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)
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
_____________________________________________________________________
Welcome to Dr. Kate Brilakis' Learning Portal
The Nervous System
CNS and PNS