What are the 3 types of neuronal pathways?
Convergent pathway
Divergent pathway
Oscillating circuit
What are the 3 elements of circuits?
Input: Originate elsewhere and terminate in synapses within the local circuit
Output: send axons to one or more targets
Interneurons: excitatory and inhibitory
What are the 4 properties of reflexes?
1. Require stimulation
2. Quick
3. Involuntary
4. Stereotyped (predictable)
The muscle spindle detects
Muscle stretch
Path of muscle stretch reflex:
Sensory nerve originates in the _____ _____ and enters the _____ root of the spinal cord
A branch then goes to the _____ horn of the cord grey matter and synapses with the _____ _____ neurons,
The _____ _____ neurons then send _____ nerve fibers back to the same muscle in which the _____ _____ fiber originated
causing _____ of the stretched muscle to ______ / ______ the stretch
Path of muscle stretch reflex:
Sensory nerve originates in the muscle spindle and enters the dorsal root of the spinal cord
A branch then goes to the anterior horn of the cord grey matter and synapses with the anterior motor neurons
Anterior motor neuron sends motor nerve fibers back to the same muscle in which the muscle spindle fiber originated
causing contraction of the stretched muscle to resist / reverse the stretch
The muscle stretch reflex:
is a _____ pathway that permits the _____ _____ time delay
The muscle stretch reflex:
is a monosynaptic pathway that permits the shortest possible time delay
Muscle stretch reflex:
An important feature of the stretch reflex is its ability to provide a _____ muscle contraction, which prevents _____ (oscillation or jerkiness)
Signals are transmitted in _____ intensities but the contraction of the muscle is _____
If the _____ _____ _____ is not functioning, then the muscle contraction is _____ during the course of the signal
Muscle stretch reflex:
An important feature of the stretch reflex is its ability to provide a smooth muscle contraction, which prevents clonus (oscillation or jerkiness)
Signals are transmitted in varying intensities but the contraction of the muscle is smooth
If the muscle spindle apparatus is not functioning, then the muscle contraction is jerky during the course of the signal
Abnormalities of Muscle stretch reflex:
Decreased or absent reflex: disruption of the input or output which often occurs in _____ or _____
Hyper-reflex: _____ _____ neuron lesions: the inhibitory effect is _____
Asymmetrical hyper-reflex: reflex not symmetrical between the left and right sides: _____ _____ _____ lesion
Abnormalities of Muscle stretch reflex:
Decreased or absent reflex: disruption of the input or output which often occurs in polyneuropathy or radiculopathy
Hyper-reflex: upper motor neuron lesions: the inhibitory effect is lessened (output signal usually disrupted)
Asymmetrical hyper-reflex: reflex not symmetrical between the left and right sides: upper motor neuron lesion
The Golgi tendon organ detects
Muscle tension
Golgi tendon reflex:
Golgi tendon organ is an _____ sensory receptor through which _____ _____ fibers pass
Golgi tendon organ is stimulated when the bundle of muscle fibers is “_____” by _____ or _____ the muscle
Golgi tendon reflex:
Golgi tendon organ is an encapsulated sensory receptor through which muscle tendon fibers pass
Golgi tendon organ is stimulated when the bundle of muscle fibers is “tensed” by contracting or stretching the muscle
Golgi tendon reflex:
Stimulated by muscle _____ in the connecting muscle
signals are transmitted to the spinal cord to cause an _____ _____ response that _____ the muscle
and an _____ response to _____ the antagonistic muscle
Golgi tendon reflex:
Stimulated by muscle tension in the connecting muscle
signals are transmitted to the spinal cord to cause an inhibitory response that lengthens the muscle (prevents development of too much tension on the muscle)
and an excitatory response to activate the antagonistic muscle
Muscle spindle vs Golgi tendon:
The muscle spindle is stimulated when _____
vs
the golgi tendon organ which is stimulated when _____
Muscle spindle vs Golgi tendon:
The muscle spindle is stimulated when stretched
vs
the golgi tendon organ which is stimulated when tensed (it can be tensed by contracting or stretching the muscle!)
Muscle spindle vs Golgi tendon:
The muscle spindle pathway _____ the stimulated muscle while reciprocally _____ the antagonist muscle
vs
The golgi tendon organ which _____ the antagonistic muscle while _____ the stimulated muscle
Muscle spindle vs Golgi tendon:
The muscle spindle pathway excites the stimulated muscle while reciprocally inhibiting the antagonist muscle (by damping efferent impulses)
vs
The golgi tendon organ which excites the antagonistic muscle while inhibiting (relaxing) the stimulated muscle
Muscle spindle vs Golgi tendon:
The muscle spindle pathway is _____ to give the _____ pathway
vs
The golgi tendon organ pathway which is an _____ _____ with _____ in the spinal cord
Muscle spindle vs Golgi tendon:
The muscle spindle pathway is monosynaptic to give the quickest pathway
vs
The golgi tendon organ pathway which is an inhibitory circuit (negative feedback circuit) with interneurons in the spinal cord
Flexor reflex:
A sensory stimulus from a limb causes the _____ muscles of the limb to _____
Stimulated most powerfully by _____ endings
Flexor reflex:
A sensory stimulus from a limb causes the flexor muscles of the limb to contract withdrawing the limb from the stimulating object
Stimulated most powerfully by pain endings
*Not limited to the limbs. If any part of the body is painfully stimulated this reflex still occurs
Flexor reflex to pain:
_____ contraction of _____ muscles to withdraw a limb from an injurious stimulus
Painful stimulus applied at the hand
Signal travels into the spinal cord _____ _____ and secondarily to the _____ _____
_____ _____ excite the _____ muscles of the arm and inhibition of _____ muscles
Hand is withdrawn from the painful signal
Flexor reflex to pain:
Quick contraction of flexor muscles to withdraw a limb from an injurious stimulus
Painful stimulus applied at the hand
Signal travels into the spinal cord neuronal pool and secondarily to the motor neurons
Motor neurons excite the flexor muscles of the arm and inhibition of relaxer muscles
Hand is withdrawn from the painful signal
Flexor reflex:
Is not a _____ pathway
The muscle still _____ after stimulus is released due to _____
Stronger stimulus (like fire) leads to _____ _____
Flexor reflex:
Is not a monosynaptic pathway
The muscle still contracts after stimulus is released due to afterdischarge
Stronger stimulus (like fire) leads to prolonged afterdischarge
Crossed extensor reflex:
_____ seconds after a stimulus elicits a _____ reflex in one limb
Signals from the sensory nerve cross to the opposite side of the spinal cord to excite the _____ muscles
so that the opposite limb begins to _____
_____ of the opposite limb can push the entire body away from the object causing pain
Crossed extensor reflex:
0.2 – 0.5 seconds (200-500 milliseconds) after a stimulus elicits a flexor reflex (pain stimulus) one limb
Signals from the sensory nerve cross to the opposite side of the spinal cord to excite the extensor muscles
so that the opposite limb begins to extend
Extension of the opposite limb can push the entire body away from the object causing pain
Crossed extensor reflex:
_____ _____ before the reflex begins
_____ afterdischarge period than the flexor reflex (to _____ _____)
Crossed extensor reflex:
Long latency before the reflex begins (while flexor responds first)
longer afterdischarge period than the flexor reflex (to maintain stablization)
Afterdischarge of flexer reflex vs crossed extensor reflex:
Crossed extensor afterdischarge is _____ than the flexor afterdischarge
Afterdischarge of flexer reflex vs crossed extensor reflex:
Crossed extensor afterdischarge is longer than the flexor afterdischarge
Superficial Reflexes:
Name 5 superficial reflexes
Superficial Reflexes:
Biceps jerk reflex
Triceps jerk reflex
Abdominal reflex
Ankle-jerk reflex (plantar reflex)
Cremastric reflex
Biceps jerk reflex:
Examiner places finger on the inside of the _____ _____ over the tendon of the _____ muscle and finger is _____.
The biceps _____ in response and the forearm _____ at the elbow
Biceps jerk reflex:
Examiner places finger on the inside of the extended elbow over the tendon of the biceps muscle and finger is tapped.
The biceps contracts in response and the forearm flexes at the elbow
Triceps jerk reflex:
Tapping the _____ tendon of the triceps muscle close to its _____ near the tip of the _____ elicits this reflex.
The muscle _____ in response, forearm _____ slightly
Triceps jerk reflex:
Tapping the short tendon of the triceps muscle close to its insertion near the tip of the elbow elicits this reflex.
The muscle contracts in response, forearm extends slightly
Abdominal reflex:
Examiner strokes the skin of the abdomen with a _____ _____ from the _____ of abdomen towards the _____ and _____ the umbilicus.
The umbilicus moves _____ the stimulated region
Abdominal reflex:
Examiner strokes the skin of the abdomen with a dull pin from the side of abdomen towards the midline and above the umbilicus.
The umbilicus moves towards the stimulated region
Ankle-jerk reflex (plantar reflex):
Tapping the _____ _____ just _____ its insertion on the _____ elicits this reflex.
The response is plantar _____, produced by _____ of the _____ and _____ muscles
Ankle-jerk reflex (plantar reflex):
Tapping the Achilles tendon just above its insertion on the Calcaneous elicits this reflex.
The response is plantar flexion, produced by contraction of the gastrocnemious and solues muscles
Cremastric reflex:
elicited in males by stroking the _____ _____ of the thigh.
In response, the _____ on the _____ side is elevated by contracting muscles.
Cremastric reflex:
elicited in males by stroking the upper inside of the thigh.
In response, the testis on the same side is elevated by contracting muscles.
Somatic Reflexes review:
Reflex: a _____, _____, _____ reaction of a gland or muscle to a stimulus
Somatic reflexes: are initiated by _____ (e.g golgi tendon) AND _____ that result in skeletal muscle response
Stretch reflex: is the tendency of a muscle to _____ when it is stretched and accompanied by reciprocal _____ of an antagonistic muscle
Somatic Reflexes review:
Reflex: a quick, involuntary, stereotyped reaction of a gland or muscle to a stimulus
Somatic reflexes: are initiated by proprioceptors (e.g golgi tendon) AND nocipceptors that result in skeletal muscle response
Stretch reflex: is the tendency of a muscle to contract when it is stretched and accompanied by reciprocal inhibition of an antagonistic muscle
Somatic Reflexes review:
Flexor reflex: is _____ of a limb from an injurious stimulus.
Crossed Extensor reflex: is _____ of the extensors on one side of the body and _____ of flexors on the other side
Golgi Tendon reflex: is the _____ of a muscle contraction that occurs when its tendon is _____ _____.
Somatic Reflexes review:
Flexor reflex: is withdrawal of a limb from an injurious stimulus.
Crossed Extensor reflex: is contraction of the extensors on one side of the body and contraction of flexors on the other side
Golgi Tendon reflex: is the inhibition of a muscle contraction that occurs when its tendon is excessively stretched (by detecting muscle tension). This reflex prevents tendon injuries and helps to distribute workload across a muscle
Stimulation of sensory fibers innervating a muscle spindle:
A. Will inhibit muscle contraction
B. Will activate an inhibitory interneuron
C. Will activate a motor neuron connected to the muscle
Stimulation of sensory fibers innervating a muscle spindle:
C.
Will activate a motor neuron connected to the muscle
The function of the golgi tendon organ is:
A. To sense the length of the muscle tendon in which it is located
B. To transmit muscle stretch information to the brain
C. To sense muscle tension and equalize the contractile force exerted by groups of muscle fibers within a muscle
The function of the golgi tendon organ is:
C.
To sense muscle tension and equalize the contractile force exerted by groups of muscle fibers within a muscle
A 4-year-old comes to the pediatrician for her routine check-up. The physician taps the patellar tendon with a small hammer to test the child’s response. Which of the following reflexes is this physician testing?
A. Cross-extensor
B. Flexor
C. Golgi-tendon
D. Muscle stretch
A 4-year-old comes to the pediatrician for her routine check-up. The physician taps the patellar tendon with a small hammer to test the child’s response. Which of the following reflexes is this physician testing?
D.
Muscle stretch
You are walking around on a nice sunny day at the beach barefoot. All of a sudden you feel a prick on your right foot. Immediately you jerk and look at your foot but see nothing. However, you still feel the pain on your foot. Which of the following explains this sensation you still feel?
A. Afterdischarge
B. Duration of the signal
C. Fatigue
D. Flexor contraction
You are walking around on a nice sunny day at the beach barefoot. All of a sudden you feel a prick on your right foot. Immediately you jerk and look at your foot but see nothing. However, you still feel the pain on your foot. Which of the following explains this sensation you still feel?
A.
Afterdischarge
