SKULL BRAIN AND CRANIAL NERVES

SKULL
AXIAL SKELETON FORMS THE LONG AXIS OF THE BODY
IT IS MADE UP OF 80 BONES, ARRANGED IN 3 REGIONS, SKULL, VETEBRAL COLUMN AND THE THORACIC CAGE
THE AXIAL SKELETON SUPORTS THEHEAD AND NECK AND PROTECTS THE BRAIN , SPINAL CORD AND THE THORACIC ORGANS
SKULL
CRANIAL BONES+ FACIAL BONES
CRANIAL BONES------CRANIUM----ENCLOSE AND PROTECT THE BRAIN AND PROVIDE ATTACHMENT TO MUSCLES
FACIAL BONES----1) FORM FRAME OF THE FACE
2) FORM CAVITIES FOR SENSE ORGANS( NOSE, EYES, ORAL)
CAVITY( TASTE
3) PROVIDE OPENINGS FOR AIR AND FOOD
4) PROVIDE CAVITIES TO HOLD TEETH
5) PROVIDE ATTACHMENT TO THE MUSCLES

SKULL
BONES OF THE SKULL ARE FLAT.
THE JOINTS BETWEEN THE BONES ARE CALLED SUTURES( INTERLOCKING AND IMMOVABLE)
CORONAL SUTURE
SAGITTAL SUTURE
LAMDOID SUTURE
SQUAMOSAL SUTURE

SKULL
THE CRANIAL VAULT -----CLAVARIA( SUPERIOR, LATERAL AND POSTERIOR ASPECT AS WELL AS THE FOREHEAD
CRANIAL BASE---- FLOOR. INTERNAL ASPECT SHOWS 3 STEPS
1) POSTERIOR CRANIAL FOSSA-- BASEMENT
2) MIDDLE CRANIAL FOSSA--- 1ST FLOOR
3) ANTERIOR CRANIAL FOSSA--2ND FLOOR)
* EACH FOSSA HAS A SPECIFIC LOBE OF THE BRAIN SITTING INSIDE IT

SKULL
SMALLAR CAVITIES INSIDE THE SKULL
INNER EAR
MIDDLE EAR
NASAL
ORBITAL
PARANASAL SINUSES
OPENINGS( FORAMINA, CANAL,FISSURES)--- 85 NAMED THESE ALLOW THE PASSAGE OF SPINAL CORD( WHICH OPENING?) , CRANIAL NERVES ( 12) , BLOOD VESSELS
* FEATURES OF THE SKULL BONES FIGURES 7.2 TO 7.4 AND TABLE 7.2 PAGES 160-161

SKULL THROUGHOUT LIFE
SKULL DEVELOPS IN MEMBRANE---- OSSIFICATION ---LATE IN THE 2ND MONTH
OSSIFICATION BEGINS IN THE MIDDLLE AND SPREADS OUTWARDS
AT BIRTH PARTS OF THE SKULL ARE STILL NOT FORMED( FONTANEL)
4 MAJOR FONTANELS ARE SEEN
ANTERIOR
POSTERIOR
MASTOID
SPHENOID
THESE ALLOW THE BONES OF THE SKULL TO SLIP OVER EACH OTHER DURING BIRTH ( MOULDING)
THE FRONTAL BONE AND MANDIBLE START AS 2 HALFS , WHICH FUSE LATER ON

SKULL THROUGHOUT LIFE
CHANGES IN THE FORM OF THE SKULL
AT BIRTH THE SKULL APPEARS LARGER THAN THE FACE
BY 9 MONTHS SKULL ATTAINS HALF THE SIZE OF THE ADULT SKULL
BY 2 YRS IT IS ¾ THE SIZE OF THE ADULT
8-9 YRS ADULT SIZE
FACE ENLARGES BETWEEN 6-13 YRS

SKULL
CRANIAL BONES---- TOTAL OF 8
PAIRED---- TEMPORAL AND PARIETAL
UNPAIRED---- FRONTAL, OCCIPITAL, SPHENOID AND THE ETHMOID
FRONTAL BONE( FEATURES)
FORMS FOREHEAD AND ROOF OF THE ORBITS
SPRAORBITAL MARGIN
SUPRAORBITAL NOTCH/FORAMEN
GLABELLA
FRONTONASAL SUTURE
FRONTAL SINUS
ANTERIOR CRANIAL FOSSA

SKULL
PARIETAL BONE ( FEATURES)
FORM THE BULK OF THE CRANIAL VAULT
FORMS SUTURES WITH THE OTHER BONES ( 4)
* SUTURAL BONES ----- SMALL BONES OCCURING WITHIN THE SUTURES( LAMDOID SUTURE)
OCCIPITAL BONE ( FEATURES)
1) FORMS THE POSTERIOR PART OF THE CRANIUM AND THE BASE
2) INTERNALLY FORMS THE POSTERIOR CRANIAL FOSSA( CONTAINS THE CEREBELLUM)
3) FORAMEN MAGNUM
4) OCCIPITAL CONDYLES
5) HYPOGLOSSAL CANAL

BRAIN
THE AVERAGE HUMAN BRAIN WEIGHS 1500 g or 3.3 POUNDS
IT CARRIES OUT COMPLEX NEURAL FUNCTIONS.
DEVELOPMENT-BRAIN ARISES FROM THE ROSTRAL( SUPERIOR ) PART OF THE NEURAL TUBE
ORGANIZATION OF THE BRAIN-
1. CEREBRAL HEMISPHERES
2. DIENCEPHALON-THALAMUS, HYPOTHALAMUA AND EPITHALAMUS
3. BRAINSTEM-MIDBRAIN,PONS AND MEDULLA OBLANGATA
4. CEREBELLUM
ALL THESE PARTS WORK TOGETHER AND ARE INTERCONNECTED

CEREBRAL HEMISPHERES
THIS CONSTITUTES SEVEN-EIGHTS OF THE TOTAL WT OF THE BRAIN, OCCUPIES MOST OF THE CRANIUM.
CONSISTS OF 2 CEREBRAL HEMISPHERES SEPERATED BY A LONGITUDINAL FISSURE
-THE SURFACE OF THE CEREBRUM IS GRAY MATTER( CONTAIN CELL BODY OF NEURONS,DENDRITES AND UNMYELINATED AXONS), THERE ARE PARTS OF GRAY MATTER DEEPER WITHIN THE WHITEMATTER ( BASAL NUCLEI). CALLED THE CORTEX
-INTERNAL TO THE GRAY MATTER IS THE WHITE MATTER( MADE UP OF MYELINATED AXONS AND DENDRITES

CEREBRAL GRAY MATTER
( CORTEX)
SURFACE STRUCTURES-
-2-4 MM THICK, FOLDED TO FORM SULCI ( GROOVES)AND GYRI( RIDGES)
-DEEPER SULCI DIVIDE EACH CEREBRAL HEMISPHERE INTO 5 MAJOR LOBES- FRONTAL, PARIETAL,OCCIPITAL,TEMPORAL AND INSULA.
GENARAL FUNCTIONAL AREAS-
MOTOR-CONTROLS VOLUNTARY MOTOR FUNCTIONS
SENSORY AREA-PROVIDES FOR CONCIOUS AWARENESS OF SENSATION
ASSOCIATION AREA-INTEGRATE DIVERSE INFORMATION , TO ENABLE A PURPOSEFUL ACTION

LOBES OF THE BRAIN

MOTOR AND ASSOCIATION AREAS
PRIMARY MOTOR AREA- LOCATED IN THE PRECENTRAL GYRUS OF THE FRONTAL LOBE. BROADMANS AREA-4.THE CORTICOSPINAL TRACTS ARISE HERE( MOTOR CONTROL)
PREMOTOR CORTEX- LIES ANTERIOR TO THE PRECENTRAL GYRUS, BROADMANS AREA -6, THIS IS AN ASSOCIATION AREA.
PREFRONTAL CORTEX-LIES JUST ANTERIOR TO THE PREMOTOR CORTEX.PERFORMS COGNITIVE FUNCTIONS( THINKING, PERCIEVING, REMEMBERING AND RECALLING INFORMATION
THE FRONTAL EYE FIELD CONTROLS VOLUNTARY MOVEMENTS OF THE EYE.FOLLOWING A MOVING OBJECT BROADMANS AREA -8
BROCA’S AREA- LIES ANTERIOR TO THE INFERIOR PART OF THE PREMOTOR CORTEX .BROADMANS AREA 44-45.SPEECH AREA. PRESENT IN THE DOMINANT HEMISPHERE

SENSORY AND ASSOCIATION AREAS
PRIMARY SENSORY AREA- LOCATED IN THE POST CENTRAL GYRUS OF THE PARIETAL , JUST POSTERIOR TO THE PRIMARY CORTEX. CORRESPONDS TO BROADMANS AREA 1-3. INVOLVED WITH CONCIOUS AWARENESS OF SENSATIONS
SOMATOSENSORY ASSOCAIATION AREAS-LIES POSTERIOR TO THE PRIMARY SENSORY AREA. BROADMANS AREA 5-7. INTEGRATES SENSORY INPUTS
PRIMARY VISUAL AREA- PRESENT IN THE POSTERIOR AND MEDIAL PART OF THE OCCIPITAL LOBE. BROADMANS AREA 17. IF DAMAGED LEADS TO CORTICAL BLINDNESS.
VISUAL ASSOCIATION AREAS- BROADMANS AREA 18-19.FOR COLOR, FORM AND MOVEMENT
PRIMARY AUDITORY AREA - PRESENT AT THE SUPEROR EDGE OF THE TEMPORAL LOBE .BROADMANS AREA 41,42
AUDITORY ASSOCIATION AREA-JUST POSTERIOR TO THE PRIMARY AUDITORY AREA. MEMORIES OF PAST SOUND ARE STORED HERE.
WERNICKES AREA-AREA INVOLVED IN COMPREHENSION OF SPEECH

LIMBIC SYSTEM( EMOTIONAL BRAIN)
THIS IS A GROUP OF STRUCTURES ON THE MEDIAL SIDE OF EACH CEREBRAL HEMISPHERE AND DIENCEPHALON
RESPONSIBLE FOR EMOTIONAL STATES OF BEHAVIOUR( FEAR , ANGER , SADNESS)-BRINGS ABOUT APPROPRIATE BEHAVIOUR
RESPONSIBLE FOR SHORT TERM MEMORY
COMMUNICATES WITH OTHER REGIONS OF THE BRAIN.

CEREBELLUM
MAKES UP A FOURTH OF THE BRAINS MAJOR PARTS
MAKES UP 11% OF THE MASS OF THE BRAIN
ALSO CALLED THE LESSER BRAIN
CONSISTS OF 2 HEMISPHERES CONNECTED BY THE VERMIS
HAS OUTER GRAY MATTER, INNER WHITE MATTER, DEEPER AREA OF GRAY MATTER THE CEREBELLAR NUCLEI
FUNCTIONALLY IT SMOOTHS AND COORDINATES BODY MOVEMENTS THAT ARE DIRECTED BY OTHER BRAIN REGIONS, AND HEPLS MAINTAIN POSTURE AND EQUILIBRIUM.
IN ORDER TO PERFORM THE ABOVE FUNCTIONS IT IS CONNECTED TO OTHER PARTS OF THE BRAIN VIA CEREBELLAR PUDUNCLES, THE SUPERIOR, MIDDLE AND INFERIOR.

BRAINSTEM
THE 3 REGIONS OF THE BRAINSTEM ARE THE MIDBRAIN, PONS AND MEDULLA OBLONGATA
MIDBRAIN
- IT HAS A CENTRAL CAVITY CALLED THE CEREBRAL AQUEDUCT WHCH DIVIDES IT INTO 2 PARTS
CEREBRAL PUDUNCLES LIE VENTRALLY
TECTUM LIES DORSALLY, WHICH ARE MADE UP OF NUCLEI CALLED THE CORPORA QUADRIGEMINA ( SUPERIOR COLLICULI- ASSOCIATED WITH VISUAL REFLEXES, INFERIOR COLLICULI- ASSOCIATED WITH AUDITORY REFLEXES
THE SUPERIOR CEREBELLAR PUDUNCLES CONNECT THE MIDBRAIN TO THE CEREBELLUM

PONS-
IT IS THE BRIDGE BETWEEN THE RT AND LEFT HALVES OF THE CEREBELLUM
THERE ARE CRANIAL NERVES ATTACHED TO IT, THE 5TH, 6TH AND 7TH.
IT IS ATTACHED TO THE CEREBELLUM VIA THE MIDDLE CEREBELLAR PUDUNCLE
MEDULLA OBLONGATA
-IT IS CONTINOUS WITH THE SPINAL CORD AT THE LEVEL OF THE FORAMEN MAGNUM
-THE CRANIAL NERVES ATTACHED TO IT ARE THE 8TH, 9TH, 10TH ,11TH AND 12TH
-IT IS ATTACHED TO THE CEREBELLUM VIA THE INFERIOR CEREBELLAR PUDUNCLE
RETICULAR FORMATION
THIS RUNS THROUGH THE CENTRAL CORE OF THE PONS, MIDBRAIN AND MEDULLA
CONSISTS OF LOOSE CLUSTER OF NEURONS
FORMS THE RETICULAR ACTIVATING SYSTEM-MAINTAINING CONCIOUSNESS AND ALERTNESS

DIENCEPHALON
PARTS ARE THE THALAMUS, HYPOTHALAMUS AND EPTHALAMUS
THALAMUS
MAKES UP 80% OF THE DIENCEPHALON
IMPORTANNT NUCLEI( GRAY MATTER) ARE PRESENT
IT IS A RELAY STATION
HYPOTHALAMUS
LIES BELOW THE THALAMUS
PROJECTING FROM THE INFERIOR ASPECT IS THE PITUITARY GLAND THAT SECRETES HORMONES
CONTAINS NUCLEI( GRAY MATTER)
IT IS THA MASTER CONTROL CENTER REGULATING THE ACTIVITIES OF THE VISCERAL ORGANS
EPTHALAMUS
CONSISTS OF NUCLEI AND THE PINEAL BODY
UNDER THE INFLUENCE OF THE HYPOTHALAMUS IT SECRETS MELATONIN ( SLEEP CYCLE)

PROTECTION OF THE BRAIN
CNS PROTECTION
BONE
MENINGES
a) dura mater
b) arachnoid mater
c) pia mater
3. Cerebrospinal fluid
a) in the ventricles and subarachnoid space
b) circulation: choriod plexus -------superior sagittal sinus
c) lumbar puncture ( spinal tap)
4. Blood brain barrier

MENINGES
CONNECTIVE TISSUE
COVERS AND PROTECTS THE CNS
ENCLOSE AND PROTECTS THE BLOOD VESSELS SUPPLYING THE CNS
CONTAINS CSF
READ UP DETAILS OF THE MENINGES FROM THE BOOK PAGES 374-377

CSF
CSF PRESENT AROUND THE BRAIN AND SPINAL CORD
REDUCES THE WT OF THE BRAIN BY 97%
100-160 ML
FORMED IN THE CHOROID PLEXUS

VENTRICLES OF THE BRAIN
EXPANSIONS OF THE BRAINS CENTRAL CAVITY ---- CONTAIN CSF
CONTINOUS WITH EACH OTHER AND THE CENTRAL CANAL OF THE SPINAL CORD
1. LATERAL VENTRICLE---- CEREBRAL HEMISPHERES
2. THIRD VENTRICLE---DIENCEPHALON
3. MIDBRAIN---CERBRAL AQUEDUCT
4. HINDBRAIN---- FOURTH VENTRICLE