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PSYC375 Exam #2 SS
PSYC375 Exam #2 Study Set
| Question | Answer |
|---|---|
| Hand movements controlled by muscles in the forearm are best described as: | controlled by extrinsic muscles for strength and finger movements |
| In myasthenia gravis, what do circulating antibodies attack? | Postsynaptic nicotinic acetylcholine receptors |
| You find you can no longer hold your pen, and you have numbness of your index and middle fingers and your thumb. Damage or compression of what nerve is the likely cause? | Median |
| A patient presents with impaired function of multiple nerve roots below L1/L2 and is experiencing a series of dysfunctions, including pain, numbness, and loss of bowel and/or bladder. What is the most likely diagnosis? | Cauda equina syndrome |
| A patient's has difficulty lifting their knee and straightening their leg. Damage is most likely: | Femoral nerve |
| What is the general term for a nerve disorder? | Neuropathy |
| Which of the following is due to damage to the brachial plexus, and results in weakness of the shoulder and parts of the arm and wrist? | Erb-Duchenne palsy |
| What is the definition of a "dermatome"? | The sensory region of skin innervated by a nerve root. |
| Which spinal cord section gives rise to the nerve roots for the arms? | Cervical section |
| Which somatosensory pathway is involved in the emotional and arousal aspects of pain? | Spinoreticular tract |
| First-order neurons are: | are the periphery "detection" neurons |
| Why are thoracic disc herniations less common than cervical or lumbosacral ones? | This region of the spinal column is less mobile and fixed by the rib cage. |
| A patient has difficulty spreading their fingers. Damage is most likely: | Ulnar nerve |
| The ventral posterior lateral nucleus (VPLN) of the thalamus has been damaged. What is the likely outcome? | Loss of sensation of vibration and fine touch |
| Which nerve injury often presents with a "wrist drop"? | Radial neuropathy |
| Which diagnostic tool measures how fast electrical signals travel along a nerve? | Nerve conduction study |
| What are the most clinically important nerve branches arising from the brachial plexus? | - Median nerve - Axillary nerve - Radial nerve - Ulnar nerve |
| What is the primary difference in organizational structure between the brachial and lumbosacral plexuses? | The brachial plexus forms cords, while the lumbosacral plexus does not. |
| Carpal tunnel syndrome is caused by compression of which nerve at the wrist? | Median nerve |
| The cauda equina primarily contains what? | Nerve roots with no spinal cord |
| What are the two main somatosensory pathways? | It is the posterior column–medial lemniscus (PCML) pathway & the anterolateral (spinothalamic) pathway. |
| Where do first-order neurons of the PCML pathway synapse? | They synapse in the nucleus gracilis (for the legs) and the nucleus cuneatus (for the arms) in the medulla. |
| Where does the PCML pathway decussate? | It decussates in the medulla as internal arcuate fibers, forming the medial lemniscus on the contralateral side. |
| What is the somatotopic organization in the posterior columns? | It is organized so that the gracile fasciculus (legs and lower trunk) is medial, and the cuneate fasciculus (arms and neck) is lateral in the posterior columns. |
| Where do second-order neurons of the spinothalamic tract decussate? | They decussate in the anterior (ventral) commissure of the spinal cord. |
| What does the spinoreticular tract carry? | It carries the emotional and arousal aspects of pain, projecting signals to the reticular formation and intralaminar nuclei of the thalamus. |
| What does the spinomesencephalic tract do? | It projects pain signals to the periaqueductal gray (PAG) and superior colliculus, helping regulate and modulate pain perception in the brain. |
| What are the characteristics of Aδ pain fibers and C pain fibers? | Aδ pain fibers are small, myelinated, and transmit fast, sharp pain. C pain fibers are unmyelinated, slow, and carry dull, burning pain. Both types of pain fibers release substance P to signal pain. |
| What is the Gate Control Theory of pain? | It is a theory that states pain signals are modulated by a spinal “gate,” where large-diameter A-beta fibers (touch/vibration) inhibit dorsal horn transmission, increasing or decreasing pain perception based on neural activity and competing input. |
| What is the descending pain modulation pathway? | Periaqueductal gray (PAG) → Rostral Ventral Medulla (RVM) → Dorsal horn, using serotonin and norepinephrine to inhibit pain signals |
| What endogenous opioids modulate pain? | It is the modulation of pain by endogenous opioids—enkephalin, dynorphin (κ receptors), and β-endorphin (from the hypothalamus)—acting at the PAG, RVM, and dorsal horn. |
| What is the major sensory relay nucleus in the thalamus for the body? | It is the Ventral Posterior Lateral (VPL) nucleus of the thalamus, which relays sensory information from the body—including touch, vibration, proprioception, pain, and temperature—to the primary somatosensory cortex. |
| What is the major sensory relay nucleus for the face? | It is the Ventral Posterior Medial (VPM) nucleus of the thalamus, which relays sensory information from the face to the primary somatosensory cortex. |
| What is the function of the reticular nucleus of the thalamus? | Its function is to regulate and inhibit activity of other thalamic nuclei using GABA, controlling sensory signal flow. It does not project directly to the cortex. |
| What is the difference between specific thalamic nuclei and nonspecific thalamic nuclei? | Specific thalamic nuclei (VPL, VPM, LGN) relay precise, modality-specific sensory information to primary cortical areas, while nonspecific (intralaminar) thalamic nuclei project diffusely to the cortex, supporting arousal, attention, and alertness. |
| What is Brown-Séquard syndrome? | It is a condition caused by damage to one side of the spinal cord (hemicord lesion). Features include ipsilateral weakness and loss of vibration/proprioception, and contralateral loss of pain and temperature below the lesion. |
| What is central cord syndrome? | It is a spinal cord injury caused by damage to the central region of the cord, often due to trauma or syringomyelia. Features include bilateral “suspended” loss of pain and temperature in a cape-like distribution over the upper limbs. |
| What is anterior cord syndrome? | It is a spinal cord injury caused by damage to the anterior portion of the spinal cord. Features include loss of pain and temperature below the lesion with motor weakness, but preserved vibration and proprioception. |
| What is posterior cord syndrome? | It is a spinal cord injury caused by damage to the posterior portion of the spinal cord. Features include loss of vibration and proprioception below the lesion, with preserved pain, temperature, and motor function. |
| What is the effect of a thalamic lesion? | It causes contralateral sensory loss and can lead to severe, chronic contralateral pain (thalamic pain syndrome), often with abnormal pain perception such as allodynia or hyperalgesia. |
| How many spinal cord segments are there? | 31 total: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal |
| Where does the spinal cord end in adults? | It ends at the L1–L2 vertebral level, forming the conus medullaris, the tapered terminal end of the spinal cord. |
| What is the cauda equina? | It is a bundle of lumbar and sacral nerve roots below the conus medullaris (L1–L2), resembling a horse’s tail, responsible for motor and sensory innervation of the lower limbs and pelvic organs. |
| What is the difference between cervical enlargements and lumbosacral enlargements? | Cervical enlargement (C5–T1) gives rise to nerves supplying the upper limbs, while the lumbosacral enlargement (L1–S3) gives rise to nerves supplying the lower limbs. |
| Where do cervical nerve roots exit relative to their vertebra? | They exit the spinal canal above their corresponding vertebrae (e.g., C5 exits above C5), except C8, which exits between C7 and T1, aiding clinical localization. |
| Where do thoracic and lumbar nerve roots exit? | They exit the spinal canal below their corresponding vertebrae (e.g., T1 exits below T1, L4 below L4), helping localize spinal nerve levels clinically. |
| What is the general rule for disc herniation and nerve root affected? | The general rule is that a disc herniation typically compresses the nerve root traveling to exit below the lower vertebra (e.g., an L4–L5 disc herniation affects the L5 nerve root). |
| What is a far lateral disc herniation? | It is a type of spinal disc herniation where the disc pushes out to the side, pressing on nerves outside the main spinal canal, often causing pain, numbness, or weakness in the limbs. |
| What is a central disc herniation? | It is a type of spinal disc herniation where the disc bulges straight back into the center of the spinal canal, potentially pressing on the spinal cord or nerves, causing pain or numbness. |
| What is the ligamentum flavum and its clinical significance? | It is a strong, elastic ligament that connects the vertebrae along the spine’s back, helping maintain posture and spinal stability. Clinically, it can thicken with age, contributing to spinal stenosis and nerve compression. |
| What is radiculopathy? | It is a condition where a nerve root in the spine is compressed or irritated, causing pain, numbness, tingling, or weakness that radiates along the nerve’s pathway in the arms or legs. |
| What is cauda equina syndrome? | It is a surgical emergency caused by a central disc herniation that compresses the lower spinal nerves, leading to bilateral leg weakness, saddle-area numbness, and bowel or bladder dysfunction. |
| What are red flag symptoms for back pain? | - Age >50 - Worsening pain - Lack of improvement - Bowel/bladder dysfunction - Saddle anesthesia |
| What is a dermatome? | It is an area of skin supplied by a single spinal nerve root, helping doctors identify and localize specific nerve root injuries or lesions. |
| What is the difference between a dermatome and a cutaneous nerve? | Dermatome = Skin area from one spinal nerve root Cutaneous nerve = Skin area from a peripheral nerve |
| What are the key dermatome landmarks? | T4 = Nipples T10 = Umbilicus (belly button) |
| What are the upper limb dermatomes? | C5 = Shoulder C6 = Thumb/index C7 = Middle finger C8 = Ring/pinky |
| What are the lower limb dermatomes? | L4 = Medial shin L5 = Lateral shin, top foot, great toe S1 = Little toe S2-S4 = Saddle area |
| What is a myotome? | It is a group of muscles controlled by a single spinal nerve root, used to assess motor function and help localize nerve root injuries. |
| What are the key myotomes? | C3-5 = Phrenic/diaphragm C5-6 = Shoulder abduction L2-4 = Hip flexion/knee extension L5-S1 = Dorsiflexion/plantarflexion |
| What nerve roots form the brachial plexus? | C5, C6, C7, C8, and T1 |
| What is a good mnemonic for remembering the brachial plexus structure? | Robert Taylor Drinks Cold Beer = Roots, Trunks, Divisions, Cords, Branches. |
| What are the major nerves of the brachial plexus? What limb do they supply? | They are the axillary, radial, median, ulnar, and musculocutaneous nerves. They supply the upper limb. |
| What is the function of the axillary nerve? | It controls shoulder abduction beyond the first 15 degrees by innervating the deltoid muscle. |
| What is the function of the radial nerve? | It enables extension of the elbow, wrist, and proximal finger joints, as well as forearm supination and thumb abduction. |
| What is the function of the median nerve? | It controls thumb opposition and flexion, flexion of the index and middle fingers, wrist flexion and abduction, and forearm pronation. |
| What is the function of the ulnar nerve? | It controls finger abduction and adduction, flexion of the ring and pinky fingers, wrist flexion and adduction, and thumb adduction. |
| What is the function of the musculocutaneous nerve? | It controls elbow flexion via the biceps, brachialis, and coracobrachialis muscles, and assists in forearm supination. |
| What is the wrist drop? | It is a classic sign of radial nerve injury, characterized by the inability to extend the wrist. |
| What is the "preacher's hand" deformity? | It is a median nerve neuropathy that prevents flexion of the index and middle fingers, making it impossible to form the “OK” sign. |
| What is the "funny bone? | It is the ulnar nerve at the elbow. Hitting it causes tingling and/or numbness in the ring and pinky fingers. |
| What is the "RUM" rule for thumb control? | Radial = Thumb out (abduction) Ulnar = Thumb in (adduction) Median = Thumb touch (opposition) |
| What are the LOAF muscles of the median nerve? | Lumbricals I & II Opponens pollicis Abductor pollicis brevis Flexor pollicis brevis (superficial head) |
| What are the functions of the lumbricals? | They flex the metacarpophalangeal (MCP) joints and extend the proximal and distal interphalangeal (PIP and DIP) joints of the fingers. |
| What are the functions of the interossei? | They control finger movements: dorsal interossei abduct the fingers, while palmar interossei adduct the fingers. |
| What is the difference between intrinsic hand muscles & extrinsic hand muscles? | Intrinsic hand muscles lie within the hand, mainly innervated by the ulnar and median nerves, enabling fine motor control and precision. Extrinsic muscles originate in the forearm, providing strength and gross movements. |
| What is Erb-Duchenne palsy? | It is an upper brachial plexus injury (C5–C6) that causes the “waiter’s tip” posture, with the shoulder internally rotated, the elbow extended, and the forearm pronated. |
| What is carpal tunnel syndrome? | It is compression of the median nerve at the wrist, causing tingling or numbness in the thumb, index, and middle fingers, weak grip, and atrophy of the thenar muscles. |
| What nerve roots form the lumbosacral plexus? | L1 through S4 |
| What are the major nerves of the lumbosacral plexus? What limb do they supply? | They are the femoral, obturator, sciatic, tibial, and fibular (peroneal) nerves. They supply the lower limb. |
| What is the function of the femoral nerve? | It controls hip flexion and knee extension by innervating the anterior thigh muscles. |
| What is the function of the obturator nerve? | It controls thigh adduction, bringing the legs together by innervating the medial thigh muscles. |
| What is the function of the sciatic nerve? | It controls knee flexion through the hamstrings and branches into the tibial and fibular nerves to innervate muscles of the lower leg and foot. |
| What is the function of the tibial nerve? | It controls plantarflexion of the foot, inversion, and flexion of the toes by innervating the posterior compartment muscles of the lower leg. |
| What is the function of the fibular (peroneal) nerve? | It controls dorsiflexion of the foot through its deep branch and foot eversion through its superficial branch, innervating the anterior and lateral compartments of the lower leg. |
| What do EMG and nerve conduction studies measure? | EMG measures the electrical activity of muscles. Nerve conduction studies (NCS) assess the speed and strength of nerve signals; slowed conduction suggests demyelination, and reduced signal amplitude indicates axonal damage. |
| Where is the primary motor cortex located? | It is located in the precentral gyrus of the frontal lobe, somatotopically organized with face and hands represented laterally, and legs and feet represented medially. |
| Where is the primary somatosensory cortex located? | It is located in the postcentral gyrus of the parietal lobe (Brodmann areas 3, 1, and 2), somatotopically organized to receive sensory input from different body regions. |
| What is the Broca's area? | It is a region located in the inferior frontal gyrus of the dominant (usually left) hemisphere, responsible for planning and producing speech by controlling articulation. |
| What is Broca's aphasia? | It is a language disorder caused by damage to Broca’s area, characterized by non-fluent, halting speech with intact comprehension—patients understand language but struggle to speak clearly. |
| What is the Wernicke's area? | It is a region located in the superior temporal gyrus of the dominant (usually left) hemisphere, responsible for understanding spoken and written language. |
| What is Wernicke's aphasia? | It is a language disorder caused by damage to Wernicke’s area, characterized by fluent but nonsensical speech and poor comprehension. People can speak smoothly but their words often lack meaning. |
| What is the function of the nondominant (usually right) hemisphere? | It controls attention to the contralateral side of the body and space; damage can cause hemispatial neglect, where the patient ignores or is unaware of that side. |
| What is hemispatial neglect? | It is a neurological condition, often caused by a stroke, where a patient ignores and/or is unaware of one side of space. It can occur on either side, but it is more common and severe in the right hemisphere. |
| What are examples of things that can happen to a person because of hemispatial neglect? | - Eating only half their plate - Drawing half a picture - Shaving one side of the face - Applying makeup to one side of the face - Bumping into objects on the neglected side - Ignoring people on that side |
| What is the Circle of Willis? | It is a ring of arteries at the base of the brain connecting the anterior and posterior circulations, providing a backup blood supply. Only about 34% of people have a complete circle. |
| What are the four segments of the internal carotid artery? | They are the cervical, petrous, cavernous, and supraclinoid segments of the internal carotid artery. |
| What are the three main cerebral arteries? | They are the anterior cerebral artery (ACA), middle cerebral artery (MCA), and posterior cerebral artery (PCA), supplying the cerebrum. |
| What is ACA stroke? | It is a type of stroke affecting the anterior cerebral artery (ACA), causing contralateral leg weakness and personality changes due to damage to the medial frontal and parietal lobes. |
| What is alien hand syndrome? | It is a rare neurological disorder and a rare effect of an ACA stroke, in which one hand moves involuntarily, often due to medial frontal or parietal lobe damage, acting as if it has a “mind of its own". |
| What is MCA stroke? | It is a type of stroke affecting the middle cerebral artery (MCA), causing contralateral face and arm weakness. Left MCA strokes often cause aphasia, while right MCA strokes can lead to hemispatial neglect. |
| What is PCA stroke? | It is a stroke affecting the posterior cerebral artery (PCA), causing contralateral visual field loss and, in some cases, alexia without agraphia, where the patient cannot read but can still write. |
| What are the lenticulostriate arteries? | They are deep penetrating branches of the middle cerebral artery (MCA) that supply the basal ganglia and internal capsule, and are common sites for lacunar infarcts and hemorrhage. |
| What is the recurrent artery of Heubner? | It is a branch of the anterior cerebral artery (ACA) that supplies the head of the caudate, anterior putamen, and anterior limb of the internal capsule. |
| What is a lacunar stroke? | It is a small vessel stroke affecting deep brain structures such as the basal ganglia, internal capsule, or thalamus, most commonly caused by chronic hypertension. |
| What is a ischemic stroke? | It is a sudden interruption of blood flow to the brain, causing tissue death (infarct) due to lack of oxygen, often from a clot. |
| What are the causes of ischemic stroke? | - Thrombosis (a clot forming within a vessel) - Embolism (a clot traveling from elsewhere) - Lacunar infarcts from small vessel disease, often due to chronic hypertension |
| What is a TIA (Transient Ischemic Attack)? | It is a transient ischemic attack (“mini-stroke”) causing temporary neurologic symptoms lasting less than 24 hours, often minutes, and serves as a major warning sign of future stroke requiring urgent evaluation. |
| What are watershed areas? | They are border zones between major arterial territories in the brain, which are especially vulnerable to ischemia during drops in blood pressure (hypotension). |
| What is transient monocular blindness? | It is temporary vision loss in one eye, usually from ophthalmic artery ischemia due to carotid stenosis or emboli, and is an important warning sign of increased risk for future stroke. |
| What is the time window for acute ischemic stroke intervention? | The treatment window is thrombolysis (tPA) within 3–4.5 hours of symptom onset, while endovascular thrombectomy can extend the window up to 6–24 hours in selected patients. |
| What is the complete visual pathway from retina to cortex? | Photoreceptors → Bipolar cells → Ganglion cells → Optic nerve → Optic chiasm → Optic tract → lateral geniculate nucleus (LGN) → Optic radiations → Primary visual cortex → Visual association cortex |
| What is the geniculate pathway? | It is a pathway that carries visual information from the retina to the lateral geniculate nucleus (LGN) and then to the cortex for conscious vision. Retina → LGN → cortex |
| What is the extrageniculate pathway? | It is a pathway that projects to the superior colliculus and pretectal area for reflexes and visual attention. Retina → superior colliculus & pretectal area |
| What happens at the optic chiasm? | Nasal retinal fibers cross to the opposite side while temporal fibers remain ipsilateral, so visual information from the left visual field goes to the right brain and vice versa. |
| What are the optic radiations and their paths? | Fibers from LGN sweep to occipital cortex. Inferior radiations (Meyer's loop) go through temporal lobe; superior radiations go through parietal lobe. |
| What are optic radiations? | They are bundles of nerve fibers that carry visual information from the lateral geniculate nucleus (LGN) to the occipital cortex. |
| What are the paths of the optic radiations? | The paths are inferior radiations (Meyer’s loop) passing through the temporal lobe, and superior radiations traveling through the parietal lobe to reach the occipital cortex. |
| What are the paths of the inferior and superior optic radiations? | Inferior radiations (Meyer’s loop): Retina → LGN → temporal lobe → occipital cortex Superior radiations: Retina → LGN → parietal lobe → occipital cortex |
| Where does the optic tract project after the chiasm? | It projects primarily to lateral geniculate nucleus (LGN) of thalamus, with minor projections to midbrain (superior colliculus, pretectal area). |
| What are the three types of retinal neurons in the vertical pathway? | - Photoreceptors (rods and cones) - Bipolar cells - Ganglion cells Photoreceptors (rods/cones) → bipolar cells → ganglion cells |
| What are photoreceptors (rods and cones)? | They are specialized retinal neurons that detect light and convert it into electrical signals, using graded potentials. |
| What are bipolar cells? | They are retinal neurons that transmit signals from photoreceptors to ganglion cells, using graded potentials. |
| What are ganglion cells? | They are retinal neurons that receive input from bipolar cells and fire action potentials to transmit visual information to the brain. |
| What are the differences between rods and cones? | Rods are specialized for low-light (night) vision, highly sensitive, do not detect color, and saturate in bright light. Cones detect color and fine detail, are concentrated in the fovea, and use three photopigments. |
| In the vertical pathway of the retina, which cells fire action potentials and which use graded potentials? | Only ganglion cells fire action potentials to transmit visual signals to the brain, while photoreceptors and bipolar cells communicate using graded potentials. |
| What are ON-center and OFF-center receptive fields? | ON-center receptive fields are activated when light hits the center and inhibited by light in the surround. OFF-center receptive fields are inhibited by light in the center and activated by light in the surround. Both enhance contrast and edge detection. |
| What are the three types of retinal ganglion cells? | - Parasol cells - Midget cells - Bistratified cells |
| What are parasol cells? | They are retinal ganglion cells that detect motion and large shapes, transmitting this information to the magnocellular layers of the LGN for processing in the brain’s visual pathway. |
| What are midget cells? | They are retinal ganglion cells that detect fine detail and color, transmitting this information to the parvocellular layers of the LGN for high-resolution visual processing in the brain. |
| What are bistratified cells? | They are retinal ganglion cells that process color information and transmit it to the interlaminar (koniocellular) layers of the LGN, contributing to color vision and visual signal integration in the brain. |
| How is the LGN organized? | It is organized into six main layers: layers 1–2 are magnocellular, processing motion and spatial information; layers 3–6 are parvocellular, processing fine detail and color; interlaminar (koniocellular) layers also contribute to color processing. |
| How are eye inputs segregated in the LGN? | Inputs from each eye remain strictly segregated into separate layers. Each hemisphere gets input from both eyes, but fibers do not mix. |
| What is the fovea? | It is the small central region of the retina containing only cones, with other retinal layers absent, allowing light to reach photoreceptors directly and providing the highest visual acuity in the visual field. |
| Why is the fovea special? | It is specialized for high-acuity vision because it contains only cones and lacks overlying retinal layers, allowing light to strike photoreceptors directly for the clearest, most detailed central vision. |
| What is the optic disc (blind spot)? | It is the region where ganglion cell axons exit the eye to form the optic nerve, containing no photoreceptors. The brain fills in the missing information, and binocular vision compensates, so it goes unnoticed. |
| What is cortical magnification? | It refers to the fovea, the small central part of the retina, taking up a much larger area in the primary visual cortex—about 50%—because it provides the sharpest, most detailed vision. |
| What is the dorsal stream and the ventral stream? | Dorsal stream (parieto-occipital) = "WHERE" pathway for motion, location, spatial relations Ventral stream (occipitotemporal) = "WHAT" pathway for color, form, identification |
| What are the three parallel processing channels from retina to cortex? | - Magnocellular - Parvocellular - Koniocellular |
| What is the magnocellular parallel processing channels? | They are retinal-to-cortex pathways that process motion and spatial information, projecting from the retina through the magnocellular layers (1–2) of the LGN to the visual cortex. |
| What is the parvocellular parallel processing channels? | They are retinal-to-cortex pathways that process form and fine detail, projecting from the retina through the parvocellular layers (3–6) of the LGN to the visual cortex. |
| What is the koniocellular parallel processing channels? | They are retinal-to-cortex pathways that process color information, projecting from the retina through the interlaminar (koniocellular) layers of the LGN to the visual cortex. |
| How do magnocellular and parvocellular pathways differ? | Magnocellular = Parasol input, motion detection, transient response, large receptive fields Parvocellular = Midget input, fine detail, color, sustained response |
| What is the extrageniculate pathway? | It is the retino-tecto-pulvinar-extrastriate pathway that mediates visual attention, eye movements, pupillary light reflex (via pretectal area), and orientation to visual stimuli. |
| What are simple cells in the visual cortex? | They are neurons that respond to oriented lines or edges at specific locations within their receptive fields. |
| What are complex cells in the visual cortex? | They are neurons that respond to oriented lines or edges regardless of exact position within their receptive fields. |
| What are hypercolumns in V1? | They are ~1 mm² functional units in V1 that contain complete sets of ocular dominance and orientation columns, allowing processing of all visual features for a specific region of the visual field. |
| What visual field defect results from optic nerve damage? | Optic nerve damage causes monocular vision loss (blindness in one eye) because the lesion occurs before visual information from both eyes can combine. |
| What defect occurs with optic chiasm compression (e.g., pituitary tumor)? | Optic chiasm compression (e.g., from a pituitary tumor) causes bitemporal heteronymous hemianopia, the loss of outer (temporal) visual fields in both eyes due to damage of crossing nasal retinal fibers. |
| What defect occurs with optic tract or LGN lesions? | Contralateral homonymous hemianopia — loss of same side of vision in both eyes (opposite side to the lesion). |
| What defect occurs with optic tract or LGN lesions? | Optic tract or LGN lesions cause contralateral homonymous hemianopia, the loss of the same side of the visual field in both eyes, opposite to the side of the lesion. |
| What defect occurs with temporal lobe damage (Meyer's loop)? | Temporal lobe damage affecting Meyer’s loop causes contralateral homonymous superior quadrantanopia, the loss of the upper visual field on the opposite side. Memory trick: “Pie in the sky" |
| What defect occurs with parietal lobe damage? | Contralateral homonymous inferior quadrantanopia — loss of lower visual field. Memory trick: "Pie on the floor" |
| What visual field defects occur with primary visual cortex lesions? | Primary visual cortex lesions cause contralateral homonymous hemianopia, scotoma, or quadrantanopia depending on lesion location. Foveal vision may be spared due to dual blood supply (macular sparing). |
| How do upper and lower bank lesions of calcarine fissure differ? | Upper bank (cuneus) lesions cause contralateral lower visual field loss, while lower bank (lingual gyrus) lesions cause contralateral upper visual field loss. |
| What is a scotoma? | It is a localized blind spot in the visual field caused by partial damage to the visual pathway, often due to lesions in the retina, optic nerve, or visual cortex. |
| What visual phenomena occur with visual association cortex lesions? | Lesions of the visual association cortex cause visual processing disorders, such as visual agnosia (perceiving objects normally but unable to recognize them) and formed visual hallucinations. |
| What causes ocular migraine visual symptoms? | Ocular migraine visual symptoms are caused by temporary reduced blood flow (ischemia) to the visual cortex, producing transient visual disturbances such as flashing lights, geometric shapes, or scotomas. |
| What are first-order neurons? | They are peripheral “detection” neurons that sense stimuli (e.g., touch, pain, or temperature) and transmit signals from sensory receptors toward the central nervous system. |
| What are second-order neurons? | They are neurons that receive input from first-order (peripheral) neurons and transmit signals to the thalamus or spinal cord. |
| What are third-order neurons? | They are neurons that receive input from second-order neurons and transmit signals to the cerebral cortex for perception. |
| Second-order neurons are: | neurons that relay signals from first-order neurons to the thalamus or brainstem |
| Third-order neurons are: | neurons that carry signals from the thalamus to the cerebral cortex |
| What are the paths of first-, second-, and third-order neurons? | First-order: Starts at the feeling place → DRG/spinal cord Second-order: DRG/Spinal cord → thalamus Third-order: Thalamus → brain cortex |
| Which somatosensory pathway transmits pain and temperature to the brain for conscious perception? | Spinothalamic tract |
| Which somatosensory pathway transmits pain signals to the midbrain for attention and orienting responses? | Spinomesencephalic tract |
| What does the spinothalamic tract do? | It transmits pain, temperature, and crude touch signals from the spinal cord to the thalamus, allowing conscious perception and localization of these sensations in the brain. |
| What is spinal shock? | It is a transient state after acute spinal cord injury marked by flaccid paralysis, loss of reflexes, and reduced sympathetic activity below the level of the lesion. |
| What thalamic nucleus receives input from nucleus gracilis and nucleus cuneatus? | Ventral posterior lateral nucleus (VPL) of the thalamus |
| What thalamic nucleus has inputs and outputs primarily from and to the basal ganglia? | Intralaminar nuclei |
| What is the only thalamic nucleus that does NOT project to the cortex? | Reticular nucleus (It is purely GABAergic and regulates other thalamic nuclei.) |
| What theory underlies TENS (transcutaneous electrical nerve stimulation) therapy? | Gate control theory (Large-diameter A-beta fibers inhibit pain transmission in the dorsal horn) |
| What type of spinal cord dysfunction is a contusion classified as? | Trauma/mechanical injury |
| What type of neurons carry signals very fast? | Large-diameter, heavily myelinated neurons (A-alpha and A-beta fibers) |
| What is the term for abnormal positive sensory phenomena? | Paresthesia (e.g., gauze-like sensation, tingling, burning) |
| What tract is associated with the location and intensity of a stimulus? | Spinothalamic tract (part of the anterolateral system) |
| What endogenous opiate peptide is found in hypothalamic neurons projecting to the PAG? | Beta-endorphin |
| What syndrome results in loss of vibration and position sense below a spinal cord lesion? | Posterior cord syndrome |
| What area receives input from hypothalamus, amygdala, and cortex and is central to pain modulation? | Periaqueductal gray (PAG) |
| What type of organization is present in primary and secondary somatosensory cortex? | Somatotopic organization (body map/homunculus) |
| What pathway carries proprioception, vibration, and discriminative touch? | Posterior column–medial lemniscus (PCML) pathway |
| Where are lesions associated with sharp, burning, or searing pain? | Anterolateral pathways (spinothalamic tract) |
| What part of the posterior column carries information from upper trunk, arms, and neck? | Cuneate fasciculus |
| What part of the posterior column carries information from legs and lower trunk? | Gracile fasciculus |
| Where is a lesion that causes ipsilateral face and contralateral body pain/temp loss? | Lateral pons or lateral medulla |
| What are the motor and sensory findings for C2 nerve root injury? | Cervical flexion weakness with pain/numbness in the back of the head |
| What are the motor and sensory findings for C3 nerve root injury? | Cervical lateral flexion weakness with pain/numbness on the side of the neck |
| What are the motor and sensory findings for C4 nerve root injury? | Shoulder elevation/shrug weakness with pain/numbness in the upper shoulder |
| What are the motor and sensory findings for C5 nerve root injury? | Shoulder abduction weakness (deltoid) with pain/numbness in the lateral upper arm |
| What are the motor and sensory findings for C6 nerve root injury? | Wrist extension and elbow flexion weakness; biceps reflex decreased; pain/numbness in lateral forearm/thumb |
| Which disc herniation typically causes C6 radiculopathy? | C5-C6 disc herniation |
| What are the motor and sensory findings for C7 nerve root injury? | Wrist flexion and elbow extension weakness; triceps reflex decreased; pain/numbness in middle finger |
| What are the motor and sensory findings for C8 nerve root injury? | Thumb extension and ulnar deviation weakness; pain/numbness in medial forearm, ring, and little fingers |
| What are the motor and sensory findings for T1 nerve root injury? | Finger abduction weakness with pain/numbness in the medial arm |
| What are the motor and sensory findings for L2 nerve root injury? | Hip flexion weakness with pain/numbness in the anterior thigh |
| What are the motor and sensory findings for L3 nerve root injury? | Knee extension weakness (quadriceps); patellar reflex decreased; pain/numbness in medial thigh/knee |
| What are the motor and sensory findings for L4 nerve root injury? | Ankle dorsiflexion weakness; patellar reflex decreased; pain/numbness in medial leg |
| Which disc herniation typically causes L4 radiculopathy? | Lateral L4-L5 disc herniation |
| What are the motor and sensory findings for L5 nerve root injury? | Great toe extension weakness; foot drop possible; pain/numbness in lateral leg and dorsal foot |
| Which disc herniation typically causes L5 radiculopathy? | L4-L5 disc herniation |
| What are the motor and sensory findings for S1 nerve root injury? | Ankle plantarflexion weakness (gastrocnemius); Achilles reflex decreased; pain/numbness in lateral foot/sole |
| Which disc herniation typically causes S1 radiculopathy? | L5-S1 disc herniation |
| What are the motor and sensory findings for S2 nerve root injury? | Knee flexion weakness (hamstrings) with pain/numbness in the posterior thigh |
| Which nerve roots share the patellar reflex? | L3 and L4 both contribute to the patellar reflex (knee jerk) |
| What reflex is decreased with S1 nerve root injury? | Achilles reflex (ankle jerk) |
| What reflex is decreased with C6 nerve root injury? | Biceps reflex |
| What reflex is decreased with C7 nerve root injury? | Triceps reflex |
| What muscle is weak with L4 nerve root injury? | Tibialis anterior (ankle dorsiflexion weakness) |
| What muscle is weak with S1 nerve root injury? | Gastrocnemius (ankle plantarflexion weakness) |
| What muscle is weak with C5 nerve root injury? | Deltoid (shoulder abduction weakness) |
| What is the anterior cerebral artery (ACA)? | It is one of the major cerebral arteries that runs through the interhemispheric fissure, supplying blood to the medial portions of the frontal and parietal lobes. |
| What is the medial cerebral artery (MCA)? | It is one of the major cerebral arteries that supplies blood to most of the lateral (outer) surfaces of the frontal, parietal, and temporal lobes. |
| What is the posterior cerebral artery (PCA)? | It is a major cerebral artery that supplies blood to the inferior and medial temporal lobes and the occipital cortex, including regions involved in visual processing. |
| What is the basilar artery? | It is a major artery formed by the union of the two vertebral arteries, supplying blood to the brainstem, cerebellum, and posterior regions of the brain. |
| What is the left hemisphere? | It is the brain’s left hemisphere, typically responsible for language, analytical thinking, and logical processing, where most language functions are lateralized. |
| What is the right hemisphere? | It is the brain’s right hemisphere, generally involved in spatial, visual, and creative processing, and less commonly associated with language functions or language disorders. |
| What is a unified system? | It is a single, integrated brain network where multiple regions in the brain work together to perform a specific function. |
| What is the left Middle Cerebral Artery (MCA) superior division? | It is the superior division of the left middle cerebral artery, supplying the frontal lobe regions involved in speech production. Blockage can lead to Broca’s aphasia. |
| What is an infarct? | It is an area of tissue death in the brain caused by insufficient blood supply (not enough blood reaches the tissue), often resulting from a blockage or reduced circulation. |
| What is a traveling embolism? | It is a type of infarct that occurs when a piece of material, usually a blood clot, forms elsewhere in the body and travels through the bloodstream to suddenly block a blood vessel. |
| What is the ophthalmic artery? | It is a branch of the internal carotid artery that supplies the eye and orbit. Blockage can cause transient monocular blindness. |
| What is hemiparesis? | It is weakness of the muscles on one side of the body, often resulting from brain injury, stroke, or neurological disorders. |
| Which type of retinal neurons has an all-or-none response? | Ganglion cells |
| Damage to what will result in blindness to half the visual field? | Optic tract |
| Damage to what area can result in contralateral homonymous quadrantanopia? | Temporal lobe |
| What part of the lateral geniculate nucleus (LGN) receives input from Parasol ganglion cells and is part of the movement and gross spatial features pathway? | Magnocellular layers |
| What part of the primary visual cortex processes fine spatial information? | Layer 4Cβ |
| What describes the organization of the primary visual cortex? | Retinotopic |
| Damage to which brain area may result in dysfunctions with movement and location? | Parieto-occipital cortex |
| What is the function of the superficial tibial nerve? | It everts the foot (turns the sole outward) and assists in plantarflexion. |
| What is the function of the deep fibular nerve? | It dorsiflexes the foot (lifts it upward) and extends the toes. |
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