Back Muscles and Spinal Cord

Question 1

Name the layers of the back and muscles associated with each layer

Answer 1

extrinsic superficial: trapezius and lats
extrinsic intermediate: levator scapulae, rhomboid major and minor, serratus posterior superior and inferior
superficial intrinsic: splenius capitis and splenius cervicis
intermediate intrinsic: erector spinae
Deep intrinsic: semispinalis capitis and cervicis, rotatores costarum, interspinales, intertransversales, multifidus

Question 2

What are the most medial lumbar back muscles

Answer 2

multifidus

Question 3

Describe the multifidi

Answer 3

slope upwards from the laminae and the mammillary processes to the spinous process of vertebrae 2 or 4 over their level, produce extension and lateral bending and are loaded with mechanoreceptors

Question 4

Describe the intertrnasversarii

Answer 4

intertransversarii are divided into medial and lateral, only medial are considered true back muscles since they are innervated by dorsal rami where lateral is ventral

Question 5

What is affected by folic acid deficiency during the 1st trimester

Answer 5

neural tube formation

Question 6

What do the neural crest cells develop into (DAMESS)

Answer 6

Dorsal root ganglia
Adrenal medulla
Melanocytes, Macroglia, Meninges (arachoid and pia)
Enteric ganglia
Schwann cells
Sympathetic ganglia 

Microglia and dura mater are derived from the mesoderm

Question 7

where does the spinal cord begin and end

Answer 7

begins at foramen magnum and ends at L1/2

Question 8

What are the two regional enlargements of the spinal cord

Answer 8

Largest at C6 and lumbosacrial for the brachial

Question 9

What is the dilated end of the spinal cord called

Answer 9

conus medullaris

Question 10

What are the nerves that leave the end of the spinal cord called

Answer 10

cauda equina

Question 11

what mater gives rise to the dentate ligaments

Answer 11

pia (innermost)

Question 12

What level does the dural sac end

Answer 12

s2

Question 13

Describe the parts of the filum terminale

Answer 13

filum terminal internum - extends from the conus medulla to the end of the dural sac at S2
filum terminal externum - is covered by a thin layer of dura and extends to the coccyx as the coccygeal ligament

Question 14

Describe the spinal cord and its segments

Answer 14

31 segments that with ventral and dorsal roots that come together to for spinal nerves

Question 15

What maters are continuous with the epineurium of the spinal nerves

Answer 15

the dura and arachnoid

Question 16

Describe the white matter of the spinal cord

Answer 16

mylenated, organized into 3 bundles of funiculi: posterior, anterior, and lateral

Question 17

What do fast-conducting myelinated axons form and what lies between them

Answer 17

fasciculi and glial cells (oligodendrocytes and astrocytes)

Question 18

Which tracts carry vibration, fine touch (two-point discrimination) and joint position sense

Answer 18

posterior or dorsal columns

Question 19

From the posterior or dorsal columns where do axons from the lower limp and upper limb synapse

Answer 19

Lower limb synapse in nucleus graciLis in the medulla

Upper limb synapse in nucleus cUneatus in the medulla

Question 20

Which tract carries pain and temperature

Answer 20

lateral spinothalamic

Question 21

which tract carries crude touch and pressure

Answer 21

ventral spinothalamic

Question 22

Which tract plays a role in mediating autonomic responses to nociception

Answer 22

spinoreticular

Question 23

Which tract plays a role in activating eye movements in response to tactile stimuli

Answer 23

spinotectal

Question 24

What function do DESCENDING tracts have

Answer 24

Carry axons that control skeletal motor function, smooth muscles and secretory glands.
ALL descending tracts are motor EXCEPT raphespinal which modulates nociception

Question 25

Describe the pathway of the dorsal column

Answer 25

1st order: Mechano-receptors vibration and fine touch 2nd order: Nuclei gracilis and cuneatus Decussation: Medulla 3rd Order: VPL nucleus of thalamus

Question 26

Describe the pathway of the spinothalamic

Answer 26

1st order: nociceptors, thermoreceptors, crude touch and pressure receptors 2nd order: lamina I and II in the dorsal horn of the gray matter Decussation: spinal cord 3rd order: VPL nucleus of thalamus`

Question 27

Describe the pathway of the dorsal spinocerebellar

Answer 27

1st order: unconscious proprioception from the ipsilateral lower limb 2nd order: Clarke's nucleus (dorsal) found in the thoracic region Decussation: Ipsilateral does not cross 3rd order: cerebellum via inferior cerebellar peduncle

Question 28

Describe the pathway of the ventral spinocerebellar

Answer 28

1st order: unconscious proprioception from the both upper and lower limbs 2nd order: lamina VII decussation: TWICE: first at the spinal cord and again at the pons 3rd order: cerebellum via superior cerebellar peduncle

Question 29

Describe the pathway of the rubrospinal

Answer 29

1st order: red nucleus decussation: midbrain 2nd order: laminae V-VIII

Question 30

Describe the pathway of the tectospinal

Answer 30

1st order: tectum of midbrain Decussation: midbrain 2nd order: laminae VI and VIII

Question 31

Describe the pathway of the lateral corticospinal (AKA pyramidal tract)

Answer 31

1st order: pre-central gyrus decussation: medullar 2nd: order laminae IV-IX

Question 32

Describe the pathway of the ventral corticospinal

Answer 32

1st order: pre-central gyrus decussation: spinal cord at the leel of exit 2nd order: laminae VI-IX

Question 33

Describe the pathway of the reticulospinal

Answer 33

1st order: reticular formation decussation various levels 2nd order: laminae VIII

Question 34

Describe the pathway of the vestibulospinal

Answer 34

1st order: vestibulospinal decussation: uncrossed 2nd order: Laminae Vi and VIII

Question 35

Describe the pathway of the raphespinal

Answer 35

1st order: raphe nucleus decussation: uncrossed 2nd order: laminae I, II, and V

Question 36

Which descending tract has voluntary control of the muscles in the limbs

Answer 36

Lateral corticospinal

Question 37

. Which descending tract has voluntary control of the muscles in the head, neck, and trunk

Answer 37

ventral corticospinal

Question 38

. Which descending tract excites proximal flexors and inhibits extensors mainly in the upper limb

Answer 38

rubrospinal

Question 39

. Which descending tract restricts voluntary movements through gamma motor neurons

Answer 39

reticulospinal

Question 40

. Which descending tract coordinates head and eye turning in response to visual input

Answer 40

tectospinal

Question 41

. Which descending tract is involved in postural reflexes - neck muscles, extensors of back and limbs

Answer 41

vestibulospinal

Question 42

. Which descending tract inhibits nociception by releasing serotonin and acts on the c fibers

Answer 42

raphespinal

Question 43

Describe the gray matter and horns

Answer 43

Arranged into 3 horns: Dorsal - sensory Ventral - motor Lateral - sympathetic

Question 44

What horn is only found in the thoracic party of the spinal cord at T1 to L2

Answer 44

lateral (interomediolateral)

Question 45

Describe rexed laminae I

Answer 45

Then layer that lies beneath the dorsolateral fasciculus (of Lissauer) Contains neurons which synapse with the first order neruons and send axons to the spinothalamic tracts on opposite sides

Question 46

Describe R. Lamina II

Answer 46

AKA substantia gelatinosa of Rolando | Substance P is found in HIGH concentrations in lamina I and II

Question 47

Describe laminae III and IV

Answer 47

Jointly referred to as the nucleus PROPius - their main input is from fibers that carry PROPrioception and light touch

Question 48

Describe lamina V

Answer 48

Contains neurons that respond to both noxious and visceral afferent stimuli

Question 49

Describe lamina VI

Answer 49

deepest layer of the dorsal horn and receives mechanical signals from skin and joints

Question 50

Describe lamina VII

Answer 50

Contains the dorsal nucleus (Clarke's column) and the intermediolateral horn

Question 51

What kind of cell bodies does the intermediolateral horn and clarke's column contain

Answer 51

intermediolateral horn: preganglionic sympathetic from T1 to L2 Clarke's Column: carries unconscious proprioception from the legs in the dorsal spinocerebellar tract from T6 - L1

Question 52

Describe lamina VIII

Answer 52

contains neurons linked with the vestibulospinal and reticulospinal tracts

Question 53

Describe Lamina IX

Answer 53

contains alpha and gamma motor neuron groups in the ventral horn Alpha: extrafusal skeletal muscle Gamma: intrafusal fibers in the muscle spindles

Question 54

Describe lamina X

Answer 54

Small area of grey matter surrounding the central canal | AKA grey commissure - function is unknown

Question 55

What arteries supply the spinal cord

Answer 55

``` Segmental spinal arteries from: ascending cervical deep cervical posterior intercostal upper two lumbar ```

Question 56

What doe segmental spinal arteries give rise to

Answer 56

radicular and segmental medullary arteries

Question 57

Describe the segmental medullary arteries roles

Answer 57

Feed into the single anterior spinal artery and two posterior spinal arteries which originate from vertebral arteries

Question 58

What is the name of the artery that supplies between the lower half to 2/3 of the spinal cord

Answer 58

A relatively large radicular artery called the Great Radicular artery of (Adamkiweicz)

Question 59

Where does the Great radicular artery usually arise

Answer 59

On the left side (68-80%) as a branch of either the lower posterior intercostal or the upper lumbar arteries

Question 60

What does the single anterior spinal artery supply

Answer 60

Approx. the anterior 2/3 of the spinal cord

Question 61

What do the two combined posterior spinal arteries supply

Answer 61

the posterior 1/3 of the spinal cord

Question 62

Describe the difference between an upper and lower motor neuron lesion

Answer 62

``` Upper: Reflexes: increased with clonus Tone: Spastic (increased) Atrophy: Absent Fasciculations: Absent Babinski sign: present (up going toe) ``` ``` Lower: Reflexes: decreased or absent Tone: Flaccid Atrophy: present Fasciculations: present Babinski sign: absent (down going toe) ```