Exam 3 - Neurobasis Flashcards
Spinal cord gray matter
Segmented and extends from 2nd lumbar vertebra to foramen magnum at base of skull
Spinal cord horns and zones
Dorsal
Ventral
Lateral zone
Intermediate zone
Dorsal horn
Receives afferent input for spinal cord
Sensory
Ventral horn
Transmits efferent impulses from spinal cord
Motor
Lateral zone
Has direct connections to brainstem for input and output from visceral nervous system
Lissauer’s zone
Intermediate zone
Contains interneuronal pools
Funiculi
White matter surrounding gray matter
Columns that allow fiber bundles to ascend from and descend to spinal segments
Dorsal, lateral, and ventral
Dorsal column
Important for proprioception, 2 point discrimination, and form perception
Lateral column
Long ascending and descending tracts
Ventral column
Short tracts for signals between spinal segments
Spinal segments and paired nerves
Cervical (8)
Thoracic (12)
Lumbar (5)
Sacral (5)
Coccygeal (1)
Distal sensory inputs
Travel medially
Lumbar and sacral
Proximal sensory inputs
Travel laterally
Cervical and thoracic
Neuron orders for ascending tracts
1st - dorsal root ganglion
2nd - crosses midline and forms lemniscus traveling toward thalamus
3rd - thalamic level travels to cortex
Ascending/afferent spinal tracts (general names)
Spinothalamic
Spinotectal
Spinocerebellar
Spinothalamic tracts
3 ascending tracts from spinal cord to thalamus
Lateral spinothalamic tract (pain, temperature, crude awareness)
Ventral spinothalamic tract (simple light touch and pressure, stereognosis, 2 point or point to point orientation)
Lateral ventral tract (exteroceptory)
Spinotectal tract (general info)
Ascends from cord to roof of brain stem
General sensory awareness and awareness in space
Spinocerebellar tracts
2 ascending tracts from cord to cerebellum
Ventral/anterior spinocerebellar tract (cutaneous input for control of direction, rate, and force of movement)
Dorsal spinocerebellar tract (proprioceptive info, coordination of posture)
Spinal cord efferent system
Lower motor neuron or final common pathway for motor response
Spinal basic unit motor response
Stretch reflex
Polysynaptic arc
Gamma loop
Cervical plexus
C 1,2,3,4
Innervate strap muscles of neck for respiration and tongue positioning
Phrenic neurons
Not plexus
Lower motor neurons located in C3 to C5
Innervate diaphragm
Brachial (arm) plexus
C5,6,7,8 and T1
Lower motor neurons that innervate muscles of rib cage, excluding the costals
Lumbrosacral plexus
Lumbar plexus - L2,3,4
Sacral plexus - L4,5 and S1,2,3,4
Lower motor neurons that innervate abdominal muscles
12 thoracic nerves
Not a plexus
Lower motor neurons that innervate costal muscles for breathing
T1-T11 serve external and internal intercostals
T12 serves subcostal
Brainstem encephalonic divisions
Mesencephalon (midbrain)
Metencephalon (pons)
Mylencephalon (medulla)
Specialized brainstem nuclei medulla level
Vestibular nuclei - gives strength to extensor pattern, part of pyramidal tract’s course toward LMN using stretch reflex and reflex arc pathways
Pyramidal system
Specialized brainstem nuclei pons level
Reticular nuclei (reticular formation) - attending and be alerting function using gamma motor neuron and internuncial pools to activate LMN
Extrapyramidal
Specialized brainstem nuclei midbrain level
Red nuclei - excitatory and inhibitory functions with influence from basal ganglia and extrapyramidal tracts. Using gamma motor neuron and internuncial pools to activate LMN
Substantia Nigra - inhibitory for basal ganglia influences, dark pigmented fibers
Extrapyramidal system
Ascending fiber tracts
Lemniscus or tracts
Medial lemniscus
Spinal lemniscus
Spinotectal tract
Medial lemniscus
Dorsal column tracts (gracilis and cuneatus)
Discriminative touch, proprioception, vibration
Travels: synapse on gracilis and cuneatus neurons of medulla at inferior olivary nucleus level
Through pons and midbrain
To thalamus
Spinal leminiscus
3 spinothalamic tracts
Travel:
Synapse in medulla neurons near inferior olivary nucleus of medulla
Through pons and midbrain
To thalamus
Spinotectal tract (travel)
Travels:
Synapse in medulla neurons near inferior olivary nucleus of medulla
Through pons
To midbrain
Spinocerebellar and dorsal spinocerebellar tracts (travel)
Only two orders
Synapse neurons of upper medulla
To inferior peduncle of cerebellum
Two major descending tracts
Pyramidal (more direct) - patterns of movement
Extrapyramidal (more indirect) - posture and tone of movement
Pyramidal tract (components)
Two components: corticobulbar tract (brainstem) - travels bilaterally
Corticospinal tract (spinal cord) - travels contralaterally with crossing at medulla pyramids
Extrapyramidal tract (travel & tracts)
Passes through specialized nuclei in brainstem forming:
Rubrobulbar and rubrospinal tracts (from red nuclei of midbrain)
Tectospinal tract (influence from midbrain nuclei)
12 Cranial nerves
C1-olfactory CII-optic CIII-oculomotor CIV-trochlear CV-trigeminal CVI-abducens CVII-facial CVIII-acoustic CIX-glossopharyngeal CX-vagus CXI-accessory/spinal accessory CXII-hypoglossal
Cranial nerves mnemonic
On occasion our trusty truck acts funny, a good vehicle any how
Non-speech cranial nerves
1 - olfactory
2 - optic
3 - oculomotor (gaze accommodation)
4 - trochlear (down and out eye motions)
6 - abducens (lateral eye movement; shifty eyes)
Speech cranial nerves
5 - trigeminal (sensory: face, motor: jaw, tongue, chewing)
7 - facial (sensory: tongue and soft palate, motor: face and stapedius)
8 - acoustic (sensory: hearing and balance, motor: efferent inhibition on hearing)
9 - glossopharyngeal (sensory: tonsils, pharynx, soft palate, motor: pharynx and stylopharyngeus)
10 - vagus (sensory: ear, pharynx, larynx, viscera, motor: phonation and swallowing)
11 - spinal accessory (motor: pharynx, larynx, soft palate, neck, helps posture)
12 - hypoglossal (motor: extrinsic and intrinsic tongue muscles, some sensory fibers for tongue)
Vagus nerve branches
Pharyngeal
Laryngeal: superior and recurrent
Brainstem final common pathway
Cranial nerves and the muscle fibers they innervate
Cerebellum location
Connected to brainstem at pons level by peduncles
Superior peduncle attaches to midbrain
Middle peduncle to pons
Inferior peduncle to medulla
Flocculonodular lobe
Related to vestibular system for balance and gait control
Archicerebellum
Cerebellum anterior surface
Related to proprioceptive system
Paleocerebellum
Cerebellum posterior surface
Related to skilled movement with control over intention tremor
Neocerebellum
Inferior cerebellar peduncle
Input from auditory nerve, spinal cord, and medulla
At medulla level
Middle cerebellar peduncle
Input from cortex and pons
At pons level
Superior cerebellar peduncle
Output from cerebellum to thalamus to cortex
At midbrain level
Cerebellum purpose
Feedback and corrective system for coordination
Receives inputs from all levels of nervous system
Inputs to cerebellum
Brainstem - pons, reticular formation, medulla, midbrain
Spinal - spinocerebellar tracts
Cerebellum outputs
Red nucleus
Thalamus
Reticular nuclei
Vestibular nuclei
