1 The NERVOUS SYSTEM Spinal Cord and Spinal Nerves and meninges Dr. K V K 23.04.2011.
-
Upload
joseph-heath -
Category
Documents
-
view
220 -
download
3
Transcript of 1 The NERVOUS SYSTEM Spinal Cord and Spinal Nerves and meninges Dr. K V K 23.04.2011.
1
The NERVOUS SYSTEM
Spinal Cord and Spinal Nerves and meninges
Dr. K V K23.04.2011
16-2
The Spinal Cord Provides a vital link between the brain
and the rest of the body. Exhibits some functional independence
from the brain. The spinal cord and its attached spinal
nerves serve two important functions. pathway for sensory and motor impulses responsible for reflexes
16-3
Structure of the Spinal Cord A typical adult spinal cord ranges between 42 and
45 centimeters (cm) (16 to 18 inches) in length. Viewed in cross section, it is roughly cylindrical,
but slightly flattened both posteriorly and anteriorly.
Its external surface has two longitudinal depressions.
the posterior (or dorsal) median sulcus, dips internally on the posterior surface
the anterior (or ventral) median fissure, is observed on its anterior surface
16-4
Location and Distribution of White Matter The white matter of the spinal cord is external to the grey
matter. White matter on each side of the cord is also partitioned
into three regions. A posterior funiculus lies between the posterior grey horns
on the posterior side of the cord and the posterior median sulcus.
The white matter region on each lateral side of the spinal cord is the lateral funiculus.
The anterior funiculus is composed of tracts of white matter that occupy the space on each anterior side of the cord between the anterior grey horns and the anterior median fissure.
The anterior funiculi are interconnected by the white commissure.
5
6
16-7
Regions of the Spinal Cord The cervical region is the superior-most region of the spinal
cord. continuous with the medulla oblongata contains neurons whose axons form the cervical spinal nerves
The thoracic region lies inferior to the cervical region. attached to this region are the thoracic spinal nerves
The lumbar region is a shorter segment of the spinal cord that
contains the neurons for the lumbar spinal nerves The sacral region lies inferior to the lumbar region and
contains the neurons for the sacral spinal nerves The coccygeal region is the most inferior “tip” of the spinal
cord. one pair of coccygeal spinal nerves arises from this region.
16-8
Spinal Nerves The spinal cord is associated with 31 pairs of spinal
nerves that connect the CNS to muscles, receptors, and glands.
Each side of the spinal cord contains 8 cervical nerves (called C1–C8), 12 thoracic nerves (T1–T12), 5 lumbar nerves (L1–L5), 5 sacral nerves (S1–S5), and 1 coccygeal nerve (Co).
16-9
Spinal Nerves 31 pairs of spinal nerves connect the central
nervous system to muscles, glands, and receptors
Each spinal nerve is formed from the union of thousands of motor and sensory axons.
Motor axons originate from the spinal cord. Each anterior root and its corresponding
posterior root unite within the intervertebral foramen to become a spinal nerve.
Contain both motor axons and sensory axons. Each spinal nerve is associated with the vertebra
of the same number.
Spinal nerves and vertebral levels
10
11
16-12
Structure of the Spinal Cord The spinal cord is shorter than the vertebral
canal that houses it. The tapering inferior end of the spinal cord is
called the conus medullaris and it marks the official “end” of the spinal cord proper.
Inferior to this point, nerve roots (groups of axons collectively called the cauda equina) project inferiorly from the spinal cord.
Within the cauda equina is the filum terminale, a thin strand of pia mater that helps anchor the conus medullaris to the coccyx.
13
16-14
Arrangement and Functions of the Spinal Meninges Are continuous with the cranial meninges. Structures that encircle the spinal cord, listed
from outermost to innermost are: vertebra epidural space Dura mater subdural space arachnoid subarachnoid space pia mater
Them Meninges of the cord
16-15
16
17
Ligament denticulatum Triangular shaped Or dental shaped Lateral extensions Of the Pia matter Attached to the Dura matter and Gives support to The spinal cord
16-18
Filum terminale(pia matter) Note the narrow cord Of pia matter just inferior to the conus Medullaris(end) of the Cord Cm:conus medullaris Ce:cauda equina
16-19
Lumbar cystern Is the sub- Arachnoid space Which is the Largest ,extends From L1 to S2 Where the Dura Matter ends.
16-20
Spinal cord in the Fetus Note in the fetus The cord extends The whole length of the Vertebral canal(into the – Sacral canal)
16-21
Cerebrospinal fluid circulation
16-22
Spinal canal 1.Intervertebral Disc 2.Body of vertebra 3.Dura matter 4.Epidural space (extradural space) 5.Spinal cord 6.Sus Arachnoid space.
16-23
Structures in the sagittal plain See the MRI picture above A sagittal view of the human thoracic spinal cord, showing the (1) intervertebral discs, (2) vertebral bodies, (3) Dura, (4) epidural space,
(5) spinal cord, and (6) subdural space. (refer the previous picture)
16-24
• Anterior spinal artery
• Is the branch of the
• vertebral artery and
• Supply the spinal
• Cord only in the
• Upper region.
• The lower regions are
• Supplied by the
• Medullary segmental
• Arteries from below.25
Arteries of spinal cord
26
16-27
Location and Distribution of Grey Matter In the spinal cord, Grey Matter is centrally
located. Its shape resembles a letter H or a butterfly. The grey matter may be subdivided into the
following components: anterior horns lateral horns posterior horns the grey commissure
28
29
16-30
Nerve Plexuses A network of interweaving anterior rami of
spinal nerves. Anterior rami of most spinal nerves form nerve
plexuses on both the right and left sides of the body.
Nerve plexuses then split into multiple “named” nerves that innervate various body structures.
Principal plexuses are the cervical plexuses, brachial plexuses, lumbar plexuses, and sacral plexuses.
31
32
Cross-sectional anatomy of the spinal cord
LUMBAR-PUNCTURE
• A lumbar puncture is done to:
• Find a cause for symptoms possibly caused by an infection (such as meningitis), inflammation, cancer, or bleeding in the area around the brain or spinal cord (such as subarachnoid hemorrhage).
• Measure the pressure of cerebrospinal fluid (CSF) in the space surrounding the spinal cord. If the pressure is high, it may be causing certain symptoms.
• A lumbar puncture may also be done to:
• Put anesthetics or medicines into the CSF. Medicines may be injected to treat leukemia and other types of cancer of the central nervous system.
33
34
Clinical Significance
Lumbar puncture between L3/L4 or L4/L5 (L4 spinous process in line with highest points on iliac crests). Used to draw CSF, measure pressure, nerve block, or epidural anastheasia,administration of cancer drugs because of the large lumbar cistern(storehouse)
PROCEDURE OF LUMBAR PUCTURE
• The needle is
• Inserted between
• Spine any level
• Below the L1 but
• Above the sacrum
• In adults.
35
36
Lumbar puncture