spinal chord 1

epidural space: def, loc, fn, contain

- spinal chord protection - Between the bony interior of the vertebral canal and the spinal dura - filled with blood vessels, fat and CT - to pad and cushion spinal cord protecting from collisions with the hard bony surrounds of the vertebral canal.

adult spinal chord length

Adult spinal cord is about 45 cm (18 inches in length) and 14 mm (0.55 in) in width.

sensory neurons' axons travel

After entering the cord, their axons travel in several white matter tracts to synapse at higher levels or with interneurons at the same level.

spinal chord: shapes

Cylindrical in cross section except for two enlargements Cervical (C4 or C5 - T1): nerves that go to the shoulder and upper limbs. Lumbar (T9—T12): nerves that go to the pelvis and lower limbs.

Spinal Cord: list

Gray and White Matter Ascending and Descending Tracts Meninges Spinal Nerves

gray matter

Gray matter: H- or butterfly shaped. Cell bodies of neurons Neuroglia Unmyelinated axons Dendrites of association fibers

mixed spinal nerve

The dorsal and ventral roots are short and fuse together to form a mixed spinal nerve.

dural connections' fn

The dural connections at the foramen magnum and the coccygeal ligament prevent longitudinal (superior-inferior) movement of the spinal cord.

division of gray matter, wat is PNS

The gray matter of the spinal cord is divided into a sensory half dorsally, and a motor half ventrally. This diagram shows both the clusters of neuron cell bodies organized into functional regions (seen on the right side), and the organization of their axons within the spinal roots and spinal nerves on the left. Remember that the dorsal and ventral roots, as well as the spinal nerves are part of the peripheral nervous system (PNS), not the CNS (spinal cord).

ventral horn: def, form,

The ventral horn contains somatic motor nuclei (cell bodies of motor neurons). They form columns of gray matter that run the entire length of the spinal cord.

Conus medullaris

spinal chord finally ending as a cone-shaped structure called the conus medullaris. End of the spinal cord at the intervertebral disc between L1 and L2.

spinal chord: def

- It is a major reflex center - spinal reflexes are initiated and completed at the level of the spinal cord. - provides a two-way conduction pathway to and from the brain.

nerve roots and innervation

- Nerve roots arise from the spinal cord, exits the vertebral canal, goes through the intervertebral foramina, at the level of the body that the nerves control . - each spinal nerve exiting the vertebral canal innervates its corresponding body somite (segment).

how to predictwhat is affected by damage to an area of gray matter?

- The gray matter neurons comprise nuclei that are organized based on their function and the part of the body they are innervating. - Thus, the gray within each horn is divided into four zones: somatic sensory (SS), visceral (autonomic) sensory (VS), visceral motor (VM), and somatic motor (SM). - Because of this high degree of organization of nuclei (and fiber tracts), it is easy to predict which areas of the body and what functions would be affected by damage to a specific area of gray matter located in a specific level of the cord.

arachnoid mater

- The middle covering is the arachnoid mater. 1. Arachnoid membrane: The inner surface of dura and outer surface of arachnoid mater are covered by simple squamous epithelium 2. between them is the subdural space.

spinal nerve roots travel

- during fetal development, the vertebral column grows faster than the spinal cord, - the lower spinal nerve roots have to travel farther and farther inferiorly through the canal to reach their exit points in order to get to the body somite that they control. - cauda equina - Filum Terminale

Filum Terminale

- structure visible arising from the conus medullaris - a fibrous extension of the pia mater that anchors the spinal cord to the coccyx so that the cord is not displaced by body movements.

pia mater: look, where, contain

-delicate mother Thin and transparent CT Adheres tightly to the surface of the spinal cord. Contains branches of the blood vessels that supply the spinal cord.

gray mater anatomy: list

1. gray commissures 2. horns -ventral h - dorsal h - lateral h

spinal chord internal anatomy

1. gray matter 2. white matter

parts of spinal chord: list

1. two grooves 2. gray n white matter

arachnoid trabeculae

Arachnoid mater means spider mother: loose CT and elastic fibers called, arachnoid trabeculae, that resemble a spider's web. The arachnoid trabeculae extend between the arachnoid membrane and the outer surface of the pia mater. Between the arachnoid and pia is the subarachnoid space which is filled with CSF

CSF: fn

Besides acting as a shock absorber, CSF helps nourish the spinal cord. It is a medium for the diffusion of oxygen and carbon dioxide gases, nutrients, chemical messengers and it washes away waste products produced by neuronal metabolism.

protection of CNS

Both the brain and the spinal cord are protected by bone, cerebrospinal fluid, and special CT coverings called the meninges (singular is meninx).

coccygeal ligament

Dura Mater (tough mother) The coccygeal ligament is an extension of dura mater that anchors spinal cord longitudinally. In the sacral canal, the spinal dura tapers forming a dense cord that blends with the filum terminale forming the coccygeal liagament.

epidural space: Clinical Note:

In an epidural block, an anesthetic is injected into the epidural space. The anesthetic will "numb" only the spinal nerves in the immediate area of injection and may not significantly affect motor fibers. It is easiest to do an epidural block in the lumbar region and below because of the tapering of the spinal cord and its termination at approximately L2. An epidural anesthesia is difficult in the cervical and midthoracic regions because the epidural space is narrow.

lateral horn

In the thoracic and superior lumbar segments of the cord, is a lateral horn of gray matter. The lateral horn neurons are autonomic, sympathetic motor neurons supplying the viscera, smooth muscle or glands. Their axons leave the cord via the ventral root along with those of the somatic motor neurons.

gray, white matter of spinal chord

Internally, the spinal cord contains gray and white matter, the arrangement of which is opposite that of the brain. Recall that in the brain, the gray matter of the cerebral cortex is located superficially, whereas the white matter is deep. In the spinal cord, the gray mater makes an H- or butterfly shape inside which is surrounded on the outside by white matter.

white matter

Myelinated axons of motor and sensory neurons.

spinal ganglion

The actual cell bodies of the sensory neurons are found in an enlarged region called the dorsal root or spinal ganglion.

amount of ventral gray matter

The amount of ventral gray matter present at a given level of the spinal cord reflects the amount of skeletal muscle being innervated at that level.

cauda equina

The collection of nerve roots found in the inferior end of the vertebral canal is called the cauda equina which literally means, horse's tail.

dorsal horn

The posterior or dorsal horns extend through the white matter to the surface of the spinal cord. They consist of mainly of interneurons that relay somatic and visceral sensory information. Afferent fibers carrying impluses from peripheral sensory receptors form the dorsal roots of the spinal cord.

horns: def, list

The projections of gray matter are called horns.

spinal chord and its meninges

The spinal cord and its meninges lie in the vertebral canal. the dura mater of the spinal cord is a single layer and is not attached to the bony walls of the vertebral column, however, it is continuous with the dura mater covering the brain. The spinal dura mater extends to sacral level 2 (S2). Dura mater Arachnoid mater Pia mater

spinal chord: loc

The spinal cord extends from the medulla oblongata of the brain stem (foramen magnum of the skull) to the level of the (L1-/ L2). It does not extend the entire length of the vertebral column that protects it, because the spinal cord stops growing before the skeleton does. The spinal cord tapers from superior to inferior, finally ending as a cone-shaped structure called the conus medullaris.

2 grooves of spinal chord

The spinal cord has two grooves, the ventral (anterior) and median fissure, and a shallower dorsal (posterior) median sulcus. These groves run the length of the spinal and almost divide it into right and left halves. Locate these features on the diagram above.

denticulate ligaments : def, fn

The spinal cord is secured to the dura mater throughout its length by saw-toothed slips of pia mater called denticulate ligaments (denticulate means toothed). The denticulate ligaments prevent lateral or side-to-side movement of the spinal cord, preventing it from smacking into the hard bony surface of the vertebral canal when we move.

gray commissures

The two large lateral masses of gray matter are connected by a bridge of gray matter surrounding the small central canal located in the center. These crossbars of gray matter are called the gray commissures and they contain axons that cross from one side of the cord to the other on each side of the central canal.

spinal chords enlargements contain

These enlargements contain neurons that form the many nerves that control the complex musculature of the upper and lower limbs.

spinal tap

This fluid can also be used for diagnosing various diseases, such as infection, bleeding, electrolyte imbalance, etc. CSF can be safely removed from the subarachnoid space by a procedure called a spinal or lumbar tap or puncture. Because the spinal cord tapers inferiorly finally ending at L1-L2, a needle can be inserted in the region of the cauda equina without the risk of puncturing the spinal cord. The patient being tested assumes the "fetal position" by bringing their knees as close to their trunk as possible. A needle is inserted and CSF is removed for testing.

CSF: where

cerebrospinal fluid (CSF) circulates through the subarachnoid space, as well as internally through the central canal of the spinal cord. Consequently, the both the brain and the spinal cord are "floating" in CSF.

nuclei

clusters of neuron cell bodies with similar functions

division of gray matter in each horn

the gray within each horn is divided into four zones: somatic sensory (SS), visceral (autonomic) sensory (VS), visceral motor (VM), and somatic motor (SM).

nervous system

the nervous system as a whole is divided into two major parts: - the central nervous system which includes the brain and spinal cord, - the peripheral nervous system that includes every other bit of nervous tissue outside of the CNS. - Remember that the dorsal and ventral roots, as well as the spinal nerves are part of the peripheral nervous system (PNS), not the CNS (spinal cord).