Neuroanatomy Flashcards

Question

Grey matter

Answer 1

Grey matter (or gray matter) (lat. Substantia grisea) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astroglia and oligodendrocytes) and capillaries. Contains numerous cell bodies and relatively few myelinated axons In living tissue, grey matter actually has a very light grey color with yellowish or pinkish hues, which come from capillary blood vessels and neuronal cell bodies.[2]

Answer 2

consists mostly of glial cells and myelinated axons that transmit signals from one region of the cerebrum to another and between the cerebrum and lower brain centers. appears pinkish white to the naked eye because myelin is composed largely of lipid tissue veined with capillaries.

Answer 3

White matter forms the bulk of the deep parts of the brain and the superficial parts of the spinal cord. Aggregates of gray matter such as the basal ganglia (caudate nucleus, putamen, globus pallidus, subthalamic nucleus, nucleus accumbens) and brain stem nuclei (red nucleus, substantia nigra, cranial nerve nuclei) are spread within the cerebral white matter. The cerebellum is structured in a similar manner as the cerebrum, with a superficial mantle of cerebellar cortex, deep cerebellar white matter (called the "arbor vitae") and aggregates of grey matter surrounded by deep cerebellar white matter (dentate nucleus, globose nucleus, emboliform nucleus, and fastigial nucleus). The fluid-filled cerebral ventricles (lateral ventricles, third ventricle, cerebral aqueduct, fourth ventricle) are also located deep within the cerebral white matter.

Answer 4

cerebellum (“little brain”) is a structure that is located at the back of the brain, underlying the occipital and temporal lobes of the cerebral cortex (Figure 5.1). Although the cerebellum accounts for approximately 10% of the brain’s volume, it contains over 50% of the total number of neurons in the brain.

Answer 5

Modifies the motor commands of the descending pathways to make movements more adaptive and accurate. Makes postural adjustments in order to maintain balance. Through its input from vestibular receptors and proprioceptors, it modulates commands to motor neurons to compensate for shifts in body position or changes in load upon muscles. Patients with cerebellar damage suffer from balance disorders, and they often develop stereotyped postural strategies to compensate for this problem coordinate the timing and force of these different muscle groups to produce fluid limb or body movement Motor learning-adapting and fine-tuning motor programs to make accurate movements through a trial-and-error process cognitive functions, such as language

Answer 6

The cerebellum consists of two major parts. The cerebellar deep nuclei (or cerebellar nuclei) are the sole output structures of the cerebellum. These nuclei are encased by a highly convoluted sheet of tissue called the cerebellar cortex, which contains almost all of the neurons in the cerebellum. A cross-section through the cerebellum reveals the intricate pattern of folds and fissures that characterize the cerebellar cortex. Like the cerebral cortex, cerebellar gyri are reproducible across individuals and have been identified and named.

Answer 7

Divisions of the cerebellum. Two major fissures running mediolaterally divide the cerebellar cortex into three primary subdivisions. The posterolateral fissure separates the flocculonodular lobe from the corpus cerebelli, and the primary fissure separates the corpus cerebelli into a posterior lobe and an anterior lobe. The cerebellum is also divided sagittally into three zones that run from medial to lateral. The vermis (from the Latin word for worm) is located along the midsagittal plane of the cerebellum. Directly lateral to the vermis is the intermediate zone. Finally, the lateral hemispheres are located lateral to the intermediate zone (there are no clear morphological borders between the intermediate zone and the lateral hemisphere that are visible from a gross specimen).

Answer 8

Decomposition of movement. Intention tremor. Dysdiadochokinesia Deficits in motor learning.

Answer 9

cerebral cortex is the outer covering of gray matter over the hemispheres. This is typically 2- 3 mm thick, covering the gyri and sulci. The neocortex represents the great majority of the cerebral cortex. It has six layers and contains between 10 and 14 billion neurons. The six layers of this part of the cortex are numbered with Roman numerals from superficial to deep. Layer I is the molecular layer, which contains very few neurons; layer II the external granular layer; layer III the external pyramidal layer; layer IV the internal granular layer; layer V the internal pyramidal layer; and layer VI the multiform, or fusiform layer. Each cortical layer contains different neuronal shapes, sizes and density as well as different organizations of nerve fibers.

Answer 10

Functionally, the layers of the cerebral cortex can be divided into three parts. The supragranular layers consist of layers I to III. The supragranular layers are the primary origin and termination of intracortical connections, which are either associational (i.e., with other areas of the same hemisphere), or commissural (i.e., connections to the opposite hemisphere, primarily through the corpus callosum). The supragranular portion of the cortex is highly developed in humans and permits communication between one portion of the cortex and other regions. The internal granular layer, layer IV, receives thalamocortical connections, especially from the specific thalamic nuclei. This is most prominent in the primary sensory cortices. The infragranular layers, layers V and VI, primarily connect the cerebral cortex with subcortical regions. These layers are most developed in motor cortical areas. The motor areas have extremely small or non-existent granular layers and are often called "agranular cortex". Layer V gives rise to all of the principal cortical efferent projections to basal ganglia, brain stem and spinal cord. Layer VI, the multiform or fusiform layer, projects primarily to the thalamus.

Answer 11

Primary somatosensory cortex (SI; areas 3,1,2) is located in the post central gyrus. This receives somatotopic input from the VPL and VPM of the thalamus. Histologically, this area would consist of granular cortex. The sensory homunculus includes cortical representation of the body based on the degree of sensory innervation.Damage to the sensory cortex results in decreased sensory thresholds, an inability to discriminate the properties of tactile stimuli or to identify objects by touch The secondary somatosensory cortex (SII; area 40) is in the lower parietal lobe. This receives connections from the primary sensory cortex and also less specific thalamic nuclei. This responds to sensory stimuli bilaterally, although with much less precision than the primary cortex. Nonetheless, lesions to this area may impair some elements of sensory discrimination.

Answer 12

The primary visual cortex (VI; area 17) also called the striate cortex, surrounds the calcarine sulcus. This area has a large granular layer with dense columns of neurons, called ocular dominance columns. Adjacent columns come from the same homonomous portions of the left and right eyes (i.e., portions that detect images from corresponding portions of the visual world). The macula, the most sensitive portion of the center of the retina, is represented at the posterior tip of the occipital lobe. The upper part of the world projects to the lower part of the striate cortex. Lesions of the occipital lobe would cause cortical blindness and difficulty tracking objects.

Answer 13

The primary auditory cortices (AI; area 41) are on the transverse temporal gyri, extending into the lateral fissures. These gyri are situated on the upper part of the superior temporal gyri. There are tonotopic maps for different tones. Unilateral cortical lesions do not effect hearing because of completely bilateral sound representation.

Answer 14

The primary motor cortex (MI; area 4) is in the precentral gyrus. This is the origin of most of the corticospinal tract and a large number of cortical bulbar fibers, particularly those controlling motor cranial nerves. This also has projections to the thalamus and basal ganglion. The VL of the thalamus makes significant input to this nucleus and the precentral gyrus also receives significant input from sensory cortical areas as well as from the premotor portions of the cerebral cortex. There is a very well-defined somatotopic organization of the motor cortex and this is the region of cortex from which movements can be generated by the lowest intensity of electrical stimulation. Specific movements tend to be represented (such as elbow flexion) rather than specific muscles. Lesions produce spastic contralateral weakness, which is most prominent in the distal extremities. The premotor cortex (area 6) is immediately anterior to the motor cortex and has many of the same connections as the motor cortex. However, most of its output is to the motor cortex, with a smaller output to the brain stem and the spinal cord. This region receives input from the sensory association cortex as well as feedback from the basal ganglia via the VA and VL of the thalamus. Electrical stimulation of this area tends to produce more complex movements and at a higher stimulus intensity than the simple movements from MI. Lesions produce less severe weakness but greater spasticity than patients with isolated precentral gyrus lesions. The supplementary motor area (MII, superiomedial part of area 6) is a part of the premotor cortex that extends onto the medial side of hemisphere. This projects to the primary motor cortex, basal ganglia, thalamus and brain stem and also has connections with the contralateral supplementary motor area. This area becomes active before movement and is felt to be involved in initiation of motion. Lesions of this area can cause inability to initiate motions, called abulia.

Answer 15

The frontal eye fields (inferior area 8) are located just inferior and rostral to the premotor cortex. Activity in this region results in conjugate horizontal eye movement of the eyes away from the stimulus. This receives input from the medial dorsal nucleus of the thalamus as well as other areas of the cerebral cortex. It makes output to the superior colliculus and the PPRF. Lesions of this area initially block voluntary movement away from the side of lesions, although patients will slowly compensate for this deficit. The occipital eye fields are located in the visual association cortex. This projects to the frontal eye fields as well as to the pontine nuclei to generate smooth pursuit eye movements. Lesions will produce difficulty in fixing on a target and also will produce abnormalities in optokinetic responses.

Answer 16

There are areas of particular importance of the cerebral cortex. The receptive language area, Wernicke's (area 22) area is in the upper temporal lobe, extending back to the supramarginal (area 40) and angular (area 39) gyri. Lesions produce receptive aphasia with problems understanding spoken and written language. Lesions of the opercular and triangular portions of the inferior frontal gyrus (areas 44 and 45), called Broca's area in the dominant hemisphere, produce expressive or motor aphasia. These patients have difficulty in generating spoken or written language. In the nondominant hemisphere, lesions of the regions of the brain that are analogous to Wernicke's and Broca's areas affect the ability to understand or to generate inflections of voice, respectively.

Answer 17

The orbitomedial prefrontal cortex is involved in impulse control, personality, reactivity to the surroundings and mood. A particular area, the anterior cingulate gyrus (areas 24 and 25; subcallosal and subgenual regions) appears to be most associated with mood (particularly depression and mania). While laterality is not as well recognized in the prefrontal cortex as it is in language, there does appear to be some laterality, with lesions of the dominant cortex tending to produce depression and, of the nondominant hemisphere tending to produce mania. The frontal lobes connect to all other cortical regions through association fibers. It receives particularly strong input from limbic cortex, amygdala and septal nuclei, areas involved in emotional responses. Patients with lesions in this area are often referred to as having a changed personality.

Answer 18

brainstem is the region of the brain that connects the cerebrum with the spinal cord. It consists of the midbrain, medulla oblongata, and the pons. Motor and sensory neurons travel through the brainstem allowing for the relay of signals between the brain and the spinal cord. The brainstem coordinates motor control signals sent from the brain to the body. The brainstem also controls life supporting autonomic functions of the peripheral nervous system.

Answer 19

Alertness, arousal, breathing, blood pressure,digestion, heart rate, and other automatic functions Relays info between peripheral nerves and spinal cords to the other parts of the brain

Answer 20

mesencephalon or midbrain is the portion of the brainstem that connects the hindbrain and the forebrain. Controls responses to sight, eye Mvmt, pupil dilation, body, Mvmt, hearing The mesencephalon consists of the tectum and tegmentum.

Answer 21

medulla oblongata is a portion of the hindbrain that controls autonomic functions such as breathing, digestion, heart and blood vessel function, swallowing and sneezing. Motor and sensory neurons from the midbrain and forebrain travel through the medulla. As a part of the brainstem, the medulla oblongata helps in the transferring of messages between various parts of the brain and the spinal cord The medulla oblongata is involved in several functions of the body including: Control of Autonomic Functions Relay of Nerve Signals Between the Brain and Spinal Cord Coordination of Body Movements Directionally, the medulla oblongata is inferior to the pons and anterior to the cerebellum.

Answer 22

In Latin, the word pons literally means bridge. The pons is a portion of the hindbrain that connects the cerebral cortex with the medulla oblongata. It also serves as a communications and coordination center between the two hemispheres of the brain. As a part of the brainstem, the pons helps in the transferring of messages between various parts of the brain and the spinal cord. Functions:Arousal, Controlling Autonomic Functions, Relaying Sensory Information Between the Cerebrum and Cerebellum Sleep Directionally, the pons is superior to the medulla oblongata and inferior to the midbrain. Sagittally, it is anterior to the cerebellum and posterior to the pituitary gland.

Answer 23

The spinal cord is composed of nervous tissue. The interior of the spinal cord consists of neurons, nervous system support cells called glia, and blood vessels. The axons that link the spinal cord to the muscles and the rest of the body are bundled into 31 pairs of spinal nerves, each pair with a sensory root and a motor root that make connections within the grey matter. These nerves must pass between the protective barrier of the spinal column to connect the spinal cord to the rest of the body. The location of the nerves in the spinal cord determine their function.

Answer 24

Neurons are the basic unit of nervous tissue. They are composed of a cell body and projections that extend from the cell body that are able to conduct and transmit nerve signals. These projections are axons (carry signals away from the cell body) and dendrites (carry signals toward the cell body). The neurons and their dendrites are contained within an H-shaped region of the spinal cord called "grey matter." Surrounding the grey matter area is a region called "white matter." The white matter section of the spinal cord contains axons that are covered with an insulating substance called myelin. Myelin is whitish in appearance and allows electrical signals to flow freely and quickly. Axons carry signals along descending and ascending tracts away from and toward the brain Neurons are classified as either motor, sensory, or interneurons. Motor neurons carry information from the central nervous system to organs, glands, and muscles. Sensory neurons send information to the central nervous system from internal organs or from external stimuli. Interneurons relay signals between motor and sensory neurons. The descending tracts of the spinal cord consist of motor nerves that send signals from the brain to control voluntary and involuntary muscles. They also help to maintain homeostasis by assisting in the regulation of autonomic functions such as heart rate, blood pressure, and internal temperature. The ascending tracts of the spinal cord consist of sensory nerves that send signals from internal organs and external signals from the skin and extremities to the brain. Reflexes and repetitive movements are controlled by spinal cord neuronal circuits that are stimulated by sensory information without input from the brain.

Answer 25

spongy spinal cord is protected by the irregular shaped bones of the spinal column called vertebrae. Spinal vertebrae are components of the axial skeleton and each contain an opening that serves as a channel for the spinal cord to pass through. Between the stacked vertebrae are discs of semi-rigid cartilage, and in the narrow spaces between them are passages through which the spinal nerves exit to the rest of the body. These are places where the spinal cord is vulnerable to direct injury.

Answer 26

``` Cervical vertebrae (1-7) located in the neck Thoracic vertebrae (1-12) in the upper back (attached to the ribcage) Lumbar vertebrae (1-5) in the lower back Sacral vertebrae (1-5) in the hip area Coccygeal vertebrae (1-4 fused) in the tail-bone ```

Answer 27

Cervical spinal nerves (C1 to C8) control signals to the back of the head, the neck and shoulders, the arms and hands, and the diaphragm. Thoracic spinal nerves (T1 to T12) control signals to the chest muscles, some muscles of the back, and parts of the abdomen. Lumbar spinal nerves (L1 to L5) control signals to the lower parts of the abdomen and the back, the buttocks, some parts of the external genital organs, and parts of the leg. Sacral spinal nerves (S1 to S5) control signals to the thighs and lower parts of the legs, the feet, most of the external genital organs, and the area around the anus. The single coccygeal nerve carries sensory information from the skin of the lower back.

Answer 28

the meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous

Answer 29

The dura mater (literally, “tough mother”) is the dense, leathery membrane covering and protecting the brain and spinal cord. The dura mater is a sac (aka thecal sac) that envelops the arachnoid mater. It surrounds and supports the dural sinuses (also called dural venous sinuses, cerebral sinuses, or cranial sinuses) and carries blood from the brain toward the heart. There are many ways the dura can become damaged, including severe head injury, tumor ingrowth (meningioma), or a surgeon’s need to open the dura for access to the brain or spinal cord during invasive surgical procedures. The two layers of dura mater run together throughout most of the skull. Where they separate, the gap between them is called a dural venous sinus. These sinuses drain blood and cerebrospinal fluid from the brain and empty into the internal jugular vein.

Answer 30

It is interposed between the two other meninges, the more superficial and much thicker dura mater and the deeper pia mater, from which it is separated by the subarachnoid space. The delicate arachnoid layer is attached to the inside of the dura and surrounds the brain and spinal cord. It does not line the brain down into its sulci (folds), as does the pia mater, with the exception of the longitudinal fissure, which divides the left and right cerebral hemispheres. Cerebrospinal fluid (CSF) flows under the arachnoid in the subarachnoid space. The arachnoid mater makes arachnoid villi, small protrusions through the dura mater into the venous sinuses of the brain, which allow CSF to exit the subarachnoid space and enter the blood stream

Answer 31

The corpus callosum is a thick band of nerve fibers that divides the cerebrum into left and right hemispheres. It connects the left and right sides of the brain allowing for communication between both hemispheres. The corpus callosum transfers motor, sensory, and cognitive information between the brain hemispheres. Functions: Communication Between Brain Hemispheres, Eye Movement, Maintaining the Balance of Arousal and Attention, Tactile Localization Directionally, the corpus callosum is located underneath the cerebrum at the center of the brain.

Answer 32

hippocampus is the part of the brain that is involved in memory forming, organizing, and storing. It is a limbic system structure that is particularly important in forming new memories and connecting emotions and senses, such as smell and sound, to memories. The hippocampus is a horseshoe shaped paired structure, with one hippocampus located in the left brain hemisphere and the other in the right hemisphere. The hippocampus acts as a memory indexer by sending memories out to the appropriate part of the cerebral hemisphere for long-term storage and retrieving them when necessary. Functions: Consolidation of New Memories, Emotional Responses Navigation, Spatial Orientation Directionally, the hippocampus is located within the temporal lobes, adjacent to the amygdala.

Answer 33

The thalamus is a large, dual lobed mass of grey matter buried under the cerebral cortex. It is involved in sensory perception and regulation of motor functions. The thalamus is a limbic system structure and it connects areas of the cerebral cortex that are involved in sensory perception and movement with other parts of the brain and spinal cord that also have a role in sensation and movement. As a regulator of sensory information, the thalamus also controls sleep and awake states of consciousness. Functions: Motor Control, Receives Auditory, Somatosensory and Visual Sensory Signals, Relays Sensory Signals to the Cerebral Cortex Controls Sleep and Awake States

Answer 34

Cerebrospinal fluid (CSF) is a clear colorless bodily fluid found in the brain and spine. It is produced in the choroid plexus of the brain. It acts as a cushion or buffer for the brain's cortex, providing a basic mechanical and immunological protection to the brain inside the skull, and it serves a vital function in cerebral autoregulation of cerebral blood flow. The CSF occupies the subarachnoid space (the space between the arachnoid mater and the pia mater) and the ventricular system around and inside the brain and spinal cord. It constitutes the content of the ventricles, cisterns, and sulci of the brain, as well as the central canal of the spinal cord

Answer 35

The brain produces roughly 500 mL of cerebrospinal fluid per day. This fluid is constantly reabsorbed, so that only 100-160 mL is present at any one time. Ependymal cells of the choroid plexus produce more than two thirds of CSF. The choroid plexus is a venous plexus contained within the four ventricles of the brain, hollow structures inside the brain filled with CSF. The remainder of the CSF is produced by the surfaces of the ventricles and by the lining surrounding the subarachnoid space.

Answer 36

Ependymal cells actively secrete sodium into the lateral ventricles. This creates osmotic pressure and draws water into the CSF space. Chloride, with a negative charge, maintains electroneutrality and moves with the positively-charged sodium. As a result, CSF contains a higher concentration of sodium and chloride than blood plasma, but less potassium, calcium and glucose and protein.[2]:519–520 [1]:764

Answer 37

CSF circulates within the ventricular system of the brain. The ventricles are a series of cavities filled with CSF that reside within the brain. The majority of CSF is produced from within the two lateral ventricles. From here, the CSF passes through the Interventricular foramina (of Monro) to the third ventricle, then the cerebral aqueduct (of Sylvius) to the fourth ventricle. The fourth ventricle is an outpouching on the posterior part of the brainstem. From the fourth ventricle, the fluid passes through three foramen to enter the subarachnoid space. It passes through the Foramen of Magendie on the midline, and two Foramen of Luschka laterally. The subarachnoid space covers the brain and spinal cord. The CSF moves in a pulsatile manner throughout the CSF system with nearly zero net flow.[citation needed]

Answer 38

It had been thought that CSF returns to the vascular system by entering the dural venous sinuses via the arachnoid granulations (or villi). However, some[3] have suggested that CSF flow along the cranial nerves and spinal nerve roots allow it into the lymphatic channels; this flow may play a substantial role in CSF reabsorbtion, in particular in the neonate, in which arachnoid granulations are sparsely distributed. The flow of CSF to the nasal submucosal lymphatic channels through the cribriform plate seems to be especially important.[4]

Answer 39

The CSF contains approximately 0.3% plasma proteins, or approximately 15 to 40 mg/dL, depending on sampling site,[5] and it is produced at a rate of 500 ml/day. Since the subarachnoid space around the brain and spinal cord can contain only 135 to 150 ml, large amounts are drained primarily into the blood through arachnoid granulations in the superior sagittal sinus. Thus the CSF turns over about 3.7 times a day. This continuous flow into the venous system dilutes the concentration of larger, lipid-insoluble molecules penetrating the brain and CSF.[6]

Answer 40

CSF pressure, as measured by lumbar puncture (LP), is 10-18 cmH2O (8-15 mmHg or 1.1-2 kPa) with the patient lying on the side and 20-30cmH2O (16-24 mmHg or 2.1-3.2 kPa) with the patient sitting up.[7] In newborns, CSF pressure ranges from 8 to 10 cmH2O (4.4–7.3 mmHg or 0.78–0.98 kPa). Most variations are due to coughing or internal compression of jugular veins in the neck. When lying down, the cerebrospinal fluid as estimated by lumbar puncture is similar to the intracranial pressure.

Answer 41

CSF serves several purposes: 1. Protection from brain injury 2. Buoyancy- the net weight of the brain is suspended in CSF 3. Chemical stability 4. Prevents brain ischemia 5. Clearing waste

Answer 42

The Circle of Willis is a part of the cerebral circulation and is composed of the following arteries:[2] Anterior cerebral artery (left and right) Anterior communicating artery Internal carotid artery (left and right) Posterior cerebral artery (left and right) Posterior communicating artery (left and right) The basilar artery and middle cerebral arteries, supplying the brain, are not considered part of the circle.

Answer 43

The anterior cerebral artery (ACA) is one of a pair of arteries on the brain that supplies oxygenated blood to most medial portions of the frontal lobes and superior medial parietal lobes. The two anterior cerebral arteries arise from the internal carotid artery and are part of the Circle of Willis. The left and right anterior cerebral arteries are connected by the anterior communicating artery.

Answer 44

Areas supplied by the anterior cerebral artery include: The medial surface of the frontal lobe by the medial orbito-frontal artery, and parietal lobes The anterior four- fifths of the corpus callosum Approximately 1 inch of the lateral surfaces of frontal and parietal lobes, next to the medial longitudinal fissure Anterior portions of the basal ganglia and internal capsule Olfactory bulb and tract

Answer 45

Paralysis or weakness of the contralateral foot and leg due to involvement of Motor leg area Cortical Sensory loss in the contralateral foot and leg Gait apraxia Impairment of gait and stance Abulia akinetic mutism, slowness and lack of spontaneity Urinary incontinence which usually occurs with bilateral damage in the acute phase Frontal Cortical release reflexes: Contralateral grasp reflex, sucking reflex, gegenhalten(paratonic rigidity)

Answer 46

The anterior communicating artery connects the two anterior cerebral arteries across the commencement of the longitudinal fissure. Sometimes this vessel is wanting, the two arteries joining together to form a single trunk, which afterward divides; or it may be wholly, or partially, divided into two. Its length averages about 4 mm, but varies greatly. It gives off some of the anteromedial ganglionic vessels, but these are principally derived from the anterior cerebral artery.

Answer 47

Aneurysms of the anterior communicating artery are the most common circle of Willis aneurysm[1] and can cause visual field defects such as bitemporal hemianopsia,[2] psychopathology and frontal lobe pathology.[3]

Answer 48

The internal carotid artery is major paired artery, one on each side of the head and neck, in human anatomy. They arise from the common carotid arteries where these bifurcate into the internal and external carotid arteries; the internal carotid artery supplies the brain, while the external carotid nourishes other portions of the head, such as face, scalp, skull, and meninges.

Answer 49

posterior cerebral artery (PCA) is one of a pair of blood vessels that supply oxygenated blood to the posterior aspect of the brain (occipital lobe) in human anatomy. It arises near the intersection of the posterior communicating artery and the basilar artery and connects with the ipsilateral middle cerebral artery (MCA) and internal carotid artery via the posterior communicating artery (PCommA).

Answer 50

Stroke Contralateral loss of pain and temperature sensations. Visual field defects (contralateral hemianopia with macular sparing). Prosopagnosia with bilateral obstruction of the lingual and fusiform gyri. Superior Alternating Syndrome (Weber's syndrome) Contralateral deficits of facial nerve (only lower face, upper face receives bilateral input), vagus nerve and hypoglossal nerve Ipsilateral deficit of oculomotor nerve Horner's Syndrome Signs and symptoms:Structures involved