Lecture 17

Question 1

Somatic Innervation

Answer 1

Arise segmentally along the developing CNS in association with somites; part of each somite (dermomyotome) gives rise to skeletal muscle and the dermis of the skin

Question 2

Hypaxial Muscles

Answer 2

Cells that migrate anteriorly give rise to muscles of the limbs and trunk and to the associated dermis

Question 3

Epaxial Muscles

Answer 3

Cells that migrate posteriorly give rise to the intrinsic muscles of the back and the associated dermis

Question 4

Dermatome

Answer 4

Area of skin supplied with afferent nerve fibers by a single posterior spinal root

Question 5

Myotome

Answer 5

All the muscles that are innervated by a single efferent anterior root; most muscles are composed of more than one myotome

Question 6

Spinal Cord

Answer 6

Approx. 1/2 meter in length and maybe 1-1.5 cm in diameter; enlarged in cervical C3-T1 and lumbar L1-S2; contains “conus medullaris”, “cauda equina”, and “filum terminale”

Question 7

Filum Terminale

Answer 7

Thin filament of meningeal tissue extending from conus medullaris to the coccyx

Question 8

Number of spinal nerves in each section of spinal cord

Answer 8

8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal

Question 9

Plexuses and which nerves they contain

Answer 9

Cervical (C1-C4), Brachial (C5-T1), Lumbosacral (L1-S4)

Question 10

Gray Matter (Horns)

Answer 10

Equivalent of CNS nuclei; posterior (dorsal) horns receive incoming sensory fibers, anterior (ventral) horns are site of cell bodies of alpha motor neurons to skeletal muscle fibers; lateral horns are located only in thoracic and upper lumbar region and are the site of cell bodies of autonomic neurons

Question 11

White Matter (Columns/Funiculi)

Answer 11

Consist of myelinated tracts; divided into posterior/dorsal columns, anterior/ventral columns, and lateral columns

Question 12

Commisures

Answer 12

Can be either white or gray and divided into anterior or posterior

Question 13

Dorsal Rootlets and Root

Answer 13

Carries afferent fibers and contains dorsal root ganglion, which are the location of cell bodies of afferent neurons

Question 14

Ventral Rootlets and Root

Answer 14

Carries efferent fibers and have NO associated ganglion

Question 15

Spinal Nerve

Answer 15

Carries a mixture of fibers; afferent/efferent, visceral/somatic, and proprioceptive

Question 16

Primary Dorsal Rami

Answer 16

To epaxial musculature (deep back muscles) and skin on either side of dorsum of back

Question 17

Primary Ventral Rami

Answer 17

To hypaxial musculature (rest of skeletal musculature including muscles of limbs) and rest of skin

Question 18

Autonomic White Ramus Communicans

Answer 18

Carries pre-ganglionic sympathetic fibers from lateral horns of central gray of spinal cord (thoracolumbar regions)

Question 19

Autonomic Gray Ramus Communicans

Answer 19

Carries post-ganglionic sympathetic fibers from paravertebral ganglia back to spinal nerve

Question 20

Dura Mater

Answer 20

Tough outer layer of meninges of spinal cord

Question 21

Subarachnoid Space

Answer 21

Contains cerebrospinal fluid

Question 22

Pia Mater

Answer 22

Delicate innermost layer of meninges of spinal cord

Question 23

Coverings and Spaces of Spinal Cord

Answer 23

Epidural space, dura mater, subdural space, arachnoid, subarachnoid space, pia mater, denticulate ligaments