Exam 1 LO's Flashcards
What is the Neural Plate?
- Thickening of Ectoderm
- The neural plate forms from surface Ectoderm. It is a thickening of neuroectoderm. It will contribute to the formation of the neural tube. Forms during week 3.
What is the Neural groove?
- Folding of plate to form longitudinal groove
- The neural groove is a shallow median groove of neural plate between the neural folds of an embryo. It’s a thick sheet of ectoderm surrounded by the neural folds, two longitudinal ridges in front of the primitive streak of the developing embryo.
Will form the neural tube and neural crest
What is the Neural folds?
- Raised Edges
- A structure that arises during neurulation: Dorsal edges of neural plate
What is the neural tube?
Forms during week 4: Will lead to the brain and spinal cord. The process of its formation is called neurulation
-Neural folds increase in heist and meet in the midline to form neural tube
When do the Neural structures (Folds, Tube, groove plate) Form?
What embryonic tissue do they form from?
Week 3-4
Ectoderm
What are the 3 layers that develop from the walls of the neural tube and what is the adult analog?
- marginal layer (outer)– White matter
- Mantle (middle) – Grey matter
- Ependymal (Inner)– Lining of ventricles
What neural structures develop from neural crest?
Neural crest is specialized ectoderm derived and forms: DRG, Spinal N., Ganglia (CN and ANS) Adrenal Medulla, Meninges
- Neural crest= tissue between neural tube and ectoderm
The spinal cord develops from:
Neural Tube
What are the primary vesicles of the Brain?
List Adult derivative and function too
- Prosencephalon -> Forebrain
- Mesencephalon -> Midbrain
- Rhombencephalon -> Hindbrain
Function: Develop intro brain
What are the secondary Versicles?
- Telencephalon -> Cerebrum
- Diencephalon -> Thalamic structures and optic vesicle
- Mesencephalon -> Tectum and tegmentum
- Metencephalon -> Cerebellum and pons
- Myelencephalon -> Medulla (continue with spinal cord)
Develop week 5
What are the 4 ventricles of the brain?
- Two lateral (paired): develop from telencephalon
- Third Ventricle: Develops from diencephalon
- 4th ventricle : Rhombencephalon
- Cerebral aqueduct: Midbrain (Mesencephalon)
Which Ventricles come from the Prosencephalon?
The two lateral (from telencephalon) and third ventricle (from Diencephalon)
Alar plate and Basal plate:
Spinal cord: Sensory dorsal is alar platean motor ventral is basal plate
Medulla Pons: lateral is Alar plate and Medial is Basal plate
Describe the major sulk of the telencephalon:
Frontal Lobe:
- Frontal pole ot central sulcus (Rolando)
- Lateral Sulcus (Sylvius) separates from the temporal lobe
Describe the major gyro of the frontal lobe:
- Precentral Gyrus
- Superior, Middle, and inferior frontal gyrus: Broca’s area (inferior gyrus L hemisphere)
What is Brocca’s area?
What is Brocca’s Aphasia?
Language output
Brocca’s aphasia: Comprehension is okay but you would have problems putting thoughts into words/meaningful language
What is the primary motor cortex?
- Initiation of involuntary movement
- Pre-motor area prepares primary cortex for paled movements and supplemental area for complex movements
- Found in the precentral gyrus of the frontal lobe
What are the major gyro of the parietal lobe:
- Postcentral gyrus (sensory)
- Inferior parietal gyrus: Wernicke’s area (along with the temporal lobe/sup temp gyrus) Language inputs/comprehension
- Superior parietal gyrus: Spatial organization
What is the primary somatosensory cortex?
The primary somatosensory cortex deals with receiving information: It’s the sensory strip.
- found in the post-cetnral gyrus of the parietal lobe
What are the major gyro of the occipital lobe?
Occipitotemporal gyro
- superior middle and inferior gyri: Wernicke’s area (superior Gyri)
Where is the primary visual cortex?
In the occipital lobe: receives information from contralateral field of vision
-Visual association cortex: Relates visual experiences
Describe Wernicke’s area:
Wernicke’s area is associated with language and speech input issues. Its with damage to this area will have problems understanding sounds and words= aphasia
- located in the superior gyro of the temporal lobe
- If damage speech may be okay but may not make sense
Where is the primary auditory cortex?
Within the lateral fissure (includes the superior temporal gyrus) in the temporal lobe
What is the insular cortex?
The insular cortex is a confluence of the parietal, frontal and temporal cortices. It functions in emotion, homeostasis, awareness and motor control. It’s deep to the lateral sulcus, and you have t peel apart the brain to see it.
What structures compose the diencephalon?
Epithalamus: Pineal gland, melatonin=circadian rhythms)
Thalamus: ( borders the 3rd ventricle, has major significance for most functional systems, including motor and sensor–
Hypothalamus: Major visceral control center (ANS). connects to the pituitary gland, is inferior to the thalamus
What are the prominent structures located in the mesencephalon?
The mesencephalon is the name for the midbrain. It is continuous rostrally with the diencephalon, and caudally with the pons, and is the smallest part of the brainstem.
- Tectum (roof):
- superior colliculus=vision
- inferior colliculus= hearing - Tegmentum (floor/ventral):
- At the base of the tetum
- contains nuclei of CN III, IV, V - Cerebral peduncles:
- connection between the spinal cord and cerebral hemispheres
- CN III emerges between the peduncles
What are the prominent structures of the mesencephalon?
- Pons:
- Basilar (ventral) and pontine tegmenjtum (dorsal)
- Relays sensory info between the cerebellum and cerebrum
- Arousal, sleep, controlling autonomic functions
- Associated with Cn V, VI, VII and VIII - Cerebellum
—Anatomical subdivisions—
- Anterior lobe:
Unconscious proprioception (position in space)
- Posterior lobe:(1)Fine motor
(2) Inhibits involuntary movement - Flocculonodular lobe
(1) Eye movement and postural adjustments to gravity
(2) Receives input from CN III - Anatomical subdivisions: sagittal
i) Vermis (wormlike)
ii) Cerebellar hemispheres
Additional question: What are the prominent structures of the myelencephalon?
Medulla oblongata:
1) Lower part of brainstem, continuous with spinal cord 2) Respiratory, cardiac, and vasomotor center
3) Area postrema-
Where is the area postrema and what is its significance?
The area postrema is part of the myelencephalon. It is the base (caudal end) of the 4th ventricle. It controls vomiting- senses toxins and can trigger vomit reaction to expel toxins.
No blood brain barrier Chemoreceptor area
What is the function of the cerebellum
Motor control, timing and coordination
What are the primary cerebellar lesion symptoms
Ataxia:
1) Decomposition of movement (non fluid)
2) Dysmetria (overshoot/undershoot- inaccuracy)
Common cerebellar lesions:
Midline
a) Trunk instability/tremors
b) Gait ataxia- irregular steps with veering off c) Test for tandem gait/station/walking
2) Cerebrocerebellum
a) Motor planning of highly skilled sequences
b) Speech ataxia
c) Ataxia of extremities
d) Check for finger to nose/toe to finger/heel to toe/rebound/speech
Describe the differentiation of the spinal cord:
1) Sulcus limitans: longitudinal groove found in the floor of the 4th ventricle- separates the alar and basal plate
2) Neural tube - spinal cord
a) Alar plate (sensory) is found dorsal
b) Basal plate (motor) is found ventral
3) Neural tube - pons/medulla
a) Roof plate expands and becomes the roof of the 4th ventricle
b) The alar lamina occupies the lateral part of the floor of the 4th ventricle,
rather than the dorsal horn layout found in the spinal cord, due to the ways the tissues expand. The basal lamina is more medial.
Flexures:
1) Cephalic flexure, between the midbrain and hindbrain
2) Pontine flexure, between the metencephalon and myelencephalon
3) Cervical flexure, between the brain and spinal cord
Corpus Callosum:
1) Connects the right and left hemispheres
2) Facilitates communication between the 2 hemispheres- integrates
motor/sensory/cognitive activity of both sides
3) Largest white matter structure in the brain
Hippocampus:
- Located in the temporal lobe, adjacent to amygdala
- Emotion, spatial organization, new memories, navigation
- Part of the limbic system
- – Korsakoff’s syndrome = B1 deficiency, alcohol abuse, long term memory gaps, lack of short term memory, and made up memories
Amygdala
- Located in the temporal lobe
- Integrative center for emotions and emotional behavior- typically intense emotions like fear/aggression
Basal Ganglia
- Collection of nuclei located on both sides of the thalamus, above the limbic system
- Contains afferent AND efferent pathways
- Controls cognition, movement coordination, voluntary movement
- — Parkinsons’s, huntington’s, tourette’s, Ocd, Schizophrenia
Where does the spinal cord begin?
The spinal cord begins at the pyramidal decussation/foramen magnum, where some tracts cross.
7 cervical 12 thoracic 5 lumbar 5 fused sacral 4 fused coccygeal
Where does the final cord end?? (Adult and baby)
The spinal cord ends at L1/L2 in adults, extends through the lumbar cistern, though the dural sac extends to S2.
In infants the spinal cord is considered longer because the spinal column hasn’t grown yet. In the image in the packet, it extends to S1 at birth
Where does the dural sac end?
S2, then the filum terminale connects to the coccyx.
Describe the anterior and posterior structures on the surface of the spinal cord:
● The anterior aspect of the spinal cord has the
○ Anterior median fissure (contains anterior spinal artery)
○ Anterolateral sulcus (where the rootlets emerge)
○ Anterior funiculus (contains the ascending/sensory and
descending/motor tracts)
● The posterior aspect has the ○ Posterior median sulcus (NO artery!) ○ Posterolateral sulcus (where rootlets emerge) ○ Posterior funiculus contains the: ■ Fasiculus gracilis (legs) ■ Fasiculus cuneatus (upper extremities)
***These are separated by the posterior intermediate and contain sensory tracts (touch and proprioception)
Describe the major structures on the interior of the spinal cord:
Grey matter:
- Horns
- Grey commissure
- Central canal
White matter:
- Funiculi
- Anterior white commissure
Intermediate zone:
1. Between DH and VH
What structures are located in the anterior horn?
Ventral horn: Motor Neurons (LMN)
What structures are located in the IML (intermediolateral sulcus)
- Clarke’s nucleus: unconscious proprioception, collection of cell bodies
- Autonomic sympathetic (ANS) in the IML
What structures are located in the posterior horn?
Dorsal Horn:
1. Lissauer’s tract: Sensory fibers entering the dorsal horn
- Substantia gelatinosa (SG): spinothalmic tract, sensory info from spine to thalamus. Made up of sensory neurons for the spinothalamic tract
Film Terminale:
Tethered cord- has an internal layer (internis = pia) and an external layer (externis = dura)
Denticulate ligaments:
Pia mater, attaches on either side to the dura and arachnoid layers. 21 attachments total
Lumbar cistern:
The subarachnoid space in which nerves are free floating due to growth of the vertebral column
Cauda equina:
Free floating nerves in the lumbar cistern, form because the vertebral column grows faster than the spinal cord, and the distance between the nerve exiting the spinal cord to exiting the vertebrae increases with growth. (“Horse’s tail”)
Name the Ventricles of the brain:
- Lateral (biggest, paired) - develops in prosencephalon:
- C shaped
- anterior horn, body, atrium, posterior horn, inferior horn
2) Third - develops in diencephalon
3) Fourth- develops in rhombencephalon
4) Central canal
What are the communications between the ventricles?
1) Foramen of monro (interventricular foramen) connects the lateral and the 3rd
2) Aqueduct of Sylvius (cerebral aqueduct) connects the 3rd and 4th
3) Median Aperture (foramen of magendie) of fourth ventricle opens into
the Cisterna magna
4) Lateral Aperture (foramen of Luschka) opens into the pontine cistern
Where is CSF produced and by what?
The choroid plexus produces CSF. Specialized epithelial cells with tight junctions, continuous with the ependymal cells that line the ventricles This has a blood/csf barrier AND a secretory function
Production occurs in all ventricles
CSF is a plasma filtrate, but has a lower concentration of cells/proteins, lower pH than blood
- CSF actively transports ions and passively transports H2)
Describe the circulatory pattern of CSF in the brain & spinal cord.
- Lateral ventricles
a. Foramen of monro/interventricular foramen - Third ventricle
a. Foramen of Sylvius/cerebral aqueduct - Fourth ventricle
a. Median aperture
OR
b. Lateral aperture
Median aperture → Cisterna magna or Lateral Aperture → Pontine cistern *Both are pathways from the ventricular system to subarachnoid space **In cisterna magna, CSF can also go down spinal cord - Subarachnoid space
a. Cerebral hemispheres
b. Spinal cord (from cisterna magna) - Subarachnoid space → dural sinuses for turnover (into venous system) a. Occurs through the arachnoid villi (projections of subarachnoid
space into the dura)
Name the meningeal layers:
A) Dura a) Periosteal b) Meningeal B) Arachnoid C) Pia These layers are continuous around the spinal cord
Name the dural septa:
1) Falx cerebri
a) Separates the two hemispheres
2) Tentorium cerebelli
a) Separates the cerebrum and cerebellum, provides space for
venous channels
3) Falx cerebelli
a) Separates the lobes of the cerebellum. Considered small/insignificant, also has a venous sinus
4) Diaphragma sellae
a) Superior to the pituitary
Name the Dural sinuses:
1) Superior sagittal sinus
a) Runs in falx cerebri, anterior pole to posterior pole
2) Inferior sagittal sinus
a) Runs into straight sinus, does not reach posterior pole
3) Straight sinus
a) Runs between the junction of the falx cerebri and tentorium
cerebelli
4) Occipital sinus
a) Runs in falx cerebelli
NOTE: 1-4 all run anterior to posterior, towards the confluence of the sinuses!
5) Transverse sinuses (R+L)
a) Forms AT the confluence of the sinuses, flow away laterally
6) Sigmoid sinus
a) Turns into the internal jugular, receives blood from the transverse
sinus and the superior/inferior petrosal sinuses
7) Superior/Inferior Ophthalmic vein
a) Drain into the:
8) Cavernous sinus
a) Drains into the:
9) Superior/inferior petrosal sinuses
a) Drain into the sigmoid sinus
What is the dural blood supply?
Anterior Cranial Fossa: Ophthalmic, ethmoidal, and middle meningeal (maxillary)
Middle Cranial Fossa: Accessory meningeal, ascending pharyngeal and
middle meningeal
Posterior Cranial Fossa: Occipital and ascending pharyngeal (off external carotid) and vertebral (off subclavian)
What does the dural nerve supply?
Anterior Cranial Fossa: V1
Middle Cranial Fossa: V1, V2, V3
Posterior Cranial Fossa: CNX, C1, C2 (sometimes C3), V1 (sometimes V2)
Anterior circulation (IC and Branches)
Anterior circulation stems from the internal carotid Supplies mainly the cerebrum
Four parts:
1) Cervical (ascending through neck)
2) Petrous (carotid canal through temporal bone)
3) Cavernous (siphon)
4) Cerebral
a) Anterior -medial frontal/parietal lobes
b) Middle frontal/parietal/temporal lobes
** Ophthalmic artery comes off of the internal carotid
● Central artery of the retina
● Supraorbital and supratrochlear
Posterior circulation (Vertebral and branches):
Posterior circulation stems from the vertebral artery
Supplies the cerebrum, cerebellum, brain stem, upper spinal cord Vertebral Artery
- Vertebral Artery: Supplies medulla, part of cerebellum, and dura of posterior cranial fossa
- Basilar Artery: Formed by the joining of vertebral arteries: goes rostrally. supplies the pons/ occipital lobe/temporal lobe brain stem/cerebelllum
Circle of Willis:
Anterior cerebral arteries
1. Anterior communicating artery joins the cerebral arteries from each side
Posterior cerebral arteries
1. Posterior communicating artery connects the internal carotid and
posterior cerebral arteries
Arterial supply of the spinal cord:
Single anterior,
Paired posterior spinal arteries
Both come off vertebral, run vertical!
Segmental branches:
Radicular arteries, intercostals, anterior and posterior, run horizontally!
Clinical considerations of vasculature:
ischemia: decreased blood flow in any tissue
ITA: transient ischemic attack- any neurological symptoms also transient infarction, tissue death due to long term ischemia
Stroke hemorrhagic stroke is an arterial rupture
Notes:
● Occlusion of the middle cerebral artery accounts for 90% of infarcts and 2⁄3 of strokes
