Motor And Sensory Cortical Homunculus (preview) - Human...

A cortical homunculus is a distorted representation of the human body, based on a neurological "map" of the areas and proportions of the human brain dedicated to processing motor functions, or sensory functions, for different parts of the body.In the motor regions of the basal ganglia, there is a motor homunculus similar to that seen in the primary motor cortex. Which motor programs should be released from inhibition at a given moment? The basal ganglia may have a major role in learning what motor acts result in rewards for the organism.The motor areas have extremely small or non-existent granular layers Histologically, this area would consist of granular cortex. The sensory homunculus includes cortical The premotor cortex (area 6) is immediately anterior to the motor cortex and has many of the same connections as the motor cortex.Which motor area both has a homunculus and has descending projection fibers? Spinal nerves have mixed motor and sensory function. Just like the cerebrum, the gray matter is found on the superficial surfaces.Homunculus have their own set of stats apart from their masters, these will have a set amount upon summoning and will vary as it levels up. This value is not shown in the Homunculus Stat Window. However, for each interval of Intimacy points the Homunculus has, the window will show

Basal Ganglia (Section 3, Chapter 4) Neuroscience Online: An...

Adapted from "Supplementary Motor Area of the Monkey's Cerebral Cortex: Short - and Long-Term Effects After Unilateral Ablation and the Effects of After the pre-frontal cortex has formulated a plan of action, it instructs the premotor cortex to orga-nize the appropriate sequence of behaviors.All the ascending (sensory) and descending (motor) nerve fibers connecting the brain and spinal cord pass through the projection fibers - conduct impulses in & out of the cerebral hemispheres. There are 31 pair of spinal nerves & each has a dorsal root and a ventral root. The dorsal root is sensory (all...Test both halves of your mind in this human anatomy quiz. Structures and functions of the human digestive system. ileum, the ascending colon, the transverse colon, the descending colon, and the sigmoid colon , which terminates in the rectum .B. Descending projections through internal capsule  forming the Corticospinal Tract. 3rd and 4th components: basal ganglia and cerebellum do not project directly to motor neurons, but rather, synapse on descending pathways and have a very important influence. 22 Motor "homunculus" (Fig. DESCENDING TRACTS Fiber Types A Fibers: Somatic, myelinated.

Chapter 11: The Cerebral Cortex | Association and Commissural Fibers

While the Homunculus Servant might be marginally beefier than a familiar, it looks like in comparison the utility can be a bit thin. I can see the benefits of not having to go out of your way to get the Magic Initiate for a familiar, and can see how it can let the Alchemist's Bonus Action perform a little bit extra...The descending tracts are the pathways by which motor signals are sent from the brain to lower motor neurones. The lower motor neurones As the fibres emerge, they decussate (cross over to the other side of the CNS), and descend into the spinal cord. Thus, they have a contralateral innervation.Known as the functional areas of the brain, each has roles and purpose. Firstly, the human brain is divided into left and right hemispheres. These are connected by a bundle of nerve fibers called the corpus callosum.A homunculus is a representation of a small human being. Popularized in sixteenth-century alchemy and nineteenth-century fiction, it has historically referred to the creation of a miniature, fully formed human. The concept has roots in preformationism as well as earlier folklore and alchemic traditions.Projection fiber. Quite the same Wikipedia. Projection fiber. From Wikipedia, the free encyclopedia. The principal efferent fibers are: (1) the motor tract, occupying the genu and anterior two-thirds of the occipital part of the internal capsule, and consisting of.

Presentation on theme: "Descending Projection Systems and Motor Functions of the Spinal Cord"— Presentation transcript:

1 Descending Projection Systems and Motor Functions of the Spinal Cord

2 Functional anatomy of motor programs and descending pathways.A. Components of the motor methods of the CNS. B. Organization and serve as of the descending pathways (i.e., lateral/medial). II. Regional anatomy of the descending techniques. A. Motor regions of the cerebral cortex. 1. Premotor (higher-order) cortical regions. 2. 1° motor cortex – enter, somatotopic organization and outflow. B. Descending projections via inside tablet  forming the Corticospinal Tract. C. Organization of the Corticospinal tract in the base of the midbrain (Basis Pedunculi) [+ get started of rubrospinal tract]. D. Passage of corticospinal tract thru Ventral Pons. E. Nuclei of dorsal pons and medulla (get started of vestibulospinal and reticulospinal tracts). F. Pathways via medulla (+ lateral corticospinal tract decussation). G. Input from the descending pathways within the spinal wire + topographic group of the grey topic and white subject. H. A note about lesions of the descending cortical pathways.

3 I. Functional anatomy of the motor methods and descending pathwaysMotor techniques of the CNS – 4 elements of motor techniques (during actions of the leg and trunk by way of regulating skeletal muscle). 1. Descending projections pathways. 2. motor neurons and interneurons. 3. basal ganglia. 4. cerebellum. Our 'tours' through motor systems might be reverse from what we skilled with sensory (order of cortex---- motor neurons). Today, we will be able to center of attention at the 1st 2 of the above. Individual lectures will probably be presented on the basal ganglia and cerebellum at a later date.

4 1st component: descending projection pathways (Fig. 10-1)

5 Motor Cortical Areas (Fig. 10-1)

6 second element; for muscle mass of the limbs and trunk - motor neurons and interneurons located in: ventral horn and interior zone of the spinal cord. A parallel exists for the muscular tissues of the top: cranial nerve motor nuclei and reticular formation within the brainstem – these are analogous to above areas. 1 serve as of the brainstem is to serve as the "spinal twine for the pinnacle". third and 4th elements: basal ganglia and cerebellum don't mission without delay to motor neurons, but rather, synapse on descending pathways and have a essential affect.

7 Overview of function the use of an instanceSee a cup  1° visual cortex  higher-order in post parietal lobe (for identification object). Prefrontal affiliation spaces (maturation and cognition – "get the speculation"). Premotor areas  "plan of action" 1° motor cortex Corticospinal tract – interneurons  motor neurons (snatch the cup) Cerebellum and bg also play a position in feedback control and movement purpose – we will speak about in a while.

8 B. Organization and serve as of descending pathways.Motor keep watch over pathways Paths that keep an eye on somatic sensory processing: somatic sensory relay nuclei (brainstem) and dorsal horn neurons (spinal twine). i.e., pain suppression triggering of motor reflexes injury  spasticity). Paths regulating ANS. Cortex , amygdala, hypothal, mind stem  preganglionic autonomic nerves of brainstem and spinal wire.

9 7 Major descending motor control pathways from cerebral cortex or brainstem nuclei: From frontal cortex: i. lateral corticospinal tract ii. Ventral corticospinal tract iii. Corticobulbar tract ( cranial n. motor nuclei). From brainstem nuclei: i. Rubrospinal tract ii. Reticulospinal tract iii. Vestibulospinal tract iv. Tectospinal tract

10 Interneuron Connections: from time to time an intermediary ahead of motor neurons:Segmental interneurons – short branches inside unmarried spinal cord segment. Propiospinal neurons – projects for more than one spinal segments ahead of synapsing onto motor n. – long projections coordinating movements of higher and lower limbs; would possibly transmit keep watch over indicators decrease, for some paths ending in cervical areas.

11 Somatotopic organization-motor (Fig. 10-2)From lateral descending paths Lateral: limbs Medial: Axial

12 Lateral Corticospinal Tract: (Fig. 10-3)LATERAL DESCENDING PATHWAYS Lateral Corticospinal Tract: (Fig. 10-3) Starts on the 1° motor cortex  decussation zone and lateral motor nuclei of cervical and lumbrosacral wire. Why segmented? Limbs.

13 Rubrospinal Tract (Fig. 10-3): LATERAL DESCENDING PATHWAYSRed nucleus (magnocellular)  midbrain decussation  lateral intermediate zone and ventral horn. Provides some additional (residual) motor keep watch over [more essential input connection is with cerebellum].

14 Medial (Ventral) Corticospinal Tract (Fig. 10-4):MEDIAL DESCENDING PATHWAYS Medial (Ventral) Corticospinal Tract (Fig. 10-4): Axial and girdle muscle groups. Ipsilateral ventral column  bilateral projections to medial gray subject. Controls particularly for head, shoulder, and higher trunk muscle groups.

15 Reticulospinal Tract (Fig 10-4):MEDIAL DESCENDING PATHWAYS Note the bilateral projections; cf., the lateral pathways (which crossed). Reticulospinal Tract (Fig 10-4): Many terminate in cervical wire. But, 2° projections to propiospinal neurons may affect decrease axial muscle tissues additionally. Pontine  ventral column. Medullary reticular formation  lateral column (ventrolateral). Autonomic movements: posture and repetitive movements. Tectospinal Tract (Fig. 10-4): From sup coll (deep)  coord head and eye

16 Vestibulospinal Tracts:Lateral vestibular n.  lat vestibulospinal tract (to all spinal limbs). Maintains stability. Medial nucleus  med tracts for control of head position (cervical only).

17 Organization of Tracts (Fig. 10-5)Note the descending and ascending tracts and their relative positions.

18 II. Regional Anatomy of Descending SystemsMotor areas of the Cerebral Cortex – in frontal lobe. 1. Higher-order cortical areas: - making plans motion. - integration of information from diverse cortex (see earlier e.g.). a. bg  VA (thal)  supplementary motor area (bimanual coordination)  prefrontal cortex b. cerebellum  VL (thal)  premotor cortex  reticulospinal tracts (control of girdle muscle groups). c. Cingulate motor spaces (a part of limbic gadget) – rhythmical actions (e.g., pedaling a bike). - is also essential in triggering movements initiated by way of emotions and drives.

19 II. Regional Anatomy of Descending SystemsPremotor regions Somatic sensory Thalamic (VL) (VA) Precentral gyrus (thick layer of 5 pyramidal neurons provide major output (massive Betz cells) Corticospinal tract Cerebellum bg

20 Premotor Areas (Lateral View) (Fig. 10-6)

21 Premotor Areas (Medial View) (Fig. 10-6)

22 Motor "homunculus" (Fig. 10-7)Somatotropic organization – analogous to sensory cortex

23 Origins of motor cortical tractsNote that the origins of cortical tracts are shown – slightly segmented

24 B. Descending projections thru Internal pill and corticospinal fibers (Fig. 10-9)Posterior limb of the IC comprises the cortico spinal tract; Somatotropic Organization is maintained.

25 Divisions of inner pill (Fig. 10-10)

26 C. Pathways inside of midbrain (Fig. 10-11)Corticospinal tract lessons in base of midbrain (foundation pedunculi). Somatotopic group is retained here. Origin of Tectospinal tract (awesome colliculus) and rubrospinal tract (purple nucleus). Also, those tracts move on the subject of their origins in midbrain.

27 D. Pathways within Pons (Fig. 10-12)Descending cortical fibres are not on ventral surface  they dive deeper inside the pons (and additionally department up into fasciculi) amongst pontine and pontocerebellar fibres.

28 Medullary DecussationNuclei of Dorsal Pons and Medulla: start of Vestibulospinal and Reticulospinal tracts (Review pathways on previous slides). Functions: Reticular formation has more than one projections, which makes this System extremely integrative (e.g., between motor and sensory). Analogous to Intermediate Zone of the spinal wire (See Fig A).

29 F. Pathways through Medulla and Decussation of Corticospinal TractF. Pathways through Medulla and Decussation of Corticospinal Tract. Fibres from cortex gather as soon as again on ventral floor, forming pyramids. Decussations occur in medulla – in particular of lateral corticospinal tract axons.

30 G. Spinal Cord Inputs: motor pathways synapse on motor neurons of ventral horn and interneurons (segmental, propiospinal) of intermediate zone. Generalized organization of grey and white matter (see Fig A and the closing slide on this set). Ventral horn: Rexed's laminae (VIII, IX). Intermediate zone: (laminae VII).

31 Spinal cord grey topic group (Rexed's laminae) (Fig. 10-16A):

32 Motor Terminations at more than a few levels of the sc.Note the descent of more than a few pathways in lateral and ventral columns. Medially descending and terminating pathways  Girdle and axial muscle tissue. Cross-overs and bilateral connectivities: coord contraction all the way through postural changes.

33 Lateral descending/terminating paths: Distal limb muscles Note: terminations simplest obtrusive in cervical and lumbrosacral segments (sensory limbs) (Fig ) Medial input = continuous Lateral input - interrupted

34 H. Some notes about lesions of the descending cortical pathways:Lesions of posterior limb of inner pill, ventral brainstem, and sc: on 1 aspect produce a sequential collection of symptoms (centered totally on limb muscle mass --- Why?) Flaccid paralysis (immed)  decr energy + muscle tone because of corticospinal interruption. Spasticity (a few weeks later)  incr muscle tone + exaggerated reflexes (Babinski signal) because of reticulospinal and sensory enter harm (decr feedback).

35 White Matter: Pathway Generalizations Review of descending and ascending tracts