T8.5: Muscle Innervation & Spinal Reflexes

Question 1

A scientist examining muscle fibers and notes that lacks sensory fibers that are only sensitive to length. What else is true of this muscle fiber he is observing?

A. Is not innervated by intrafusal fibers
B. Is the Nuclear chain fiber
C. Lacks secondary sensory endings
D. Is the Static Nuclear bag

RFA

Answer 1

Ans. C- The sensory fibers being described are II fibers which are not in Dynamic nuclear Bag fibers( they only have Ia sensory) and also lack secondary sensory endings

Question 2

In the inverse myotatic reflex_____ fibers make____ synapse_____ the alpha motor neuron.

A. Ia, exicitory, inhibits
B. Ia, inhibitory, inhibits
C.Ia, exicitory, excites
D. Ib ,exictory, inhibits
E. Ib, inhibitory, inhibits 
F. Ib, inhibitory, exicites

RFA

Answer 2

D. Ib, exictory, inhibits

Question 3

Ahmed age, 28 is a world champion marathon masterbater. What type of muscle fibers does Ahmed have?

A. Type I
B. Type IIA
C. Type IIB
D. Type Mac and Cheese

RFA

Answer 3

Ans. A- Type I= slow-twitch fibers low tension fatigue resistant.

B. Type IIA= fast, relatively, fatigue-resistant , large tension, some aerobic capacity

C. Type IIB- Fast, fatigue- susceptible large tension

D. Type Mac and Cheese- is Ahmed’s body type not his muscle type

Question 4

In a patient with hypoxia, which type of motor unit will be most affected? (MG)

A. Type I
B. Type IIA
C. Type IIB
D. Type Mac and Cheese

Answer 4

A. Type I followed by IIa which has some aerobic ability.

Type I is aerobic so low oxygen would decrease the motor units’ ability to function and fire.

Question 5

During your rotations down at the St. George’s hospital, you meet a patient who gave birth last month. She has a history of hyperreflexia, spasticity and weakness of her lower limbs, and walks abnormally. What virus is she at risk for transmitting to her baby? When she breastfeeds? (MG)

A. ALS
B. HTLV-1 associated myelopathy
C. HIV
D. Poliomyelitis

Answer 5

B. HTLV-1 associated myelopathy

can be transmitted via breast milk and is commonly found in people from tropical locations. The diagnosis is tropical spastic paraparesis caused by HAM (HTLV-1 associated myelopathy)

Question 6

What is the afferent limb of the inverse myotatic reflex? (MG)

A. None of the below
B. Golgi tendon organ only
C. Golgi tendon organ & Ib afferents
D. Ib afferents only

Answer 6

C. Golgi tendon organ & Ib afferents

Question 7

A patient comes in with weakness in limbs and trouble walking for the past two weeks after she pancaked Ryan Averil in a football game breaking all his bones. You test her reflexes and they are absent. Being a colleague of Ryan you know he studied in the Caribbean and has a wild sex life. Your patient admits she regularly received sex from Ryan for the past 10 years. You run tests. She comes back two weeks later her reflexes are back. Which of the following is most likely your patients diagnosis?

A) TSP
B) Spinal Shock
C) Multiple Sclerosis
D) ASAS

Answer 7

Answer = B b/c of the absent spinal reflexes that returned within several weeks

A- passed thru fucking, from carribean, in women more than men, can remain dormant for 10 years, would present with hyperreflexia and weakness of lower limbs though

C- progressive UMN and LMN disorder, would have limb weakness, and tongue fasciculation’s usually
d- would present with weakness, bilaterally plantar response, and poor sexual function

Question 8

Explain the flexion crossed extension reflex

Answer 8

Aff signals of the flexion reflex promote ipsilateral flexion and suppress extension and then cross the cord to promote contralateral extensor responses while suprressing contralateral flexion