Presentation is loading. Please wait.

Presentation is loading. Please wait.

Contents of the Neurocranium, Part II The Brain, its Blood Supply and the Cranial Nerves.

Similar presentations

Presentation on theme: "Contents of the Neurocranium, Part II The Brain, its Blood Supply and the Cranial Nerves."— Presentation transcript:

1 Contents of the Neurocranium, Part II The Brain, its Blood Supply and the Cranial Nerves

2 Embryology Central nervous system begins as neural tube Anterior portion of neural tube differentiates into three primary divisions: –Hindbrain –Midbrain –Forebrain

3 Embryology Lateral walls of the forebrain expand and protrude from both sides of the neural tube Median portion of forebrain is the diencephalon Lateral projections form the telencephalon

4 Embryology Two primary axes of growth in the developing brain 1. Longitudinal flexion of anterior neural tube 2. Inferior spiral rotation of the telencephalon

5 Ventricles Lumen of neural tube becomes the CNS ventricular system Shape of ventricular system reflects developmental deformation of neural tube

6 Ventricles Lateral ventricles –Anterior horn –Body –Posterior horn –Inferior horn Third ventricle –Interventricular foramen (of Monro) –Cerebral aqueduct Fourth ventricle

7 Hindbrain Cerebellum Motor coordination Cognitive functions –temporal coordination –planning

8 Hindbrain Medulla Oblongata Anatomical and physiological junction of brain and spinal cord Initiates respiration Regulates heart rate Origin of cranial nerves IX, X, XI, and XII

9 Hindbrain Pons Bridge between cerebellum and the rest of the brain Origin of cranial nerves V, VI, VII, and VIII

10 Midbrain Least differentiated primary brain division Contains cerebral aqueduct Origin of cranial nerves III and IV (from dorsal surface)

11 Midbrain Corpora Quadrigemina Superior Colliculi Visual tracking Coordination of head turning & eye movements Inferior Colliculi Sound location Focusing attention to auditory stimuli

12 Midbrain Substantia Nigra Darkly pigmented (neuro- melanin) nucleus Produces dopamine Parkinsons disease destruction of the cells of the substantia nigra

13 Midbrain Substantia Nigra In 1982, 6 drug addicts in Santa Clara, CA manifested with Parkinsons disease (oldest patient was 41 yrs. old) Each had injected synthetic heroinMPPP (1- methyl-4-phenyl-4-propionpiperidine), an analog of meperidine (Demerol) The poorly synthesized designer drug contained a contaminantMPTP (1-methyl-4-phenyl-1,2,5,6- tetrahydropyridine), which kills the cells of the substantia nigra

14 Midbrain Cerebral Peduncles Major fiber bundles connecting forebrain to hindbrain Contain descending axons of upper motor neurons from cortex

15 Diencephalon Thalamus Potato-shaped structure Sensory relay for all afferents except olfaction

16 Diencephalon Thalamus Thalami form walls of 3 rd ventricle

17 Diencephalon Hypothalamus –Body temperature –Hunger –Thirst –Sexual activity –Goal-seeking behavior –Endocrine functions –Affective behavior –Visceral motor system 4 g neural structure Connected to pituitary gland Regulates:

18 Telencephalon Basal Ganglia Caudate nucleus Globus pallidus Putamen Modulate and integrate components of motor activity (and cognitive functions) System depends on dopamine affected by Parkinsons disease

19 Telencephalon Amygdala Lies at tail of caudate nucleus but is not functionally part of the basal ganglia Involved in the control of rage, aggression and sexuality

20 Telencephalon Hippocampus Composed of three-layered cortex (archicortex) Fornixmajor output pathway Involved in the formation of new episodic memories

21 Telencephalon Cerebrum Composed of six-layered neocortex and deep white matter Center of sensory input, motor output, and higher cognitive functions

22 Cerebrum Primary Fissures Longitudinal cerebral fissure

23 Cerebrum Primary Fissures Lateral fissure Central sulcus

24 Cerebrum Lobes Frontal Parietal Occipital Temporal

25 Cerebrum Lobes Insula

26 Cerebrum White Matter Corpus callosum primary connection between left and right cerebral hemispheres

27 Cerebrum White Matter Internal capsuleprimary pathway of fibers ascending to cortex from thalamus and descending from cortex to cerebral peduncles

28 Motor Cortex Primary motor cortex lies along the precentral gyrus in the frontal lobe Motor output projects to contralateral side

29 Motor Output Pathways Voluntary movementconducted to lower motor neurons via the pyramidal pathway

30 Motor Output Pathways Balance, posture, limb coordination information conducted by numerous extrapyramidal pathways

31 Somatosensory Cortex Primary somatosensory cortex lies along the postcentral gyrus in the parietal lobe Representation of body is from contralateral side

32 Somatosensory Cortex Somatosensory cortex (like motor cortex) is mapped somatotopically and proportionate to sensitivity, not size

33 Other Sensory Cortices Visual cortex occipital lobe Auditory cortex superior portion of temporal lobe Rhinal (olfactory) cortexanterior medial temporal lobe Gustatory (taste) cortexinferior aspect of postcentral gyrus

34 Language Areas Occur only in the left hemisphere of most people (96 % of right-handed individuals, 72% of left- handed individuals) Brocas areamotor speech center, in frontal lobe Wernickes arealanguage interpretation center, in temporal & parietal lobes

35 Cranial Nerves I.Olfactory II.Optic III.Occulomotor IV.Trochlear V.Trigeminal VI.Abucens VII.Facial VIII.Vestibulocochlear IX.Glossopharyngeal X.Vagus XI.Spinal Accessory XII.Hypoglossal

36 Cranial Nerves Exit from Neurocranium I Cribriform plate

37 Cranial Nerves Exit from Neurocranium II Optic canal

38 Cranial Nerves Exit from Neurocranium III, IV, VI Superior orbital fissure

39 Cranial Nerves Exit from Neurocranium V 1 Superior orbital fissue V 2 Foramen rotundum V 3 Foramen ovale

40 Cranial Nerves Exit from Neurocranium VII, VIII Internal auditory meatus

41 Cranial Nerves Exit from Neurocranium IX, X, XI Jugular foramen

42 Cranial Nerves Exit from Neurocranium XII Hypoglossal Canal

43 Cranial Nerves Exit from Neurocranium

44 Blood Supply Vertebral arteries –Provide ~30% of blood supply to brain Internal carotid arteries –Provide ~70% of blood supply to brain

45 Circle of Willis Vertebral aa. basilar a. posterior cerebral aa. Internal carotid a. middle cerebral aa. anterior cerebral aa. Posterior communicating arteries connect posterior cerebral aa. and internal carotid aa. Anterior communicating ARTERY (sing.) connect anterior cerebral arteries

46 Blood Supply


48 Venous Drainage Blood from the cortex drains to surface veins that drain into the dural venous sinuses

49 Venous Drainage Blood from the deep brain (thalamus, basal ganglia) drains into great cerebral vein (of Galen) before entering the straight sinus Blood from the lower brainstem drains through the foramen magnum into the vertebral venous plexus

50 Cerebrovascular Accident (CVA) Ruptured aneurysmfailure of a localized defect in the elasticity of a vessel Arterial thrombusblockage of an artery Embolismclot from elsewhere in the body that lodges in a cerebral artery Hypertensive apoplexysudden effusion of blood into cerebral tissue due to rise in blood pressure

Download ppt "Contents of the Neurocranium, Part II The Brain, its Blood Supply and the Cranial Nerves."

Similar presentations

Ads by Google