Ch. 5- Spinal Meninges and Spinal Cord

Question 1

Dura Mater

Answer 1

(Tough Mother) - outermost and strongest

• single layer in spinal area is continuous with meningeal layer of cranial dura mater, fused with periosteum of occipital bone at margin of foramen magnum
• extends inferiorly to SV2
• continued laterally along all spinal nerves to fuse with neural sheath distal to dorsal root ganglia and with the margins of the IV foramina
• attached to posterior longitudinal spinal ligament, especially in upper cervical and lower lumbar regions - provides support for spinal cord
• dura below SV2 surrounds filum terminale to form the coccygeal ligament which attaches inferiorly to the periosteum of the coccyx
• epidural space

Question 2

Filum Terminale

Answer 2

the Dura below Sv2surrounds the filum terminale (final nerve) to form the cocygeal ligament which attaches inferiorly to the periosteum of the coccyx

The filum terminale (“terminal thread”), is a delicate strand of fibrous tissue, about 20 cm in length, proceeding downward from the apex of the conus medullaris. It gives longitudinal support to the spinal cord and consists of two parts:

• The upper part, or filum terminale internum, is about 15 cm long and reaches as far as the lower border of the second sacral vertebra. It is continuous above with the pia mater and contained within a tubular sheath of the dura mater. In addition, it is surrounded by the nerves forming the cauda equina, from which it can be easily recognized by its bluish-white color.
• The lower part, or filum terminale externum, closely adheres to the dura mater. It extends downward from the apex of the tubular sheath and is attached to the back of the first segment of the coccyx in a structure sometimes referred to as the coccygeal ligament.

Question 3

Epidural Space

Answer 3

space brtween periosteum lining bony wall of vertebral canal and dura mater filled with fat and blood vessels; location of internal vertebral venous plexuses and ensheathed roots of spinal nerves

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Question 4

Subdural Space

Answer 4

area enclosed by dura, a potential space, filled with fluid which moistens the apposed surfaces of dura and arachnoid mater

Question 5

Arachnoid Mater

Answer 5

• (spidery mother) - delicate trabeculated layer continuous with cranial arachnoid mater
• follows limits of dura to SV2
• adheres directly to dorsal and ventral roots to become continuous with neural sheath at spinal nerve
• encloses the subarachnoid space
• rootlets covered with arachnoid mater lie within the dural sac. as they course laterally and fuse to form spinal nerves, they become invested with dura mater where all three meningeal layers fuse with the neural sheath of the spinal nerve

Question 6

subarachnoid space

Answer 6

space enclosed by the arachnoid mater which contains CSF; and spinal arteries and veins

• between arachnoid mater and pia mater
• continuous with cranial subarachnoid space

Question 7

pia mater

Answer 7

• (faithful mother) - direct c.t. that covers the spinal cord
• invests blood vessels of the cord; continuous along dorsal and ventral roots to spinal nerve
• forms filum terminale at conus medullaris (where nerve ends and cauda equina begins); extends to SV2 where it becomes ensheathed by the dura
• laterally forms denticulate ligaments

Question 8

Denticulate Ligaments

Answer 8

• the spinal cord is suspended in the dural space by the filum terminale and the right and left denticulate ligaments, which run longitudinally along each side of the spinal cord
• these ligaments consist of a fibrous sheet of pia extending midway between the posterior and anterior nerve roots from the lateral surfaces of the spinal cord
• note: these ligaments along with filum terminale anchor the spinal cord while CSF in the sbuarachnoid space acts as a shock absorber

Question 9

Conus Medullaris

Answer 9

• taperd end of the spinal cord, which ends opposite of LV1-LV2 and contains Sacral/Coccygeal nerves 1-3
• pia-glial extension continues inferiorly to SV2 as the filum terminale

Question 10

Dorsal Root Ganlion

Answer 10

• contains cell bodies of origin (CBO’s) of most of the sensory neurons which innervate the body below the level of the head

Question 11

31 pairs of spinal nerves

Answer 11

• 8 cervical
• 12 thoracic
• 5 lumbar
• 5 sacral
• 1 coccygeal

Question 12

Cauda Equina

Answer 12

lower lumbar and sacral rootlets leave the spinal cord at the conus medullaris and form the cauda equina

• enlargements of the spinal cord in cervical and lumbar regions correlate to the increased number of nerve cell bodies located in the anterior horns (motor region) where the brachial and lumbar plexuses originate

Question 13

Anterior Spinal Artery

Answer 13

• arises from both vertebral arteries which courses in the ventral median fissure; supplies anterior gray and white matter. the continuity of this arter is dependent upon anastomotic connections with segmental medullary aa.

Question 14

posterior spinal artery

Answer 14

• most often arise as branches of the posterior inferior cerebella artery (PICA); course along the dorsal root entry zone anastomosing freely with its opposite counterpart