gray and white matter of spinal cord #anatomy

1. ANATOMY
Grey and white matter

2. Submitted by : Nimra, Sabia, Arfa Arshad, Aqsa Arif , Farah Mansoor
Topic : Grey and white matter of spinal cord
Class : DPT-4
Date : 03-07-2021
Subject : Neuroanatomy
Submitted to : Dr Afia

3. Spinal cord
• The spinal cord is the long cylindrical lower part of central nervous system.
• It is the main pathway for information connecting the brain and central nervous system.
• It occupies upper two-third of vertebral canal and it is enclosed in three meninges.
• It gives rise to 31 pairs of spinal nerves and retains the basic structural pattern.

4. Gray matter: The cortex of the brain, which contains nerve cell bodies.
The gray matter is so named because it is darker than the white matter, the
part of the brain that contains myelinated nerve fibers.

5. Grey matter
The grey matter extends from the brain into the spinal cord. The grey
matter creates a horn like structure throughout the inside of the spinal cord while
the white matter makes up the surrounding sections of the spinal cord. The grey
matter does extend to the spinal cord to make signaling more effective. The grey
matter is in the form of "H" with a grey commissure joining the grey and white
matter of right and left sides.
Horns of grey matter:
Grey matter comprises one posterior and anterior horn on each side in the entire
extent of the cord.
Only in T1-L2 AND S2-S4 segments there is an lateral horn for the supply of
viscera. This is part of autonomic nervous system.

6. Horns of grey matter:
❑ Nuclei in anterior grey column or horn:
The anterior horn is divided into a ventral part ,the head and the dorsal part, the base. The nuclei in anterior horn innervate
the skeletal muscles. Most prominent neurons and alpha neurons. Their axons leave the spinal cord through ventral nerve roots
to innervate skeletal muscles. Smaller neurons are gamma neurons. These supply intrafusal fibers of muscle spindles. The cells
in anterior horn are arranged in the following three main groups:
▪ Medial groups:
It is present throughout the entire extent of spinal cord and innervates the axial muscles of the body.
▪ Lateral group:
Present only in cervical and lumbar enlargements and supplies musculature of limbs.it is subdivided into three subgroups:
a. Anterolateral supplying proximal muscles of limbs(shoulder and arm/gluteal region and thigh)
b. Posterolateral supplying intermediate muscles of limbs(forearm/leg).
c. Post-posterolateral innervating the distal segment(hand/foot).
▪ Central group:
Only in upper cervical segments as phernic nerve nucleus and nucleus of spinal root of accessory nerve.

7. Nuclei in lateral horn
Nuclei in lateral horn are as follows:
1. Intermediolateral nucleus: This acts as both efferent and afferent nuclear columns. this nuclues is seen at two levels.
▪ From T1 to L2 segments, giving rise to preganglionic sympathetic fibers(thoracolumbar outflow).
▪ From S2 to S4 segments , giving rise to preganglionic parasympathetic fibers chiefly for the pelvic viscera
2. Intermediomedial nucleus: This is mostly internuncial neuronal column.
Nuclei in posterior grey column:
The four main afferent nuclei are seen in this are:
1. Posteromarginal nucleus: Thin layer of neurons caps the posterior horn .It receives some of incoming dorsal root fibers.
2. Substantia gelatinosa: This is found at the tip of posterior horn throughout the entire extent of spinal cord.
3. Nucleus proprius: It lies subjacent to the substantia gelatinosa throughout the entire extent of cord.1-3 groups of nuclei
are present in laminae 1-4.
4. Nucleus dorsalis : of clarke also known as thoracic nucleus at the medial part of base of posterior horn extending from
C8 to L3 segments .These are situated in laminae 5 and 6.

8. Grey matter of spinal cord:

9. White matter:
White matter is found in the deeper tissues of brain
(subcortical).

11. Anterior spinothalamic tract: carries fibers for crude touch and
pressure.first neuron fibers in dorsal root ganglia .second neuron fibers ascend
and cross to opposite side in white commissure
Fasiculus gracilis: it commence at caudal limit of spinal cord and composed
mainly of long ascending branch of medial division of fibers of dorsal nerve
root.these are first order neuron from dorsal root ganglia . it contain fibers
derived from lower thoracic',lumbar,sacral and coccygeal segment of spinal cord
Fasiculus cuneatus: commencein mid thoracic region .derieve its fibers from
upper thoracic and cervical segment.first neuron fibers from central processof
dorsal root ganglia

14. Lateral spinothalamic tract: carries sensation of pain and temperature.first
neuron fibers start in dorsal root ganglia.second neuron fibers cross
immediately to opposite side close to central canal.

17. Descending tract are of two types . Pyramidal or corticospinal tract:
1-lateral corticospinal tract which lies in lateral funiculus
2- anterior corticospinal tract which lies in anterior funiculus
Extrapyramidal tract are: 1- rubrospinal
2 medial reticulospinal
3 lateral reticulospinal
4 olivospinal
5 lateral vestibulospinal
6 tectospinal
Rubrospinal tract: formed by axon of red nucleus .situated in midbrain.the tract

18. Rubrospinal tract: formed by axon of red nucleus .situated in midbrain. the tract
descends through pons and medulla and enter lateral white column of spinal cord. control
tone of limb flexor muscles. Lateral reticulospinal tract: originates from reticular formation
in brainstem and descends thoracic segment of spinal cord. lies anterolateral column of
spinal cord. facilitates flexor
Medial reticulospinal tract: formed by fibers from reticular formation in pins and descends
in cervical segment only .lies in anterior white column of spinal cord .influence voluntary
movement ,reflex activity and muscle tone
Olivospinal tract: originates from inferior olivary nucleus in medulla oblongata and
descends to spinal cord.lies anterolateral column of white matter
Tectospinal tract: formed by axon of neuron lying in superior colliculus of midbrain.
descend through pons, medulla and anterior white column of spinal cord. mediates reflex
movement of head and neck
Vestibulospinal tract: arise from lateral vestibular nucleus lying at pontomedullary
junction. fibers descend uncross to spinal cord. situated anterior white column of
spinal cord.it has two types: lateral :control extensor muscle tone. Medial : for,
movement of head
Intersegmental tract: formed of fibers connecting various segment of spinal cord. present
in anterior ,posterior and lateral column of white matter adjacent to grey matter of spinal
cord