Lecture 0 (DSA): General Terminology and SC Morphology Flashcards
What is Gray vs. White Matter?
Gray: areas containing neuronal/glial cell bodies and dendrites
White: areas where there is a collection of axons; many covered w/ myelin
Fasciculus, funiculus, lemniscus, peduncle and tract are ALL terms for?
White matter
Most tracts have 2-part names, what is the 1st and 2nd part referring to?
- 1st part: location of neuronal cell bodies from which axons originate
- 2nd part: site the axons terminate
What is the thin strand of pia mater that helps anchor the conus medularis to the coccyx?
Filum Terminale
What are the 2 prominent parts of the Posterior Horn, present at all spinal levels?
1) Substantia gelatinosa: distinctive region of gray matter that caps the posterior horn
2) Body: consists of interneurons and projection neurons that transmit somatic and visceral sensory information
Where is Lissauer’s tract and what does it contain?
- White matter located b/w substantia gelatinosa and surface of cord
- Contains the finely myelinated/unmyelinated fibers with which the substantia gelatinosa deal
What cell bodies are found within the Anterior Horn, why are the important?
- Cell bodies of large motor neurons that supply skeletal muscle, lower motor neurons
- The cells are the means by which the CNS can exercise control over body movements (voluntary or involuntary)
What does the Intermediate Gray Matter contain?
- Autonomic neurons (preganglionic autonomic neurons)
- At specific levels, it also includes Clarke’s nucleus
Pre-ganglionic sympathetic neurons lie in which spinal segments and are found located in what?
- T1-L3
- Found in the intermediolateral cell column
- Forms a pointy lateral horn on the spinal gray matter
What is Ckarke’s Nucleus responsible for and at what levels are they found?
- Collection of large cells located on the medial surface of the base of the posterior horn (T1 to L2)
- Has a prominent role in sensory processing and is typically treated as part of the posterior horn
What are the 10 laminae of the spinal cord gray matter?
What is the nucleus, vertebral levels, and function of the Lamina I (marginal zone) of spinal cord grey matter?
- Nucleus = Marginal zone
- ALL vertebral levels
- Some spinothalamic function
What is the nucleus, vertebral levels, and function of the Lamina II of spinal cord grey matter?
- Nucleus = Substantia gelatinosa
- ALL levels
- Modulate transmission of pain and temperature info
What is the nucleus, vertebral levels, and function of the Lamina III-VI of spinal cord grey matter?
- Nucleus = Body of Posterior Horn
- ALL levels
- Sensory processing
What are the 3 nuclei, vertebral levels, and function of the Lamina VIII of spinal cord grey matter?
1) Clarke’s: from T1-L2
- Posterior spinocerebellar tract cells
2) Intermediolateral column: from T1-L3
- Preganglionic sympathetic neurons
3) Sacral parasympathetic nucleus: from S2-S4
- Preganglionic parasympathetic neurons –> pelvic viscera
What are the 2 nuclei, vertebral levels, and function of the Lamina IX of spinal cord grey matter?
1) Accessory nucleus: from Medulla to C5
- Motor neurons –> SCM and trapezius
2) Phrenic nucleus: from C3-C5
- Motor neurons –> diaphragm
What does the Fasciculus cuneatus (FC) carry vs. Fasciculus gracilis (FG) carry in regards to information?
Fasciculus cuneatus: carries sensory info from the arms
Fasciculus gracilis: carries sensory info from the middle thoracic and lower limbs of the body
What are the 4 prominent sulci which divide each cerebral hemisphere into 5 lobes?
1) Central sulcus
2) Lateral sulcus (fissure)
3) Parietooccipital sulcus
4) Cingulate sulcus
__________ fibers connect cortical areas within the same sulci/gyri
Arcuate fibers
_________ connect cortical areas within the same hemisphere
Longitudinal/association fasciculi
________ tracts connect cortical areas within R/L hemispheres
Commissural tracts
________ tracts connect cortical areas within other body regions
Projection tracts
What is the largest fiber bundle in the brain that connects the two cerebral hemispheres?
Corpus Callosum
The ________ sends commisural fibers to/from temporal lobe
Anterior commissure
What is the insula and where is it found?
- Additional area of cerebral cortex not included in the 5 lobes
- Lies buried in lateral sulcus
- Concealed by portions of frontal, parietal, and temporal opercula
Which 4 gyri make up the lateral surface of the frontal lobe?
1) Precentral gyrus
2) Superior frontal gyrus
3) Middle fronta gyrus
4) Inferior frontal gyrus
Which gyrus of the frontal lobes houses the primary motor cortex?
Precentral gyrus
The premotor and supplementary motor areas occupy which gyri?
- Remainder of precentral, not occupied by primary motor cortex
- Posterior portions of the superior and middle frontal gyri
Which gyri houses Broca’s area and what is it important for?
- Opercular and triangular parts of inferior frontal gyrus (one hemisphere, usually left)
- Important in motor aspects of written and spoken language
Where is the prefrontal cortex and what is it important for?
- Occupies the rest of frontal lobe
- Involved with executive functions, personality, decision making, insight, and foresight
What gyrus and lobules are found in the parietal lobe?
- Postcentral gyrus
- Superior parietal lobule
- Inferior parietal lobule
What are the functions of the postcentral gyrus, inferior parietal lobule and remainder of parietal cortex?
1) Postcentral gyrus: controls w/ processing of tactile and proprioceptive info, and sensory localization
2) Inferior parietal lobule: involved in language comprehension
3) Remainder of parietal cortex has aspects in spatial orientation and directing attention
The contralateral half of the body is mapped in each _______ gyrus in a ________ map, called a ________
The contralateral half of the body is mapped in each postcentral gyrus in a somatotopic map, called a homunculus
The temporal lobe is composed of which 3 gyri, and what additional gyrus makes up the inferior surface?
- Composed of superior, middle, and inferior temporal gyri
- Inferior surface is made up of the broad occipitotemporal (fusiform) gyrus
What 4 functions is the Temporal lobe associated with, including the superior temporal gyrus, inferior surface, and most medial part?
- Superior surface, continuing as a small area of the superior temporal gyrus, is the primary auditory cortex
- Wernicke’s area is located on the posterior portion of the superior temporal gyrus, important in comprehension of language
- Inferior surface is invovled in higher-order processing of visual info
- Most medial part is involved in learning and memory
The primary visual cortex is found where?
- Contained in the wall of the calcarine sulcus of the Occipital lobe
The limbic lobe is mostly composed of which 2 gyri?
1) Cingulate
2) Parahippocampal
The anterior end of the parahippocampal gyrus hooks backward on itself, forming a medial bump, the ________
Uncus
Folded into the temporal lobe at the hippocampal sulcus is the _________
Hippocampus
The Amygdala lies beneath?
The uncus of the temporal lobe
The limbic lobe is important for what 3 things?
Emotional responses, drive-related behavior, and memory
What are the 4 divisions of the Diencephalon?
- Thalamus
- Hypothalamus
- Epithalamus
- Subthalamus
The brainstem is subdivided into what 3 structures?
- Midbrain is continous w/ diencephalon
- Pons
- Medulla, continous w/ spinal cord
What are the Basal Nuclei?
- Group of nuclei that lie deep to the cerebral cortex in each hemisphere
- Caudate and lentricular nucleus (subdivided into putamen and globus pallidus)
- Lentricular nuclei are physically separated from the thalamus and caudate by a thick sheet of fibers, the internal capsule
Primary afferents in the CNS on which neurons, and these neurons then project where?
- Primary afferents terminate in the CNS on second-order neurons, which project to third-order neurons
- Remember afferent = approach the CNS
With a few exceptions, the components of sensory primary afferents are on which side?
Ipsilateral
Second-order neurons relay a signal from ________ (in the periphery) to where; are they able to cross the midline?
- From primary afferents
- To a target in the CNS
- Can cross the midline of the body
Third-order neurons relay info where?
Relay message to a final target in a specific cortical area(s)
Axons of lower motor neurons (LMN) leave th CNS w/o doing what; these cells are the only way the CNS can do what?
- Leave the CNS w/o crossing the midline
- Only way the CNS can cause muscle contraction is by way of LMN’s
LMN’s have their cells bodies within where; what and where do their axons travel through?
- Cell bodies within the CNS (i.e., anterior horn of SC)
- Have axons that travel through peripheral nerves to end on ipsilateral muscle fibers
Which neurons often cross the midline and why is this important?
- Second-order neurons can cross the midline; first-order neurons (afferents) can as well
- Knowledge of crossover points is crucial in deciding where a lesion is
How do Corticospinal axons from the UMN’s travel and what occurs with damage to one cerebral hemisphere?
- Single neurons with very long axons project all the way from motor cortex to the contralateral half of the SC and cross the midline
- Damage to one cerebral hemisphere will result in weakness in the contralateral arm and leg
- Outputs from the cortex do NOT have a relay stopover
