Neuroanatomy Flashcards
Regions of the brain from caudal to rostral
. Brainstem (medulla, pons, and midbrain) and cerebellum
. Diencephalon
. Telencephalon
What regions make up cerebrum?
Telencephalon and diencephalon
What is considered the axial structure of CNS?
. Spinal cord and brainstem
. Receive and send info from/to periphery through peripheral organs (nerves)
What is considered Supra-axial part of CNS?
. Cerebrum and cerebellum
. Communicate w/ periphery only through axial CNS (besides olfaction)
Spinal cord functions
. Receives primary sensory inputs from receptors in skin, skeletal m. And tendons, and from receptors on thoracic, abdominal and pelvic viscera, sensory input may have spinal reflexes, conveyed higher on neuraxis, or both
. Contains ascending(project to rostral structure) and descending (to spinal motor neurons) fibers
. Contains somatic motor neurons and visceral motor neurons that innervate skeletal and smooth mm.
Ventral (ant.) median fissure
. Ant. Spinal a. Courses here
Ventrolateral sulcus
. 2 of them
. Ventral rootless attach here
Dorsolateral sulcus
. 2 of them
. Dorsal rootlets attach here
. Post. Spinal aa. Located just medial to these
Dorsal (post.) median sulcus
. Less conspicuous than ventral median fissure
Dorsointermediate sulcus
. 2 of them
. Seen only at servical and upper thoracic spinal levels (C1-T6)
. Fasciculus gracilis is med. to this sulcus
. Fasciculus cuneatus is lat. to sulcus
Basic development of spinal cord
. Alar plate gives rise to sensory area of dorsal horn ( receives general somatic and visceral afferent from central process of DRG neurons)
. Neurons give rise to axons of several long ascending sensory pathways
. Basal plate gives rise to motor neurons of ventral horn, axons exit spinal cord to be ventral roots (general somatic and visceral efferent)
Gray matter in pineal cord
. Dorsal and ventral horns and intermediate one where horns meet
. Shaped as an H
Laminae I-VI are from ___
Dorsal horn
Laminae VII from ___
Intermediate gray matter
Laminae VIII and IX from ___
. Ventral horn
. VIII is interneurons
. IX is alpha motor neurons
Lamina X comes from ___
. Midline area of gray matter around central canal
Dorsal horn
. Sensory horn of spinal cords bc it receives DRG neurons
. Substantia gelatinosa (Lamina II) is most distinct structure
. Laminae III and IV are located below the substantia gelatinosa and groups as nucleus proprius
. Laminae V and VI form base of posterior horn
Intermediate zone
. Extends from area of central canal to lat. edge of spinal gray
. Varies in shape at different levels of cord
. Characteristic of lamina VII at thoracic and upper lumber levels and have posterior thoracic nucleus (dorsal nucleus of Clarke) and lateral horn that contains nuclei assoc. w/ GVA or GVE
Ventral horn
. Motor horn
. Alpha motor neurons are GSE and form ventral roots of spinal n. To then directly innervate skeletal m.
. Lamina IX has alpha motor neurons but also gamma motor neurons that innervate muscle spindles
. Large motor neurons are organized into 2 general but overlapping patterns: cells innervating prox. Muscle are med. and cell innervating distal mm. Are progressively lat. 4
Regions of white matter
. Posterior funiculus
. Lateral funiculus
. Anterior funiculus
. Each is composed of individual tracts/fascicule
. Part of anterior white commissary and posterolateral tract (Lissauer’s tract)
Posterior funiculus
. Btw post. Median sulus and median edge of post. Horn
. Contains only ascending tracts (epicritic touch and conscious proprioception)
. Above T6 has gracilis and cuneatus fasciculi (both together referred to as posterior columns)
. Below T6 is just fasciculus gracilis
Lateral funiculus
. Located btw posterolateral and ventrolateral sulci
. Contains both ascending and descending tracts
. Dorsal to ventral: dorsal spinocerebellar tract, lat. corticospinal tract, rubrospinal tract, ventral spinocerebellar tract, anterolat. System
Dorsal spinocerebellar tract (DSCT)
. Carries unconscious proprioception to cerebellum
Lateral corticospinal tract (LCST)
. One of the important descending tracts from motor cortices to influence spinal motor neurons to make movement
Rubrospinal tract (RST)
. Descending tract for parallel processing info from motor cortex to spinal motor neurons
. Located just ventral to LCST
Ventral spinocerebellar tract (VSCT)
. Carries unconscious proprioception to cerebellum
Anterolateral system (ALS)
. Carries pain and temp to sensory subcortical and cortical areas
Anterior funiculus
. Located btw anterolat. Sulcus and ventromed. Fissure
. Contains both ascending and descending but is primarily descending
. From lat. to med.: part of ALS, reticulospinal (RST) and vestibulospinal (VST) tracts (descending in charge of controlling involuntary movement), ant. Cortocospinal (ACST) tract
Anterior white commissure
. Located on ant. Midline btw central canal and ventral median fissure
Posterolateral tract (tract of Lissauer)
. Small bundle of lightly myelinated and unmyelinated fibers capping the posterior horn
Cavity of spinal cord
. Central canal
. Caudal continuation of ventricular system of the brain
. Continuous w/ the 4th ventricle
Spinal nerves
. Formbed by junction of the post. And ant. Roots of spinal nn.
. Each nerve contains GSA and GVA from DRG, and GSE and GVE from motor neurons in ventral horn
Brainstem region locations
. Spinal cord is continuous w/ medulla (spino-medullary junction)
. Medulla is continuous w/ pons (Ponto-medullary junction)
. Pons is continous w/ midbrain
. Midbrain is continous w/ diencephalon (mesencephalic-diencephalic junction)
Brainstem regions from dorsal to ventral
. Tectum: dorsal to ventricular cavity
. Ventricular cavity: 4th ventricle (medulla/pons)/mesencephalic aqueduct (midbrain)
. Tegmentum: ventral to ventricular cavity
. Appended structure: most ventral area, occupied by white matter fibers connecting brainstem to other area of CNS
Gray and white matter distribution in brainstem
. Gray matter is divided into clusters or neurons (nuclei) hat are sparse w/in white matter
. Gray matter includes nuclei proper and nuclei assoc. w/ cranial n.
Nuclei proper
. Host neurons in charge of specific functions (relay stations from ascending and descending pathways)
. Mostly involved in circuits w/ CNS w/ no projections to the PNS
Nucleus associated w/ cranial nerves
. Either receive sensory inputs from afferents or are site of origin (where body of motor neuron is) of efferent directed to smooth do skeletal mm. Of head and neck
. Projections to/from nuclei are not always w/in CNS and can become part of PNS
. Found w/in tegmentum and are close to the ventricle
. Sensory nuclei more later. Compared w/ motor
. Visceral nuclei are in mid position compared to somatic
Alar and basal plates in brainstem
. Alar plates shift more lateral compared to the basal plates
Structures present in ventral surface of medulla
. 2 pyramids
. Pyramidal decussation
. 2 olives
. Hypoglossal, accessory, vagus, and glossopharyngeal nn.
Pyramid in medulla
. Located on either side of ventral median fissure
. Represent the corticospinal tracts
Pyramidal decussation
. Occurs at spinomedullary junction
. Majority of fibers in corticospinal tract decussate to enter contralateral spinal cord
Olive in the medulla
. Large, oval swellings lat. to the pyramids on both sides
. Represent the inf. Olivary complexes
Location of CN XII in medulla
. Exits medulla btw olive and pyramid in postolivary sulcus
Location of CN XI in medulla
. Exits medulla lat. to olive in postolivary sulcus
. Occupy caudal portion of postolivary sulcus
. Only the cranial portion is in medulla, not spinal portion
CN X location in medulla
. Exits in postolivary sulcus
. Rootlets interposed btw CN IX ands XI
CN IX location in medulla
. Exits in postolivary sulcus
. Rostral portion of postolivary sulcus
Dorsal surface anatomy of caudal/closed medulla
. . Central canal of spinal cord persists
. Fasciculus gracilis and fasciculus cuneatus begin to synapse on nucleus gracilis and nucleus cuneatus
. Small protrusions on dorsal surface (gracile tubercle and cuneatus tubercle) mark site of nuclei
Dorsal surface anatomy of rostral/open medulla
. Central canal opens into space o the diamond-shaped 4th ventricle
. Junction of central canal and 4th ventricle is the obex
. Dorsal surface of medulla forms floor of 4th ventricle (rhomboid fossa)
. Several protrusions and grooves made by underlying nuclei and tracts in medulla evident in rhomboid fossa
Internal anatomy of medulla
. Contains nuclei proper, nuclei of cranial nn., and ascending/descending tracts
. From caudal to rostral: spinomedullary junction (transition from spinal cord to medulla), caudal medulla (caudal to obex), and rostral medulla (rostral to obex)
What makes up nuclei proper?
. Reticular formation
. Inf. Olivary complex
. Nucleus gracilis
. Nucleus cuneatus
Ascending tracts pathway to medulla
. Originate from spinal cord gray matter (anterolat. System, post. And ant. Spino-cerebellar tracts) and from sensory neurons assoc. w/ DRG (facliculus gracilis and cuneatus) continue into medulla
Descending tracts pathway to medulla
. Originate from cerebral cortex (corticospinal), midbrain (rubrospinal and tectospinal) and pons (reticulospinal and vestibulospinal)
.traverse medulla en route to spinal cord
. Medulla contributes additional fibers to the last 2 fiber tracts
. Corticospinal tract traverse medulla ventrally (appended structures) forming the pyramids
Spinomedullary junction
. Still has central canal, dorsomedian sulcus and ventromedian fissure
. Rostrally has decussation of pyramids
. Gray matter enlarges and new nuclei appear
. Substantia gelatinosa becomes spinal trigeminal nucleus
. Lissauer’s tract becomes spinal trigeminal tract (lat. to spinal trigeminal nucleus)
. Fasciculus cuneatus/gracilis end and their respective nuclei begin dorsal to central canal
. ALS fibers continue as spinal lemiscus
. Dorsal and ventral spinocerebellat tracts stillthere in ventrolat. Position w/in tegmentum
. Can see caudal extent of reticular formation
What occurs at decussation of the pyramids?
. Majority of fibers decussate here to become lat. corticospinal tracts in lat. funiculi of spinal cord
. Descending fibers from cerebral cortex destined to terminate in contralateral ventral horn of spinal cord
Hypothalamic-autonomic tract (HAT)
. Descending pathway from hypothalamus to brainstem autonomic nuclei
. Located in same general area as spinal lemniscus in lat. medullary tegmentum
Caudal medulla
Rostral to spinomedullary junction, caudal to obex
. Central canal does not open to 4th ventricle yet
. Spinal trigeminal nucleus and tract still seen
. Nucleus gracilis/cuneatus both seen
. Most faciculus gracilis is already terminated in nucleus, but some fasciculus cuneatus is still there dorsal to it’s nucleus
. Mid-lat. tegmentum has 3 ascending spinal lemniscus, post. And ant. Spinocerebellar tracts
. Med. lemnischi on top of pyramids ventral o central canal separated by ventromed. Fissure
. Core of tegmentus: reticular formation, internal arcuate fibers
Internal arcuat fibers
. Arise from neurons in nucleus gracilis and cuneatus
. Fibers course ventromed. Direction through medullary tegmentum
. Cross the midline to form contralateral medial lemniscus
Rostral/open medulla
. Central canal enlarges so 4th ventricle seen
. Pyramids, med. lemniscus, spinal lemniscus, ant. And post. Spinocerebellar tracts, and spinal trigeminal nucleus and tracts still there
. Reticular formation has central core of tegmentum
. Inf. Olives lat. to med. lemnischi and dorsal to pyramids
. Many nuclei at inf. Border of 4th ventricle
. Dorsolat. Aspect of medullary tegmentum represented by inf. Cerebrellar peduncles (restiform bodies)
. Med. and dorsal longitudinal fasciculus/le exist
Nuclei in rostral medulla from medial to lateral
. Hypoglossal nucleus . Dorsal motor nucleus of vagus . Nucleus of solitary tract and solitary tract . Vestibular nuclei . Cochlear nuclei . Nucleus ambiguous
Hypoglossal nucleus
. Fairly large, round shaped nucleus
. Hosts motor neurons that give rise to GSE component of CN XII
Dorsal motor nucleus of the vagus
. Immediately lat. to hypoglossal nucleus
. Gives rise to GVE component of CN X
Nucleus of solitary tract and solitary tract
.lat. to dorsal motor nucleus of vagus
. Pale staining w/ fiber tract (tract of solitary nucleus) running right through center
. Giving this nucleus a “bull’s eye” appearance
. Receives visceral afferent (GVA and SVA) info from CNS VII, IX, and X
Vestibular nuclei
. 4 different nuclei: sup., inf., med., lat.)
. Receives special sensory afferent (SSA) from Scarpa’s ganglion assoc. w/ vestibular component of CN VIII
. Complex of nuclei at border btw medulla and pons
. Only med. and inf. Nuclei present in rostral medulla
Cochlear nuclei
. 2 nuclei: dorsal and ventral
. Recessive SSA from ganglion of corti assoc. w/ acoustic division of CN VIII
. Located dorsolat. To And ventrolat. To inf. Cerebellar peduncle respectively
Nucleus ambiguous
. Located dorsal to inf. Olivary complex, med. to spinal lemniscus, and ventral to spinal trigeminal nucleus
. Very difficult to see in myelin stained sections
. Nucleus gives. Rise to special visceral efferent (SVE) Enron’s that contribute to CNS IX, X, and XI
Medial longitudinal fasciculus (MLF)
. Located immediately ventral to hypoglossal nucleus along midline of medullary tegmentum
Dorsal longitudinal fascicule (DLF)
. Just dorsal to hypoglossal nucleus
. Looks like eyebrow above hypoglossal nucleus
Ventral surface anatomy of pons
. Basilar pons: numerous fiber tracts and some nuclei that function in motor system
. Vestibulocochlear n. (2): enter pons at lat. aspect of pontomedullary junction at pronto cerebellar angle
. Facial n. (2): enters/exit med. to CN VIII
. Abducens n. (2): exits at pontomedullary junction lat. to midline
. CN V: enters/exits lat. aspect of pons by coursing through middle cerebellar peduncle
Basilar sulcus
. Shallow groove in midline of basilar pons that carries basilar a.
Dorsal surface anatomy of pons
. Visible when cerebellum is removed
. Corresponds to sup. Triangle of rhomboid fossa
. Most dorsal aspect (tectum) defines floor of 4th ventricle
. Several protrusions and grooves made by underlying nuclei/tracts in pons evident in fossa
. Facial colliculi prominent in caudal pons and represent fibers of CN VII looping over CN VI nucleus
Internal anatomy of pons
. Most ventral aspect is basilar pons
. Has pontine tegmentum that hosts nuclei assoc. w/ CNS
. Rostral continuation of reticular formation and many ascending and descending pathways
. Major ascending pathways: med. lemniscus, spinal lemniscus, ant. Spinocerebellar tract)
. Descending pathways: many tracts originated from cortex or subcortical structures and directed to brainstem and spinal cord (corticospinal tract, corticobulbar tract, rubrospinal tract, and med. longitudinal fasciculus)
Basilar pons
. Contains some proper nuclei of pons (pontine nuclei, sup. Olivary nuclei)
. Contains massive bundle of fibers that course in several directions
. Most oriented horizontally (from side to side) and continue posterolat. In middle cerebellar peduncle
. Has corticospinal, corticobulbar, and corticopontine fibers
. Transverse pontine fibers (Pontocerebellar) course lat. and end forming the middle cerebellar peduncle, some pontine nuclei can be detected in transverse fibers
Regions of pons
. Caudal pons
. Mid pons
. Rostral pons
Caudal pons location and landmarks
. Rostral to pontomedullary junction by facial motor neurons
. 4th ventricle: anatomical boundary btw pons, ventral to pons and cerebellum, dorsal to cavity
. Most cerebellar deep nuclei can be identified dorsal to 4th ventricle
. Region ventral to ventricle is tegmental subdivision, most ventral aspect of pons occupied by basilar pons
. Border btw basilar pons and ventral tegmentum from med. to lat. has med., spinal, and lat. lemnischi
. Lat. to lat. lemniscus is ant. Spinocerebellar tract
. Has core of tegmentum
How are fibers of medial lemniscus organized?
. In a bundle
. Mediolaterally oriented while in medulla they were dorsomedially oriented
Core of tegmentum on caudal pons
. Reticular formation, DLF and MLF white matter structures seen on both side of midline ventral to 4th ventricle
. Ventral to facial motor nucleus is sup. Olivary nucleus
. Dorsal closer to inf. 4th ventricle border has nucleus from cranial nn.
Nuclei from cranial nerves in caudal pons
. Abducens nucleus: med. in dorsal pontine tegmentum w/ GSE, some nerve fibers seen
. Facial motor nucleus: ventrolat., gives rise to SVE of CN VII, nerve fibers seen
. Spinal trigeminal nucleus and tract: lat. in pontine tegmentum, med. to middle cerebellar peduncle and lat. to facial n. Fibers, give off GSA from face
. Vestibular nuclei: 2 of 4 (sup., lat.) present and receive SSA neurons assoc. w/ CN VIII
Pathway of facial n. Fibers in caudal pons
. Axons leave nucleus and travel dorsomedially
. Loop around abducens nucleus to form genu of facial n.
. Axons exit pons at cerebellopontine angle, med. to CN VIII
Midpons location and landmarks
. CN V exits pons
. Corticospinal tract, corticobulbar tract, coerticopontine tract, transverse pontocerebellar fibers, med., spinal., and lateral lemniscus, MLF and DLF, and middle cerebellar peduncles still seen in this section
. Nuclei proper can still be seen
. Lat. to 4th ventricle has sup. Cerebellar peduncles and Ant. Spinocerebellar tract is post. To them
. Nuclei form CNS housed here
Pathway of fibers in an. Spinocerebellar tract in mid pons
. Fibers travel through sup. Cerebellar peduncle to reach cerebellum
Nuclei of cranial nerves in mid pons from med. to lat.
. Motor nucleus of CN V: in dorsal pontine tegmentum med. to CN V fibers, site of origin of SVE component of CN V
. Chief sensory nucleus of CN V: slightly dorsolat. To motor nucleus, receives GSA
. Mesencephalic nucleus of CN V: dorsomedially to chief sensory and motor nuclei btw lat. aspect of 4th ventricle and sup. Cerebellar peduncle
Rostral pons location and landmarks
. 4th ventricle narrows (is aqueduct in midbrain)
. 4th ventricle surrounded by periventricular gray that becomes periaqueductal gray
. Basilar pons still there
. Corticospinal, corticobulbar, corticopontine tracts, transverse pontine pontocerebellar fibers and pontine nuclei still there
. All 3 lemniscus and DLF and MLF still there but DLF is immersed w/ periventricular gray
. Sup. Cerebellar peduncles shaped as 2 ( on both side of ventricle
. Reticular formation still in core of tegmentum ventral to MLF
. Only nuclei from CNS is mesencephalic nucleus and tract of CN V in same position
Ventral surface anatomy of midbrain
. Crus cerebri (2): cerebral peduncles w/ several fiber tracts
. Interpeduncular fossa: space btw crus cerebri
. CN III (2): exits midbrain through interpeduncular fossa
Dorsal surface anatomy of midbrain
. Tectum (corpora quadrigemina): 2 pairs of elevations (sup. Colliculi and inf. Colliculi)
. CN IV (2): exits midbrain on its dorsal surface just caudal to inc. colliculi
Internal anatomy of midbrain
. Mesencephalic aqueduct (cerebral aqueduct of Slyvius) is continuoation of 4th ventricle
. Tectum
. Most ventral aspect is represented by appended structures (crus cerebri/cerebral peduncles) occupied by corticospinal, corticopontine, and corticobulbar tract)
Components of tectum in midbrain
. Corpora quadrigemina: inf. And sup. Colliculi
. Periaqueductal gray: pale staining surrounding aqueduct
. Ventral to aqueduct has tegmentum w. The rest of the nuclei assoc. w/ CNS and some nuclei proper of midbrain (red nucleus, substantia Nigra, reticular formation) and ascending/descending tracts
Levels of midbrain
. Caudal midbrain
. Rostral midbrain
. Mesencephalic-diencephalic junction
Caudal midbrain location and landmarks
. At level of inf. Colliculi and can recognize lat. tectum
. Surrounding colliculi in ventrolat. Position has C-shaped lat. lemnischi
. Median position has aqueduct and periaqueductal gray w/ DLF in ventrolat. Aspect
. Tegmentum on both sides of midline ventral to periaqueductal gray has MLF
. Lat. to MLF is trochlear nucleus
. Has core of tegmentum
. 2 appended structures occupy most ventral part of this section don’t belong in midbrain and are still part of basilar pons
Pathway of CN IV nerve fibers
. Nucleus is site of origin for GSE component of CV IV
. Fibers exit nucleus and course dorsolat. And caudally in midbrain
. Fibers decussate and exit brainstem on dorsal surface immediately caudal to inc. colliculi
. Only CN exiting brainstem dorsally
Core of tegmentum in caudal midbrain
. Occupied by decussation of sup. Cerebellar peduncles
. Reticular formation in lat. tegmentum
. Inferolat. To reticular formation are ascending menischi that are shaped like boomerang while
What makes up ascending menischi?
. Medial lemniscus forms long arm of the boomerang
. Spinal lemniscus forms shorter and more lat. arm of the boomerang
Rostral midbrain location and landmarks
. Level of sup. Colliculi that form 2 tectum elevations
. Lat. lemniscus not present (terminated in inf. Colliculus)
. Brachium of inf. Colliculus is lat. to spinal and med. lemniscus
. DLF, MLD, reticular formation, and periaqueductal gray in same place as caudal midbrain
. Central tegmentum has sup. Cerebellar peduncles coursed by fibers of CN III
. Nuclei assoc. w/ CNs
. Substantia nigra at border btw ventro-lat. tegmentum and crus cerebri
Fiber pathway of CN III
. Originate from homonymous nucleus
. Exit brainstem, from interpeduncular fossa
Type of neurons in substantia nigra
. Dopaninergic
. Utilize dopamine as neurotransmitter
Nuclei assoc. w/ cranial nerves in rostral midbrain
. Edinger-Westphal nucleus: small, ventral to periaqueductal gray on both sides of midline, gives rise to GVE of CN III (preganglionic parasympathetic)
. Oculomotor nucleus: V-shaped complex in midline ventral to periaqueductal gray btw 2 MLF and edinger-westphal nuclei, gives rise to GSE part of CN III
Mesencephalic-diencephalic junction
. Most rostral border before entering midbrain
. Dorsal to periaqueductal gray fibers of post. Commissure are partially visible
. All structure in rostral midbrain still here
. Brachium of sup. Colliculi in most dorsolat. Aspect of tectum (lat. to sup. Colliculi)
. Red nucleus
Red nucleus
. Nuclei proper of midbrain
. Involved in many ascending and descending projections btw different structures along sensory and motor pathways
. Paint of egg shaped nuclei in med. tegmentum immediately med. to substantia nigra
. Surrounded by fibers of sup. Cerebellar peduncle and central tegmental tract
. Nucleus has a pinkish appearance in fresh preparations
Cerebellum
. Occupies most of post. Cranial fossa
. Lays dorsal (post.) to brainstem that is connected by 3 bundles called cerebellar peduncles that connect brainstem to cerebellum
Peduncles of cerebellum
. Inf. Cerebellar (2): restiform body that connects medulla to cerebellum
. Middle cerebellar (2): brachium Pontis, connects pons to cerebellum, CN V goes through this
. Sup. Cerebellar (2): brachium conjunctivum, connects midbrain to cerebellum
Surface anatomy of cerebellum
. Folia (transverse folds) separated by shallow sulci or deep fissures
. Deep primary fissure that separates it into ant. And post. Loves in sup. Point of view
. Flocculonodular lobe visible in ventro-dorsal view
Cerebellar folia function
. Inc. the SA of cerebellar cortex
. More than half of all neurons in entire CNS are in cerebellum
Functional subdivision of cerebellum
. Vermis: midline region
. Lat. hemispheres (2): lat. to vermis, occupy bulk of cerebellum
. Paravermis: in lat. hemispheres bordering vermis
. Flocculonodular lobe (2): nodulus located in inf. Part of vermis on midline and flocculi located lat., smallest lobe
Internal anatomy of cerebellum
. Consists of cerebellar cortex and nuclei (gray matter) and deep layer of white matter carrying info to/from cerebellum
. Folium organized into molecular, purkinje cell, and granular layers from external to internal
. Subcortical arbor vitae (white matter) below granular layer has branched appearance
. Deep in medullary center has 4 paired nuclei that is mandatory station along efferent pathways (cerebellofugal)
Arbor vitae
. White matter in cerebellum
. Consists of fibers arriving (afferents to cortex) or leaving (efferent of cortex) the cerebellar cortex
Paired nuclei from medial to lateral in cerebellum
. Fastigial: near midline, spherical shape
. Globose: lat. to fastigial
. Emboliform: lat. to globose nucleus, slightly larger and oval shaped
. Dentate: most lat., largest, and most complex of the nuclei
Diencephalon
. Continuous w/ midbrain
. Most caudal part of cerebrum
Surface anatomy of diencephalon components
. Mid-sagittal section divides 3rd ventricle on midline
. Thalamus and hypothalamus are just lat. to 3rd ventricle
. Hypothalamic sulcus separated thalamus (dorsal/sup.) from hypothalamus (ventral/inf)
. Massa intermedia (interthalamic adhesion: in 70% brains, connection btw thalami w/ no function
. Maxillary bodies (2)
. Tuber cinereum and median eminence
. Epithalamus
. Subthalamus (2)
. Eye (2)
Thalamus
. Egg-shaped nuclear complex, largest part of diencephalon
. Relay center for all sensory info except olfaction
. Relays info from basal ganglia, cerebellum, and reticular formation of brainstem to cerebral cortex
What is the ventral surface of the brain in diencephalon made up of?
Hypothalamus
Maxillary bodies
. 2 of them
. Part of the hypothalamus
. Present just rostral to midbrain
. Marks the caudal extent of hypothalamus
Tuber cinereum and median eminence
. Intermediate regions of hypothalamus post. To stalk of pituitary
. Form floor of 3rd ventricle
. Infundibulum of pituitary attaches here
. Optic chasm is not part of hypothalamus but can be seen just rostral to infundibulum
Epithalamus
. Dorsal structure of diencephalon
. Consists of pineal gland and several micro nuclei (habenula)
. Main function os pineal gland is to secrete melatonin
Subthalamus
. 2 of them
. Located ventral and caudal to hypothalamus
. Nucleus functions in motor systems
Eye connection to diencephalon
. Posterior portions of the eye (retina) developed from diencephalon
Internal anatomy of thalamus
. External medullary lamina: lat. shell of thalamocortical and corticothalamic fibers, Separates thalamic reticular nucleus from rest of thalamus
. Internal medullary lamina: inward extensions of thalamocortical and corticothalamic fibers used to divide thalamus into 4 regions
Regions of thalamus
. Lat. nuclear group
. Med.
. Ant.
. Intralaminar
Nuclei of thalamus in lateral nuclear group and functions
. Med. geniculate nucleus (MGN): receives auditory inputs
. Lat. geniculate nucleus (LGN: receives visual input
. Ventral posterolat. Nucleus (VPL): sensory info from body
. Ventral posteromed. Nucleus (VPM): sensory info from head
. Ventral lat. nucleus (VL): input from cerebellum and basal ganglia
. Ventral ant. Nucleus (VA): input from cerebellum and basal ganglia
Nuclei of medial nuclear group and functions
. Dorsomedially nucleus (DM)
. Integral part of lambic system circuitry
Nuclei of thalamus in anterior nuclear group and functions
. Anterior thalamic neurons (A)
. Integral part of lambic system circuitry
Hypothalamus
. Ventral to thalamus
. 0.3% brain but controls ANS and endocrine system
. Indirectly controls homeostasis
Nuclei of hypothalamus and functions
. Paraventricular: fluid balance, ANS and ant. Pituitary control, milk, parturition
. Preoptic: lat. ant. Thermoregulation, sexual behavior
. Anterior: same as preoptic
. Suprachiasmatic: biological rhythms
. Supraoptic: fluid balance, milk, parturition
. Dorsomedial: emotion (rage)
. Ventromedial: appetite, weight, insulin reg.
. Arcuate: ant. Pituitary, feeding
. Posterior: thermoregulation
. Maxillary: emotion, short term memory
. Lateral complex: appetite and weight control
Dorsal longitudinal fasciculus (DLF)
. Assoc. w/ hypothalamus
. Ascending and descending fibers to and from periaqueductal gray and some nuclei assoc. w/ CNs
. Projection has ability to influence preganglionic neurons of both PNS and SNS
Medial forebrain bundle (MFB)
. Assoc. w/ hypothalamus
. Originated from olfactory areas (septum and ventral striatum) and passes through lat. preoptic and hypothalamic zones
. Contains descending fibers directed to brainstem
Hypothalamus-hypophyseal tract
. Neuronal projection connecting hypothalamus to pituitary
. Axons arise from neurons in. Supraoptic and paraventricular nuclei
. Large neurosecretory cells (magnocellular nuclei) in both nuclei produce either ADH or oxytocin
Hypophyseal portal system
. Vascular link from hypothalamus to adenohypophysis
. 2 capillary beds and connecting portal vein
. Hypothalamic releasing and inhibiting factors produced in neurons of arcuate and tuberal nuclei
. Factors released into 1st capillary bed travel down portal vein to adenohypophysis where releasing/inhibiting factors promote/prevent release of hormones in pituitary
Telencephalon
. R/L cerebral. Hemispheres separated on the surface by interhemispheric (longitudinal) fissure
Surface anatomy of telencephalon
. Cerebral cortex: thin sheet of gray matter external to white matter
. Gray matte appears as series of continuous folds (gyri) and sulci
. Several deeper sulci are called fissures
. Hemispheres divided into lobes defined by general ovation of gyri and sulci
. Frontal, parietal, temporal, and occipital have distinct boundaries
. Lambic lobe does not
Frontal lobe boundaries
. Ant. Tip of hemisphere is ant. Limit
. Central sulcus (of Rolando) is post. Limit
. Lat. fissure (of Slyvius) is inf. Limit
. Interhemispheric fissure is its medial limit
Frontal lobe gyri
. Precentral gyrus: ant. And parallel to central sulcus
. Sup., middle, and inf. Frontal gyri: ant. To precenral gyrus, oriented parallel to each other but perpendicular to precentral gyrus
. Orbital gyrus: located on ventral surface of frontal lobes, named for their position relative to the orbital plates of the frontal bones
. Gyrus rectus: med. to orbital gyri, located on ventral and med. surface of frontal lobe, olfactory tract and bulb in sulcus btw gyrus rectus and orbital gyri
Parietal lobe boundaries
. Central sulcus its ant. Limit and the lat. fissure is its inf. Limit
. Interhemispheric fissure is its med. limit
. Post. Limit is imaginary line drawn from parieto-occipital sulcus to preoccipital notch
Parietal lobe gyri
. Postcentral gyrus: post. And parallel to the central sulcus
. Sup. Parietal lobule: pos. To the postcentral gyrus and superior to intraparietal sulcus
. Inf. Parietal lobule: post. To postcentral gyrus and inf. To intraparietal sulcus (has supramarginal gyrus surrounding post. Limit of lat. fissure and angular gyrus surrounding post. Limit of the sup. Temporal sulcus
Occipital lobe boundaries
. Parieto-occipital sulcus and the imaginary line from parieto-occipital sulcus to pre-occipital notch is ant. Limit
. Interhemispheric fissure is its medial limit
. Ventral surface of hemisphere is it’s inf. Limit
. Occipital pole of hemisphere is its post. Limit
Occipital lobe gyri
. Calcarine sulcus on med. surface of the lobe
. Cerebral cortex on either side of calcarine sulcus is called upper and lower ranks of calcarine sulcus
Temporal lobe boundaries
. Lat. fissure of Slyvius is sup. Limit
. Ventral surface of hemisphere is inf. Limit
. Imaginary line from parieto-occipital sulcus to the pre-occipital notch is its post. Limit
. Ant. Tip of temporal lobe is ant. Limit
Temporal lobe gyri
. Sup., middle., inf. Temporal gyri: 3 gyri following long axis of temporal lobe
. Transverse temporal gyri (of Heschl): 2 small gyri on sup., post. Surface of sup temporal gyrus and coursing perpendicular to long axis of sup. Temporal gyrus
. Occipitotemporal gyrus: on ventral surface of temporal lobe, med. to to inf. Temporal gyrus and lat. to parahippocampal gyrus
. Name implies that it extends into the occipital lobe, but that is not always the case
Limbic lobe boundaries
. Indistinct, consists of parts of other lobes and some brains tructures surrounding diencephalon
Limbic lobe Gyri
. Cingulate gyrus: located sup. To corpus callosum, continuous post. W/ parahippocampal gyrus
. Parahippocampal gyrus: best even in ventral view, med. to occipitotemporal gyrus, continuous w/ cingulate gyrus and hippocampus formation, rostral portion has uncus (prominent bump)
formation to forebrain structures
Hippocampus location
. complex structure
. Not seen in surface view
. Located deep to parahippocampal gyrus
. Part of limbic lobe
Fornix of limbic lobe
. large fiber bundle courses in inf. Margin of septum pellucidum, carries outputs from hippocampus
Insular cortex of limbic lobe
. Insular cortex (insula or island of Reil): located deep w/in lat. fissure of Slyvius
T/F basal nuclei can participate in the decision for a movement
T
. Descending pathways can stop and involve the basal nuclei
Classes of white matter in cerebral hemispheres
. Projection fibers
. Commissure fibers
. Association fibers
Projection fibers
. Include fibers originating outside telencephalon and projecting to cerebral cortex (corticopetal) and fibers from cerebral cortex that project to subcortical structures (corticofugal)
Pathway of projection of lemnischi
. Project to thalamus (receives all sensory but olfaction)
. Go from thalamus o specific area of stimulo-specific(devoted to process a certain type of sensory input/specialized sensory cortices/sensory cortex)
Thalamic radiation
. Projections from thalamus ascend through a narrow corridor of white matter (internal capsule)
What happens to projecting fibers after they reach he internal capsule?
. The white matter opens up into corona radiata and then the centrum semilovale (fibers course in all direction looking for their cortical target)f
Projecting fibers in the descending pathway path
. Originate from motor cortices
. Run into the centrum semiovale 1st, then down into the corona radiate and internal capsule (not all, but most)
. Leaves the cerebral cortex and ready to continue down in midbrain (crus cerebri) then pons (basilar pons), medulla (pyramids) and spinal cord where they form specific tracts
Internal capsule
. Large bundle of white matter interconnecting cerebral cortex w/ subcortical structures
. Compromised of:
. Corticospinal projections to spinal cord
. Corticopontine projections to reticular formation
. Corticoreticular projections to brainstem
. Corticothalamic projections to thalamus
. Thalamocortical projections to cerebral cortex
V shaped structure of projecting fibers components
. Anterior limb: btw caudate nucleus and lentiform nucleus
. Post. Limb: btw lentiform and nucleus and thalamus
Genu
. Bend btw ant. And post. Limbs
. Best see in horizontal sections
Commissural fibers
. Fiber bundles connecting structures in. Hemisphere w/ structures in contralateral hemisphere
. Corpus callosum: 300 million fibers divided into 4 parts
. Ant. Commissure: ant. To hypothalamus and inf. To rostrum of corpus callosum, interconnects temporal lobe and olfactory structures
. Post. Commissure: small bundle post. To thalamus that interconnects parts of midbrain
Parts of corpus callosum
. Rostrum: forms ant. Boundary of 3rd ventricle
. Genu: bend w/ fibers interconnecting frontal lobes
. Body: interconnect frontal and parietal lobes
. Splenium: post. Portion interconnects temporal and occipital lobes
Association fibers
. Short or long association fibers that interconnect different areas of the cortex w/in same hemisphere
Gray matter in telencephalon
. Cerebral cortex and basal nuclei
Cerebral cortex
. Thin layer sheet of neurons located on surface of hemispheres
. Variable in thickness and structure depending on cortical layer structure
. Has 6 layers of cortices with different components in each layer
Neocortex
. Phylogenetically newest area of cerebral cortex where neurons are organized in 6 layers
. Comprises of 90% of total cortex
Allocortex
. Phylogenetically old areas of cerebral cortex in neurons organized in 3 layers
. Counts for 10% of cortex
. Subdivisions: paleocortex (primary olfactory cortex) and archicortex (hippocampal formation)
Granule cells
. Multipolar neurons
. Small (under 10 um)
. Short axons do’t leave cerebral cortex
. Function as cortical interneurons
Pyramidal cells
. Cell body are pyramidal-shaped multipolar neurons from 10-100 um in diameter
. Apical dendrite ascend towards outer surface of the cortex while the long axon leaves the cerebral cortex (corticofugal) to project to other cortical areas in same hemisphere (assoc. fibers), other cortical areas of opposite hemisphere (commissural fibers), or subcortical areas (projection fibers)
Betz cells
. Giant 100 um pyramidal cells
. Only found in primary motor cortex
. Largest neurons in CNS
Fusiform cells
. Spindle shaped bipolar neurons located in deepest cortical layer (layer VI)
. Functions as projection neurons to thalamus-corticothalamic projections
Organization of the neocortex
. Most represented type of cortex is neocortex organized in 6 horizontally oriented layers of cells and fibers (axons and dendrites)
. Layers commonly designated by Roman numeral
Layers of neocortex and what is in them
. Molecular I: most superficial and cell free layer, receives assoc. and commissural fibers
. External granular II: many granule cells, receives assoc. and commissural fibers
. External pyramidal III: small pyramidal cells and granule cells, receives and gives rise to assoc. and commissural fibers
. Internal granule IV: granule cells and receives thalamocortical-cortical projections
. Internal pyramidal layer V: larger pyramidal cells that send their axons to subcortical structures
. Multiform VI: contains mostly fusiform cells that send axon to thalamus (corticothalamic projection)
. Cortical columns
. Column extends from surface to underlying white matter so all layers are represented in 1 column
. Incoming cortical afferents from thalamus (thalamic radiations) end in layers III and IV and then course vertically to layer I
. Neurons stacked above and below are similar, but side to side are very different
. Each column is stimulus specific
. Specificity of function is tied to incoming afferent info to each column
Homotypical cortex
. 6 layers are well defined
. Constitutes most of the neocortex of the cerebral cortex and functions primarily as “association cortex”
Heterotypical cortex
. 6 layers not well delineated
. Obscured by predominance of granule cells or pyramidal cells
Granular cortex
. Predominant while few large pyramidal cells are present
. Results in thin cortex
. Does not give rise to many long axions but projects to either adjacent cortical areas or the thalamus
. All sensory cortices are considered to be this
Agranular cortex
. Layers II-V contain abundance of pyramidal cells
. Very thick cortex
. Primary motor cortex and in general all motor cortices are this type
Motor cortices
. Primary motor cortex (Broadman’s area 4) . Premotor cortex (6) . Frontal eye fields (8) . Supplementary motor area/cortex (6) . Broca’s area (44 and 45)
Primary motor cortex location
. Precentral gyrus
Premotor cortex location
. Post. Portions of sup. And middle frontal gyri
. Ant. Portion of precentral gyrus
Frontal eye fields location
. In post. Aspect of middle frontal gyrus
Supplementary motor area/cortex location .
. Medial aspect of sup. Frontal gyrus on med. surface of hemisphere
Broca’s area location
. Opercular and triangular parts of inf. Frontal gyrus in dominant hemisphere only
Sensory cortices
. Primary somatosensory cortex (3, 1, 2)
. Multimodal somatosensory association cortex (5, 7)
. Primary visual cortex (17)
. Unimodal visual assoc. cortex (18, 19)
. Primary auditory cortex (41, 42)
. Unimodal auditory association cortex (22)
. Multimodal auditory association cortex (39, 40)
Primary somatosensory cortex location
. Postcentral gyrus
Multimodal somatosensory association cortex location
. Superior parietal lobule
Primary visual cortex location
. Occipital cortex along the calcarine sulcus
Unimodal visual association cortex location
. Located in cortex which surrounds area 17
Primary auditory cortex location
. Transverse temporal gyri of Heschl on sup. Surface of the sup. Temporal gyrus
Unimodal auditory association cortex location
. Surrounds areas 41 and 42 in sup. Temporal gyrus
. In dominant hemisphere overlap w/ wernicke’s area
. Involved in speech/language functions
Multimodal auditory association cortex location
. Localized in inf. Parietal lobule
Basal nuclei
. Large masses of gray matter (nuclei or nuclear complexes) located deep w/in each cerebral hemisphere
Basal ganglia
. Located deep w/in each cerebral hemisphere
. Composed of caudate nucleus, putamen, and globus pallidus (collectively called corpus striatum)
Caudate nucleus
. Shaped nucleus hat borders portions of the lat. ventricle
. Separated from putamen and globus pallidus by the ant. Limb of internal capsule
Putamen
. Located lat. to globus pallidus
Globus pallidus
. Located med. to putamen
. Separated from thalamus by post. Limb of internal capsule
Term for putamen and caudate nucleus
Striatum
Term for putamen and globus pallidus
Lentiform nucleus
Lateral ventricles
. C-shaped space w/ 1 ventricle in each cerebral hemisphere
. Septum pellucidum separates the 2 lat. ventricles in the midline
Subdivisions of each lateral variable
. Anterior horn: located in frontal horn
. Body: located primarily in parietal lobe
. Post. Horn: in occipital lobe
. Inf. Horn: temporal lobe
. Trigone: area in which the body, post. And inf. Horns converge
Interventricular foramen of Monro
. 2 of them
. Openings that connect each lat. ventricle w/ the 3rd ventricle
3rd ventricle
. Slit-like space on midline
. Unpaired
. Separates diencephalon of each cerebral hemisphere
Cerebral aqueduct of Slvius
. Small channel w/in midbrain that connects 3rd and 4th ventricles
4th ventricles
. Diamond-shaped space located on the dorsal surface of the pons and rostral medulla
. Inf. Portion of the ventricle tapers caudally, and at the obex
. Becomes continuous w/ central canal of the spinal cord
Foramen of Magendie
. Impaired, midline opening in inf. Medullary velum (sheet of tissue covering 4th ventricle)
. Allows communication w/ subarachnoid space
Foramina of Luschka
. 2 of them
. Lateral opening on each side of the 4th ventricle
. Close to pontomedullary junction
. Allows communication w/ subarachnoid space
Central canal
. Channel w/in spinal cord
. Filled w/ CSF and cellular debris
. Flow of CSF through central canal is slow and inconsistent
Dura mater
. Outermost membrane
. Outer endosteal and inner meningeal laminae
. Separated only where venous sinuses run btw the 2 laminae
. Meningeal lamina forms 4 inward-projecting folds to compartmentalize the brain (falx cerebri, falx cerebelli, tentorium cerebelli and diaphragm sellae
Arachnoid mater
. Thin Web-like membrane consisting of delicate CT stands btw dura and pia
. Subdural space btw dura and arachnoid
. Subarachnoid space btw arachnoid and pia and is filled w/ CSF
. Certain areas of subarachnoid space are expanded (subarachnoid cisternae)
Pia mater
. Innermost membrane directly on the brain
. Follows all the gyri and sulci of the brain
. Extends into the 4 brain ventricles and the capillary network of this portion of pia becomes the choroid plexus
