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Head and Neck Test 1


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5 layers of scalp
S skin
C connective tissue (dense)
A aponeurosis
L loose connective tissue
P pericranium
description of scalp layer 1
skin: hair bearing with sweat and sebaceous glands
clinical rep of scalp layer 1
common infections of skin: sebaceous cysts that move freely with the scalp and don't invade underlying subcutaneous tissue
description of scalp layer 2
dense CT: subcutaneous layer of dense connective tissue; consists chiefly of collagen bundles with fat interspersed in between
attachments in 2nd layer
collagen fibers criss cross and attach to skin above and aponeurotic layer below
what courses through 2nd layer of scalp?
arteries, veins, and nerves course through the dense CT
description of 3rd layer of scalp
aponeurotic layer: musculo-aponeurotic helmet
aponeurotic part covers the dome and 2 pairs of muscle bellies located ant and post.
epicranius of 3rd layer of scalp:
frontalis muscle and occipitalis muscle
location of epicranius
frontalis muscle: arises from aponeurotic part and attaches to skin and CT over eyebrows
occipitalis muscle: arises from superior nuchal line of occipital bone and mastoid part of temporal bone and inserts on the aponeurosis
nerve supply to epicranius
branches of CNVII
aponeurosis attaches to:
post to the occipital bone and laterally attached to the zygomatic arch
clinical rep of 3rd scalp layer
aponeurosis: scalp wound which splits the aponeurosis in coronal plane produces a GAPING wound since fibers are directed ant/post in sagittal plane
description of 4th scalp layer
loose CT: forms cleavage plan between first 3 layers and 5th layer. accounts for mobility of the scalp on the skull.
clinical rep of 4th layer of scalp
danger plane: loose CT allows pus or fluid to spread rapidly and extensively being only limited by the attachments of the overlying aponeurotic layer----infections result in inflammation of emissary veins resulting in thrombophlebitis of the dural venous sinuses
description of the 5th layer of the scalp
pericranium: periosteum covering the outer lamina of skull bones; adheres weakly over bone surfaces, but firmly fixed at sutures where it connects to inner periosteum
clinical rep of 5th layer of scalp
because of firm attachment at sutures, in skull fractures collections of blood have a tendancy to outline the affected bone
blood supply of scalp: what two sets of branches
indirect branches of ICA and direct branches of ECA
4 parts of ICA
1) cervical ICA
2) petrous ICA
3) sigmoid or intercavernous ICA
4) supraclinoid ICA
where is the cervical part of the ICA?
ascends the neck and gives off no branches in the neck; at base of skull cervical ICA enters the carotid canal in the petrous temporal bone.
where is the petrous part of the ICA?
when ICA enters carotid canal in the petrous temporal bone, it courses upward and then forward to the apex of the petrous temporal bone in the MCF.
where is the sigmoid/intercavernous part of the ICA?
the petrous ICA crosses the upper part fo the foramen lacerum (between petrous temporal bone and body of sphenoid) and enters cavernous sinus. this 3rd part has an S-shaped coarse within sinus, first ascending toward the posterior clinoid process and then turning fwd horizontally
where is the supraclinoid part of the ICA?
the supraclinoid ICA pierces the dura of the roof of the cavernous sinus medial to the ant clinoid process
branches of supraclinoid ICA
gives off terminal branches most of which supply the brain, but one branch, the ophthalmic artery enters the optic canal and courses to the orbit where it gives off numerous named branches, including the supratrochlear and supraorbital arteries
Indirect branches of ICA: flow---->
ICA ---> ophthalmic a. ---> supratrochlear a. and supraorbital a.
direct branches of the ECA:
numerous branches in the neck, 3 of which supply blood to the scalp: superficial temp a.
post. auricular a.
occipital a.
superficial temporal a.
direct branch of ECA; one of the two terminal branches of the ECA, supplies area in front of (ant) to the ear and superior to the ear (temple)
posterior auricular a.
direct branch of ECA:
area behind the ear
occipital a.
direct branch of ECA: posterior aspect of the scalp
clinical importance of blood supply to scalp:
richest cutaneous blood supply in the body.
possible to reattach lg areas of scalp that become detached b/c of frequent anastomosis between terminal branches of scalp arteries
clinical impt. of blood supply to scalp: rel to collagen
outer art walls of vessels attach to criss crossing collagen of 2nd layer so when lacerated, separated ends of arteries cannot retract to close, profuse bleeding occurs.....have to apply local pressure to compress severed ends.
clinical impt of blood supply to scalp, rel to bones of skull
art of scalp for most part do not supply bones of skull, so a scalp wound does not produce necrosis of the bony cranium
nerve supply of scalp: (2 parts)
CNV (3 div) and branches of cervical nerves (C2 and C3)
nerve supply of scalp: V1
V1: ophthalmic div: supratrochlear n. and supraorbital n.
nerve supply of scalp: V2
V2: maxillary div: zygomaticotemporal n. (temple)
nerve supply of scalp: V3
V3: mandibular div: auriculotemporal n.
nerve supply of scalp: branches of cervical nerves
a) lesser occipital n.: from cervical plexus, supplies skin behind and above the ear
b) great auricular n.
c) greater occipital n.: is dorsal ramus of C2---supplies post portion of the scalp (medial to occipital a.)
what does the skull consist of?
2 plates of compact bone: outer and inner laminae, with spongy bone in between (the diploe)
Meninges: top of 3 layers
dura mater: inelastic thick membrane, 2 layers not easily separated except sinuses
2 types of dura: outer
periosteal dura (also endosteal): outer rough texture; fuses with pericranium at sutures and skull foramina, and at FM
blood supply to dura
primary blood supply to dura is in periosteal layer: middle meningeal artery
laceration of MMA produces what?
epidural hematoma: rapidly expanding mass of blood accumulates between the periosteal dura and calvarium; may press on underlying primary motor area of brain
sequence of clinical signs of an epidural hematoma:
1) brief loss of consciousness
2) lucid interval of sev hrs
3) relapse into coma; contralateral motor paralysis of opp side of body
inner layer of dura
meningeal layer: inner, smoothe texture. sends 4 partitions inward which divide the cranial cavity into 3 freely communicating compartments
inner layer of dura is continuous with what
con't with dura covering spinal cord and forms tubular sheaths for CN
subdural space
potential space between meningeal dura and underlying arachnoid membrane
clinical rep of meningeal dura
cerebral veins traverse meningeal dura to enter the SSS, tearing of these veins produces a subdural hematoma
difference between subdural and epidural hematoma
subdural: low pressure venous leakage, bet meningeal dura and arachnoid, symptoms occur slowly
epidural hematoma: arterial high pressure leakage, fast acting, may press on underlying cortex
middle layer of meninges
arachnoid mater
avascular membrane, underlies the meningeal dura
covers gyri, but does not dip into the sucli
lower layer of meninges
pia mater: dips into sulci, can't be readily peeled
subarachnoid space SAS
between arach and pia mater
contains CSF, arteries and veins of brain and SC pass through
clinical rep of SAS
follows rupture of aneurysm of a cerebral vessel such as anterior, middle, or post cerebral arteries which traverse the SAS. MOST EXCRUCIATING HEADACHE OF MY LIFE
lumbar puncture shows blood in CSF
Dural partitions: 2 vertical and 2 horizontal
Vertical: falx cerebri, falx cerebelli
horizontal: tentorium cerebelli and diaphragma sellae
Falx cerebri
vertical partition of meningeal dura, occupies the logitudinal fissure; attaches ant to crista galli and crest of the frontal bone
inf border overlies the corpus callosum; posteriorly fuses with upper surface of the tentorium cerebelli
clinical note of falx cerebri
when increased intracranial pressure occurs, sharp edges of falx cerebri can result in damage to the cingulate gyrus, located dorsal to corpus callosum
falx cerebelli
meningeal dura sep 2 cerebellar hemispheres; attached to internal occipital crest and to inf part of tent. cerebelli
tentorium cerebelli
tent shaped roof over posterior cranial fossa; separates occipital lobes from cerebellum
fixed border of tent. cbl
outer, attached to margins of the grooves for transverse sinuses on occip bone, to the crest of the petrous temp bone, and attaches anteriorly to post clinoid processes
free border of tent cbl
concave around midbrain and its 2 ends course fwd, cross the fixed part and attach to ant clinoid processes of sphenoid bone
clinical note of tent cbl
free border surrounds midbrain , just above is the medial aspect of temp bone (uncus). when intracranial pressure above tentorium is higher than below, the brain is displaced downward and the uncus may herniate through the free border of the tent cbl and be lacerated by taut edges. also inc pressure can cause part of cbl to herniate through FM
diaphragma sellae
forms roof over depression in the sella turcica for pit gland. central aperture in partition for the infundibular stalk to connect pit to hypothal
definition of dural venous sinuses
triangular, endothelial lined space formed between 2 layers of the dura
outpocketings along the sides of some sinuses, chiefly from SSS
venous lacunae
function of dural venous sinuses
act as collecting channels for drainage of blood from 4 sets of veins:
1) cerebral v.: drain brain hemispheres and upper brain stem
2) meningeal veins: drain meninges
3) diploic veins: drain bones of cranium
4) emissary veins: scalp and other head regions have veins outside skull that course through foramina in skull and drain into venous sinuses
arachnoid granulations
cauliflower-like elevations of arachnoid project through the dura into SSS or its venous lacunae (lakes); CSF is diffused passively from subarachnoid space via arachnoid gran into DVS into internal jugular vein
all dural venous sinuses communicate with each other and drain....
either directly or indirectly into the internal jugular vein
SSS occupies what and joins what
occupies triangular interval between periosteal dura and diverging meningeal dural layers in fixed, convex border of falx cerebri; joins the right transverse sinus
ISS situated where and unites with what
situated between 2 layers of meningeal dura in the free inferior margin of the falx cerebri; unites posteriorly with the great vein of galen to form straight sinus
straight sinus occupies and joins what
occupies the line of junction between the falx cerebri posteriorly with the upper peaked portion of the tent cbl; joins the left transverse sinus
transverse sinuses: begin and occupy where/what
begin as continuations of the SSS and straight sinuses; ;occupy the peripheral attached circumference of the tent cbl up to the base of the peterous temp bone where join the sigmoid sinuses on each side
sigmoid sinuses: where
arch down from petrous temporal bone, groove the mastoid part of the temporal bone, and turn forward over the occipital bone to enter the jugular foramen; empty into the jugular bulb of internal jug veins in jug formaina
superior petrosal sinuses located where and join what
located in attachment of tentorium cbl to the superior margin of the petrous temp bone; join cavernous sinuses ant and sigmoid sinuses posteriorly
cavernous sinuses situated where and formed between what
situated on either side of the body of the sphenoid bone, lateral to the diaphragma sellae, formed between MD and PD
cavernous sinus is unique why?
each cavernous sinus has nerves:
Outer wall of sinus: CNIII, IV, V1, V2
in the sinus: CNVI and ICA with the VI nerve lateral and inferior to the ICA; each sinus drains into superior and inferior petrosal sinuses
sphenoparietal sinuses
located along post border of the lesser wing of the sphenoid bone; drain into cavernous sinuses
inferior petrosal sinuses
lie in petro-occipital fissure posterior and inferior to the cavernous sinuses; pass through jugular foramen and end separately in the bulb of the internal jug vein
basilar sinus
plexus like collection of venous channels bet layers of dura on the clivus
what sinus serves to connect the two inferior petrosal sinuses?
basilar sinus!
occipital sinus
located in the fixed border of the falx cerebelli; drains into confluens of sinuses or the left transverse sinus
confluens of sinuses
dilatation at one side of internal occiptal protuberance; represents the jcn of the SSS, straight, occipital sinuses with the transverse sinuses of each side.
clinical note on sinuses:
profuse bleeding often occurs with skull fractures due to the fact that there is no smooth muscle in the walls of the dural venous sinuses to constrict the walls.; also because of the comm of veins outside the skull (i.e. scalp veins) with the venous sinuses via emissary veins, infections produced outside the skull can produce inflammation in the walls of the emissary veins resulting in thrombophlebitis of the sinuses.
bones of anterior cranial fossa
FRONTAL BONE: inner surface adn crest, orbital plates
ETHMOID BONE: cribiform plate and crista galli
SPHENOID BONE: lesser wing and ant clinoid processes; jugum of sphenoid
parts of brain assoc with ant cranial fossa
median part: olfactory bulbs, tracts, and stria; gyrus rectus
lateral part: orbital gyri of frontal lobe
foramina in ant cranial fossa
foramina in cribiform plate in ethmoid bone: olfactory nerves from the nasal septum to the olfactory bulb
foramen cecum in base of frontal crest: emissary vein from nose to SSS
ant and post ethmoidal foramina at jcn of ethmoid and orbital plate: ant and post ethmoidal vessels and nerves
structures of ACF
frontal crest: attachment of f. cerebri
crista galli: attachment of falx cerebri
ant clinoid process: attachment of free border of tent cbl
bones of middle cranial fossa
SPHENOID BONE: body (tuberculum sellae, hypophoseal fossa, dorsum sellae with post clin processes) and greater wings
TEMPORAL BONE: squamous portion and superior portion of the petrous temporal bone
sphenoid body is also called
sella turcica: tuberculum sellae, hyp fossa, and dorsum sellae
parts of brain assoc with middle cranial fossa
medial portion: diencephalic structures at base of brain
lat portion: temporal lobes
foramina of MCF
OPTIC CANALS: CNII and ophthalmic artery
FORAMEN ROTUNDUM: greater wing of sphenoid, CNV2
FORAMEN OVALE: greater wing: CNV3
FORAMEN LACERUM, apex of petrous temp, filled with cartilage, ICA crosses it going to cavernous sinus
Structures of MCF
GROOVE FOR G. PETROSAL N.: petrous temporal: greater pet n.
TRIGEMINAL IMPRESSION: behind apex of petrous temp; semilunar ganglion
ARCUATE EMINANCE: pet. temp, anterior semicircular canal
HYPOPHYSEAL FOSSA: body of sphenoid, houses pit gland
POST CLINOID PROCESSES: attachment of fixed border of t. cbl
CAROTID CANAL: ICA, sympathetic plexus
bones of post cranial fossa
OCCIPITAL: 3 portions: basilar, lateral, squamus
TEMPORAL: petrous temporal, mastoid portion of temp bone
SPHENOID: post surface o fdorsum sellae of sphenoid
parts of brain assoc with PCF
median: brain stem (midbrain, pons, medulla)
lateral: cerebellar hemispheres, above tentorium are occipital lobes
foramina of PCF
FORAMEN MAGNUM: medulla SC jcn, spinal accessory nerve, vertebral a.
JUGULAR FORAMEN: hiatus between occipital-petrous temp: ant part: Inf pet sinus; inf part: CNIX, X, XI; post part: Int Jug vein
MASTOID FORAMEN: mastoid of temp: emissary vein
structures of PCF
int occipital crest: attachment of falx cerebelli
int occip protub: attachment of t. cbl; confluens of sinuses
Telencephalon: CN, foramen, CF
CNI; cribiform llplate, ACF
Diencephalon: CN, foramen, CF
II, optic canal MCF
mesencephalon: CN, foramen, CF
Metencephalon: CN, foramen, CF
VI and V1: SOF
V2: foramen rotundum
V3: foramen ovale
VIII and VII: internal accoustic meatus;
all MCF except IAM which is in PCF
mylencephalon: CN, foramen, CF
IX, X, CRXI: jugular foramen
XII: hypoglossal canal
all in PCF
telencephalon: forebrain: cerebral hemispheres, certain subcortical fiber bundles, basal ganglia
between brain: thalamus, hypothalamus, subthalamus
pons and cbl
orientation of cerebral hemispheres and diencephalon
anterior = rostral
posterior = caudal
superior = dorsal
inferior = ventral
orientation of brain stem and spinal cord:
anterior = ventral
posterior = dorsal
superior = rostral
inferior = caudal
what gyrus is the primary motor cortex:
precentral gyrus
lateral: Face, hand, upper ext, trunk
medial: lower ext and genetalia
broca's area:
pars triangularis of IFG, and pars opercularis of IFG: speech formation in dominant hemisphere
primary somatosensory ctx:
postcentral gyrus: lateral: F, H, Upper ext, trunk
medial: lower ext and genetalia
functions of IPL
lesion of dominant IPL (usually left): verbally mediated spatial functions, can't put words into proper relationships
lesion of non-dominant IPL disturbances of perception of spatial function other than language related, neglect of contralateral side of body
primary auditory ctx
transverse gyrus of heschl, mostly bilaterally
function of insula
integrate visual, auditory, and somatosensory fcns
cingulate sulcus turns up dorsally and ends as the
marginal sulcus
fcn of paracentral lobule
motor and sensory functions of the lower ext and external genetalia
organization of the brain stem: roof, central zone, basilar zone
MIDBRAIN: roof: tectum (sup and inf coll)
central zone: tegmentum
basilar: crus cerebri
PONS: roof: cerebellum
central zone: tegmentum
basilar zone: basilar pons
MEDULLA: roof: cerebellum
central zone: reticular formation (aka tegmentum)
basilar zone: pyramids
ventricular cavities lined by
ventricular cavities of brain subdivisions: cavities of cerebral hemispheres:
paired lat ventriclels I and II
ventricular cavities of brain subdivisions: cavity of diencephalon
unpaired third ventricle
ventricular cavities of brain subdivisions: cavity of mesencephalon
cerebral aqueduct
ventricular cavities of brain subdivisions: cavity of pons and upper medulla (metencephalon)
IV ventricle
ventricular cavities of brain subdivisions: cavity of lower medulla and spinal cord (myelencphalon)
central canal
communicating foramina of the ventricular system
choroid plexus is located in the:
body, trigone and inferior horn of LV;
roof of III ventricle;
caudal part of IV ventricle;
foramina of Luschka
regions where SAS is expanded forms:
cisterns, eventually become continuous with SAS surrounding cerebral hemispheres
putamen + globus pallidus make up:
lentiform nucleus
strial terminalis
communicates amygdala to septal region (happy place) but not other way around
SAS expanded to form cisterns:
cerebulomedullary cistern: (cisterna magna), between inf surface of cbl and medulla
Superior cistern: (cisterna ambiens) lies dorsal to the midbrain
pontine, interpeduncular, and chiasmatic cisterns: lie ventral to base of pons, the interpeduncular fossa and the optic chiasm
one way direction of CSF circ: lateral ventricles:
lat ventricules through formaina of munro into III ventricle, through cerebral aqueduct to IV ventrical. CSF exits the IV through paired foramina of luschka and unparied foramen of magendie
one way direction of CSF circ: from foramen of magendie:
From foramen of magendie, CSF enters the cerebellomedullary cistern, flows backward in SAS over post cbl, the superior cistern, the cerebral hemispheres, and drains chiefly into the SSS from arach granulations
one way direction of CSF circ: from foramina of luschka:
from f of luschka: CSF enters SAS of the pontine cistern and flows forward to the interpeduncular and chiasmatic cisterns, the SAS over the lat hemispheres and drains chiefly into the SSS from arach gran
where is CSF formed chiefly?
by choroid epithelia loc in portions of the lat ventricles, roofs of 3rd and 4th vent, and the formamina of luschka
CSF is replaced how many times a day
3-4 times
chief functions of CSF
maintenance of constant ext environment for n. and glia
removal of harmful brain metabolites through 1 way flow of CSF from vent syst around SC into SAS and into Vsinuses
protection of CNS from trauma by the buoyancy effect reducing momentum of brain to trauma
protein concentration of CSF vs plasma
dramatically reduced in CSF
what concentrations are sl lower in CSF than plasma
glucose, Ca, K
pH of CSF in rel to art blood
sl less in CSF
CSF contains how many cells
less than 4 cells: monocytes and lymphocytes
CSF pressure is measured by what
lumbar puncture bet 4th and 5th lumbar vertebrae
clinical sig of CSF: color
grossly bloody or yellow color indicates hemmorhage
clinical sig of CSF: protein content
protein over 150 indicates that biliruben bound to albumin has been brought from plasma to CSF; over 500 block in Spinal SAS by tumor, meningeal cancer or other compressing lesion
clinical sig of CSF: WBC
greater than 4/ml pathological: fungal inf: lymphocytes; bacterial meningitis: mostly neutrophils
clinical sig of CSF: tumor cells
exfoliate tumor cells may be in CSF in primary or metastatic brain cancer patients
clinical sig of CSF: glucose
conc of glucose is decreased in acute bacterial infection but rarely in viral infection
clinical sig of CSF: MS
in MS and other inflammatory diseases, the gamma-globulin content is increased in CSF whereas blood level of gamma globulin is normal
"water brain": expansion of ventricles caused by increase of intracranial pressure caused by:
oversecretion of CSF
impaired absorbtion of CSF
obstruction of CSF circulation
communicating hydrocephalus
oversecretion or impaired reabsorption of CSF
noncommunicating hydrocephalus
obstruction of CSF by blockage at cerebral aqueduct or foramina of IV ventricle
hydrocephalus ex vacuo
in aged indiv: no increase in intracranial pressure, due to thinning of cortical tissue; cerebral atrophy is primary pathology, not imbalance bet CSF formation and absorption
types of brain edema
vasogenic and cytotoxic
vasogenic brain edema: cause, mechanism, manifestation/structures
vasogenic brain edema: caused by ischemia, head trauma, meningitis
mechanism: inc perm of BBB, proteins and ions leak across capillary walls
manifestations: inc in brain interstitial fluid, esp around white matter bordering ischemic zones
inc. ICP
decrease in size of ventricles
brain edema indicates:
inc water content
cytotoxic brain edema: cause, mech, manifest, structures
cause: drug poisoning, hyponatremia (hypoxia)
mech: net shift of water from brain extracellular compartment to interior of cells
manifest: dec in brain ISF, intracelular swelling of neurons, glia, and endothelia
increased ICP
dec in size of ventricles
3 fluid compartments of nervous system
three specific barriers:
Blood-CSF barrier
CSF-brain barrier
consists of endothelial cells with tight junctions
continuous basement membrane of the endothelial cells;
transports substances that the brain consumes rapidly (glucose, aa, lactate, ribonucleosides)
blood-CSF barrier
located at tight junctions which interconnect apical regions of cuboidal, choroid epithelium; transfer of nutrients that are needed in small amounts over extended pd: vit c, vit 6, folates
CSF-brain barrier
no tight jcns, therefore molecules move bidirectionally bet CSF and intercellular space of CNS
transport mech across BBB
passive and active carrier type transporters
ion channels and exchangers
nonselective luminal ion channel
inhib by amiloride and atrial natriuetic peptide in capillary endothelial cells
K+ channels
expressed in astrocytes, play role in removal of extracellular K+ during intense neuronal activity
Na+/H+ and Cl-/HCO-3 exchangers
suggested to be expressed in luminal membrane

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