Spinal Cord 2

Question 0

Nucleus dorsalis

Answer 0

Found in the intermediate zone in the dorsal medial portion of lam 7 of segments C8-L2
Receives proprioceptive input from muscle, sends axon projections to the ipsilateral cerebellum.

Question 1

Dorsal horn lamina

Answer 1

Lamina I, V- posteromarginal nucleus, receive nociceptive I put via lightly or up myelinated afferents
Laminae 3,4- receive non-noxious input via large ,myel afferents
Lam2- receives input from nociceptive afferents, collateras from lrg afferents
Lam6-rec input from descending motor pathways, proprioceptive input from periphery

Question 2

Intermediolateral cell column

Answer 2

In segments t1 to L2, give rise to pregang sympathetic efferent fibers, found in the lateral part of the 7th lam, intermediate zone.

Question 3

Sacral autonomic nuclei

Answer 3

Found in the s2-4 region in the lateral part of the intermediate zone but give rise to preganglionic parasympathetics

Question 4

Lam 8

Answer 4

In the ventral horn contains mostly interneurons that relay and integrate segmental and descending inputs to motor neurons

Question 5

Lamina 9

Answer 5

Is the main somatic motor area of the ventral horn.contains lrg alpha and smaller gamma motorneurons.
Innervate skeletal muscle and intrafusal muscle fibers of muscle spindle organs.

Question 6

Phrenic nucleus

Answer 6

Located centrally in the ventral horn of sc segments c3-5, provide Innervation to the diaphragm through the phrenic nerv

Question 7

Spinal accessory nucleus

Answer 7

Contains neurons that Innervate the SCM and the traps. Found in ventral horn of c1-5

Question 8

Ventral horn, lam 9 organization

Answer 8

Neurons that Innervate flexor muscles located dorsaly
Neurons that Innervate ext muscles loc. ventraly
Neurons Innervation axial and proximal extremity musc., located medially in the ventral horn.

Question 9

Withdrawal reflex

Answer 9

Peripheral stimulus connects centrally through the dorsal roots to activate some muscles and inhibit others
Is is through excitatory and inhibitory interneurons which then Innervate motor neuron pools that supply the muscles

Question 10

Crossed extensor reflex

Answer 10

Reflex pathway that crosses the midline
Relaxed extensor a from the withdrawal reflex are accompanied by contraction of the contract earl extensors for balance and support.

Question 11

Stretch reflexes

Answer 11

Muscle spindles detect changes in length and rate of stretching of muscle
Their output travels through the dorsal roots where they activate or inhibit groups of motor neurons.

Question 12

Nuclear bag fibers

Answer 12

Detect dynamic aspects of stretch-ap increase as a muscle is stretched

Question 13

Nuclear chain fibers

Answer 13

Produce increased AP as a result of changes in muscle length

Question 14

Tendon reflex

Answer 14

Rapid stretch of. Tendon causes contraction of the same muscle and inhibition of opposing muscle
Accomplished through activation of dynamic and static aspects of muscle spindles.
There are direct connections to motor (alpha)neurons in this reflex while inhibition is accomplished through interneurons.

Question 15

Gamma motor inervation

Answer 15

Of intrafusal contractile elements

Contract in response to muscle contraction to adjust spindle sensitivity

Question 16

Muscle spindle contraction

Answer 16

Can cause a contraction of extrafusal muscle. This is accomplished through gamma fibers and is used in control of muscle tone (mostly involuntary) like with the erector spinal muscles

Question 17

Golgi tendon organs

Answer 17

Nerve endings Located near the myotendinous jnxn, inhibitory counterpart of spindles
Strong stretch of a tendon will activate inhibitory interneurons that Innervate alpha motor neurons
This prevents strong spcontraction that might injure the muscle

Question 18

Anterior white commisure

Answer 18

A major pain pathway neurons that contribute to the anterolateral system cross here
Located at the dorsal end of the anterior median fissure