7 - Skull, Brain, CN Grays

7/29/2019 7 - Skull, Brain, CN Grays

1/58

Skull, Brain and Cranial Nerves

streetanatomy.comwww.uberreview.com


2/58

Skull

Part of Axial Skeleton

Cranial bones = cranium

Enclose and protect brain Attachment for head + neck muscles

Facial bones =framework of face

Form cavities for sense organs Opening for air + food passage

Hold teeth

Anchor face muscles

pg 800


3/58

Cranial and Facial Bones

Cranial - 8

Frontal

Occipital Sphenoid

Ethmoid

Parietal (2)

Temporal (2)

Facial14

Mandible

Maxilla (2) Zygomatic (2)

Nasal (2)

Lacrimal (2)

Palatine (2)

Vomer

Inf. Nasal Conchae(2)


4/58

Bones of Skull

Flat bones: thin, flattened, some curve

Sutures: immovable joints joining bones

Calvaria = Skullcap =Vault Superior, Lateral, Posterior part of skull

Floor = Base

Inferior part of skull

85 openings in skull

Spinal cord, blood vessels, nerves

Foramina, meatus, canal, fissure, notch

pg 818

pg 825


5/58

Cranial Fossae

Created by bony ridges

Supports, encircles brain

3 Fossae Anterior

Middle

Posterior

All the bones visible from this view are the

cranial bones!!

pg 825


6/58

Other Cavities of Skull

Orbits

Nasal CavityMiddle Ear

Inner Ear

pg 904pg 813


7/58

Skull through Life

Ossifies late in 2nd month of development

Frontal + Mandible start as 2 halves-then fuseGrowth of Skull

adult size by age 9 months

adult size by 2 years 100% adult size by 8-9 years

Face enlarges between ages 6-13 years


8/58

Fetal Skull

Skull bones separated by unossified membranes =

Fontanels

Allow compression of skull during delivery Allows rapid growth of brain

Mostly replaced w/bone after 1st year

www.aafp.org


9/58

4 Parts

Cerebrum

*Diencephalon

Brain Stem Midbrain

Pons

Medulla

CerebellumGray matter surrounded by White matter w/outer cortex ofgray matter

*some texts consider this part of brain stem

The Brain

Pg 836


10/58

Meninges: 3 membranes around

brain and spinal cord

Made of Connective tissue

Functions

Cover, Protect CNS Enclose, protect blood vessels supplying CNS

Contain CSF

3 Layers

Dura Mater (external)

Arachnoid Mater (middle)

Pia Mater (internal)pg 833


11/58

Meninges (continued)

Dura mater

Strongest, 2 Layers, Fibrous Connective Tissue

Periosteal layer (Periosteum): External/superficial layer

Meningeal layer: Internal/deep layer

Layers fused except around dural sinuses (venous

blood filled internal jugular vein)

pg 818


12/58

Extensions of Dura Mater

Partitions: limit movement of brain

Falx Cerebrivertical, between cerebral hemispheres

Falx Cerebelli-vertical, between cerebellar hemispheres

Tentorium Cerebellihorizontal, between cerebrum and

cerebellum

pg 831


13/58

Meninges

Arachnoid Mater

Middle layer

Subarachnoid Space-between arachnoid mater and piamater (contains most of CSF, blood vessels)

Arachnoid Villi (Granulations)- projections of

arachnoid mater through dura into superior sagittalsinus, act as valves to help CSF pass into dural sinuses

pg 833


14/58

Meninges (continued)

Pia Mater

Innermost layer

Delicate, highly vascular

Clings directly to brain tissue, dips into convolutions

pg 833


15/58

Ventricles

Expansions of brains central cavity

Lined with Ependymal Cells

Filled with CSF (cerebrospinal fluid)

Ventricles continuous w/each other + central canal of spinal cord

Pg 836


16/58

Ventricles (continued)Lateral Ventricles (#1+2)

Cerebral Hemisphere

Separated by Septum Pellucidum

Third Ventricle

Diencephalon Interventricular Foramen: connects to lateral ventricle

Fourth Ventricle

Hindbrain

Cerebral Aqueduct: connects 3rd and 4th ventricles

Connects to central canal of spinal cord & medulla

3 openings connect 4th to subarachnoid space

2 lateral apertures

1 median aperture health.howstuffworks.com


17/58

Cerebrospinal Fluid

Liquid cushion for brain and spinal cord

Nourishes brain

Removes waste

Conducts chemical signals between parts of CNS (e.g.

hormones)

Forms as a filtrate of blood in choroid plexuses

health.allrefer.com


18/58

Choroid Plexuses

Choroid Plexuses: groups of capillaries

surrounded by ependymal cells

Made of sodium, chloride ions, proteins, glucose, O2

www.daviddarling.info


19/58

Flow of CSF

Formed in Choroid plexuses

Through Ventricles

Into Subarachnoid space & central canal from 4thventricle

Through Arachnoid Villi into Superior Sagittal Sinus

Into Internal Jugular Vein

faculty.washington.edu


20/58

Organization of the Brain

Composed of gray and white matter

Different organization than in the spinal cord

Centrally located gray matter surrounded by white matter Cortex: external sheets of gray matter in cerebrum &

cerebellum (some parts of brain)

Nuclei: deep masses of gray matter surrounded by white matter

(some parts of brain)


21/58

Cerebrum

Executive Suite of nervous system

Self-awareness, initiate + control voluntary movements,

communicate, remember, understanding, language

Most superior region

Covers diencephalon + top of brain stem like

mushroom cap

Cerebral cortex

pg 836


22/58

Cerebral Hemispheres

Fissures and Grooves

Fissuresdeepest

Transverse cerebral fissure

Separates cerebral hemispheres from cerebellum

Longitudinal fissure

Separates R and L cerebral hemispheres

Sulci Grooves on surface

Gyri

Ridges of brain tissue among the sulci

pg 836

pg 833


23/58

Cerebral Hemispheres:

Each hemisphere divided into 5 lobes

Frontal

Parietal

Occipital

Temporal

Insula

Created by deep sulci

Functional areas: motor, sensory

Associative areas: integrate

pg 836


24/58

Cerebral Hemispheres

The 2 hemispheres control opposite sides of body

Corpus callosum

The largest commissure between the hemispheres

Hemispheres specialized for different cognitive

functions

Left Cerebral hemisphere Language, mathematics and logic

Right Cerebral hemisphere

Visual-spatial, interpreting facial expressions, intuition,

emotion, artistic/musical skills


25/58

Diencephalon

Surrounded by cerebral hemispheres

Made of 3 Paired Structures

Thalamus gateway

Communicates sensory info of cerebral cortex

Hypothalamus Regulates many body activities

Emotion, sleep, memory, etc.

Pituitary Gland Growth Hormone

Thyroid Stimulating Hormone

Epithalamus

Pineal Gland

Melatonin

pg 836


26/58

Brainstem

Midbrain, Pons, Medulla Oblongata Passage of all signals between spinal cord and brain

Regulates basic physiological functions

Innervation of head and neck


27/58

Brainstem

Midbrain

Visual and Auditory reflex centers

Attachment for CN III, IV

Pons

Attachment for CN V, VI, VII, VIII

Medulla oblongata Regulates several basic physiological functions

Attachment of CN IX, X, XI, XII


28/58

Smooths + coordinates body movements directed

by other parts of brain

2 Cerebellar Hemispheres

Cerebellar cortex surrounds Arbor vitae

Functions

Information on equilibrium

Movement of neck, trunk, limbs Information from cerebral cortex on voluntary

movement

Cerebellum


29/58

Blood Brain Barrier

Protects brain from blood-borne toxins (e.g. urea, food

toxins, bacteria)

Endothelium of brain capillaries are loaded with tightjunction to decrease permeability

Not complete protection, some things still have to get

through (e.g. fat-soluble molecules can pass through)


30/58

Blood Supply to Brain

Arteries

External carotid arteries and branches

Tissues of head & face, skin, muscles

Middle meningeal a. = brain Boxers!

Internal carotid arteries and branches Opthalmic a. = Eye & Orbits

Ant & Middle Cerebral arts = Cerebrum

Branches form Cerebral Arterial Circle = Anastomosis Vertebral arteries

Posterior brain

Vertebrae & Cervical Spinal Cord

Branches form Cerebral Arterial Circle = Anastomosis

pg 832

pg 838


31/58

Blood Supply to the Brain

Veins

Dural sinuses

Superior & Inferior Sagittal, transverse, sigmoid, straight, etc

Internal jugular

Receives from dural sinuses External jugular

Drains scalp and face (superficial)

Vertebral

Drains cervical vertebrae, cervical spinal cord, small neck muscles

pg 842pg 870


32/58

Cranial Nerves

12 Pairs: I-XII

Numbered Anterior to Posterior

Attach to inferior surface of brain

Exit brain through foramina in skull

I + II attach to Forebrain (cerebrum + diencephalon)III-XII attach to Brainstem (midbrain, pons, medulla)

Only X goes beyond the head-neckpg 851


33/58

Foramina serving Cranial Nerves

You must know what foramina eachCN leaves the skull through

(refer to lab manual)


34/58

How to Remember CN I-XII

Oh! Oh! Oh!

To Touch And Feel

Very Good Velvet!

Ah Heaven!


35/58

I Olfactory (oh)

II Optic (oh)

III Oculomotor (oh)

IV Trochlear (to)

V Trigeminal (1-3) (touch)

VI Abducens (and)

VII Facial (feel)

VIII Vestibulocochlear (very)

IX Glossopharyngeal (good)

X Vagus (velvet)

XI Accessory (ah)

XII Hypoglossal (heaven)


36/58

Motor vs. Sensory Nerves

Sensory = Afferent

Send nervous impulse from sensory receptors to

brain to bring in information e.g. pressure, temperature, pain

Motor = Efferent

Send nervous impulses from brain to body toaccomplish an action

e.g. movement of a muscle, activation of a gland


37/58

Sensory Nerves

Sensory = Afferent

Visceral Sensory (sensory innervation of viscera)

stretch, pain, temp., chemical changes, irritation in viscera Special: taste

Somatic Sensory (sensory innervation of outer part body)

touch, pain, pressure, vibration, temp. in skin, body wall, limbs

Special: hearing, equilibrium, vision, smell


38/58

Motor Nerves

Motor Nerves

Visceral Motor(motor innervation muscle in viscera + glands)

innervation smooth + cardiac muscle, glands Somatic Motor(motor innervation of skeletal muscle)

innervation of skeletal muscles (except pharyngeal arch m.)

M i f CN F ti


39/58

Mnemonic for CN FunctionSome (CN I)

Say (CN II)

Marry (CN III)Money (CN IV)

But (CN V)

My (CN VI)

Brother (CN VII)Says (CN VIII)

Big (CN IX)

Brains (CN X)

Matter (CN XI)Most! (CN XII)

S = Sensory function M = Motor function

B = BOTH (Sensory and Motor function)


40/58

I Olfactory--------Sensory--smell

II Optic-------------Sensory--vision

III Oculomotor----Motor----extrinsic eye muscles

IV Trochlear-------Motor----extrinsic eye muscles

V Trigeminal

V1 Opthalmic-----Sensory-cornea, nasal mucosa, face skinV2 Maxillary------Sensory-skin of face, oral cavity, teeth

V3 Mandibular---Motor-muscles of mastication

---Sensory-face skin, teeth, tongue (general)

Cranial Nerve Function


41/58

VI Abducens--------------Motor-----eye abduction muscles

VII Facial-------------------Sensory---part of tongue (taste)

-------------------Motor------muscles of facial expression

VIII Vestibulocochlear---Sensory----hearing, equilibrium

IX Glossopharyngeal----Motor------stylopharyngeus muscle

----Sensory----tongue (gen & taste), pharynx

X Vagus------------------Motor-------pharynx, larynx

-------------------Sensory----pharynx, larynx, abd. organs

XI Accessory-------------Motor------trapezius, sternocleidomastoid

XII Hypoglossal----------Motor-------tongue muscles

Cranial Nerves (continued)


42/58

CN I: Olfactory Nerve

Attaches to cerebrum

Many nerve endings from olfactory bulbs

Pass through olfactory foramina in cribriform plate of ethmoid

bone to receptors in roof of nasal cavity

Sensory for smell

Fig 8.48


43/58

CN II: Optic Nerve

Attaches to Diencephalon

Enters orbit through optic canal

Sensory for vision

Fig

8.83


44/58

CN III: Oculomotor Nerve

Attaches to Midbrain

Enters orbit through superior orbital fissure

Motor to 3 of 4 extrinsic muscles of eye

Superior, inferior and medial rectus muscles & inferior oblique muscle

Parasympathetic to muscles controlling pupil & lens of eye

Fig

8.83


45/58

CN IV: Trochlear Nerve

Attaches to Midbrain


Motor to superior oblique muscle of eye

Fig

8.83


46/58

CN V1: Ophthalmic Nerve

First branch of Trigeminal nerve (CN V)

Attaches to Pons

Enters orbit through superior orbital fissure, then exits orbit

through supraorbital foramen/notch

Sensory-cornea, nasal mucosa, face skin

Fig

8.83

CN V M ill N


47/58

CN V2 : Maxillary Nerve

Second branch of Trigeminal nerve (CN V)

Attaches to the pons

Passes through the foramen rotundum, inferior orbital fissure and outthe infraorbital foramen

Sensory-skin of face, oral cavity, teeth

Fig

8.138


48/58

CN V3: Mandibular Nerve

Third branch of Trigeminal nerve (CN V)

Attaches to Pons

Exits cranial cavity through foramen ovale, into the mandibularforamen and out the mental foramen

Motor-muscles of mastication

Sensory-face skin, teeth, anterior 2/3 tongue (general)

Fig

8.139

Di t ib ti f i ti


49/58

Distribution of sensory innervation

to skin of face from CN V

CN V = TrigeminalV1 = Opthalmic

V2 = Maxillary

V3 = Mandibular

pg 867


50/58

CN VI: Abducens Nerve

Attaches to Pons


Motor to lateral rectus muscle of eye

Fig

8.83


51/58

CN VII: Facial Nerve

Attaches to Pons

Exits cranial cavity through internal acoustic meatus, then exitsskull through stylomastoid foramen

Sensory to anterior 2/3 tongue for tasteMotor to muscles of facial expression

Parasympathetic to Mandibular & Sublingual glands,Lacrimal gland

Fig 8.60


52/58

CN VIII: Vestibulocochlear Nerve

Attaches to Pons

Enters inner ear through internal acoustic meatus

Sensory to organs of hearing and equilibrium

Fig

8.119


53/58

CN IX: Glossopharyngeal nerve

Attaches to medulla oblongata

Exits cranial cavity through jugular foramenMotor to stylopharyngeus muscle

Sensory to posterior 1/3 tongue (general & taste), pharynx

Parasympathetic to parotid gland

Figs

8.162,

8.247


54/58

CN X: Vagus Nerve

Attaches to Medulla oblongata

Exits cranial cavity through jugular foramen

Nicknamed the wanderer

Motor to pharynx, larynx

Sensory to pharynx, larynx, abdominal organs

Parasympathetic to thoracic and abdominal organs

Figs

8.164


55/58

CN XI: Accessory Nerve


Exits cranial cavity through jugular foramen

Joined by a spinal segment passing through foramen magnumMotor to trapezius & sternocleidomastoid muscles

Fig 8.165


56/58

CN XII: Hypoglossal Nerve


Exits cranial cavity through hypoglossal canal

Motor to tongue muscles

Fig 8.166


57/58

Summary of Functional Groups

Purely Sensory = I, II, VIII

Primarily Motor = III, IV, VI, XI, XII

Mixed = V, VII, IX, X

Parasympathetic Fibers = III, VII, IX, X

(Division of Autonomic NS = Visceral Motor)


58/58

Parasympathetic Fibers

CN III = Oculomotor

Contracts Iris (controls pupil)

Contracts Ciliary Muscle (controls lens)

CN VII = Facial

Innervates Salivary glands (mandibular & sublingual)

Innervates Lacrimal gland

CN IX = Glossopharyngeal

Innervates Parotid Salivary gland

CN X = Vaguspg 48

Documents

7 - Skull, Brain, CN Grays