| What is the function of the rubrospinal tract? |
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Definition
minor alternate route to spinal cord limb movements and posture tract very small in humans |
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Term
| trace the path of the reticulospinal tract. |
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Definition
| secondary neurons originate in reticular formation --> descends anterior (ipsilateral) or lateral (bilateral) funiculi of spinal cord --> synape in all levels of SC |
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Term
| what is the function of the reticulospinal tract? |
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Definition
alternate pathway for motor movements (e.g. walk, postural) related to many cerebellar functions and motor control functions autonomic functions (e.g., breathing, heart rate) |
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Term
| trace the path of the lateral and medial vestibulospinal tract. |
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Definition
secondary neurons originate in the lateral vestibular nuclei --> ipsilateral ventral funiculus --> synapses in all levels of SC secondary neurons originate in the medial vestibular nuclei --> bilateral medial longitudinal fasciculus --> synapses in all levels of SC |
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Term
| what is the function of the vestibulospinal tract? |
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Definition
lateral: postural control (e.g., antigravity muscles) medial: establishing head when walking, coordinating head with eye movements |
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Term
| trace the tectospinal tract. |
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Definition
| secondary neurons from the superior colliculus --> cross in superior colliculus --> descends contralateral anterior funiculus --> synapses on cervical spind cord. |
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Term
| what is the function of the tectospinal tract? |
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Definition
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Term
| Where do nerve bodies of motor neurons lie? |
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Definition
| CNS - brain and spinal chord |
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Term
| Where do nerve bodies of sensory neurons lie? |
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Definition
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Term
What are the functional divisions of the PNS? |
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Definition
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Term
| What structures does the autonomic nervous system control? |
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Definition
cardiac muscle, smooth muscle and glands Also recieves sensory input from these structures |
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Term
| How many pairs of spinal nerves are there? |
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Definition
31 pairs cervical - 8 thoracic - 12 lumbar - 5 sacral -5 coccygeal - 1 |
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Term
| What type of neurons do dorsal root ganglia have? |
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Definition
pseudounipolar cells (there are no synapses within the DRG) |
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Term
Through what do spinal nerves exit the vertebral canal? |
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Definition
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Term
Spinal nerves are composed of many _? |
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Definition
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Term
| Fascicles are composed of many _? |
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Definition
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Term
| What factors affect nerve fiber conduction? |
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Definition
Myelination greater diameter/cross-section results in smaller longitudinal resistance --> greater velocity Thicker nerves have a higher membrane capacity which increases resistance, but this effect is outweighed by the smaller longitudinal resistance. |
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Term
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Definition
A stimulus modality is a type of physical phenomenon that can be sensed. |
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Term
| What are the 4 types of sensory receptors? |
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Definition
1. chemoreceptors, baroreceptors? 2. photoreceptors 3. thermoreceptors 4. mechanoreceptors, baroreceptors – nociceptors |
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Term
| What are the two classifications of cutaneous receptors? |
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Definition
| encapsulated and non-encapsulated |
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Term
| Describe the 3 encapsulated mechanoreceptors. |
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Definition
1. Pacinian corpuscle (vibration) - subcutaneous all over body - layers of thin epithelial cells - rapidly adapting, very sensitive 2. Meissner corpuscle (fine touch /discrimination) - just under epidermis (dermal papillae of hairless skin); fingertips - elongated endings, oriented perpendicularly - a thin outer capsule, layer of stacked Schwann cells inside capsule - rapidly adapting, fine discrimination 3. Ruffini endings (pressure) - in dermis and subcutaneous and other CT sites - cigar-shaped capsule -slowly adapting |
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Term
| Describe the 3 non-encapsulated mechanoreceptors. |
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Definition
4. endings around hair (touch) - rapidly adapting - detects bending of hair 5. Merkel endings (touch) - disc-shaped expansion of terminal of sensory fibre - ending is applied to base of Merkel cell - Merkel cells at basal layer of epidermis - role is uncertain - slowly adapting (free endings) |
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Term
What mechanoreceptors have free endings? |
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Definition
nociceptors, thermoreceptors and some mechanoreceptors |
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Term
| What are the three muscle receptors? |
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Definition
muscle spindles golgi tendon organs free nerve endings |
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Term
| What are the three divisions of the ANS? |
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Definition
sympathetic parasympathetic enteric |
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Term
| What is the NT used preganglionic and post ganglionic PS neurons? |
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Definition
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Term
| What is the NT used preganglionic and post-ganglionic SS neurons? |
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Definition
preganglionic - Ach post-ganglionic - norepinepherine |
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Term
| What are the preganglionic PS nerves? |
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Definition
cranial nerves: III-Edinger-Westphal VII-superior salivatory nucleus IX-inferior salivatory nucleus X-nucleus ambiguous, dorsal motor nucleus sacral nerves: S2-S4 |
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Term
| What are the post-ganglionic PS nerves? |
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Definition
cranial nerves: III - iris and lens apparatus VII - lacrimal, nasal, submandibular and sublingual glands IX - parotid gland X - heart and other organs sacral nerves: S2-S4 |
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Term
| From what spinal chord regions do preganglionic SS neurons emerge? |
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Definition
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