Auditory Tests

Conduction deafness middle ear deafness (e.g otosclerosis, otitis media) nerve deafness - sensorineural deafness (e.g., presbycusis AC air conduction BC bone conduction. Conduction deafness middle ear deafness (e.g otosclerosis, otitis media) nerve deafness - sensorineural deafness (e.g., presbycusis AC air conduction BC bone conduction. 1. Weber's test is performed by placing a vibrating tuning fork on the vertex of the skull. Normally, a patient hears equally on both sides. a. A patient who...

Tuberoinfundibular Tract

Infundibulum Cerebral Artery

The hypothalamus is a division of the diencephalon that subserves three systems the autonomic nervous system, endocrine system, and limbic system. The hypothalamus helps to maintain homeostasis. B. Major hypothalamic nuclei and their functions 1. The medial preoptic nucleus (Figure 19-1) regulates the release of gonadotropic hormones from the adenohypophysis. It contains the sexually dimorphic nucleus, the development of which depends on testosterone levels....

Dentatothalamic Pathway

Tegmentum Decussation

The cerebellum has three primary functions A. Maintenance of posture and balance C. Coordination of voluntary motor activity 1. The superior cerebellar peduncle contains the major output from the cerebellum, the dentatothalamic tract. This tract terminates in the ventral lateral nucleus of the thalamus. It has one major afferent pathway, the ventral spinocerebellar tract. 2. The middle cerebellar peduncle receives pontocerebellar fibers, which project to the neocerebellum...

Viregeneration Of Nerve Cells

Effective regeneration does not occur in the CNS. For example, there is no regeneration of the optic nerve, which is a tract of the diencephalon. There are no basement membranes or endoneural investments surrounding the axons of the CNS. B. PNS. Regeneration does occur in the PNS. The proximal tip of a severed axon grows into the endoneural tube, which consists of Schwann cell basement membrane and endoneurium. The axon sprout grows at the rate of 3 mm day. VII. GLIAL CELLS are the...

Motor Ocular De Penfield

Septal Area

The cerebral cortex, the thin, gray covering of both hemispheres of the brain, has two types the neocortex 90 and the allocortex 10 . Motor cortex is the thickest 4.5 mm visual cortex is the thinest 1.5 mm . II. THE SIX-LAYERED NEOCORTEX. Layers 11 and IV of the neocortex are mainly afferent i.e., receiving . Layers V and VI are mainly efferent i.e., sending . A. Layer I is the molecular layer. B. Layer II is the external granular layer. C. Layer III is the external pyramidal...

Internal Capsule Function

Lateral Geniculate Body

The thalamus is the largest division of the diencephalon. It plays an important role in the integration of the sensory and motor systems. II. MAJOR THALAMIC NUCLEI AND THEIR CONNECTIONS Figure 16-1 A. The anterior nucleus receives hypothalamic input from the mamillary nucleus through the mamillothalamic tract. It projects to the cingulate gyrus and is part of the Papez circuit of emotion of the limbic system. B. The mediodorsal dorsomedial nucleus is reciprocally connected to...

Iiilocation Of The Major Motor And Sensory Nuclei Of The Spinal Cord

The ciliospinal center of Budge, from C-8 to T-2, mediates the sympathetic innervation of the eye. B. The intermediolateral cell column, from C-8 to L-3, mediates the entire sympathetic innervation of the body. C. The nucleus dorsalis of Clark, from C-8 to L-3, gives rise to the dorsal spinocerebellar tract. D. The parasympathetic nucleus, from S-2 to S-4 E. The spinal accessory nucleus, from C-l to C-6 F. The phrenic nucleus, from C-3 to C-6 IV. THE CAUDA EQUINA. Motor and sensory roots L-2...

Tongue Deviation Lesion

Corneal Reflex Arc

THE OLFACTORY NERVE, the first cranial nerve CN I Figure 13-1 , mediates olfaction smell . It is the only sensory system that has no precortical relay in the thalamus. The olfactory nerve is a special visceral afferent SVA nerve. It consists of unmyelinated axons of bipolar neurons that are located in the nasal mucosa, the olfactory epithelium. It enters the skull through the cribriform plate of the ethmoid bone see appendix . 1. Olfactory receptor cells are first-order neurons that project...

Info

Fornix Dentate Gyrus Subiculum

The limbic system is considered the anatomic substrate that underlies behavioral and emotional expression. It is expressed through the hypothalamus by way of the autonomic nervous system. II. MAJOR COMPONENTS AND CONNECTIONS A. The orbitofrontal cortex mediates the conscious perception of smell. It has reciprocal connections with the mediodorsal nucleus of the thalamus. It is interconnected through the medial forebrain bundle with the septal area and hypothalamic nuclei. B. The...

Left Inferior Quadrantanopia

Conjugate Gaze Palsies

The visual system is served by the optic nerve, which is a special somatic afferent nerve. II. THE VISUAL PATHWAY Figure 17-1 includes the following structures. A. Ganglion cells of the retina form the optic nerve cranial nerve CN II . They project from the nasal hemiretina to the contralateral lateral geniculate body and from the temporal hemiretina to the ipsilateral lateral geniculate body. Figure 17-1. The visual pathway from the retina to the visual cortex showing visual...

The Labyrinth

Caloric Irrigations

Three semicircular ducts lie within the three semicircular canals i.e., superior, lateral, and posterior . 2. These ducts respond to angular acceleration and deceleration of the head. a. They contain hair cells in the crista ampullaris. The hair cells respond to en-dolymph flow. - - Juxtarestiform I body I - Vestibular nerve and ganglion in internal auditory meatus Figure 12-1. Peripheral connections of the vestibular system. The hair cells of the cristae ampullares and the maculae of the...

Combined Motor And Sensory Lesions

Spinal cord hemisection Brown-Sequard syndrome see Figure 8-2E is caused by damage to the following structures 1. The dorsal columns gracile leg and cuneate arm fasciculi . Damage results in ipsilateral loss of tactile discrimination and position and vibration sensation. 2. The lateral corticospinal tract. Damage results in ipsilateral spastic paresis with pyramidal signs below the lesion. 3. The lateral spinothalamic tract. Damage results in contralateral loss of pain and temperature...

Hippocampal Formation

Meynert Projects

IMPORTANT TRANSMITTERS AND THEIR PATHWAYS A. Acetylcholine is the major transmitter of the peripheral nervous system, neuromuscular junction, parasympathetic nervous system, preganglionic sympathetic fibers, and postganglionic sympathetic fibers that innervate sweat glands and some blood vessels in the skeletal muscles Figure 22-1 . Acetylcholine is found in the neurons of the somatic and visceral motor nuclei in the brain stem and spinal cord. It is also found in the basal nucleus of...

Trigeminal System

Trigeminal Nucleus Spinal Thalamus

OVERVIEW, The trigeminal system provides sensory innervation to the face, oral cavity, and supratentorial dura through general somatic afferent GSA fibers. It also innervates the muscles of mastication through special visceral efferent SVE fibers. II. THE TRIGEMINAL GANGLION semilunar orgasserian containspseudounipolarganglion cells. It has three divisions A. The ophthalmic nerve cranial nerve CN V-l lies in the wall of the cavernous sinus. It enters the orbit through the superior orbital...

Trigeminal Reflexes

Ophthalmic Artery Infundibulum

The corneal reflex is a consensual disynaptic reflex. The cell bodies are found in the mesencephalic nucleus of CN V. CN - cranial nerve. The cell bodies are found in the mesencephalic nucleus of CN V. CN - cranial nerve. 2. The jaw jerk reflex is a monosynaptic myotatic reflex Figure 10-3 . 3. The tearing lacrimal reflex 4. The oculocardiac reflex occurs when pressure on the globe results in bradycardia. B. Clinical correlation. Trigeminal neuralgia tic douloureux is characterized by...

Tumors Of The Cns And Pns are shown in Figure

Pituitary Adenoma Visual Field Defect

One-third of brain tumors are metastatic, and two-thirds are primary. In metastatic tumors, the primary site of malignancy is the lung in 35 of cases, the breast in 17 , in the gastrointestinal tract in 6 , melanoma in 6 , and the kidney in 5 . B. Brain tumors are classified as glial 50 or nonglial 50 . C. According to national board questions, the five most common brain tumors are 1. Glioblastoma multiforme, the most common and most fatal type 2. Meningioma, a benign noninvasive tumor of...

Igray And White Communicating Rami Figure

Lateral Horn Ganglion

Gray communicating rami contain unmyelinated postganglionic sympathetic fibers. They are found at all levels of the spinal cord. B. White communicating rami contain myelinated preganglionic sympathetic fibers. They are found from T-l to L-3 the extent of the lateral horn and the intermediolat-era I cell column . II. TERMINATION OF THE CONUS MEDULLARIS see Figure 2-1 occurs in the newborn at the level of the body of the third lumbar vertebra L-3 . In the adult, it occurs at the level of the...

Hypothalamospinal Tract Figure

The hypothalamospinal tract projects without interruption from the hypothalamus to the ciliospinal center of the intermediolateral cell column at T-1 to T-2. It is found in the spinal cord at T-l or above in the dorsolateral quadrant of the lateral funiculus. It is also found in the lateral tegmentum of the medulla, pons, and midbrain. B. Clinical features. Interruption of this tract at any level results in Horner's syndrome i.e., miosis, ptosis, hemianhidrosis, and...

Axial Image Through The Midbrain Mamillary Bodies And Optic Tract Figures 110 111 112 and 113 The location of the

Vessels The Quadrigeminal Cistern

Substantia nigra Red nucleus Hippocampus Trochlear nucleus Nucleus of inferior colliculus Cerebral aqueduct 1-10. Axial section of the brain at the level of the midbrain, mamillary bodies, and amygdala. Note substantia nigra separates the crus cerebri from the tegmentum ot the midbrain. Interhemispheric fissure -Gyrus rectus Optic tract Mamillary nucleus Red nucleus Figure 1-11. Axial magnetic resonance imaging MR1 section at the level of the midbrain and mamillary bodies. Because of the high...

Cross Sectional Anatomy of the Brain

Mid Sagittal Brain Fornix

The illustrations in this chapter are accompanied by corresponding magnetic resonance imaging MRI scans. Together they represent a mini-atlas of brain slices in the three orthogonal planes i.e., midsagittal, coronal, and axial . An insert on each figure shows the level of the slice. The most commonly tested structures are labeled. II. MIDSAGITTAL SECTION Figures 1-1, 1-2, and 1-3 . The location of the structures shown in the figures should be known. Fornix column...

Crosssection Through The Medulla Figure

Pons Cross Section

The hypoglossal nucleus of CN XII 2. The medial lemniscus, which contains crossed fibers from the gracile and cuneate nuclei 3. The pyramid corticospinal tracts Lateral geniculate body Medial geniculate body Crus cerebri Superior cerebellar peduncle Middle cerebellar peduncle Inferior cerebellar peduncle Gracile tubercle Cuneate fasciculus Gracile fasciculus Figure 9-1. The dorsal surface of the brain stem. The three cerebellar peduncles have been removed to expose the rhomboid fossa. The...

Neurohistology

Nerve Endings Motor Neuron

NEURONS are classified by the number of processes Figure 5-1 . A. Pseudounipolar neurons are located in the spinal dorsal root ganglia and sensory ganglia of cranial nerves CN V, VII, IX, and X. Nerve endings in muscle myoneural junction Figure 5-1. Types of nerve cells. Olfactory neurons are bipolar and unmyelinated. Auditory neurons are bipolar and myelinated. Dorsal root ganglion cells cutaneous are pseudounipolar and myelinated. Motor neurons are multipolar and myelinated. Arrows...

Xcongenital Malformations Of The

Children With Chiari Malformation

Anencephaly meroanencephaly results from failure of the anterior neuropore to close. As a result, the brain does not develop. The frequency of this condition is 1 1000. Figure 4-5. Midsagittal section through the hypophysis and sella turcica. The adenohypophysis, including the pars tuberalis and pars intermedia, is derived from Rathke's pouch oroectoderm . The neurohypophysis arises from the infundibulum of the hypothalamus neuroectoderm . Figure 4-5. Midsagittal section through the...

Diseases Of The Motor Neurons And Corticospinal Tracts Figures 81 and

Tabes Dorsalis Tracts

Upper motor neuron UMN lesions are caused by transection of the corticospinal tract or destruction of the cortical cells of origin. They result in spastic paresis with pyramidal signs Babinskis sign . B. Lower motor neuron LMN lesions are caused by damage to the motor neurons. They result in flaccid paralysis, areflexia, atrophy, fasciculations, and fibrillations. Poliomyelitis or Werdnig-Hoffman disease see Figure 8-2A results from damage to the motor neurons. Gracile fasciculus, Cuneate...

The Vertibrobasilar System see Figure

Middle Cerebral Artery Superior Branch

The vertebral artery is a branch of the subclavian artery. It gives rise to the anterior spinal artery see I and the posterior inferior cerebellar artery PICA , which supplies the dorsolateral quadrant of the medulla. This quadrant includes the nucleus am-biguus CN IX, X, and XI and the inferior surface of the cerebellum. B. The basilar artery is formed by the two vertebral arteries. It gives rise to the following arteries. 1. The paramedian branches of the pontine arteries supply the base...

Coronal Section Through The Mamillary Bodies Figures 16 and

Mamillary Corpus

The location of the structures shown in the figures should be known. Figure 1-6. Coronal section of the brain at the level of the thalamus, mamillary bodies, and hippocampal formation. Note that the internal capsule lies between the thalamus and the lentiform nucleus. Figure 1-6. Coronal section of the brain at the level of the thalamus, mamillary bodies, and hippocampal formation. Note that the internal capsule lies between the thalamus and the lentiform nucleus. Corpus callosum Caudate...

Dorsal Columnmedial Lemniscus Pathway Figure 72 see also Figure

Crura Cerebri Transection

The dorsal column-medial lemniscus pathway mediates tactile discrimination, vibration sensation, form recognition, and joint and muscle sensation conscious proprioception . B. Receptors include Pacini's and Meissner's tactile corpuscles, joint receptors, muscle spindles, and Golgi tendon organs. C. First-order neurons are located in the dorsal root ganglia at all levels. They project axons to the spinal cord through the medial root entry zone. First-order neurons give rise to 1....

Axial Image Through The Thalamus And Internal Capsule

Ventricular Trigone Axial

The location of the structures shown in the figures should be known. Figure 1-8. Axial section of the brain ar the level of the internal capsule and basal ganglia. Note that the internal capsule has an anterior limb, a genu, and a posterior limb. Note also that the corpus callosum is sectioned through the genu and splenium. Figure 1-9. Axial magnetic resonance imaging section at the level of the internal capsule and basal ganglia. Note that the caudate nucleus bulges into...

Ventricular System

Kernohan Notch

The choroid plexus is a specialized structure that projects into the lateral, third, and fourth ventricles of the brain. It consists of infoldings of blood vessels of the pia mater that are covered by modified ciliated ependymal cells. It secretes the CSF. Tight junctions of the choroid plexus cells form the blood-CSF barrier. B. Ventricles contain CSF and choroid plexus. 1. The two lateral ventricles communicate with the third ventricle through the interventricular foramina of Monro. 2. The...

Development of the Nervous System

Embryology Brain

. THE NEURAL TUBE Figure 4-1 gives rise to the central nervous system CNS i.e., brain and spinal cord . A. The brain stem and spinal cord have 1. An alar plate that gives rise to the sensory neurons 2. A basal plate that gives rise to the motor neurons Figure 4-2 B. The neural tube gives rise to three primary vesicles, which develop into five secondary vesicles Figure 4-3 . C. Alpha-fetoprotein AFP is found in the amniotic fluid and maternal serum. It is an indicator of neural tube defects...

Viiangiography

Middle Cerebral Artery Anatomy

Figures 3-5A and B show the internal carotid artery, anterior cerebral artery, and middle cerebral artery. Superior cerebral veins Superior sagittal sinus Branches of MCA PCA Figure 3-4. Magnetic resonance angiogram, lateral projection, showing the major venous sinuses and arteries. Note the bridging veins entering the superior sagittal sinus. JCA internal carotid artery MCA middle cerebral artery PCA posterior cerebral artery. Superior cerebral veins Superior sagittal...

Coronal Section Through The Optic Chiasm Figures 14 and

Coronal Section Through The Optic Chiasm

The location of the structures shown in the figures should be known. Lateral ventricle -Septum pellucidum Figure 1-4. Coronal section of the brain at the level of the anterior commissure, optic chiasm, and amygdala. Note that the internal capsule lies between the caudate nucleus and the lentiform nucleus globus pallidus and putamen . Figure 1-4. Coronal section of the brain at the level of the anterior commissure, optic chiasm, and amygdala. Note that the internal capsule lies between the...

Blood Supply

Anterior Cerebral Artery Stroke

THE SPINAL CORD AND LOWER BRAIN STEM are supplied with hlood through the anterior spinal artery Figure 3-1 . A. The anterior spinal artery supplies the anterior two-thirds of the spinal cord. B. In the medulla, the anterior spinal artery supplies the pyramid, medial lemniscus, and root fibers of cranial nerve CN XII. Figure 3-1. Arteries of the base of the brain and brain stem, including the arterial circle of Willis. Figure 3-1. Arteries of the base of the brain and brain stem, including...

Meninges Ventricles and Cerebrospinal Fluid

Meninges Ventricle

MENINGES are three connective tissue membranes that surround the spinal coal and brain. A. They consist of the pia mater, arachnoid, and dura mater. 1. The pia mater is a delicate, highly vascular layer of connective tissue. It closely covers t he surface of the brain and spinal cord. 2. The arachnoid is a delicate, nonvascular connective tissue membrane. It is located between the dura mater and the pia mater. 3. The dura mater is the outer layer of meninges. It consists of dense connective...