Brain, Brainstem And SC Flashcards
What does the forebrain consist of?
The cerebral hemispheres and deep structures
What is the hindbrain divided into?
Pons, medulla and cerebellum
The midbrain and hindbrain collectively form what?
The brainstem
What is a gyrus?
Ridge of cortical tissue
What is a sulcus?
Groove located between gyri
What are fissures?
Particularly deep sulci
What is gray matter?
Areas containing neuronal/glial cell bodies and dendrites
Includes nuclei and cortex
What is the cortex?
Layers of gray matter over other parts of the CNS (i.e. cerebral and cerebellar cortices)
What is white matter?
Areas where there is a collection of axons, many covered with myelin
Fasciculus, funiculus, lemniscus, peduncle and tract are all terms for white matter
Describe the 2-part naming system for white matter tracts
1st part: location of neuronal cell bodies from which axons originate
2nd part: site where the axons terminate
What are the four prominent sulci that divide each cerebral hemisphere into 5 lobes?
Central, lateral, parietooccipital and cingulate sulcus
What separates the frontal lobe from the parietal lobe?
The central sulcus and the lateral fissure separates it from the temporal lobe
Where are primary motor areas housed?
In the precentral gyrus in the frontal lobe
What do the lateral and medial surfaces of the frontal lobe regulate?
Voluntary motor behavior and deciding which movements should be performed
Motor aspects of language are processed on the lateral surface
What are prefrontal association areas?
Concerned with emotion, motivation, personality, initiative, judgement, ability to concentrate and social inhibitions
Within the frontal lobe
What is the cingulate gyrus?
Within the frontal lobe
Also modulates emotional aspects of behavior
The parietal lobe includes what structures?
Postcentral gyrus, posterior paracentral gyrus, and superior and inferior parietal lobules
What are some functions of the parietal lobe?
Post central gyrus = primary somatosensory cortex which controls with processing of tactile and proprioceptive info
Inferior parietal lobule (one hemisphere usually left) = involved in language comprehension
Remainder of parietal cortex has aspects in spatial orientation and directing attention
What is the homunculus?
Contralateral half of the body is mapped in each precentral (motor) and postcentral (sensory) gyri in a somatotopic map
Map is spatially distorted and reflects the amount of innervation to a given body area
The temporal lobe is composed of what structures?
Superior, middle and inferior temporal gyri
Inferior surface is made up of the board occipitotemporal (fusiform) gyrus
What are the four functions that the temporal lobe is associated with?
Primary auditory cortex: superior surface of superior temporal gyrus
Wernicke’s area: comprehension of language (posterior portion of superior temporal gyrus, also includes part of parietal lobe (supramarginal and angular gyri))
Higher order processing of visual information
Learning and memory
Describe the visual areas of the occipital lobe
Lateral surface contains the lateral occipital gyri
Cuneus is a wedge shaped area b/w parietooccipital and calcarine sulci
Primary visual cortex is contained in the walls of the calcarine sulcus
Remainder of lobe is the visual association cortex which is involved in higher order processing of visual information
What is the limbic lobe?
Not a true discrete lobe but covers parts of the frontal, parietal and temporal lobes
Includes the cingulate gyrus and parahippocampal gyrus
Important in processing complex aspects of learning, memory and emotion
What is the insular lobe?
Lies buried in lateral sulcus and can be seen by prying open the lateral sulcus
Can also remove the opercula (portion of given lobe that is overlying)
-frontal, parietal and temporal opercula
-circular sulcus outlines the insula and marks its borders with the opercular areas of cortex
The diencephalon includes which structures?
Thalamus, hypothalamus, epithalamus (contains the pineal gland) and subthalamus
Third ventricle is associated with it
The thalamus is a gate keeper for what?
The cerebral cortex
What does the hypothalamus regulate?
Hormonal, autonomic and visceral functions
What is the epithalamus?
Connects limbic system to other brain areas and regulates circadian rhythms
What do association fibers connect?
Cortical areas within the same hemisphere
What do commissural fibers connect?
Areas of cortex in one hemisphere with that of the contralateral side
Includes the corpus callosum and anterior commissure
What does the corpus callosum connect?
Interconnects cerebral hemispheres
What does the anterior commissure connect?
Commissural fibers to/from temporal lobe (especially inferior parts)
What are projection fibers?
Carry information to/from the cerebral cortex (corona radiata)
What is the internal capsule?
White matter bundle of fibers traveling via the corona radiata
Divided into limbs each containing specific fibers including anterior limb, genu, posterior limb, sublenticular limb and retrolenticular limb
What structures are within the anterior limb of the internal capsule?
Frontopontine fibers, anterior thalamic radiation and frontal eye field fibers
What structures are within the genu of the internal capsule?
Corticonuclear fibers
What structures are within the posterior limb of the internal capsule?
Pallidothalamic f.
Corticorubral, corticoreticular, corticonigral and corticosubthalamic f.
Superior thalamic rad, corticospinal f, and parietopontine f.
What structures are within the retrolenticular limb of the internal capsule?
Optic radiation
Corticotectal, corticorubral and corticotegmental f.
What are the basal nuclei?
Critical in the initiation and control of voluntary movement
The internal capsule contains most of the fibers interconnecting what structures?
the cerebral cortex and deep structures (thalamus, basal nuclei and brainstem)
Describe the brainstem
Plays major roles in CN function
Conveys info to/from forebrain
Includes midbrain, pons and medulla
Describe the midbrain
Houses the tectum of the midbrain
Superior and inferior colliculi which are paired bumps posterior to the cerebral aqueduct
Paired cerebral peduncles which make up most of the midbrain
Describes the pons
Protruding basal pons and
Pontine tegmentum forms part of the floor of 4th ventricle
Describe the medulla
Rostral open portion, containing part of the 4th ventricle
Caudal closed portion, continuous with the SC
Describe the cerebellum
Functions in sensory info processing and influences motor neurons
Damage can result in problems w/ equilibrium, postural control and coordination
Surface is made up of transverse ridges of gray matter (folia)
White matter in the medullary center
Posterior rootlets enter the SC via what?
Posterolateral sulcus which is a shallow longitudinal groove
Anterior rootlets leave the SC via what?
Anterolateral sulcus
Posterior and anterior rootlets —> posterior and anterior roots —> form what structure?
Spinal nerves
What structures are within the posterior horn of the SC?
Substantia gelatinosa, body and Lissauer’s tract
Clarks nucleus
What is the substantia gelatinosa?
Region of gray matter that caps the posterior horn
What is the body of the posterior horn?
Interneurons and projection neurons that transmit somatic and visceral sensory info
What is Lissauer’s tract of the posterior horn?
White matter located between the substantia gelatinosa and surface of the SC
What is Clark’s nucleus (posterior thoracic nucleus)?
Cells located on the medial surface of the base of the posterior horn (T1-L2)
Prominent role in sensory processing and typically treated as part of posterior horn
Describe the anterior horn of the SC
Cell bodies of lower MNs supplying skeletal muscle
Influenced by different pathways to modulate moments
What is intermediate gray matter?
Collection of projection neurons, sensory interneurons and interneurons
Preganglionic sympathetic neurons (T1-L3) of intermediolateral cell column, form the lateral horn
Sacral parasympathetic nucleus spans S2-4 (no distinct lateral horn)
What are the different laminae of the SC?
Lamina I, II, III-VI, VII, VIII, IX and X
What is lamina I (marginal zone)?
Thin gray matter covering the substantia gelatinosa
What is lamina II?
The substantia gelatinosa
Modulates transmission of pain and temperature info
Explain the interconnections of the NS during voluntary motion
- Primary afferent convey info from the PNS
- Terminate in the CNS on second order neurons
- Relay to lower motor neurons (LMNs) convey info from CNS to skeletal muscle
Example of an ipsilateral pathway (left sided stimulus pulls left hand away)
What are second order neurons?
Relay a signal from primary afferents (in the periphery) to a target in the CNS
Can cross the midline of the body
What are third order neurons?
Relay the message to a final target in a specific cortical area
Cortex decides given output
Axons with similar connections bundle together to form what?
Tracts of the SC
Naming of SC tracts indicates three important facts. What are they?
- If they are ascending or descending (corticospinal vs spinocerebellar)
- Location of the cell body of origin (cortex vs SC)
- Location where the axons will terminate (SC vs cerebellum)
Which tracts are ascending?
Posterior column-medial lemniscus system (PCMLS), spinocerebellar tracts, and anterolateral system (ALS)
What is the posterior column-medial lemniscus system (PCMLS)?
Conveys ipsilateral proprioceptive, tactile and vibratory info from the body (not face)
What are spinocerebellar tracts?
Information relays to cerebellum, thalamus and motor cortex to influence efficiency of motor activity
What is the anterolateral system (ALS)?
Relays pain, temperature and non-discriminative touch from body (not face)
Which tracts are descending?
Corticospinal tract (CST), vestibulospinal tract and rubrospinal fibers
What does the corticospinal tract (CST) control?
Voluntary, fine movements of musculature
What does the vestibulospinal tract influence?
Motor neurons innervating primarily axial and neck musculature
What are rubrospinal fibers?
Excite flexor motor neurons and inhibit sensory extensor motor neurons
What are laminae III-VI?
Body of the posterior horn
Sensory processing
What is lamina VII?
Intermediate gray matter including Clarke’s nucleus
What is lamina VIII?
Interneurons of the anterior horn
What is lamina IX?
Motor neurons of the anterior horn
What is lamina X?
Gray matter surrounding the central canal
