CNS: Spinal Cord & Spinal Nerves
Gross Anatomy of External Spinal Cord
​
​
​Denticulate ligaments (dentate ligaments):
anchor the spinal cord to the dura mater.
base of triangle shaped ligament attached at the
pia mater and attached to the arachnoid/dura mater
at the apex.
​
​Conus medullaris (conus terminalis):
lower end of the spinal cord near L1/L2
​
Cauda equina (horse tail):
bundle of spinal nerves:
2nd - 5th lumbar nerve pairs
1st - 5th sacral nerve pairs
coccygeal nerve
​
Filum terminale (terminal thread):
20cm string of fibrous tissue extending from the apex
of the conus medullaris
​
​Sympathetic chain ganglia (paravertebral ganglia):
extend from both sides of cord at ventral and lateral positions from neck to coccyx
(ganglion = a structure containing nerve cell bodies often seen as an enlarged area on a nerve)
​
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​
​
​Cross- Sectional Anatomy of a Spinal Segment
Meninges
​ dura mater, arachnoid mater, pia mater
​ these three membranes line the skull and
vertebral canal and cover the brain and
​ spinal cord.
​
​Epidural space
​
​Subarachnoid space
​Anterior median fissure
Posterior median sulcus
Central canal (w.CFS)
Gray commissure (X)
​
​
​
​Dorsal root
Dorsal nerve roots carry
sensory info via afferent
fibers to the
CNS from the PNS.
​
Dorsal root ganglion
A ganglion is a cluster
nerve cell bodies found
outside the CNS. Dorsal
root ganglia are found on
the dorsal/posterior root
of nerves entering the spinal
cord. Dorsal root ganglia
transmit sensory info receptors
to the CNS.
Ventral root
​ Ventral roots carry info
from the CNS via efferent
fibers to a muscle/gland
etc to initiate a response.
Spinal nerves
The ventral root joins
with the dorsal root
outside the vertebral column
to form a spinal nerve.
​
Grey matter vs White matter:
grey matter contains many cell bodies but few myelinated axons,
white matter contains few cell bodies but myelinated axons
the color difference is due to the white myelin)
​​White matter columns:
White matter is subdivided
into dorsal/posterior,
lateral and
​ ventral/anterior columns.
Each type of column contains
axons with specific functions.
Ascending tracts of column fibers
carry sensory information up to the brain.
Descending tracts carry motor
info/instructions down from the brain.
​
​
​
​Gray matter horns:
Gray matter forms three
pairs of horns:
Dorsal/posterior horns
have neurons that receive
sensory information from the body
which is relayed via ascending
pathways, to the brain.
Ventral/anterior horns have
motor neurons that leave
the spinal cord to control skeletal muscle.
Intermediate columns and lateral horns
also contains neurons that control visceral organs.​
Week 2:
Spinal Nerve Plexuses & Peripheral Nerves:
​ When adjacent spinal nerves combine their nerve fibers,
a Nerve Plexus (braid) is produced.
(reference pages 446 + in our text)
*for each nerve, identify and learn the tissue that nerve innervates
​
​
​1. Cervical Plexus: (nerves C1-C5)
​(ears, neck, back of head, shoulders and diaphragm)
lesser occipital nerve
great auricular nerve
transverse cervical nerve
supraclavicular nerve
phrenic nerve ​
​
​
​2. Brachial Plexus: (nerves C5-T1)
(controls muscles of the shoulder, elbow, wrist and hand)
Musculocutaneous nerve
​ Axillary nerve
Radial nerve
Median nerve
Ulnar nerve
​
​
3. Lumbar Plexus: (nerves L1-L4)
Femoral nerve
Obturator nerve
Iliohypogastric nerve
Ilioinguinal nerve
Genitofemoral
Lateral femoral cutaneous nerve
​
​4. Sacral Plexus (nerves L4-S4)
Sciatic nerve (w/fibular and tibial branches)
Inferior Gluteal nerve
​ Superior Gluteal nerve
Pudendal nerve
Posterior Femoral Cutaneous nerve
​
​5. Thoracic Nerves T2-T12
Spinal nerves arising from the thoracic vertebrae do not form a plexus
for nerves T2-T12...
each nerve runs along one rib to innervate the rib, skin and muscle in that thoracic area.
​ ​​ Week 3:
Brain Anatomy & Cranial Nerves
Major Regions of the Brain:
Cerebrum
Diencephalon
Cerebellum
Pons
Medulla
​
​The cerebrum has a right and left hemisphere joined by the corpus callosum.
Functions: initiate/coordinate movement, vision, hearing, touch, judgment and
reasoning along with problem solving, emotions, and learning.
The brainstem includes the pons, midbrain, and the medulla.
Functions: movement of eyes/mouth, sensory relay of heat/pain, respiration, consciousness, cardiac function, involuntary muscle movements, sneezing, coughing, vomiting/swallowing.
The pons controls eye/face movements.
The medulla is the control center for the heart/lungs.
The cerebellum's functions include:
coordinating voluntary muscle movements/maintaining posture, balance, and equilibrium.
External features of the Cerebrum:
​​Cerebral cortex (= crinkled surface of grey matter)
Longitudinal fissures
Cerebral hemispheres
Cerebral lobes: frontal, parietal, temporal, occipital
Gyrus (gyri) & sulcus (sulci)
(= ridges & grooves on cerebral cortex)
Central sulcus
Primary sensory cortex (= post-central gyrus)
Primary motor cortex (= pre-central gyrus)
(see Sagittal and Inferior Views)
​​
sagittal and inferior views:
​Corpus callosum
Fornix
Lateral ventricles
​ (fluid-filled chamber
​ enclosed within each hemisphere)
Choroid plexus
Thalamus
Hypothalamus
Pineal gland
Pituitary gland
Infundibulum
(attaches pituitary gland
to hypothalamus)
Optic chiasm
Olfactory bulbs
Optic tracts (nerves)
Optic nerve
Mammillary body
​​
​Brain Stem (identify in both sagittal and external views)
Pons
Medulla oblongata
Corpora quadrigemina:
superior colliculi & inferior colliculi
Cerebral peduncles
​​​Cerebellum
Arbor vitae...white matter
Cortex...grey matter
3 Layers of cranial meninges:
​Dura mater, Arachnoid mater, Pia mater
Subarachnoid space
Superior sagittal sinus
(a vein that drains blood from brain)
​Ventricles:
Lateral ventricle
Third ventricle
Fourth ventricle
Cerebral aqueduct
​ (connects 3rd & 4th ventricle)
​
​Cranial Nerves (12): know names & #(roman numeral) of each cranial nerve
# Name of Nerve Fiber Type Major Function(s)
(sensory/motor/mixed)
_____________________________________________________________________
I
_____________________________________________________________________
II
_____________________________________________________________________
III
_____________________________________________________________________
IV
_____________________________________________________________________
V
_____________________________________________________________________
VI
_____________________________________________________________________
VII
_____________________________________________________________________
VIII
_____________________________________________________________________X
_____________________________________________________________________
X
_____________________________________________________________________
XI
_____________________________________________________________________
XII
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Welcome to Dr. Kate Brilakis' Learning Portal
The Nervous System
CNS and PNS