the macroscopic spinal cord

what is the spinal cord?

tubular bundle of nervous tissue + supporting cells

where does the spinal cord arise from?

as a continuation of the medulla oblongata

what does the spinal cord travel within?

vertebral canal

how much of the vertebral canal does the spinal cord fill?

2/3s

at what vertebral level does the spinal cord taper off?

L2

what does the spinal cord form when it tapers off?

conus medullaris

what happens to the spinal nerves at the end of the spinal cord?

they are bundled together

what is this bundle of spinal nerves called?

cauda equina

which vertebral level do the nerve roots of the cauda equina arise from?

L2-S5

how many point of enlargement are there on the spine?

2

what vertebral levels do the first point of enlargement happen?

C4-T1

what is the enlargement from C4-T1 called?

cervical enlargement

what does the cervical enlargement represent?

the origin of the brachial plexus

what vertebral levels does the second enlargement happen?

T11-L1

what is the enlargement from T11-L1 called?

lumbar enlargement

what does the lumbar enlargement represent?

origin of the lumbar and sacral plexus

what are the 2 depressions on the surface of the spinal cord?

- anterior median fissure

- posterior median sulcus

what is the anterior median fissure?

deep groove extending the full length of the anterior surface of the spinal cord

what is the posterior median sulcus?

groove on posterior surface of spinal cord

what do the spinal nerves form?

peripheral nervous system

what does each spinal nerve originate as?

anterior + posterior nerve root

what function does the anterior root have?

motor

what function does the posterior root have?

sensory

where do the anterior + posterior nerve roots join?

intervertebral foramina

how do the spinal nerves leave the vertebral canal?

via the intervertebral foramina

what happens to the spinal nerves after leaving the vertebral canal?

they divide into 2

what are the 2 divisions of the spinal nerves?

- posterior rami

- anterior rami

what do the nerves of the posterior rami supply?

- synovial joints of vertebral column

- deep muscles of the back

- overlying skin of back

what do the nerves of the anterior rami supply?

all the other remaining areas of the body

how many main arteries supply the spinal cord?

3 longitudinal arteries

what are the 3 longitudinal arteries?

- anterior spinal artery

- paired posterior spinal arteries

where does the anterior spinal artery arise from?

vertebral arteries

what do the anterior spinal arteries travel in?

anterior median fissure

where do the posterior spinal arteries arise from?

vertebral arteries or posteroinferior cerebellar artery

where doe the posterior spinal arteries anastomose with each other?

pia mater

what are 2 more arteries that supply the spinal cord?

anterior + posterior segmental medullary arteries

which veins drain the spinal cord?

- three anterior spinal veins

- three posterior spinal veins

what is different about these veins?

they do not contain valves

where do the spinal veins empty into?

internal + external vertebral plexuses

which are the afferent nerves coming into the spinal cord?

dorsal

which are the efferent nerves leaving the spinal cord?

ventral

how can you tell which part is dorsal/ventral?

dorsal - larger wings

ventral - ridge