cranium, Brain, Cranial nerves Flashcards
Neuro Cranium Bones
(1) frontal
(1) ethmoid
(1) sphenoid
(1) occipital
(2) temporal
(2) parietal
Viscerocranium- 15 bones
(1) mandible
(1) ethmoid**
(1) vomer
(2) maxilla
(2) inferior nasal concha (turbinate)
(2) zygomatic
(2) palatine
(2) nasal
(2) lacrimal
Anterior cranial fossa
Cribriform foramina in cribriform plate
Frontal lobe of the brain
Axons of olfactory epithelium that form olfactory nerve (CN I)
Middle cranial fossa–
- optic canals
- Superior orbital fissure
- Foramen rotundum
- Foramen ovale
- Foramen spinosum
- Foramen lacerum
- Carotid canal
Temporal lobes of brain
- Optic nerves (CN II) and ophthalmic arteries
- Ophthalmic veins, ophthalmic nerve (CN V1), Oculomotor nerve (CN III), trochlear nerve (CNIV) and Abducens nerve (CNVI), and sympathetic fibers
- Maxillary nerve (CN V2)
- Mandibular nerve (CN V3)
- Middle meningeal artery/vein
- Nothing passes through but opening is traversed by internal carotid artery
- Internal carotid artery, sympathetic fibers
Posterior cranial fossa
contents
- Foramen magnum
- Jugular foramen
- Hypoglossal canal
- Internal auditory meatus
Cerebellum, pons and medulla oblongata
- cord and meninges, vertebral arteries, dural veins, anterior and posterior spinal arteries
- Glossopharyngeal nerve (CN IX), vagus nerve (CNX), Spinal accessory nerve (CNXI); internal jugular vein, inferior petrosal and sigmoid sinuses
- Hypoglossal nerve (CN XII)
- Facial (CN VII) and Vestibulocochlear nerves (CN VIII)
Whats the main bone of the ear
Internal auditory meatus…..main bone of the ear location
Cranial Meninges types
Dura,pia and arachnoid matter
Function of cranial meninges
Coverings of the brain that lie immediately internal to the cranium
Protect and enclose brain in a fluid-filled cavity, the subarachnoid space
Form the supporting framework for arteries, veins, and venous sinuses
Dura matter
Tough, thick external fibrous layer
Bone layer and meningeal layer.meningeal layer continues to become dural mater of the spinal cord
Two layered membrane that is adherent to the internal surface of the cranium
External periosteal layer
Internal meningeal layer
Continuous at the foramen magnum with the dura covering the spinal cord
Reflects away from the periosteal layer of the dura to form dural infoldings (reflections)
Divide the cranial cavity into compartments and support parts of the brain
Four dural infoldings: falx cerebri, tentorium cerebelli, falx cerebelli and diaphragma sellae
Arachnoid mater
Thin, nonvascular, intermediate layer
Subarachnoid space
Contains cerebral spinal fluid
Pia mater
Delicate internal vascular layer
Subdural space
Potential space
Dural partitions are
falx cerebri
Tentorium cerebelli
Falx Cerebelli
Diaphragma Cerebelli
Falx Cerebri
Largest dural infolding, separates the right and left cerebral hemispheres
Tentorium cerebelli
Separates the occipital lobes of the cerebral hemispheres from the cerebellum
Divides the cranial cavity into supratentorial and infratentorial compartments
Falx cerebelli
Partially separates the cerebellar hemispheres
Diaphragma sellae
Circular extension that forms a partial roof over the Hypophyseal fossa
seals off the pituitary Gland
Middle meningeal artery
Branch of the maxillary artery which is the terminal branch of the external carotid artery
Enters the middle cranial fossa through the foramen spinosum
Rupture may lead to epidural hematoma- “talk and die”
Innervation of Dura mater
Innervation is largely supplied by the three branches (V1, V2, V3) of cranial nerve V (trigeminal)
Small amount innervation by C2 and C3 fibers which are conveyed by CN X (vagus) and CN XII (hypoglossal)
Explains why there is little pain associated with intracranial surgery once the dura has been resected
Arachnoid mater
Closely applied to the dura but held in place by the pressure of the CSF in the subarachnoid space
Avascular
Contain prolongations that protrude through the dura mater into the dural sinuses called arachnoid granulations
Transfer CSF to the venous system
Subarachnoid space
Subarachnoid space contains CSF and arachnoid trabeculae which pass between the arachnoid and pia mater
The only non-pathological meningeal space
(epidural space and subdural space do not naturally exist unless in pathology; hemorrhage)
Pia mater
Thin, highly vascularized
Adheres to contour of the brain
Subarachnoid bleed
well tolerated,does not cross midline…slowly expanding with veinous blood
Epidural hematoma
rapidly expanding
Cerebrum
Divided into cerebral hemispheres which are separated by a longitudinal fissure into which falx cerebri extends
Frontal lobe occupies the anterior cranial fossa, contains primary motor cortex
Temporal lobe
location and function
Temporal lobe occupies the lateral parts of the middle fossa, contains hearing cortex
Parietal Lobe
location and function
lies between the frontal and occipital lobes, contains primary sensory cortex
Occipital Lobe
location and function
extend posteriorly over the tentorium cerebelli, contains visual cortex
Diencephalon
location and function
Central core of the brain; composed of the epithalamus (pineal gland), thalamus and hypothalamus; surrounds the 3rd ventricle
Midbrain
location and function
Uppermost area of brainstem, gives rise to CN III and IV
Cavity forms the cerebral aqueduct that conducts CSF from lateral and 3rd ventricles to 4th ventricle
pons location and function
Part of the brainstem that lies between midbrain and medulla oblongata, gives rise CN V
Cavity in the pons forms the upper portion of the 4th ventricle
Medulla oblongata
Most caudal part of brainstem, continuous with spinal cord; gives rise to CN IX, X, XII
CN VI and VIII at junction of medulla oblongata and pons
Cavity of the medulla oblongata forms the inferior part of the 4th ventricle
cerebellum
Lies beneath tentorium cerebelli
Receives information from the sensory systems, the spinal cord, and other parts of the brain and then regulates motor movements.
Where is the CSf Produced
CSF is produced by the choroid plexus located all four ventricles
400-500ml/day
CSF Pathway
(2) lateral ventricles which open into the third via interventricular foramina (of Monro)
Third ventricle lies between the halves of the diencephalon and continuous with the cerebral aqueduct
Fourth ventricle then tapers into a narrow channel that continues into the spinal cord as the central canal
CSF drains from the fourth ventricle through a single median aperture (of Megendie) and paired lateral apertures (of Luschka) into subarachnoid space
If these apertures become blocked CSF builds up and distends ventricle system
CSF is then absorbed into the venous system through the arachnoid granulations
Internal carotid and vertebral arteries
Receives 1/6 of the the cardiac output
Consumes 1/5 of the body’s oxygen at rest
Internal carotid
Arise from common carotid
Enters cranial cavity through carotid canals
Exits into cranial cavity passing over the foramen lacerum
Terminal branches are the anterior and middle cerebral arteries
2 Vertebral arteries
Arise from subclavian arteries
Enters cranial cavity through the foramen magnum
Posterior inferior cereballar artery braches off .
Anterior inferior cerebellar artery branches off
Anterior spinal artery
Basillar artery becomes main runoff….pontine branches come off here.
Superior cerebellar
artery
Posterior cerebral artery
2 posterior communicating arteries
2 main Internal Carotid arteries that form the middle cerebral artery
and 2 anterior cerebral artery.
These anterior cerebral arteries come together to form the Anterior communicating artery.
Somatic efferent
voluntary striated muscle
Visceral efferent (motor):
glands and involuntary smooth muscle, autonomic nervous system-parasympathetic (CN III, VII, IX, X)
Parasympathetic
General visceral afferent
sensation from the viscera
General somatic sensory
sensation from skin and mucus membranes (CN V, VII, IX, X)
Special sensory
taste, smell, vision, hearing, balance
Olfactory nerve (CN I)
Special sensory (olfaction) from nasal mucosa Foramina in cribriform plate of ethmoid bone
Optic Nerve (CN II)
Exits cranium through optic canal/foramen
Special sensory, vision from retina
Oculomotor Nerve (CN III)
So4LR(abducens)
Exits cranial cavity through the superior orbital fissure
Somatic motor to all eye muscles except superior oblique and lateral rectus
Visceral motor
Parasympathetic innervation to sphincter pupillae and ciliary muscles in eye constricts pupil and accommodates lens of eye (lens becomes more rounded) for near vision
Presynaptic fibers carried on CNIII, synapse in the CILIARY GANGLION, postsynaptic fibers pass to the eyeball via short ciliary nerves
TROCHLEAR NERVE (CN IV)
Exits cranium by the superior orbital fissure
Motor to superior oblique eye muscle
Injury results in diplopia when looking down
ABDUCENT NERVE (CN VI)
Exits cranium by the superior orbital fissure
Motor to lateral rectus eye muscle
Injury results in inability to abduct the eye on the affected side
Sympathetic innervation of the eye
Presynaptic sympathetic fibers originate T1-T3, travel to the superior cervical chain ganglion and synapse
Postsynaptic sympathetic fibers then travel with internal carotid artery, pass through the ciliary ganglion into the short ciliary nerves into the
Trigeminal Nerve number 5
Ophthalmic (CN V1)
Exits via superior orbital fissure
General somatic sensory from the cornea, skin of forehead, scalp, eyelids, nose and mucosa of nasal cavity and paranasal sinuses
Maxillary (CN V2)
Exits via foramen rotundum
General somatic sensory from skin of face over maxilla(Cheek), upper lip, maxillary teeth, mucosa of nose, maxillary sinuses, palate, nasopharynx
Mandibular (CN V3)
Exits via foramen ovale
General somatic sensory from skin over mandible, lower lip, side of head, mandibular teeth, temporomandibular joint, mucosa of mouth, and anterior 2/3 of tongue
Somatic motor to muscles of mastication
Facial nerve number 7
Exits via stylomastoid foramen via the internal acoustic meatus
Sharp bend geniculum of the facial nerve, contains geniculate ganglion (sensory component of CN VII)
Somatic motor to muscles of facial expression, posterior belly of digastric, stylohyoid and stapedius
Terminal branches: posterior auricular, temporal, zygomatic, buccal, mandibular and cervical
Visceral motor
Via pterygopalatine ganglion for innervation to lacrimal, nasal, pharyngeal and palatine glands
Via submandibular ganglion for innervation to sublingual and submandibular salivary glands
Somatic sensory to small area close to the external acoustic meatus
Special sensory via lingual nerve (of CN V) transmits taste from anterior 2/3 of tongue and soft palate
Parasympathetic pathway of CN7
1.Great petrosal+ pterygopalatine ganglion+ Lacrimal nerve> all join up to innervate the lacrimal gland.
2.Chordae tympani+Lingual nerve+submandibular ganglion> then innervate submandibular gland and sublingual gland
increase saliva in the mouth.
Visceral innervation of cranial nerve 7
Review slide 34
CN 8 Vestibulocochlear Nerve
Vestibular
Exits via the internal acoustic meatus
Special sensory for balance and equilibrium from semicircular ducts
stays in the brain
Cochlear
Exits via internal acoustic meatus
Special sensory of hearing from the spiral organ
Glossopharyngeal Nerve (CN IX)
slide 36
Exits via the jugular foramen
Somatic motor to the stylopharyngeus muscle to assist with swallowing, responsible for gag reflex
General somatic sensory to the external ear, oropharynx, and middle ear
Cell bodies contained within the superior and inferior ganglia
Special sensory taste from posterior 1/3 of tongue
Cell bodies contained within the superior and inferior ganglia
Visceral motor-Parasympathetic innervation to parotid gland via otic ganglion
Visceral sensory to the carotid body and sinus
Cell bodies contained within the superior and inferior ganglia
Parasympathetic innervation of CN IX
Lesser patrossel –Otic ganglion-Auriculotemporal nerve-parotid gland
VAgus nerve
Exits via jugular foramen
Somatic motor to constrictor muscles of pharynx, intrinsic muscles of larynx, muscles of palate (except tensor veli palatini), and striated muscle in superior 2/3 of esophagus
General somatic sensation from auricle, external acoustic meatus and dura mater of posterior cranial fossa
Special sensory of taste from epiglottis and palate
Visceral motor-Parasympathetic innervation to smooth muscle of trachea, bronchi, digestive tract and cardiac muscle of heart
Visceral sensory from base of tongue, laryngopharynx, larynx, trachea, bronchi, heart, esophagus, stomach and intestine
Spinal Accesory nerve 11
Exits via jugular foramen
Somatic motor to the sternocleidomastoid and trapezius muscles
Hypoglossal nerve (CN XII)
Exits via hypoglossal canal
Somatic motor to the extrinsic muscles- styloglossus, hyoglossus, genioglossus (expect palatoglossus) and intrinsic muscles of the tongue via lingual branches
Provides superior root of the Ansa cervicalis to supply the infrahyoid muscles
