copy right hongqi of anatomy fudan systematic...

Copy Right‐ Hongqi ZHANG‐Department of Anatomy‐Fudan University

Copy Right‐ Hongqi ZHANG‐Department of Anatomy‐Fudan University 1

Dr.Hongqi Zhang (张红旗)Email: [email protected]

Systematic Anatomy

Nervous system- Part 1

Spinal nerve-2



Spinal cord

BrainTelencephalonDiencephalonCerebellumBrain stem

1-Midbrain2-Pons3-medulla oblongata

Spinal cord

Central nervous system (CNS)

Position of the Spinal Cord

Position: Lies in vertebral canal, 45cm long approximately

Upper end: Continuous with medulla oblongata at foramen magnum

Lower end: at the lower border of L1 in adult at newborn at level of L3

Sexual difference: usually a little lower in female than in male

Clinic significance: anaesthesia done usually at below the L1



Anaesthesia in the vertebral canal

L1

Draw cerebrospinal fluidFrom the vertebral canalFor lab examination

Lower endOf spinal cord

Needle puncture

SkinSubcutaneous fasciaSupraspinal lig.Interspinal lig.Yellow lig.

External feature:A long cylindrical structure & slightly flattened anteroposteriorly

Two enlargementsCervical enlargement corresponds to C4 -T1 of spinal cordLumbosacral enlargement corresponds to L2 to S3 of spinal cord

Filum terminale-only thin filamentConus medullarisCauda equina

External Features of Spinal Cord

Conus medullaris and cauda equina

Lumbosacral enlargement

Conus medullaris

Filum terminale

Cauda equina

External Features of Spinal Cord

Fissure and sulci1 - Anterior median fissure 2 - Posterior median sulcus3 - Anterolateral sulcus - connect with ant.root (motor)4 - Posterolateral sulcus - connect with post.root (sense)

Ant.root

Post.root

Spinal ganglion

Ant.branch

Post.branch

1

2

3

4

Segments of Spinal CordA portion of the cord that

gives rise to a pair of spinal nerve constitutes a segment.

There are 31 segments

8 cervical ss

12 thoracic ss

5 lumbar ss

5 sacral ss

1 coccygeal s

Segment - s



Relationship of SC Segments to Vertebral body

In the third month of fetal life,the spinal cord occupies the entire length of the vertebralcanal.After that time,there are some

difference between spinal cord & vertebral canal in growth speed,that is, the vertebral canal grow faster than that of spinal cord,

At 3rd fetal month

Sc length = vertebral canal

Spinal cord

Vertebral canal



Relationship of SC Segments to Vertebrae

At birthThe inferior ends is

below at the lower border of L1 in adult;at birth at level of L3, usually a little lower in female than in male.

But each spinal nerve have to come out from their corresponding intervertebral foramina.

After 3rd month At birth

Sc inf. end is higherThan that of canal

Sc inf. end isAt the level of L 1 at adult

L3



More high levelMore almost horizental.More lower levelMore obliquity

Relationship of SC Segments to Vertebral Numbers

Spinal segments Vertebral levels (spines)Upper cervical region (C1~C4) Lie opposite the corresponding vertebrae

Lower cervical and upper thoracic region (C5~8；T1-4)

One lower in number than corresponding vertebrae

Middle thoracic region (T5~T8) Two lower in number than corresponding vertebrae

Lower thoracic region (T9~T12) Three lower in number than corresponding vertebrae

Lumber segments T10~T12

Sacral and coccygeal segments L1

Spinal segments Vertebral levels (spines)

Upper cervical region (C1~C4) = C1 ~ C4Lower cervical and upper thoracic region (C5-8；T1~4)

－1 = C4 ~ T3

Middle thoracic region (T5~T8) －2 = T3 ~ T6

Lower thoracic region (T9~T12) －3 = T6 ~ T9Lumber segments = T10 ~ T12

Sacral and coccygeal segments = L1

Relationship of SC Segments to Vertebral Numbers

Internal structure of spinal cord

1 - Gray matter2 - White matter3 – reticular formation

1

2

3S

L

T

C

C‐cervical;T‐tharacic;L‐lumbar;S‐sacral Central canal

Fasciculus gracilis

Fasciculus cuneatus

Ant.root

Post.root

Spinal ganglion

Spinal n.

Lat.corticospinal tractLat. spinothalamic tract

Nucleus proprius

Motor neuron of ant.horn

Spinal pia matar

Spinal arachnoid

Spinal dura matar.

White matter

Gray matter

Internal structure of spinal cord



Gray matter of Spinal CordLike a butterfly or letter “H”Consist of cell body,neuroglia and dendriteLocated around the central canal

Ant. horn (column)

Post. horn (column)

Post. gray commissures

Ant. gray commissures

Intermediate zone

Gray Matter of Spinal Cord

Anterior horn (column) Posterior horn (column)

Lateral horn (column) is present in the thoracic & upper lumber segmentsof the cord (T1-L3) only

Intermediate zone Ant. gray commissuresPost. gray commissures

Gray Matter of Spinal CordPosterior horn (column): 1- Marginal layer 2- Substantia gelatinosa

Situated at the apex of posterior horn throughout the length of spinal cord. Receives fibers are associated with the senses cord.

3- Nucleus propriusSituated anterior to the substantia gelatinosa throughout the length of spinal cord. Concerns the sensations of pain and temperature

1

2

3



Posterior horn (column):Nucleus thoracicus (lable A)

Situated at the base of posterior horn and extending from segments C8~L3. Associated with proprioceptive endings

A

Gray Matter of Spinal Cord

Intermediate zone Intermediolateral nucleus (labeled 1) Extends from segments

T1~L3, Containing sympathetic preganglionic neurons Sacral parasympathetic nucleus : Extends from segments S2~S4,

Containing parasympathetic preganglionic neurons

Intermediomedial nucleus (labled A): Throughout the whole length of spinal cord.Associated with receiving viscera afferent information

1



Anterior horn (column): Two groups of nuclei

1-Medial nuclear group: present in most segments of spinal cord, innervating axial (trunk) muscles2-Lateral nuclear group: present only in cervical and lumbosacral enlargements, innervating limb skeletal muscles

12

Anterior horn (column): labeled with red color three kinds of neurons (motor neuron 2)

α- motor neuron: large multipolar neuron, innervates skeletal muscles, producing contraction of muscles

γ- motor neuron: smaller multipolar neuron, innervates intrafusal muscle fibers of neuromuscular spindles, regulating muscular tonus

Interneuron —Renshaw’s cell: negative feedback

Rexed’s laminaPosterior horn is formed by laminaⅠ to Ⅵ；

Intermediate zone is corresponding to lamina Ⅶ；

Anterior horn is composed laminae Ⅷ and Ⅸ；

lamina Ⅹ is the gray matter around the central canal.



laminae nucleiⅠ Posterior marginal nucleusⅡ Substantia gelatinosa

Ⅲ Ⅳ Nucleus propriusⅤ Reticular nucleusⅥ Base of posterior columnⅦ Thoracic nucleus

Intermediomedial mucleusIntermediolateral nucleus

Sacral parasympathetic nucleus

Ⅷ Ⅸ Medial motor neuron columnLateral motor neuron column

Ⅹ gray matter around central canal

Important Subdivision of Spinal Cord Gray Matter



White matter of spinal cordOrganizationNerve fiber (tract)Around the grey matterThree partsAnt. Funiculus (A.F)Lat. Funiculus (L.F)Ascending & descending fiberPost. Funiculus (P.F)Ascending fiber onlyWhite commissureAnt.commissure of WM

Post.commissure of wm

A.F

P.F

L.F

WM‐white matter

White Matter of Spinal Cord

White matter contains three kinds of fibers: ascending, descending and fasciculus proprius

Ant. funiculus

Lat. funiculus

Post. funiculus

Ant. white commissure

Post. white commissure



Fiber tract:in CNS, fiber bundle which has similar origin, terminal, course and function.Ascending tract:to conduct the sensory impulse from the trunk and limbs to the brain.Descending tract.to convey the motor information from central nervous system to the trunk and limbs.

White matter of spinal cord



Nomenclature : Course: pyramid tractOrigin and terminal : Corticospinal tract.

Spinothalamic tractAppearance of the tract: Fasciculus gracilisGeneral: lateral corticospinal tract.Fasciculus proprius: both origin & termination of the fascisulus are in the spinal cord.with two direction (ascending & descending), the function take part in different segment reflex.

White matter of spinal cord

Major Ascending or sensory Tracts

Fasciculus gracilis

Fasciculus cuneatus

Pos. spinocerebellar tract

Ant. spinocerebellar tract

Spinothalamic tract

Lat.Spinothalamic tract(rough tonch)Ant.Spinothalamic tract(pain,temperature,sensation)

Red color means important

Fasciculus gracilis

Fasciculus cuneatus

Fasciculus gracilis and fasciculus cuneatus

Spinothalamic tract

From pain and temperatureAnd some touch receptors

Lateral and anterior spinothalamic tract

Summary-ascending tractsTract Site of origin Funiculu

s Termination Function

Fasciculus gracilis

Spinal ganglia below segment T5

Posterior Gracile nucleus

Conscious proprioceptive (vibratory sense, and muscle joint sense) and fine touch sensation of trunk and limbs

Fasciculus cuneatus

Spinal ganglia above segment T4

Cuneate nucleus

Posterior spinocerebellartract

Homolateral nucleus thoracicus

Lateral Cerebellum Unconscious proprioception from limbs and trunk

Anterior spinocerebellartract

Contralateral Laminae Ⅴ~Ⅶ

LateralSpinothalamictract

Laminae Ⅰ, Ⅳ~Ⅶ

Lateral Dorsal thalamus

Pain, temperature and crude touch sensation of trunk and limbs

anteriorSpinothalamictract

anterior

Descending TractsLateral corticospinal tract

Anterior corticospinal tract

Rubrospinal tract

Vestibulospinal tract

Reticulospinal tract

Medial longitudinal fasciculus

Tectospinal tract

Fasciculus proprius

Red color means important content

Lateral corticospinal

tract

Anterior corticospinal

tract

Coranal section of cerebrum

horizental section of cerebrum

horizental section of midbrain

horizental section of pons

horizental section ofmedulla ablongata

horizental section ofspinal cord

Lateral and anterior corticospinal tract

Summary - descending tractsTract Site of origin Funiculus Termination Function

Lateral corticospinal

Cerebral cortex Lateral Laminae (Ⅳ~Ⅸ)anterior hornMotor neurons &interneurons

Voluntary movementof skeletal muscle of trunk and limbsAnterior

corticospinalCerebral cortex Anterior

Rubrospinal Red nucleus Lateral Laminae (Ⅴ~Ⅶ)anterior hornMotor neurons& interneuron(for flexor)

Facilitates activity of flexor muscles

Vestibulospinal Homolateral vestibular nuclei

Anterior Laminae (Ⅶ~Ⅷ)anterior hornMotor neurons& interneuron(for extensor)

Facilitates activity of extensor muscles

Reticulospinal Reticular formation

Anterior & lateral

Laminae (Ⅶ~Ⅷ) Control Voluntary movement of skeletal muscle of trunk & proximal extremity

Summary - descending tractsTract Site of origin Funiculus Termination Function

Medial longitudinal fasciculus

Vestibular nuclei

Anterior Laminae (Ⅶ~Ⅷ）Anterior horn cell

Coordinate of head and eye movement

Tectospinal Superior colliculus

Anterior Laminae（Ⅵ~Ⅷ） Reflex head turning

Fasciculus proprius

Spinal cord Anterior, lateral & posterior

Spinal cord Intrinsic reflex mechanism of spinal cord

Main functions of spinal cord Conduction of excitations

bridge; brain - periphery Sensory impulse to brainMotor impulse to periphery

ReflexSomatic reflex (skeletal m contration)superficial and deep reflexTendon (stretch reflex ) arcFlexor reflexAbdominal reflexVisceral reflex (sm,cardiac m,gland)Defecation reflexCarotid reflex



Spinal cord transverse section lesionComplete spinal cord transection results in the immediate Loss of all neural function below the level of the lesion.thereis a complete lose below the level of the lesion of :

All somatic sensationAll motor functionAll visceral sensationAll reflex activityAll muscle tone,etc

Spinal shock: last for 1~6 weeks



sensation

motor

Right:deep sensation,limb paralysisLeft :superficial sensation disfunction

Hemisection of the spinal cord (brown-sequard syndrome)

Injured main sensory fasiculus：

1-Fasciculus gracilis

2-Fasciculus cuneatus

3-Spinothalamic tract

12

3

3

Injured motor fasiculus：

4 - Lat.corticospinal tract

5 - Ant.corticospinal tract

4

5



Hemisection of the spinal cord

Brown-sequard syndromeResult in:The ipsilateral motor neuron paralysis below the level of lesion

Resulted from damage to the ipsilateral corticospinal tract.Loss of the ipsilateral deep sensation (proprioceptive,vibratroy

and two–point discrimination sense)below the level of lesion .resulted from damage to the fasciculus gracilis and fasciculuscuneatus.Loss of the contralateral superficial sensation (pain & thermal

Sense)below the level of lesion. resulted from damage to thelateral spinothalamic tract.



Lesion of anterior horn of the spinal cord

It causes ipsilateral lower motor neuron paralysis in the segments of the lesion (resulting from damage to lower motor neurons)such as infantile paralysis (Poliomyelitis).

Motor neuron

Usually it is caused by poliomyelitis virus



Meningocele cleft spine

Meningocele



FIGURE 3.1.3At upper thoracic and all cervical levels the dorsal funiculus is further subdivided, as shown here This view also shows the named sulci, fissures and septi, as well as the course taken by entering and departing axons.



answer 9 1 -intermediolateral cell column2 - dorsal funiculus3 - lateral funiculus4 - ventral funiculus



FIGURE 3.1.4Most of the structures labeled on these slides are ones you have identified in earier views of this module. Try to reconcile the appearance of the structure here with that in views of the brain's surface. All the sections, except the 3 spinal cord ones, are clickable. Clicking on one leads you to enlarged view of the section.



Hardworking

Harvest

The end!

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