Download Skull and Spinal Cord Laboratory

Skull and Spinal Cord Laboratory
OBJECTIVES
1. To review the bony environment of the brain to appreciate the relationships of the brain to the
bony cranium and the foramina thru which cranial nerves exit (or enter), and to appreciate the
compartments inside the cranium created by the tentorium cerebelli and falx cerebri:
supratentorial (containing cerebrum) and infratentorial (posterior fossa), providing certain
natural routes for expanding tumors within these compartments.
2. To identify all of the cranial foramina that transmit cranial nerves, the ridges and protuberances
where meninges attach, the cranial fossae and the lobes of the brain contained therein, and the
impressions in the skull left by the various dural sinuses.
The student is encouraged to review the skull and to see the actual spinal cord for orientation before
moving on to the two-dimensional images of Chapter 3 “Skull, Meninges, and Spinal Cord” of the
Digital Neuroanatomy PPT’s. Then the student can use the quiz mode of the same chapter of
Digital Neuroanatomy Interactive CBI Program for self-test.
DVD #1 contains a video on “Spinal Cord, Meninges, and Spinal Cord” for independent study in
which most of the structures on the laboratory list are demonstrated.
I.
ANTERIOR CRANIAL FOSSA: above orbital plate of frontal bone, contains frontal lobe
of the brain
Crista galli- bony attachment of the falx cerebri
Cribriform plate of ethmoid bone (exit of fibers of olfactory nerve, C.N. I)
II.
MIDDLE CRANIAL FOSSA: depression for temporal lobes
Superior orbital fissure (exit of C.N. III, IV, ophthalmic V, and VI into orbit)
Foramen rotundum (exit of C.N. maxillary V)
Foramen ovale (exit of C.N. mandibular V)
Foramen spinosum (middle meningeal artery supplying dura but coursing between dura and
bone; note its impression on the lateral wall of the skull)
Sphenoid bone greater and lesser wings, sella turcica (pituitary fossa), anterior clinoid
processes (attachment of tentorium cerebelli)
Optic foramen (exit of C.N. II)
Cavernous sinus identify depression on sides of body of sphenoid bone, just lateral to sella
turcica; review its contents (C.N. III, IV, VI, Ophthalmic. & Maxillary V, internal
carotid artery)
Temporal bone petrous portion (housing semicircular canals, cochlear duct, etc.), petrous
ridge (attachment of tentorium cerebelli, containing superior petrosal sinus)
Internal carotid foramen internal carotid artery enters cranial vault through cavernous
sinus, carotid canal horizontal canal between external and internal carotid foramina
through which internal carotid artery runs to enter the middle cranial fossa thru the
internal carotid foramen
III.
POSTERIOR CRANIAL FOSSA: infratentorial compartment (depression below
tentorium cerebelli for cerebellum and brainstem (midbrain , pons, medulla).
Note: the brainstem (midbrain) connects to the cerebrum thru a large opening in the
tentorium cerebelli (tentorial notch or incisure)
Internal auditory meatus (exit of C.N. VII and VIII)
Jugular foramen (exit of C.N. IX, X, and XI and internal jugular vein)
Transverse sinus in attached margin of tentorium cerebelli
Sigmoid sinus continues inferiorly from transverse sinus, below tentorium, empties into
internal jugular vein (jugular foramen; origin of internal jugular vein)
Confluence of sinuses: confluence of occipital, transverse, and superior sagittal sinuses
Foramen magnum, spinal cord and vertebral arteries
Hypoglossal foramen (exit of C.N. XII)
* Link to Netter Image 1.17
* Link to Netter Image 1.18
IV.
SPINAL CORD
Dura mater, dural sac- extends to vertebral level S2; its inferior portion contains the lumbar
cistern of the subarachnoid space with the cauda equina
Arachnoid membrane- transparent; in fixed spinal cord it has shrunk over the surface of the
cord, but in normal circumstances it would be pushed against the inside of the dura (lines
the dural sac) by CSF pressure in the subarachnoid space
Dorsal median sulcus
Dorsal intermediate sulcus- above spinal level T6, it divides dorsal funiculus into two tracts
Dorsolateral sulcus- exit of dorsal roots
Dorsal roots- sensory roots entering spinal cord
See interlacing (anastomosing) branches of the posterior spinal arteries across the dorsal
cord
Ventrolateral sulcus- exit of ventral roots
Ventral roots- motor roots leaving spinal cord
Spinal nerves
Dorsal root ganglia- in outpocketings of dural sac; on dorsal root where dorsal & ventral
roots merge to form the spinal nerve; in situ this is located right at the intervertebral
foramen
Ventral median fissure- deepest fissure, it contains the ventral (anterior) spinal artery
Conus medullaris- tapering lower part of the cord; contains sacral and coccygeal spinal cord
segments; this ends at vertebral level L2
Cauda equina- rootlets of dorsal and ventral roots from lower segments of the cord,
descending to their intervertebral foramen of exit
Pia mater- on surface of the cord; spinal cord blood vessels run in its loose upper surface
(epi-pia)
Denticulate ligament- about 20 pairs of these tooth-shaped attachments; a tiny filament
coming off its tip attaches pia to the dura; covered by arachnoid; alternate between exits
of spinal nerves; they anchor the cord laterally
Filum terminale- extension of the pia below the conus medullaris; it extends to the bottom of
the dural sac (S2) where it becomes surrounded with dura to form the coccygeal
ligament which attaches to the coccyx, anchoring the cord inferiorly
Identify features that distinguish: cervical, thoracic, lumbar and sacral levels of spinal cord
Cervical enlargement
Lumbar enlargement
White and gray matter
* Link to Netter Image 1.37
* Link to Netter Image 1.38A
* Link to Netter Image 1.38B
* Link to Netter Image 1.39A
* Link to Netter Image 1.39B