LEC-8 Reflexes Flashcards Preview

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Flashcards in LEC-8 Reflexes Deck (46):

Innate (Primitive) Reflexes - later suppressed by frontal lobes

- Glabellar: after repeated taps on forehead, the person should blink once - Snout: tapping a baby's closed lips near the midline should cause the lips to pucker/purse - Rooting: Within the first 2 weeks of life, baby will turn their head in little circles towards a direction if their cheek or mouth is stroked - Palmomental: stroking a certain part of the palm of the hand should elicit movement of a chin muscle - Grasp: place something on the palm of the baby's hand, the baby will curl its fingers around the object and pull in


Developmental Reflexes

- Moro: (Newborn - 7 mo) when startled, baby spreads out its arms and legs as if trying to "grasp" something (newborn - 7 mo) - Tonic Neck: (Newborn - 7 mo) When baby's head is bent to one side, the arm on the same side as their face straightens and the other arm bends (like "I'm a little teapot") - Crossed adductor: (Newborn - 7 mo) Tapping patellar tendon elicits both an extension of the knee and a slight adduction of the thigh - Neck Righting: (by 10 months) When the baby's head passively turns to one direction while lying supine, they try to 'roll over' so that their face and chest are on the same plane - Supporting reaction: (by 10 monhs) when lifted in the air while upright, the baby will extend their legs and wiggle them around - Landau: (by 10 months) when held up on their stomach, babies will straighten their legs and head as if they were swimming - Parachute: (by 12 months) when rotating the child from upright to 'face-first' position (making the child think they're falling), the baby holds out their arms as if to 'break' the fall



Intrinsic resistance of a person to passive movement (i.e. one person tries to lift another person's hand) - indicative of frontal lobe damage and dementia


Brainstem Reflexes

Corneal: blink upon poking cornea Pupillary Light: pupils contract in response to light Gag: gag in response to 'tickling' of back of throat


Corneal Reflex

Afferent Cranial Nerve: Trigeminal (CN5) Efferent Cranial Nerve: Facial (CN7)


Pupillary Light Reflex:

Afferent Cranial Nerve: Optic (CN2) Efferent Cranial Nerve: Oculomotor (CN3)


Gag Reflex

Afferent Cranial Nerve: Glossopharyngeal (CN9) Efferent Cranial Nerve: Vagus (CN10)


Myotatic Reflex

Patellar Tendon jerk


Sensory Fibers from Muscle

Ia: Primary Spindle endings, for muscle length/rate of change of length (12-20 um myelinated) Ib: Golgi tendon organs, for muscle tension (12-20 um myelinated) II: Secondary spindle/non-spindle endings, for muscle length and deep pressure (6-12 um myelinated) III: Free nerve endings, for pain, temperature, and chemical stimuli (2-6 um myelinated) IV: Free nerve endings, for pain, temperature, and chemical stimuli (0.5-2 um nonmyelinated)


Upper Motor Neuron Syndrome

Weakness, spasticity and increased muscle tone, hyperactive myotatic reflexes, loss of cutaneous reflexes


Lower Motor Neuron Syndrome

Weakness, flaccidity and decreased muscle tone, hypoactive myotatic reflexes, loss of cutaneous reflexes


Superficial Reflexes

Abdominal: when skin over abdomen is lightly stimulated, abdominal muscles contract (bellybutton moves towards direction of stimulation) Cremasteric: when inguinal canal is stimulated, the ipsilateral testicle rises into the pelvis Hoffman: tapping fingernail elicits flexion of thumb of same hand Plantar: stroking the sole (plantar) of the foot from lateral side to across the ball of the foot causes flexion of foot


Urogenital Reflex

Anal wink: stimulation around the anus leads to puckering of anus Bulbocavernosus (bulbospongiosus) reflex: squeezing the glans of the penis/clitoris causes the anal sphincter to tighten


Cutaneous Dermatome Innervations

C4: Clavicle C5: Lateral Upper Arm C6: Thumb and lateral forearm C7: Middle finger C8: Pinky finger T4: Nipple T10: Umbilicus L4 & L5: Calf L5: Big toe S1: Little toe S3-5: Perineum L1-L2: Cremaster


Congenital Spinal Cord Disorders

Pathophysiology: Failure of neural tube closure, especially around lumbosacral region Disease: Spina Bifida Occulta Disease: Myelomingocele Disease: Meningocele Risk Factors: Anti-epileptic drugs (valproate), folate deficiency, diabetes, obesity, elevated body temperature



Disease type: congenital or acquired (trauma, neoplasm) Pathophysiology: presence of a syrinx in the middle of the spinal cord, obstructing sensory pathways Presentation: loss of pain and temperature sensation across entire arm and upper chest (a "cape-like pattern")

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Friedrich's Ataxia

Disease type: Autosomal recessive hereditary spinal cord disorder Pathophysiology: Reduced levels and loss of function of frataxin, a mitochondrial matrix protein that protects against Fe overload Onset: usually 10 yrs or younger Presentation: Ataxia, loss of proprioception, optic atrophy, kyphoscoliosis, cardiomyopathy, diabetes mellitus

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Disease type: X-linked recessive hereditary spinal cord disorder Pathophysiology: Abnormal peroxisomal fatty acid beta oxidation, causing VL chain FA's to accumulate in oligodendrocytes, Schwann cells, adrenal cortex, & Leydig cells (testicular) Presentation: if in boys 10 or younger, cerebral form (progressive CNS degeneration), if in young adult males, myelopathy with progressive paraparesis Treatment: "Lorenzo's Oil" or bone marrow transplant

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Hereditary Spastic Paraparesis

Disease type: Hereditary (X-linked, autosomal dominant or recessive) spinal cord disorder Presentation: Progressive UMN symptoms, bladder dysfunction, variable impaired vibration sensation

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Neoplastic Spinal Cord Disorders

Intramedullary: astrocytoma, ependymoma Extramedullary, extradural: meningioma, schwanomma


Epidural Abscess

Disease type: Infectious Spinal Cord Disease Presentation: rapidly progressive myelopathy, tenderness to percussion

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Syphilis - Tabes Dorsalis

Disease type: Infectious spinal cord disease Presentation: Paraparesis with steppage gait, hyporeflexia with Babinski sign

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HIV Spongiform myelopathy

Disease: Infectious spinal cord disease

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Subacute Combined degeneration

Pathophysiology: B12 or Cu deficiency Presentation: peripheral neuropathy, LE weakness with UMN signs, associated anemia (B12 also shows cognitive dysfunction)

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Herniated Disc

Pathophysiology: Nucleus populous pushes nuclear annulus outwards, sometimes breaking through the nucleus annulus



Pathophysiology: degenerative osteoarthritis of the vertebrae

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Hangman's Fracture

Pathophysiology: C1 vertebrae (usually) slips abnormally forward on head

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Compression Fracture

Vertebral bodies are compressed in trauma

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ATPase Immunohistochemical stain

Common muscle staining method using a pH-dependent staining gradient (darker the stain, 'quicker' the fiber)


Slow Twitch Fiber

Type: I Many mitochondria, myoglobin, & extensive capillary blood supply Fatigue resistant Needed for aerobic exercise


Intermediate Fibers

Type: IIA Fast twitch Fatigue resistant


Fast twitch Fibers

Type: IIB Few mitochondria, less vascular supply, glycogen storage site with extensive Sarcoplasmic Reticulum Needed for extended anaerobic exercise (i.e. weight training)


Components of a Muscle Stretch Reflex

Excitatory stimulation of alpha-motor neuron of agonist muscle Inhibitory stimulation of alpha-motor neuron of antagonist muscle Excitatory stimulation of sensory fibers on muscle stimulated


What myotome level is responsible for the jaw jerk reflex?



What myotome level controls the diaphragm muscles?



What myotome level controls the deltoid and biceps muslces and is responsible for the biceps reflex?



What myotome level controls the triceps and extensors of wrist and finger and is responsible for the triceps reflex?



What myotome level controls the interossei and abductor of fifth finger?



What myotome level controls the quadriceps and is responsible for the knee jerk reflex?



What myotome level is controls the long extensor of great toe and anterior tibial muscles?



What myotome level controls the plantar flexors and gastronemius muscles and is responsible for the ankle jerk reflex?



What spinal nerve roots are involved in the cutaneous reflexes above the umbilicus?



What spinal nerve roots are involved in the cutaneous reflexes below the umbilicus?

T10 - T12


What spinal nerve roots are involved in the cremasteric cutaneous reflexe?



What spinal nerve roots are involved in the bulbocavernosus cutaneous reflexe?



What spinal nerve roots are involved in the anal wink cutaneous reflexe?