Anatomy Flashcards
What is gastrulation ?
Conversion of the bilaminar embryo to a trilaminar embryo
What germ layer gives rise to the brain and CNS?
Ectoderm; specifically neuroectoderm which divides into neural crest cells and neural tube (forms CNS).
What are some examples of neural tube defects?
Anencephaly- failure to close the cranial neuropore at day 25. Essentially born without a calvarium. Spinal bifida- 3 types: Meningocele-protrusion of meninges Meningomyelocele-protrusion of menings and spinal cord Rachischisis (ra-kiss-ca-sis)- open neural tube Solved with folate/B-12
What is neurulation and when does it take place?
Neurulation- folding of the neural plate into a closed tube of ectoderm. 16-24 days Neural plate, elevates, folds and fuses 25 closure of cranial neuropore 27 closure of caudal neuropore
Describe the segmentation of the neural tube; when it takes place and what adult structures arise from these segments
prosencephalon (forebrain) Mesencephalon (midbrain) Rhombencephalon (hindbrain) Prosencephalon: telencephalon: cerebral hemispheres Diencephalon: thalamus, epi, hypo mesencephalon: Tectum, tegmentum, and cerebral peduncles Rhombencephalon: Metencephalon-pons and cerebellum Myelencephalon-medulla
When do sulci and gyri form in the brain, and what is there purpose?
Between 20-30wks Help increase surface area in the brain Brain also increases in size from the 3rd trimester through early childhood as the result of myelination
How does the eye form? What are some congenital defects associated with improper formation?
Optic grooves–> optic vesicles–> vesicle and stalk invaginate and form the choroid fissure and optic cup–> inner layer of the cup becomes the neural retina Coloboma can result if there is incomplete closure of the choroid fissure
What are the embryonic beginnings of the spinal cord?
3 layers Ventricular-become central canal (sulcus limitans narrows) Mantle layer= alar plate then grey matter Marginal layer= basal plate then white matter (margin or border which forms outside)
How does the spinal cord change positions?
The end of the spinal cord (medullary cone) ascends into adulthood to L1. The cauda equina descends to about S1. The dural sac inferior to the spinal cord is attached to the spinal cord and descends just past the cauda equina and is connected by the filum terminale; the the attachment of the dura mater goes all the way to the tailbone.
what are neurocristopathies?
Disorders related to neural crest cell progeny throughout the body. i.e. DeGeorge syndrome
What’s the function of the neural crest
The peripheral nervous system develops from neural crest cells This includes afferent and efferent neurons coming of the alar and basal plates Cranial nerve sensory ganglia Sympathetic and parasympathetic post ganglionic neurons Even found in hind gut-Hirschsprung’s disease results from a failure of neural crest migration to this location=constipation w/o obstruction
The lateral striate and anterior choroidal artery are a branch of which larger artery? What area of the brain do they supply blood to?
Internal carotid artery Inner capsule along with many other locations
Most of the external face receives blood supply from which major artery? What is one major exception?
External carotid artery Ophthalmic artery
You loose sensation in your lower body due to a vascular ischemia. What’s the most likely location? A) vertebral artery B) Basilar artery C) Anterior cerebral artery D) Middle cerebral artery
C- anterior cerebral artery supplies the midline of the brain near the division of the hemispheres. According to the humunculus this is primarily the location of lower body sensation.
A patient comes into the clinic with some neurologic vascular impairment. Your attending tells you it’s an occlusion of one of the major brain arteries. What’s the most likely location of this occlusion?
Posterior cerebral artery
What artery primarily supplies the internal capsule? Which supplies it somewhat?
Middle cerebral artery IC
Where is the most likely location of a berry aneurysm? Why is this such a dangerous location for an aneurysm?
anterior and then posterior communicating arteries Circle of Willis is a major crossroads of vessels and nerves.
After entering the cranial cavity through the dural roof of the cavernous sinus aka the ______, this artery immediately branches under CN II forming what artery, before bifurcating again into two major arteries of the cerebrum. What artery is this?
diaphragma stellae ophthalmic artery This is the IC artery
The tentorial notch is part of what structure? Where are the attachment points for this structure?
Tentorium cerebelli Anterior and posterior clinoid processes of the sphenoid bone
your patient goes blind in the left eye, what is one possible explanation that makes sense? A) The red neck drank methanol by mistake B) CN II tumor C) ophthalmic artery occlusion D) Posterior cerebral artery ruptured E) All of the above
E is correct
What are some signs of a ACA stroke? MCA stroke?
Possible signs of ACA stroke: Sensorimotor deficits in contralateral foot & leg (crossing over) Urinary incontinence (lower body sensory information is vascularized by this artery; humunculus) Contralateral frontal lobe signs? Possible signs of MCA stroke: Severe sensorimotor deficits in contralateral face & _upper limb. _With dominant hemisphere involvement → global aphasia (left side; written & spoken language) With nondominant hemisphere → amorphosynthesis (no sensation on one side of the body)
What could you expect to occur with a vertebral-basilar artery occlusion?
This supplies all parts of the posterior cranial fossa
Ipsilateral pain & temp loss on face (V; pons) & contralateral loss on body (lateral spinothalamic tract). These arteries feed the cerebellum so most problems will be ipsilateral.
Wallenberg’s syndrome
The corpus striatum and the internal capsule are vascularied by which arteries?
Thalamus?
Mainly MCA
some IC
Posterior communicating arterys
basilar
PCA
Define the following terms:
Hemiparesis
Aphasia
Ataxia
Agnosia
Anopia
Hemiparesis-weakness of either the left or right side of the body
Aphasia-Difficulty comprehending or expressing language
Ataxia-lack of volluntary coordination of muscle movements
Agnosia-inability to process sensory information
Anopia-defect in the visual field
How would occlusion of each of the following arteries be manifest?
ACA
MCA
PCA
IC
ACA
Contralateral Hemiparesis and
hemisensory loss, mainly leg and foot
MCA
Contralateral hemiparesis and
Hemisensory loss, mainly face arm
Aphasia (dominant hemisphere)
PCA
Visual agnosia
Contralateral homonymous
Hemianopia, contralateral sensory
Loss (thalamus)
Internal Carotid
May be well compensated
Similar to MCA
