A&P 2.7. crossed extensor reflex

Question 1

Flexor/withdrawal reflex

Review

Answer 1

Look at 2.6

Question 2

Crossed extensor reflex

General

Answer 2

Maintains standing posture while withdrawing the limb in pain

Stepping on a tack

Question 3

Stimulus

Answer 3

Pain

Question 4

Sensory receptor

Answer 4

Nocicepter

Question 5

Sensory neuron

Answer 5

From nocicepter to CNS

Question 6

Integrating center

Answer 6

Sensory neurons synapse with interneurons that crosses to the other side of the spinal cord.

Goes up and down other segments

POLYSYNAPTIC MULTISEGMENTAL, CONTRALATERAL RESPONSE

Question 7

Motor neuron

Answer 7

To the EXTENSOR MUSCLE OF THE OPPOSITE LOWER LIMB (stimulation), (reciprocal innervation - flexor muscle of limb are inhibited)

Question 8

Effector

Answer 8

Extensor muscle of CONTRALATERAL limb

Question 9

Response

Answer 9

Extensor muscle of CONTRALATERAL limb stimulated, flexor muscle are inhibited (CONTRALATERAL also)

Question 10

Types of reflexes

4

Answer 10

Ipslilateral reflex
CONTRALATERAL
Unisegmental
MULTISEGMENTAL

Question 11

Ipsilateral

Answer 11

All 7 components of the reflex on the Same side of the body
Stimulus on one side trigger response on same side

STRETCH, TENDON AND FLEXOR REFLEXES

Question 12

CONTRALATERAL reflexes

Answer 12

The response is on the opposite side of the body from the stimulus

Interneurons in the integrating center cross to the opposite side

CROSSED EXTENSOR RESPONSE

Question 13

Unisegmental

Answer 13

Sensory neuron and motor neuron are found in the same spinal segment

If the sensory neuron enters L3, then the motor neuron exits at L3

STRETCH AND TENDON REFLEX

Question 14

MULTISEGMENTAL

Answer 14

Interneurons ascend or descend to cord segments different from that of the sensory neuron.
Motor neurons exit from more than one spinal segment
One sensory neuron can affect multiple motor neurons

FLEXOR AND CROSSED EXTENSOR REFLEX

Question 15

Basal ganglia

General

Answer 15

ONLY GANGLIA IN CNS
3 Clusters of grey matter deep within each cerebral hemisphere

• function to initiate and terminate movements
• regulates muscle tone required for movement
• control subconscious movement (arm swinging while walking)
  Affected area in PARKINSON’S disease

Question 16

Reticular formation

Answer 16

Network/web-like
Several clusters of grey matter mixed with white matter spread throughout the brainstem, it has the appearance of a “net”

• ascending fibers - form the reticular activating system (RAS) - responsible for consciousness and waking from sleep
• descending fibers- have been described as regulating muscle tone (slight degree of contraction in resting muscles) or TETANUS

Question 17

Limbic system

Answer 17

Borders the cerebrum and diencephalon (including portions of both)
- the emotional brain it plays a primary role in regulating a range of emotions including pain, pleasure, docility, affection and anger
- behavior is a function of the entire nervous system. However the limbic system controls most of its involuntary aspects related to survival (fight or flight)
- also functions in memory
EMOTIONAL BRAIN

Question 18

PNS

terminology

Answer 18

PNS

White matter - nerve, axion bundles

Grey matter - ganglion, cell bodies and synapse

Question 19

CNS

Terminology

Answer 19

CNS

White matter - tracts, axion bundles

Grey matter - nucleus, cell bodies and synapse clusters

Question 20

Splenius cervicis

A, I, O

Answer 20

O - SP of T3-T6

I - TP OF C1-C3

A - unilaterally ipsilateral flexion and ipsilateral rotation;
Bilaterally - extend/hyperextended the neck HYPEREXTENSION

Splenius - bandage ,

Question 21

Brachialis

A, I, O

Answer 21

O - distal 1/2 of anterior shaft of humerus

I- tuberosity and coronoid process of the ulna

A - flexion of the elbow

*the only elbow flexor that attaches to the ulna, makes it effective no matter what position the forearm is in.

Question 22

Scapular movements

6

Answer 22

Elevation
Depression
Abduction (protraction)
Adduction (retraction)
Upward rotation
Downward rotation