CHAPTER 3:  MACROSCOPIC BASIS OF NEUROANATOMY  (Spinal Nerves, Spinal Cord, Medulla)

 

 

Spinal Nerve

 

1. Formation
1. Receptors

a.1.  Exteroceptor

a.2.  Proprioceptor

a.3.  Interoceptor

a.4.  Encapsulated

a.5.  Unencapsulated / Free

* Samples of Cutaneous Receptors:

1)  Pacinian Corpuscles – pressure sensation; located deep in the skin

2)  Meissner’s Corpuscles – touch sensation on glabrous skin (hairless skin)

3)  Krause’s Corpuscles – cold sensation

4)  Rufini’s Endings – warm sensation

5)  Merkel’s Disc – touch sensation on glabrous skin (hairless skin)

6)  Peritrichial Endings – touch sensation on skin with hair; located @ base of hair follicles

2. Spinal Nerve

b.1.  Dermatome

b.2.  Myotome

3. Dorsal Root
4. Dorsal Root Ganglion
5. Ventral Root
6. Sensory Neuron
7. Motor Neuron
8. Unipolar Neuron
9. Central and Peripheral Process
1. Reflex Arc or Sensory-Motor Arc
1. Connector neurons
2. Ramus
1. Dorsal Ramus
2. Ventral Ramus

 

Spinal Cord

 

1. External Consideration
1. Ventral View

·        Foramen Magnum

·        Ventral Median Fissure

·        Ventrolateral Sulcus

·        Conus Medullaris

·        Filum Terminale

·        Cervical Enlargement

·        Lumbar Enlargement

·        Spinal/Vertebral Column

2. Dorsal View

·        Dorsal Median Sulcus

·        Intermediate Sulcus

·        Dorsolateral Sulcus

·        Fasciculus Gracilis

·        Fasciculus Cuneatus

·        Descending Spinal Nerves

·        Cauda Equina

·        Intervertebral Foramen

2. Internal Consideration
1. Gray Matter

a.1.  Parasympathetic Division

·        Posterior Gray Commissure

·        Anterior Gray Commissure

*  Commissure Areas:  Commissural/Contralateral Fibers & Association/Ipsilateral Fibers

·        Substancia Gelatinosa

·        Nucleus Dorsalis of Clarke (Dorsal Nucleus of Clarke)

·        Lateral Motor Nuclei

·        Medial Motor Nuclei

a.2.  Sympathetic Division

·        Intermediolateral Horn

·        Intermediolateral Nucleus (Nucleus Intermediolateralis)

·        Sympathetic / Autonomic Ganglia

·        Sympathetic Pre-Ganglionic Visceral Efferent Fiber

·        Sympathetic Post-Ganglionic Visceral Efferent Fiber

2. White Matter

Nerve Fiber  à  Fasciculus à  Funiculus

Fiber Tracts = bundle of fibers with the same origin, same termination, same function

*  Fasciculi within Funiculus:

1)  Ascending Fiber Tracts

·        Fasciculus Gracilis

·        Fasciculus Cuneatus

·        Lateral Spino-Thalamic Tract

·        Ventral Spino-Thalamic Tract

2)      Descending Fiber Tracts

·        Lateral Cortico-Spinal Tract

3)      Characteristic Features of Different Segments of the Spinal Cord

 

Medulla (Myelencephalon)

 

1. External Consideration
1. Ventral View

a.1.  Parts

·        Pyramids

·        Pyramidal decussation

·        Inferior olives

·        VMF

·        VLS

a.2.  Divisions

·        Level of pyramidal decussation

·        Level of sensory decussation

·        Level of inferior olives

a.3.  Cranial nerves associated with medulla

·        Glossopharyngeal

·        Vagus

·        Spinal accessory

·        Hypoglossal

2. Brain ventricles

·        I & II:  Cerebral hemisphere

·        III:  Diencephalon or Interbrain

·        IV:  Pons & Medulla

3. Dorsal View

·        Rhomboid Fossa

·        Stria Medullaris

·        Sulcus Limitans

·        Cuneate Tubercle

·        Gracilis Tubercle

·        DMS, IMS, DLS

·        3 Triangles formed by bifurcation along Rhomboid Fossa (contains respective CN):

o       Trigonum Hypoglossi (Hypoglossal Triangle)

o       Areah Vestibularis

o       Trigonum Vagi (Vagal Triangle)

·        Cerebellar Peduncles:

o       Inferior Cerebellar Peduncles (Restiform Body)

o       Middle Cerebellar Peduncles (Brachium Pontis)

o       Superior Cerebellar Peduncles (Brachium Conjunctivum)

1. Internal Consideration
1. Level of Pyramidal Decussation

·        VMF, VLS; DMS, IMS, DLS

·        Central Canal

·        Central Gray

·        Reticular Formation

·        Spinal Nucleus of V (Descending Nucleus of V)

·        Spinal Tract of V (Descending Tract of V)

2. Level of Sensory Decussation

·        VMF, VLS; DMS, IMS, DLS

·        Central Canal

·        Central Gray

·        Reticular Formation

·        Spinal Nucleus and Tract of V

·        Pyramids

·        Nucleus Gracilis

·        Nucleus Cuneatus

·        Fasciculus Gracilis

·        Fasciculus Cuneatus

·        Internal Arcuate Fibers

·        Medial Lemniscus

3. Level of Inferior Olives

·        VMF, VLS

·        Spinal Nucleus and Tract of V

·        IV Ventricle

·        Trigonum Hypoglossi

·        Trigonum Vagi

·        Area Vestibularis

·        Hypoglossal Nucleus

·        Dorsal Nucleus of the Vagus

·        Medial Vestibular Nuclei

·        Inferior Vestibular Nuclei

·        Dorsal External Arcuate Fibers

·        Accessory Cuneate Nucleus

·        Vagus nerve

·        Ventral Nucleus of the Vagus

·        Medial Lemniscus

·        Pyramids

·        Hypoglossal nerve

·        Inferior Olivary Nucleus

·        Inferior Olives

·        Reticular Formation

·        Solitary Nucleus and Tract

·        Restiform Body