BIOL 325 Lecture 13: bio235
CHAPTER 13
Describe the protective structures and the gross anatomical
features of the spinal cord.
spinal cord anatomy
1.spinal meninges
three protective, connective tissue coverings that encircle the spinal cord and brain.
Spinal meninges surround spinal cord and are continuous with cranial meninges.
2.Epidural space
The spinal cord is also protected by a cushion of fat and connective tissue located
in the epidural space, a space between the dura mater and the wall of the
vertebral canal
– dura mater (superficial), thick strong
Between the dura mater and the arachnoid mater is a thin subdural space,
which contains interstitial fluid.
– arachnoid matter (middle layer), thin. Spiderweb arrangement of collagen
and elasic fibers. Avascular
Between the arachnoid mater and pia mater is a space, the subarachnoid
space, which contains shock-absorbing cerebrospinal fluid.
– pia matter (deepest layer). Thin, transparent connective tissue. Vascular.
All three spinal meninges cover the spinal nerves up to the point where they exit
the spinal column through the intervertebral foramina.
external anatomy of the spinal cord
1.cervical and lumbar enlargement
cervical:extends from the fourth cervical vertebra (C4) to the first thoracic
vertebra (T1). Nerves to and from the upper limbs arise from the cervical
enlargement.
Lumbar:extends from the ninth to the twelfth thoracic vertebra. Nerves to and
from the lower limbs arise from the lumbar enlargement.
2.conus medullaris
Inferior to the lumbar enlargement, the spinal cord terminates as a tapering, conical
structure called the conus medullaris which ends at the level of the intervertebral disc
between the first and second lumbar vertebrae (L1–L2) in adults.
3.filum terminale
arrising from the conuns medullaris is the filum terminale. an extension of the pia
mater that extends inferiorly, fuses with the arachnoid mater and dura mater,
anchors the spinal cord to the coccyx.
4.spinal nerves
paths of communication between the spinal cord and specific regions of the body.
The spinal cord appears to be segmented because the 31 pairs of spinal nerves
emerge at regular intervals from intervertebral foramin
5.cauda equina (horses tail).
As spinal nerves branch from the spinal cord, they pass laterally to exit the
vertebral canal through the intervertebral foramina between adjacent vertebrae.
However, because the spinal cord is shorter than the vertebral column, nerves that
arise from the lumbar, sacral, and coccygeal regions of the spinal cord do not leave
the vertebral column at the same level they exit the cord. The roots of these lower
spinal nerves angle inferiorly alongside the filum terminale in the vertebral canal
like wisps of hair.
internal anatomy of the spinal cord
Document Summary
Describe the protective structures and the gross anatomical features of the spinal cord. spinal cord anatomy. 1. spinal meninges three protective, connective tissue coverings that encircle the spinal cord and brain. Spinal meninges surround spinal cord and are continuous with cranial meninges. The spinal cord is also protected by a cushion of fat and connective tissue located in the epidural space, a space between the dura mater and the wall of the vertebral canal. Between the dura mater and the arachnoid mater is a thin subdural space, which contains interstitial fluid. Between the arachnoid mater and pia mater is a space, the subarachnoid space, which contains shock-absorbing cerebrospinal fluid. All three spinal meninges cover the spinal nerves up to the point where they exit the spinal column through the intervertebral foramina. external anatomy of the spinal cord. 1. cervical and lumbar enlargement cervical:extends from the fourth cervical vertebra (c4) to the first thoracic vertebra (t1).
