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Transcript
Gross Brain and Spinal Cord
BLOCK 3 – 2011-12
Robert R. Terreberry, PhD
Room 142 Ph 864.327.9827
[email protected]
Layers of Scalp
Scalp
B
O
N
E
Skin
Connective Tissue
Aponeurosis
Loose CT
Pericranium
Scalp
• A. Extends from the superior nuchal line posteriorly to the
supraorbital margins anteriorly
• B. Laterally the scalp extends into the infratemporal fossae
to the level of the zygomatic arches
• C. Classically defined as having five (5) layers
–
–
–
–
–
1.
2.
3.
4.
5.
Skin
Connective tissue
Aponeurosis epicranialis
Loose connective tissue
Pericranium (periosteum)
• D.
Scalp cont…
Skin
– 1.
– 2.
– 3.
• E.
Thin, especially in elderly persons
Contains many sweat and sebaceous glands and hair follicles
Abundant arterial supply, good venous and lymphatic drainage
Connective tissue (Dense)
– 1.
Thick, dense subcutaneous layer of connective tissue is richly
vascularized and well innervated
– 2.
Collagen and elastic fibers criss-cross in all directions attaching to
the epicranial aponeurosis
– 3.
Fat is enclosed in lobules between connective tissue fibers
• a.
Amount of subcutaneous fat in scalp is relatively constant, varying little in
emaciation or obesity
– Does decrease with advancing age
Scalp cont…
• F.
Aponeurosis epicranialis (epicranial aponeurosis)
– 1.
Strong membranous sheet that covers the superior
aspect of the calvaria
• a.
Term galea aponeurotica is sometimes used to indicate its
helmet-like nature
• b.
Continuous laterally with the temporal fascia overlying the
temporalis muscle
– 2.
Serves as the membranous tendon of the fleshy
bellies of the epicranius muscle
– 3.
Epicranius muscle
• a.
• b.
Two (2) occipital bellies (occipitalis muscle)
Two (2) frontal bellies (frontalis muscle)
Frontalis
Muscle
Epicranial
Aponeurosis
Frontalis muscle
Occipitalis Muscle
Epicranial Aponeurosis
Occipitalis muscle
Scalp cont…
• G. Loose connective tissue
– 1.
• a.
Consists of loose, areolar connective tissue
Allows for free movement of the superficial 3 layers
– 2.
Due to loose connective tissue, this layer has
numerous potential spaces capable of allowing fluid to
accumulate
• H. Pericranium (periosteum)
– 1.
Dense layer of connective tissue firmly attached
to the bones of the calvaria via Sharpey’s fibers
Innervation of Scalp and Face
Blood Supply of Scalp & Face
Skull Views
• Superior – Norma verticalis
• Inferior – Norma basalis
• Posterior – Norma occipitalis
• Anterior – Norma frontalis
• Lateral – Norma lateralis
Calvaria
•
•
Calvaria
1.
Consists of flat bones of the skull
– a.Frontal
– b.Parietal
– c. Occipital
•
2.
Each flat bone has an outer (external) table and an inner (internal)
table of compact bone
– a.Between the two tables is cancellous (spongy) bone termed the diploë
•
•
•
3.
Outer table is usually thicker and tough
4.
Inner table is thinner, denser and more brittle
5.
Removal of calvaria allows one to examine the internal aspects of the
skull including the cranial fossae
Norma Verticalis
•
•
•
•
•
•
•
•
Frontal bone
Parietal bone
Occipital bone
Coronal suture
Sagittal suture
Bregma
Lambda
Parietal foramen
Inner Calvaria
•
•
•
•
•
•
Frontal bone
Parietal bone
Coronal suture
Sagittal suture
Frontal sinus
Groove for superior
sagittal sinus
• Groove for middle
meningeal artery
• Granular foveolae
Cranial Fossae
Anterior
Middle
Posterior
Anterior Cranial Fossa
• Orbital plate of frontal bone
• Cribriform plate of ethmoid
bone
• Lesser wing of sphenoid
bone
• Body of sphenoid
Anterior Cranial Fossa
•
•
•
•
•
Crista galli of ethmoid bone
Frontal sinus
Anterior clinoid process
Optic groove
Optic canal
Middle Cranial Fossa
• Lesser wing of sphenoid
bone
• Anterior clinoid process
• Chiasmatic sulcus
• Petrous temporal
• Dorsum sellae of
sphenoid bone
Middle Cranial Fossa
• Squamous temporal
bone
• Parietal bone
• Greater wing of
sphenoid bone
Middle Cranial Fossa
• Sella turcica (TS +
HF+ DS)
•Tuberculum sellae
•Hypophysial fossa
•Dorsum sellae
Middle Cranial Fossa
• Foramen ovale
• Foramen spinosum
• Foramen lacerum
Middle Cranial Fossa
• Carotid groove
• Hiatus for greater
petrosal nerve
• Hiatus for lesser
petrosal nerve
Posterior Cranial Fossa
• Basioccipital portion of
occipital bone
• Petrous temporal
• Internal occipital crest
• Internal occipital
protruberance
Posterior Cranial Fossa
• Foramen magnum
• Jugular foramen
• Internal acoustic
meatus
• Hypoglossal canal
Meninges
• Dura mater
Pachymeninx
Outer
• Arachnoid
Middle
• Pia Mater
Inner
Leptomeninges
Meninges
Cranial Dura Mater
Spinal Dura Mater
Spinal Dura
Subdural Space
Dura Mater
Epidural Space
• Loose CT
• Fat
• Epidural venous plexus
Spinal Dura
• Ends at S2 vertebral level
• Filum terminale externum  S2
Terminal end
Cranial Dura
Cranial Dura
Meningeal layer
Endosteal layer
Fused Cranial Dura
Cranial Dura
• Endosteal layer
• Thick bundles of collagen
• Cell rich
• Numerous blood vessels
• Meningeal layer
• Thinner than endosteal layer
• Inner layer smooth with squamous mesothelium
• Inner layer forms sheet-like extensions
Cranial Dura – Blood Supply
• Anterior meningeal as.
• Off ethmoidal as.
• Middle meningeal a.
• Off maxillary artery
• Largest meningeal artery
• Posterior meningeal brs.
• Off vertebral /occipital as.
Cranial Dura - Innervation
Spinal Arachnoid
Pia mater
Arachnoid
Dura mater
Spinal Arachnoid
• Ends at S2 vertebral level
• Filum terminale externum  S2
Terminal end
Cranial Arachnoid
• Similar to spinal arachnoid structurally
• Does not extend into sulci or fissures
• Enlargements of subarachnoid space
are termed cisterns
Spinal Pia
Pia mater
Arachnoid
Dura mater
Spinal Pia
Conus Medullaris
• Ends at L1/L2 vertebral level
• Filum terminale internum
 conus medullaris
Filum Terminale Internum
Pia Mater
• Tightly adherent to surfaces of CNS
• Follows sulci and fissures
• Highly avascular
• Spinal pia mater is firmer and less
vascular than cranial pia mater
Cranial Pia Mater
• Invaginates to form tela choroidea
• 3rd ventricle
• 4th ventricle
• Forms choroid plexuses
• 3rd ventricle
• 4th ventricle
• Lateral ventricles
Dural Folds (Reflections)
• The inner (meningeal) layer of cranial dura mater
is folded inwards as four (4) septa that partially
divide the cranial cavity into freely communicating
spaces
–
–
–
–
1. Falx cerebri
2. Falx cerebelli
3. Tentorium cerebelli
4. Diaphragma sella
Falx Cerebri
•
•
•
•
•
•
•
•
•
1.
Strong, crescent-shaped vertical sheet of dura located in the
interhemispheric (longitudinal) fissure between the cerebral hemispheres
2.
Attached anteriorly to the crista galli of the ethmoid bone
3.
Attached posteriorly to the tentorium cerebelli where it blends in the midline
of the tentorium
4.
Convex upper margin is attached to the internal cranial surface on each side
of the median plane as far back as the internal occipital protuberance
5.
Narrower anteriorly, broader posteriorly
a.
Anterior part is thin and may be fenestrated
6.
Superior sagittal sinus runs along upper margin
7.
Inferior margin is free and concave and contains the inferior sagittal sinus
8.
The straight sinus is located along the point of attachment between the falx
cerebri and tentorium cerebelli
Falx cerebelli
• 1. Small, crescent-shaped fold in the midline of
the posterior cranial fossa
• 2. Attached to posterior part of the internal
occipital crest of the occipital bone
• 3. Partially separates the lateral hemispheres of
the cerebellum
• 4. Occipital sinus is located in margin attached
along the internal occipital crest
Tentorium cerebelli
•
1.
Crescent-shaped fold of dura located between the occipital lobes and the
cerebellum
– a.Midline attachment of falx cerebri to superior aspect of tentorium draws the tentorium
upwards
•
•
2.
Concave anterior edge is free and between it and the dorsum sellae of the
sphenoid bone is the tentorial incisure (notch) that allows the midbrain to pass
superiorly
3.
Posteriorly it is attached to the petrous portions of the temporal bones and
the margins of the sulcus for the transverse sinuses in the occipital bone
– a.Transverse sinuses course along this posterior margin of the tentorium
•
4.
Tentorium cerebelli defines supratentorial and infratentorial compartments of
the cranial cavity
– a.Infratentorial compartment is commonly referred to as the posterior cranial fossa
Diaphragma sella
• 1. Roofs over the sella turcica of sphenoid
bone
• 2. Small, circular layer of dura with a
small central opening that transmits the
infundibular stalk of the pituitary gland
Cranial Dural Folds
Falx Cerebri
Falx Cerebelli
Cranial Dural Folds
Falx Cerebri
Tentorium
Cerebelli
Cranial Dural Folds
Falx Cerebri
Tentorium Cerebelli
Cranial Dural Folds
Cranial Dural Folds
Falx Cerebri
Falx Cerebelli
Cranial Dural Folds
Hypophysis
Diaphragma
Sella
Sphenoid
Sinus
Pons
Spinal Cord
8 Cervical
12 Thoracic
5 Lumbar
5 Sacral
1 Coccygeal
Spinal Cord
Dorsolateral Sulcus
Dorsointermediate Sulcus
Dorsal Median Sulcus
(Dorsal, in situ)
Cervical Segment C8
Dorsal Median Sulcus Dorsointermediate
Sulcus
Dorsolateral Sulcus
Ventrolateral Sulcus
Ventral Median Fissure
Thoracic Segment T10
Dorsal Median Sulcus
Dorsolateral Sulcus
Ventrolateral Sulcus
Ventral Median Fissure
Thoracic (T10)
Dorsal Horn
Lateral
Horn
Ventral Horn
Thoracic Gray Matter (T10)
Lissauer’s Tract
Substantia Gelatinosa
Nucleus Proprius
IML
VH
Clarke’s Nucleus
Ventral (anterior) Horn
Rexed's laminae
• In 1952, Bror Rexed, a Swedish neuroanatomist, devised a system for
subdividing the spinal gray matter into layers or laminae, based upon
differences in cytoarchitecture
• Scheme was initially developed for animal models, but is widely used in
discussions of the human spinal cord
• Ten different laminae described for the human spinal cord
Laminae I-VI
=
dorsal horn
Lamina VII
=
intermediate gray matter
Laminae VIII & IX
=
ventral horn
(VIII = interneurons)
(IX = alpha () motorneurons)
Lamina X
=
midline area of gray matter around the central canal
White Matter
White matter is made up primarily of neuronal axons,
some of which are directed rostrally from neuronal cell
bodies in the spinal cord gray matter or the dorsal root
ganglia (DRG), while others have descended into the spinal
cord from cell bodies in the cerebral cortex or brainstem
nuclei
Funiculus
• Funiculus - composite bundles of tracts
– Dorsal (posterior) funiculus or the “dorsal columns”
• Between the dorsal root entry zone (dorsolateral sulcus) and
dorsomedian sulcus
• Composed of ascending tracts
– Lateral funiculus
• Between the dorsolateral and ventrolateral sulci
• Composed of both ascending and descending tracts
– Ventral (anterior) funiculus
• Between the ventrolateral sulcus and ventromedian fissure
• Composed of both ascending and descending tracts
Cervical Enlargement (C8)
DREZ
FC
LCST
FG
STT
Thoracic (T10)
DREZ
FG
LCST
STT
The 9
main
pathways
of the
spinal cord
Medulla
Ventral
Medulla
Olive
Pyramid
Ventral Median Fissure
Pyramidal Decussation
Ventral
Medulla
Post-olivary
Sulcus
Pre-olivary Sulcus
Pyramid
Lateral
Olive
Medulla
CN IX
CN X
CN XI
Ventral CN XII
Medulla
CN IX
CN X
CN XI
CN XII
Olive
Ventrolateral
Medulla
Rhomboid
Fossa of 4th
Ventricle
Obex
Gracile Tubercle
Dorsal
Cuneate Tubercle
Pons
Ventral
Pons
Basilar Pons
Basilar Sulcus
Ventral
Pons
CN V
CN VI
CN VII
CN VIII
Ventral
Pons
CN VII
CN V
CN VIII
Ventrolateral
CN VI
Pons
CN V
Lateral
Middle Cerebellar Peduncle
Pons
Facial Colliculus
Dorsal
Rhomboid
Fossa of 4th
Ventricle
Midbrain
Ventral
Midbrain
Interpeduncular Fossa
CN III
Crus Cerebri
Ventral
Midbrain
CN III
Interpeduncular
Fossa
Ventral
Crus Cerebri
Midbrain
Superior Colliculus
Inferior Colliculus
CN III
Crus Cerebri
Lateral
Midbrain
Superior Colliculus
Inferior Colliculus
CN IV
Dorsal
Midbrain
Superior
Brachium
Sup. Coll.
Inf. Coll.
Dorsal
Inferior
Brachium
CN IV
Cerebellum
Midbrain
Pons
4th Vent
Medulla
Mid-sagittal
Cerebellum
Posterosuperior
Cerebellar
Peduncles
Midbrain
SCP
Pons
MCP
Medulla
ICP
Cerebellar
Peduncles
SCP
MCP
Ventral
ICP
Cerebellum
Anterior Lobe
Posterior Lobe
Posterosuperior
PF
Cerebellum
Primary Fissure
Anterior
Lobe
Flocculonodular
Lobe
Posterior
Lobe
Posterolateral
Fissure
Mid-Sagittal
Cerebellum
Anterior Lobe
Posterior Lobe
Anterior Lobe Flocculonodular
Lobe
Posterior Lobe
Cerebellum
Vermis
Paravermis
Lateral
Hemisphere
Cerebellar Cortex
Granular layer
Deep Cerebellar Nuclei
Fastigial nucleus
Globose nucleus
Emboliform nucleus
Dentate nucleus
FGED
Diencephalon
Interventricular Foramen
Lamina
Terminalis
Mid-sagittal
Posterior Commissure
3rd Ventricle
Diencephalon
Thalamus
MI
Hypothalamus
Mid-sagittal
Pineal Gland
Diencephalon
Tuber Cinereum Mamillary Body
Optic Chiasm
Infundibulum
Mid-sagittal
Diencephalon
Optic Nerve
Optic Chiasm
Median Eminence
Optic Tract
Ventral
Mamillary Body
Cerebral Hemispheres
Interhemispheric
Fissure
Gyri
Dorsal
Sulci
Brodmann’s Areas
Select Cortical Areas
Functional Designation
Brodmann’s
Anatomical Name
Primary Motor Cortex
Area 4
Precentral Gyrus
Premotor Cortex
Area 6 (lateral)
Sup/Mid Frontal Gyri
Frontal Eye Fields
Area 8
Middle Frontal Gyrus
Supplementary Motor Area
Area 6 (medial)
Sup. Frontal Gyrus
Broca’s Area
Areas 44 & 45
Inf. Frontal Gyrus
Primary Somatosensory Cx
Area 3,1,2
Postcentral Gyrus
Unimodal SS Assoc. Cx
Areas 5 & 7
Sup. Parietal Lobule
Multimodal SS Assoc. Cx
Areas 5 & 7
Sup. Parietal Lobule
Primary Visual Cortex
Area 17
Banks Calcarine Sul.
Primary Auditory Cortex
Areas 41 & 42
Transverse Temp. G.
Wernicke’s Area
Area 22
Surrounds 41 & 42
Cerebral Hemispheres
Parietal
Lobe
Occipital
Lobe
Temporal
Lobe
Lateral – Right Hemisphere
Frontal
Lobe
Centrum Semiovale
Horizontal cut
Internal Capsule
Internal Capsule
Corona Radiata
Putamen
Internal Capsule
Anterior Limb
Genu
Horizontal cut
Posterior Limb
Corpus Callosum
B
G
R
S
Deep Gray Matter
• There are large masses of gray matter
(nuclei or nuclear complexes) located
deep within each cerebral hemisphere
– Diencephalon
– Basal ganglia
– Amygdaloid complex
Deep Gray matter cont…
• Diencephalon
– Thalamus and hypothalamus are located at the center of the
cerebrum
• Basal ganglia
– Set of nuclei (gray matter) located deep within each hemisphere
• Caudate nucleus
• Putamen
• Globus pallidus
• Amygdaloid complex (amygdala)
– Nuclear complex deep to cortex of the uncus
– Anterior to hippocampal formation
– Part of the limbic system
Diencephalon
Anterior Commissure
Lamina
Terminalis
Mid-sagittal
Posterior Commissure
3rd Ventricle
Basal Ganglia
Caudate
Putamen
Globus Pallidus
Thalamus
Horizontal cut
Ventricular System
Ependymal Cells
• Ciliated, cuboidal
epithelium
• Lines ventricles of
CNS
• Discontinuous
basal lamina
allows for
movement of
material between
CSF and brain
rather easily
Ventricular System
Lateral Ventricle
Third Ventricle
Cerebral Aqueduct
Fourth Ventricle
Cerebral Blood Flow
• Central nervous system
•
•
•
•
2% of body by weight
15% of all cardiac output
20% of all O2 consumed
Total brain blood volume every 5-7/min
• Loss of consciousness after 10 sec
• Necrosis after 4-5 min of hypoxia
Cerebral Blood Flow
• Arterial supply to brain and much of spinal
cord derived from 2 sets of arteries
• Internal carotid arteries
• Anterior circulation - 80% of blood supply
• Vertebral arteries
• Posterior circulation - 20% of blood supply
• Linear extent of capillaries/Unit volume
• Gray matter > White matter
• Sensory, interneurons > Motor
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