Week 1 Flashcards
What do large venous sinuses do for the CNS?
Act as fluid “cushions” to protect the delicate nervous tissues
What is the ventricular system of the CNS?
Analogous to a plumbing system both within and surrounding the CNS. It contains clear, colorless fluid- the cerebrospinal fluid (CSF) which protects and nourishes the neuraxis
What produces CSF? How many and where?
Choroid plexus which are in each of the four ventricles (all interconnected)
What takes the CSF from the cerebellum into the subarachnoid space?
Lateral apertures under the cerebellum
Where is the CSF in the spinal cord?
In the central canal
What does the ventricular system develop from? And where is each part? Why is the ventricular system important?
It develops from the neural tube of the embryo. There is a different part of the ventricular system for each division of the brain. This helps identify the part of the brain on cross sections
Name the meninges from external to internal
dura mater, arachnoid mater, and pia mater
What is the epidural space? Where is there no epidural space?
External to the dura mater and contains fat and the vertebral venous lexis. It only exists around the spinal cord. It is obliterated in the mid cervical region, C3 (C2 to C4) by fusion of the dura with periosteum. The fusion begins ventrally and is completely circumferential by the level of the foramen magnum. NO epidural space within the cranium, however there is the potential e.g. haemorrhage after trauma (epidural haematoma)
What is the dura mater?
- Dense, tough fibrous covering (composed of dense connective tissue with collagen fibres) that fuses with the periosteum of the cranial vault. - encloses the spinal roots as they leave the spinal cord and fuses with the epineurium at the intervertebral foramen.
Where is the arachnoid mater not present?
Follows the larger contours and issues but not the absolute contours of the CNS. e.g. into the longitudinal issues but not the sulci
What is the pia mater?
-Very delicate membrane which is fused to the contours of the CNS - subarachnoid space lies between the arachnoid and pia mater. It is filled with CSF. - arachnoid trabeculae are fine meningeal filaments that cross the arachnoid space between the arachnoid mater and the pia mater
What is the falx cerebri?
The fold in the longitudinal fissure between the two cerebral hemispheres. Runs from the ethmoid bone to the osseous tantrum. Contains the dorsal sagittal venous sinus draining the dorsal forebrain.
What is the tenorium cerebella?
Fold separating cerebral hemispheres from the cerebellum. Runs from the petrosal crest to the osseous tentorium, bilaterally. Inverted U, the midbrain passes through the notch along the ventral edge. - divides the cranial vault into: -the rostral fossa (rostral to the tentorium and contains the forebrain) - the caudal fossa (caudal to the tantrum and contains the cerebellum and the caudal brain stem). (often ossifies in cats)
What is the diaphragm sella?
Bridges from the dorsal sella to the caudal cloned process of the sphenoid bones near the optic canal area. It can make removal of the entire brain, with pituitary intact, difficult.
What occurs with brain herniation?
Movement of a portion of the brain under another structure. - the inelastic nature of the dural septa and the skull protect the normal brain, but compromise the diseased brain as they limits its ability to swell or adjust to expanding masses. - Swelling of the forebrain may cause herniation under the tentorium cerebella. - Swelling of the brain or any structure within the cranial vault may cause herniation through the foramen magnum
What is the essential information in order to perform a neurological examination?
* organisation of the nervous system and hierarchy of control
* cranial nerve areas and types of innervation and function
* major peripheral nerves and areas of innervation and functions
Essential information in order to interpret a neurological exam
* major structural organization of the spinal cord and brain (and tracts of the spinal cord) (what areas are most vulnerable?? what happens with a bulged disc??)
* Areas of origin of major nerves in the CNS and their function
* Paths of the cranial and peripheral nerves from the CNS to the area innervated
Other important anatomical information for clinical diagnosis in neurological cases?
* Anatomy of the meninges and their associated spaces in brain and spinal cord
* Blood supply to brain and spinal cord
* Formation and resportion areas for CSF and where to sample
Where are the cell bodies for the motor neurons? What about the sensory neurons? What are interneurons?
* Motor nerve cell bodies are in the CNS
* Sensory nerve cell bodies are outside- in a ganglion- not in the spinal cord
* Interneurons connect the two
What is a reflex arc?
The simplest form of communication.
One step further- adding an interneuron
Where is the sensory input? What is the motor output?
Sensory input- dorsal horn
motor output- ventral horn
why is it that a chicken can still run around with it’s head cut off?
Animals with less developed brains, a lot of neurological control is a result of neurological pathways at the spinal level
Basically a series of reflexes!
What reflex is for stability and postural support?
Mobility reflex?
Myotactic
Flexor withdrawal
What is an upper motor neuron?
* UMN are motor neurons that originate in the motor region of the cerebral cortex or the brain stem and carry motor information down to the LMNs (efferents are in the spinal cord and synapse with LMNs or interneurons)
What is a lower motor neuron? What are the levels of control of motor activity?
* alpha motor neuron- final common pathway for motor control– cell body in the spinal cord– impacts on the muscle cell (efferents are alpha motor neurons i.e. supply muscle fibres)
What is meant by the motor system hierarchy?
Motor cortex= senior management
Interneurons in the spinal cord= junior management
Worker= alpha motor neuron- initiating the movement
What is a nucleus?
What is a ganglion?
* Nucleus- Collection of nerve cell bodies inside the CNS- WHITE AND GRAY MATTER.
* Ganglion- collection of nerve cell bodies outside of the CNS- i.e. autonomic ganglia, sensory ganglia
Name three nuclei in the brain stem
* Red nucleus- rubrospinal tract
* Vestibular nucleus- vestibulo-spinal tract
* Reticular formation - reticulospinal tract
What does it mean to say brain stem pathways are EXTRA pyramidal?
Do not travel through the medullary pyramids
What provides most of the refined degree of motor control?
Primary motor cortex
What is the corticospinal tract? Are they pyramidal or extra-pyramidal?
Motor tract originating from the cerebral cortex. Pyramidal tract.
What does it tell us if a tract is pyramidal vs. extra pyramidal?
anatomical description. The tracts that go through the pyramids go through the cortex. Extra- pyramidal tracts go through the brain stem and are more important in animals with LESS DEVELOPED BRAINS.
What are funiculi?
Bundles of nerve fibers in the spinal cord
What is the hierarchy of control?
What is the function of the forebrain generally?
* Perception of sensory input
* Initiation of motor activity
* integration/associaton of information
* cranial nerves I and II
What is the general function of the midbrain?
* thoroughfare for ascending and descending information
* major UMN nuclei for movement
* cranial nerves III and IV
* Consciousness (during anathesia rendered unconscious)
What is the function of the hindbrain?
* Thoroughfare for ascending and descending information
* major UMN nuclei for movement
* coordination of muscle activity (cerebellum)
* cranial nerves V to XII
* regulation of many organ functions (cardiovascular, resp, gastrointestinal)
What is co transmission?
One neuron can release different neurotransmitters from different neuron processes (at one set of dendrites, compared to another). Also, that multiple neurotransmitters can be released from the same neuron process.
e.g. VIP and ACh depending on the frequency stimulation will release one or the other or both. they act as neuromodulators- which can affect the amount of release and the function. It is not just YES/NO- it depends on how much is released, frequency of impulses down the pre-synaptic nerve, and a feedback loop back to the pre-synaptic nerve
What are the steps of neurotransmission?
What are the different types of neuroreceptors?
What are the fast neurotransmitters in the CNS
* Amino acids: glutamate, glycine, gamma amino butyric acid (GABA)
* Acetyl choline
What are the slow neurotransmitters?
( slow “maranade”- important in memory, mood- changes slowly)
* Acetyl Choline
* Mono amines- dopamine, noradrenaline, 5 HT
* NANC- histamine, purines (ATP)
* Neuropeptides- endorphins, substance P
How do drugs target neurotransmitters?
What is the notorchord?
Column of cells - develops the neural tube and neural crest cells
** have to have the notochord to get development of the nervous sytem- one of the first to start developing but the last to finish (i.e. foal or calf walking straight away)
** does not form the vertebral column- marks the future location of the vertebral column (bone comes from schleritome from the somites)
What is the ectoderm? Mesoderm? Endoderm?
What is neurulation?
* The initial development of the gut, heart, and formation of the nervous system
* ectoderm above the notochord thickens to form neural plate
What is the neural groove?
Midline depression due to thickening of the neural ectoderm
What are somites?
Age an embryo by the number of somites that are there
What are neuroepithelium?
Cells lining the neural tube
* Neuroepithelium produces all neurons
* cells migrate from there to form neural crest
*neural crest cells form the peripheral ganglia
* rostral end forms the brain and the rest of the neural tube forms the spinal cord
What are the plates here? What does the mantle layer differentiate into?
What are the three parts of somites?
(somites split and peripheral nerve migrates between)
Why is there bending and folding as the brain develops?
Because it is occuring inside the skull.
What are the ventricles and what part of the brain are they developing from?
What ventricle is in the myelencephalon?
Fourth ventricle
What happens with development in the metencephalon?
Still in the hindbrain, becomes more complicated.
What level of the brain is developing here?
What happens to the midbrain in a developed brain?
Forebrain “flops” over the midbrain
Venous drainage of the brain
choroid plexus
What is cerebrospinal fluid?
An ultrafiltrate of blood. Mostly produced by the choroid plexus which develops where the ependyma is in direct contact with the pia mater on the wall of each ventricle. The choroid plexus epithelium is actively involved in numberous exchange processes in both directions as well as other processes involved in brain homeostasis.
Main arteries to the nervous system
What are the two cerebral hemispheres?
What is the ventricular system?
Cerebellum and the brain stem
The ventricular system is an expansion of the spinal cord.
What produces the CSF? Where? How does CSF flow?
Produced by the choroid plexus within the ventricles
Flows rostral to caudal and then out into the subarachnoid space and flow gradually down beside the spinal cord
What are the 12 cranial nerves?
I olfactory
II optic
III oculomotor
IV trochlear
V trigeminal- mandibular, maxillary, ophthalmic
VI abducens
VII facial
VIII vestibulocochlear
IX glossopharyngeal
X vagus
XI accessory
XII hypoglossal
“On Old Olympus’ Towering Tops A Fair Voluptuous German Vaulted And Hopped”
What happens when the CSF is at a higher pressure then the venous system?
The little balloons bulge out and you get reabsorption of the CSF into the venous system. If the production of CSF drops or pressure drops for any reason, then balloons collapse. As long as the venous pressure is lower, you get circulation and reabsorption back into the venous sinuses.
What happens at the intercostal foramina?
Nerves and blood vessels travel through. More potential CSF reabsorption. But because of the thinning of the separation between blood supply and CSF– potential route for infection!
Are any nerves purely motor? Which nerves are purely sensory?
No nerves are purely motor. They always carry proprioceptive sensory fibre afferents (muscle proprioception). However there are purely sensory nerves (I, II, VIII)
What is unique about CN I, II, and VIII?
They have meningeal coverings that extend into the periphery. Technically, they are not nerves but are evaginations of teh brain and are potential routes for the transport of bacteria, etc. into the CSN; the optic and olfactory nerves are considered to be tracts of the CNS.
What does the position of where the nerve joins the brain tell you?
The position of where the nerve joins the brain is related to the position of the cranial nerve nucleus within the brain.
Most fibres join ventrally or ventrolaterally except the trochlear nerve.
What can occur with CN V, VII, and VIII? Why?
They all attach together so they may be involved in one lesion.
What nerves would be affected by otitis interna? Why?
CN VII and VIII because they exit together through the internal acoustic meatus.
What is the innervation of the pharynx?
Sensory- IX
musculature- IX and X
What is the innervation of the larynx?
Sensory- X and XI
Musculature- X and XI
Transduction
The free nerve endings, nociceptors, of primary afferent neurones respond to noxious stimuli (tissue damage and inflamation)
What are the parts of a nociceptive pathway?
What are the three stages of nociceptive pathways?
Under general anaesthesia, what stage is blocked?
Describe the 1st stage of nociceptive pathways
* Stimuli: mechanical, thermal, chemical
* Nerve fibres: myelinated A fibers and unmyelinated C fibers
* Nociceptors: Mechanical, thermal, polymodal, silent
* Silent C fibers– only start working with an inflammatory process- the threshold will change- start decreasing (become more and more sensitive)– very painful when turned on!
* Transduction- stimulus into electric pulse. Lots of transduction channels. Transient Receptor Potential Ion Channel (TRP), Acid- sensing ion channel (ASIC), Serotonin receptors
* Transduction- Sodium channels (1.1-1.9) and Calcium channels- many different kinds
* Afferent neurons are bipolar: The body is in the dorsal root ganglia (DRG), one end is free ending in the periphery, the other finishes in the dorsal horn, corelease of aminoacids (glutamate, asparate), neuropeptides (substance P, neurokinin, CGRP)
2nd Stage of nociceptive pathways
* Spinothalamic tract (STT)- major ascending pathway
* Crosses midline and communicates with different nuclei in the thalamus (then to the cortices)
* glutamate (neurotransmitter in the thalamus)
3rd Stage of nociceptive pathways
*Thalamic nuclei
* 3rd order neurons
* Different area of the cortex- sensory-discriminative aspects of pain, motivational-affective aspects of pain, sensory and motor integration
Third order neurons
Carries sensory information from the thalamus to the cerebral cortex
Second order neuron
Carries information from the central nervous system to the thalamus. Information traveling along second order neurons deccussates from one side of the CNS to the other side of the CNS
First order neurons
Conduct impulses from receptors of the skin and from proprioceptors (receptors located in a joint, muscle, or tendon) to the spinal cord or brain stem, where they synapse with second-order neurons. First order neuron’s cell bodies reside in ganglion
Main tracts (part of the 2nd stage of nociception)
* Spinohypothalamic (SHT), Spinoreticular (SRT), Spinomesencephalic (SMT)
* SRT reaches the reticular formation (emotional reactions)
* SHT associated with neuroendocrine and autonomic changes associated with the stress response
* SMT project to the PAG
Modulation in the dorsal horn
Grey matter- cell bodies. White matter- myelin.
C fibers are the inhibitors!!
When we are pain there is a fight between the three guys in this picture….
The Gate Theory of Pain
Non-painful input closes the “gates” to painful input, which prevents pain sensation from traveling to the CNS. Therefore, stimulation by non-noxious input is able to suppress pain.
What is the antinociceptive pathway?
What pathways are involved in the antinociceptive pathways?
What are some neurotransmitters in the antinociceptive pathways (dorsal horn)?
What areas are connected to the dorsal horn that are impacted by analgesia?
Name the input to the dorsal horn from different parts of the body
What are some neurotransmitters involved in nociceptive modulation?
Peripheral sensitisation
Reduction in threshold and an increase in responsiveness of the peripheral ends of nociceptors, the high-threshold peripheral sensory neurons that transfer input from peripheral targets through peripheral nerves to the CNS.
Goes from physiological pain to pathological pain.
Direct consequence of tissue trauma and inflammation
HYPERsensitisation
* Can happen if you don’t give enough anaesthetic in surgery
e.g. male children circumsized- no analgesia- increased pain sensation later in life
Central sensitization
An increase in the excitability of neurons within the CNS, so that normal inputs begin to produce abnormal responses.
Constant activation of peripheral receptor
Glutamate and asparate activate NMDA receptors- when they are activated they tend to stay activated- do not deactivate on their own frequently
** NMDA receptors are a common target when treating chronic pain (intensive surgeries). Ketamine is the best NMDA med in the world.
Allodynia
More sensitive to normal stimulation
Acute pain vs. chronic pain
Malformations of all kinds
Cyclopic, Arthrogropotic
Reflect early and dramatic problems during CNS development- some are inherited while others reflect in utero or early post-natal exposure to teratogens (e.g. viruses, toxins, drugs, nutrient deficiencies or excesses)
Some species need post- natal development. Important point is exposure post- natally to teratogens can impact these species more.
(has to do with development of cerebellum)
Cerebellar hypoplasia causes a number of syndromes (one Walker-Warburg in humans similar to muscular dystrophy, for example)
Type of malformation. Nodules visible are cells that were supposed to divide and migrate. Clinical signs vary depending on where this occurs.
* Defect- lamb’s brain- something got in that was lytic late in foetal life. In utero intense necrosis and effective phagocytic response. May not be able to mount a complete inflamm. or immune response, but macrophages are developed and working.
* second picture excessive tissue
BVDV- early in pregnancy because no immune response mounted
BVDV late in pregnancy and therefore immune response mounted
Undersized thymus- accelerated involution and lymphoid death
Dysraphic syndrome- problem is zipping up neural tube.
Something has gone wrong with neuralation.
Supplemented with folate or folic acid which helps prevent dysraphic syndromes. Viruses can do this as well. Any disruption in neuralation.
Neurulation
Neuralation
Anencephaly- complete absence of a brain
Acrania- absence of head
Dysraphic sydnrome: agenesis of the prosencephalon- failuare of neural tube closure rostrally (absence of forebrain- prosencephalon)
Cranium bifidum- meningocoele and meningoencephalocoele
* rostral neural tube closes and hence formation of at least the leptomeninges but fails to separate from the surface ectoderm–> focal failure of induction of dorsal skull bones and overlying musculature +/- dura mater
* cranium bifidum is characterised by usually a dorsal midline defect in the skull through which protrude fluid-filled meninges (meningocoele) or brain within meninges (meningoencephalocoele)
Lined by meninges, covered by skin, no protrustion of skin
* called meningocoele (because lined by meninges and just fluid in there- no brain)
* missing dorsal skull bone and muscles there… so focal failure of overlying mesodermal differential
meningocoele (just fluid)
and/or meningoencephalocoele (brain withing meninges and fluid)
Spina bifida- myeloschisis (focal or diffuse failure of closure of the spinal part of the neural tube–> absence of the spinal cord, meninges, dorsal vertebral arches, overlying muscle and skin along the affected segments)
meningocoele vs. meningomyelocoele
spina bifida- meningocoele or meningomyelocoele
and arthrogryposis
May develop space occupying masses due to congenital defects characteristic of Rhodesian Ridgebacks- stratified squamous and keratinized tube that connects the original ectoderm with deeper structures (often supraspinous ligaments)– sometimes tube connects down to dorsal dura… Gradally accumulates keratin in the space
Myelodysplasia- Hydromyelia (distension of the central canal) can develop later but more often developmental defect
When not lined by ependyma and is it the original central spinal canal… Syringomyelia (fluid filled pocket that is not the central canal, not lined by ependyma)
When not lined by ependyma and is it the original central spinal canal… Syringomyelia (fluid filled pocket that is not the central canal, not lined by ependyma)
When not lined by ependyma and is it the original central spinal canal… Syringomyelia (fluid filled pocket that is not the central canal, not lined by ependyma)
What is the connection with the spinal and vertebral abnormalities and the arthrogryposis?
Any animal with serious spinal cord abnormalities often have arthrogryposis. Nervous system issues. With arthrogryposis- muscles are too short for the growing bones because something has gone wrong with the innervation of those muscles.
Causes: Viruses like BVDV at strategic periods of gestation, inherited problems, toxins, manganese deficiency (lack of growth cartilage development)
Holoprosencephaly= a spectrum of forebrain (prosencephalon) malformations which typically include agenesis or severe hypoplasia of the olfactory bulbs and tracts
Skunk cabbage is one cause of cyclopia- from severe malformation of the forebrain, absence of several cranial bones (e.g. ethmoids, lacrimal bones, premaxillae, and nasal septum) presence of a tube-like proboscis located above the midline eye and not communicating with the pharynx and displacement or absence of the pituitary gland–> prolonged gestation and foetal gigantism
cebocephaly- eyes too close together- less severe expression of holoprosencephaly (cleft lip, cleft palate are other variations)
What is the venous drainage of the spinal cord?
What is the arterial supply of the spinal cord?
3 longitudinally oriented arteries (2 dorsolateral arteries supply the dorsal grey matter and white matter AND ventral spinal artery- major supply to later and ventral grey matter and the ventral white matter– only consistent spinal artery ***)
* at the foramen magnum or C1, it becomes the basilar artery supplying the brain
** Radicular arteries- occur at each intervertebral foramen (supplied from the vertebral, intercostal, lumbar, and sacral arteries– they follow the spinal roots entering the vertebral canal and split into dorsal and ventral radicular branches– they mostly supply lateral white matter)
** note: collateral circulation: radicular and dorsolateral arteries are somewhat inconsistent. Therefore while collateral circulation does occur, it is not very efficient and the spinal cord is very susceptible to hypoxia.
What arteries supply the brain?
Internal carotid (left and right), basilar (direct continuation of the ventral spinal artery), rete mirabile- name given to any blood vessel that breaks up into a plexus and reforms into a single blood vessel.
* Circle of Willis- from the basilar and internal carotids
* From the arterial circle three vessels supply the cerebrum- rostral cerebral artery- lateral to the optic chiasm, supplies rostralmedial half of the cerebral hemispheres, middle cerebral artery- largest vessel- arises just rostral to hypophysis- supplies lateral part of cerebral hemispheres and rostral brain stem, and caudal cerebral artery- arises near the oculomotor nerve, supplies caudomedial part of the cerebral hemispheres)
* cerebellar blood supply- rostral (from arterial circle) and caudal (from basilar a.) cerebellar artery
* brain stem supply from basilar artery supply medulla and the pons
* meningeal arteries: rostral, middle, and caudal meningeal arteries
What is the venous drainage of the canine brain?
* dorsal and ventral set which communicate freely
* paired and unpaired ones
* run in dural folds or boney canals within the calvarial walls
* drainage is to the large veins draining the head region
* maybe a pathway for infection into the brain (e.g. the cavernous sinus)
Potential routes of blood supply to the arterial circle
Arterial supply coming off the circle of willis
What is the telencephalic septum/ septum pellucidum?
Thin membrane which lies like a window between the rostral aspect of the 2 lateral ventricles. Arises from the dorsal aspect of the hippocampal fornix and stretches dorsally to the corpus callosum.
Relationship between the third ventricles and lateral ventricles
What is the interventricular foramina?
Connect each lateral ventricle to the cenrally located third ventricle
Hippocampal fornix
Part of the limbic system- brain structures involved in emotional behaviour
What is the third ventricle associated with? What forms the hole of its donut shape?
What are the three recesses associated with the third ventricle?
Diencephalon. Interthalamic adhesion forms the “hole” of its donut shape.
- optic recess
- infundibular recess
- suprapineal recess
What is the mesencephalic aqueduct?
aka aqueduct of Sylvius is part of the neural tube which lies in the mesencephalon and connects the third and fourth ventricles- widens caudally. Common site of hydrocephalus (congenital or acquired- a build up of CSF)
What is the fourth ventricle associated with?
Two brain divisions: metencephalon and myelencephalon
* ventral to cerebellum and dorsal to the brain stem parenchyma
* Lateral apertures (foramen of Luschke) which are openings between the fourth ventricle and the subarachnoid space at the level of the CNVIII
What is the subarachnoid space?
Lies between the pia and arachnoid and is filled with CSF
What is a CSF cistern? What are the two clinically important ones?
Formed by the arachnoid mater shortcutting across between brain tissues to form an enlarged space between it and the pia.
- Cerebelomedullary cistern- lies in the angle between the caudal cerebeelum and the medulla oblongata
- Lumbar cistern which lies at the caudal end of the spinal cord, and may be approached by inserting a needle between L7 and the sacrum in the dog.
** used to sample CSF and to insert radio-opaque dye into the subarachnoid space to outline the shape of the spinal cord for radiography to look for spinal cord swelling or compression
- intercrural cistern- the third cistern and lies between the crus cerebri, caudal to the hypophysis and rostral to the pons
Radio opaque
Substances appear white (inability of electromagnetic radiation to pass through a material). Bottle cap in the picture
What is CSF? Composition too.
A clear straw coloured fluid which surrounds the neuraxis (the axis of the CNS- denotes the direction in which the CNS lies)
Composition:
* potassium, calcium, chloride, sodium, magnesium, glucose, protein (albumin), cells (mainly acellular but some WBCs)
What are arachnoid villi?
Arachnoid granulations or arachnoid villi are small protrusions of the arachnoid (the thin second layer covering the brain) through the dura mater
What are the layers of the neurectoderm?
What does each layer of the neuroectoderm turn into functionally in terms of neurons?
* germinal layer- initially proliferative becomes ependyma (squamous to columnar) when proliferative function exhausted
* mantle layer- primitive neurons and spongioblasts which form grey matter of the CNS. It is the middle layer except where it becomes external in the cerebral hemispheres.
* Marginal layer- primarily axons of the mantle layer which form the white matter. It is the outer layer except in the cerebral cortex.
What is a sclerotome?
Each complete vertebrae is a product of the fusion of four sclerotomes. Vertebral anomalies aries due to abnormal segmentation of somites or formation of sclerotomes.
What does the notochord remnant become?
Nucleus pulposus of the intervertebral disc.
What forms the tectum? What forms the tegmentum?
Tectum formed by the alar plate. Tegmentum formed by the basal plate.
What is the hypophysis?
The pituitary gland. The smallest but most important endocrine gland. Anterior and Posterior Pituitary Gland.
What is this showing the development of?
Pituitary gland aka hypophysis
What is the crus cerebri?
Anterior portion of the cerebral peduncle which contains motor tracts.
** the corticospinal tract constitutes a large part of the internal capsule, carrying motor information from the primary motor cortex to the lower motor neurons in the spinal cord. Above the basal ganglia the corticospinal tract is part of the corona radiata. Below the basal ganglia the tract is called the crus cerebri (a part of the cerebral peduncle) and below the pons it is referred to as the corticospinal tract
What is the internal capsule?
A white matter structure in each cerebral hemisphere that carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the global pallidus. ** the internal capsule contains both ascending and descending axons. Contains fibers going to and coming from the cerebral cortex.
** the corticospinal tract constitutes a large part of the internal capsule, carrying motor information from the primary motor cortex to the lower motor neurons in the spinal cord. Above the basal ganglia the corticospinal tract is part of the corona radiata. Below the basal ganglia the tract is called the crus cerebri (a part of the cerebral peduncle) and below the pons it is referred to as the corticospinal tract
What bone is the foramen magnum part of? What comes out?
Occipital bone
Contents: spinal cord, basilar artery, venous plexus, spinal part of CNXI (accessory n.)
What bone is the hypoglossal canal part of? What comes out?
Occipital bone
CNXII (hypoglossal n.)
What bone is the stylomastoid foramen part of? What comes out?
Temporal bone
CNVII (Facial n.)
What bone is the tympano-occipital fissure part of? What comes out?
Temporal and Basioccipital bones
CNIX (Glossopharyngeal n.), CNX (vagus n.), CN XI (accessory n.), sympathetic nerves, small veins, internal carotid artery
What bone is the external acoustic meatus part of? What comes out?
Temporal bone
Contents: External ear canal
What bone is the oval foramen part of? What comes out?
Sphenoid bone
CNV (trigeminal n.) mandibular branch
What bone is the round foramen (cat) part of? What comes out?
Sphenoid bone
CNV maxillary branch (trigeminal n.)
What bone is the alar canal (in dogs- name two parts) part of? What comes out?
Sphenoid bone
Rostral alar foramen: maxillary artery and vein
Caudal alar foramen: maxillary artery and vein and CNV maxillary branch
What bone is the orbital fissure part of? What comes out?
Sphenoid bone
Contents: CN III (Oculomotor n.), CN IV (trochlear n.), CN V ophthalmic branch, CN VI (Abducens n.)
What bone is the optic canal part of? What comes out?
Sphenoid bone
CN II (optic n.)
What bone is the cribiform plate part of? What comes out?
Ethmoid bone
CN I (olfactory)
What bone is the infra-orbital canal (name the two) part of? What comes out?
Maxilla bone
Maxillary foramen & infraorbital foramen: Maxillary artery, vein, and nerve which continue as the infraorbital artery, vein, and nerve
What bone is the jugular foramen part of? What comes out?
Temporal and Occipital bones
Contents: CN IX (Glossopharyngeal), CN X (vagus), CNXI (accessory), sigmoid sinus
What bone is the internal acoustic meatus part of? What comes out?
Temporal Bone
CN VII (facial), CN VIII (vestibulocochlear)
What bone is the round foramen part of? What comes out?
Sphenoid bone
CNV (trigeminal) maxillary branch (DOG)
What bone is the trigeminal canal part of? What comes out?
Temporal bone
CNV and trigeminal ganglion
What bone is the mandibular canal (name two holes) part of? What comes out?
Mandible
Two holes: Mandibular foramen and mental foramen
CNV mandibular branch continuing as the inferior alveolar nerve and running with the inferior alveolar artery and vein
What is the hypothalamus?
Small area in the ventral diencephalon of the forebrain, in the floor of the third ventricle, and is a functional link between the nervous and endocrine systems. Controls the endocrine glands. Vital in regulation of homeostasis including thermoregulation.
What is the sympathetic trunk?
* Bilateral paired strand of sympathetic and visceral afferent fibres
* runs in a craniocaudal direction just ventrolateral to the vertebral column from C8 to L4/L5, occasionally as far caudal as L7
* Sympathetic trunk (paravertebral) ganglia- a ganglion occurs where each ramus communicans connects to the sympathetic trunk, fibres may pass through several ganglia before synapsing
What are the splanchnic nerves?
* sympathetic supply to the abdomen
* Originates from sympathetic fibres which leave the sympathetic trunk in the caudal thoracic and cranial lumbar area
* prevertebral ganglia: Splanchnic nerves synapse in a ganglion within the body cavity when they are going to deeply located viscera e.g. coeliac, cranial mesenteric, and caudal mesenteric ganglia
* postsynaptic fibres: travel with blood vessels to terminate in the abdominal organs
What is the cranial cervical ganglion?
Located deep to the tympanic bulla. Fibres exiting this ganglion travel in association with arteries to supply the head.
