Exam 1 Week 1 Flashcards
Why is the face unique? (4)
- thin or thick skin?
- any glands?
- fascia?
1- Skin on face is THIN and MOVEABLE
2- Skin has MANY sebaceous and sweat glands
3- Superficial fascia of face is LOOSE, except at nose (moveable for facial expression)
4- There is NO DEEP fascia over face
Where are the muscles of facial expression found/embedded in?
Embedded in SUPERFICIAL FASCIA
(Innervation - facial nerve CN VII)
**superficial fascia of face is loose, except at nose (so it can be moveable for facial expression)
In severe damage to the face, what is required and why?
What can’t you use?
- FACIAL TRANSPLANT required
- because muscles of facial expression insert onto skin rather then tendons (so you CANNOT use grafts of other body muscles
What are the 3 unique properties of facial muscles
1- embedded/origin
2- what type of control
3- how are muscle contractions detected and why
1- Embedded in superficial fascia and take origin form underlying bones (mostly) and INSERT INTO SKIN
2- NEURAL control is BOTH VOLUNTARY and EMOTIONAL/INVOLUNTARY control
3- Muscle contractions are DETECTED BY STRETCHING OF SKIN since facial muscles have FEW or NO muscle SPINDLES
There are 2 main disorders of facial nerve CN VII. Identify this;
- associated with VIRAL infection HERPES SIMPLEX
- Symptoms; sudden onset PARALYSIS OF ALL FACIAL MUSCLES on ONE SIDE (drooling, inability to close eye)
- loss of taste to anterior tongue
- pain in or behind EAR
- Hyperacousia
BELL’S PALSY - LOWER motor neuron disorder of facial nerve CN VII
**
Drooping EYEBROW AND UPPER LIP
(Muscles of BOTH upper and lower face affected)
There are 2 main disorders of facial nerve CN VII. Identify this;
- SPARING of UPPER face
- After critical stokes, often ONLY MUSCLE OF LOWER FACE are PARALYZED on ONE SIDE
- muscles of upper face are not affected (brow, orbicularis oculi)
- cortical projections (CONTROL) are bilateral to upper face and unilateral (contralateral) to lower face
UPPER MOTOR NEURONS DISORDER OF VII
**Drooping of ONLY upper lip (not eyebrow)
Identify the appropriate control of muscles of facial expression
1- upper motor neuron lesion and control
2-Lower motor neuron lesion and control
1- UPPER
- cortical stroke (vascular occlusion)
- Affects only muscles of lower face (sparing of upper face)
- UPPER FACE CONTROL IS BILATERAL
- lower face control is UNILATERAL/CONTRALATERAL CORTEX
2- LOWER
- Bell’s palsy
- Affects all muscles of facial expression
- Symptoms are UNILATERAL
The circulatory system supplies the heart and then the brain. The brain is supplied with what main artery? Where does it come directly from?
COMMON CAROTID ARTERY
1- Left common carotid artery; comes directly from the ARCH OF AORTA
2- Right common carotid artery comes from the BRACHIOCEPHALIC TRUNK
The COMMON CAROTID a. Is the main artery that supplied the head. What does this artery further divide to in order to supply ;
- the brain?
- the face and head?
1- Common carotid ; EXTERNAL and INTERNAL carotid arteries
2- Internal carotid artery and vertebral artery SUPPLY BRAIN
3- External carotid artery SUPPLIES FACE AND HEAD Branches; 1- Superior thyroid 2- Ascending pharyngeal 3-Lingual 4-FACIAL 5-Occipital 6-Posterior auricular 7-SUPERFICIAL TEMPORAL 8-Maxillary
What are the 3 sites to take pulse?
1- PULSE OF CAROTID ARTERY: Palpate CAROTID BIFURCATION at upper border of thyroid cartilage at vertebral level C4
2- FACIAL PULSE (a branch of external carotid artery); courses first medial to mandible and then anterior
3- SUPERFICIAL TEMPORAL ARTERY (a branch of external carotid a.); arises anterior to external auditory meatus (opening to ear), deep to parotid
The main artery that supplies the face/head/brain is the common carotid artery. It branches off to external carotid (supply face and head) and internal carotid (supply brain).
**What are the 2 main arteries that supply the HEAD?
1- FACIAL a.
-extremely winding and tortuous (skin moves) WIGGLE WIGGLE WIGGLE
-arises from anterior side of external carotid a.
-courses first medial to mandible and then anterior
-site of facial pulse
**2 BRANCHES of facial artery:
A-Superior and Inferior LABIAL arteries; upper and lower lips (anastomoses with opposite side, lead to profuse bleeding when you cut lip)
B-ANGULAR artery; nose, angle/corner of eye
2- SUPERFICIAL TEMPORAL a.
-one of terminal branches
-arises anterior to external auditory meatus (Opening to ear), deep to parotid
-many branches to scalp
Branch to face is ;
A- TRANSVERSE facial artery; above parotid duct
What artery supplies the brain and also branches to eye and face?
Further branches
**what is the major route for nerves/blood vessels to get to face and nasal cavity
INTERNAL CAROTID ARTERY (enters skull WITHOUT branching)
A. Ophthalmic artery; many branches to orbit but also has a number of named branches to face, forehead and nose ;
- SUPRAORBITAL a. (Above orbit)
- SUPRATROCHLEAR a. (On medial and superior side of orbit)
**Orbit/eye socket contains the eye and muscles that move the eye; orbit is also a MAJOR ROUTE for nerves/blood vessels to get to other places like face and nasal cavity
NAME THE ARTERY
1- courses through foramina transversaria C1-C6; supplies brain stem and spinal cord and go to skull
2- ascends without branching into skull (via carotid canal)
1- VERTEBRAL artery
2- INTERNAL CAROTID artery
**Both supply the brain
What is unique about veins of face?
- how many valves?
- drain to?
- anastomosis?
**what are the 3 veins that supply face
VEINS OF FACE have NO VALVES or few and variable
- drain to neck and into skull
- extensive anastomoses btw branches of facial and ophthalmic veins
3 veins (Branches follow arteries) 1- Facial vein; STRAIGHT course
To ophthalmic veins;
1- SUPRAORBITAL vein
2- SUPRATROCHLEAR vein
How does infection spread from face to brain?
Pass through what to what?
What is the clinical sign?
**what is the anastomosis of facial and ophthalmic vein called?
- PROLONGED INFECTIONS spread VIA VEINS (low pressure and no valves)
- Pass through orbit to CAVERNOUS SINUS (anastomoses of facial and ophthalmic veins - ophthalmic veins drain to cavernous sinus (venous sinus inside skull))
CLINICAL SIGN ; blurred vision/ DIPLOPIA (cranial nerves - III,IV,VI to eye muscles pass through cavernous sinus); infections LATERAL to nose particularly dangerous
Name the 12 cranial nerves and function
I. OLFACTORY - sense of smell
II. OPTIC - vision
III. OCULOMOTOR - eye movement
IV. TROCHLEAR - eye movement
V. TRIGEMINAL - touch, general sensation to skin, oral cavity, nasal cavity and more
VI. ABDUCENS - eye movement
VII. FACIAL - muscles of facial expression and lots more
VIII. VESTIBULO-COCHLEAR - hearing and balance
IX. GLOSSOPHARYNGEAL - SENSORY to pharynx and more
X. VAGUS - SENSORY and MOTOR to larynx (voice box), pharynx and rest of body
XI. ACCESSORY - sternocleidomastoid, trapezius
XI. HYPOGLOSSAL - muscles of tongue
The dermatome/sensory innervation of the trigeminal nerve - to skin of head has 3 divisions. What are they?
**What type of sensation and neuron?
V1- OPHTHALMIC division
Boundary - lateral edge of EYE
V2- MAXILLARY division
Boundary - lateral edge of MOUTH
V3- MANDIBULAR division
- *SOMATIC SENSORY
- *PRECISE SENSATION
The sensory supply of trigeminal nerve to face has 3 branches. What are the further divisions/
V1 Ophthalmic - to skin ABOVE ORBIT
- Lacrimal
- SUPRAORBITAL
- SUPRATROCHLEAR
- Infratrochlear
- External nasal nerve
V2 Maxillary - to skin of cheek BELOW ORBIT
- Zygomaticotemporal
- Zygomaticofacial
- Infraorbital
V3 MANDIBULAR - to skin of jaw and face BELOW ANGLE OF MOUTH
- Auriculotemporal
- Buccal
- Mental
What muscles ;
Move skin of face, close eyes and mouth, allow to convey emotions by facial gestures like sneering and contempt)
**what is the innervation
How do you test for nerve function
MUSCLES OF FACIAL EXPRESSION (all skeletal muscles)
-most attached to bones and insert upon skin
- *CN VII - facial nerve
- movements elicited in test for facial nerve function
There are 15 total muscles of the facial expression. What is the 1 muscle in the eye? What is the action ?
Nerve
ORBICULARIS OCULI
Action
1) Orbital part (surrounds eyelids) - buries eyelids (as in sandstorm)
2) Palpebral part (within eyelids) - CLOSES EYELID
Nerve
VII
Why is closing the eyelid by the orbicularis oculi important?
CLOSING EYELID essential to PREVENT CORNEA DAMAGE
-cover, sew eyelids shut (neonates) in facial paralysis
There are 15 total muscles of the facial expression. 1 in the eye and 3 in the nose. What are the muscles in the nose and the actions
NOSE
1- COMPRESSOR NARIS; compress nasal cartilage
2- DILATOR NARIS; dilates nostrils (contempt)
3- PROCERUS; wrinkles skin of nose (sneering)
There are 15 total muscles of the facial expression. 1 in the eye, 3 in the nose and 7 in the mouth. What are the mouth muscles and actions
2 upper lip
3 angle of mouth
2 lower lip/chin
MOUTH
1- ORBICULARIS ORIS; closes mouth (surrounds lips)
2- LEVATOR LABII SUPERIORIS; lifts upper lip
3- ZYGOMATICUS MAJOR AND MINOR; raise and pull upper lip laterally
4- LEVATOR ANGULI ORIS; raises corner of mouth
5- RISORIUS (smiling muscle); smiling muscle
6- DEPRESSOR ANGULI ORIS; tragedy muscle
7- DEPRESSOR LABII INFEIORIS; depresses lower lip
Bell’s palsy exhibit various syspoms
- Drooping of corner of mouth in Bell’s palsy is as a result of what muscle affected?
- difficulty ‘eating food’, drooling
- Drooping of eye brow
**what muscles are affected?
1- LEVATOR ANGULI ORIS
2- BUCCINATOR
3- Frontalis and occipitalis
There are 15 total muscles of the facial expression. 1 in the eye, 3 in nose, 7 in mouth and 4 others
OTHER
1- MENTALIS; wrinkles skin of chin
2- BUCCINATOR; compresses mouth and keeps food btw teeth when chewing
3- FRONTALIS AND OCCIPITALIS ; move scalp (attach to epicranial aponeurosis); frontalis raises eyebrows
4- PLATYSMA; stretches skin of neck
What is the clinical test for FACIAL nerve function
1- wrinkle head by raising eyebrows; FRONTALIS
2- purse lips; ORBICULARIS ORIS
3- smile; RISORIUS
4- show teeth; LEVATOR LABII SUPERIORIS, ZYGOMATICUS MAJOR etc.
What is the MOTOR innervation to muscles of facial expression via facial nerve
What are the 5 terminal branches
- nerve leaves skull via STYLOMASTOID FORAMEN
- enters parotid gland
- divides into 5 terminal branches;
- Temporal
- Zygomatic
- Buccal
- MANDIBULAR
- Cervical
How does the face develop to five facial primordial
- what week do they form
- 3 processs of face
- what do they surround
-form in FOURTH WEEK in development and surround developing stomodeum (primitive mouth)
- Frontonasal process; formed by MESENCHYME below brain; UNPAIRED
- Maxillary processes; form first branchial arch; PAIRED
- MANDIBULAR processes; form first branchial arch, inferior to maxillary process
What is the sequence of development of face
- what form on each side of frontonasal process
- what form at margins of nasal placode
- what from upper part of nostril
- what form upper lip
- how is nasolacrimal duct formed (major function)
- THICKENINGS (NASAL PLACODES) form on each side of frontonasal process
- Medial and lateral nasal processes form at MARGINS of NASAL PLACODES
- Upper parts of medial and lateral nasal processes fuse to form UPPER PART OF NOSTRIL
- Inferior part of medial nasal processes fuse with maxillary process on each side to form UPPER LIP
- Nasolacrimal duct
- connects anterior eye to nasal cavity; - DRAINS TEARS,
- forms in development as a solid epithelial cord that extends from medial angle of eye to nasal cavity, cord BECOMES CANALIZED to from duct
What condition results from FAILURE OF FUSION of medial nasal processes with maxillary process on that side
CLEFT LIP
- *can be unilateral or bilateral
- *occurs in 1 in 1000 births
- can occur in combination with cleft palate
What condition results from failure of duct to canalize; must be opened for tears to drain to nasal cavity
What is tx?
OBSTRUCTED NASOLACRIMAL DUCT
**opened surgically for tears to drain to nasal cavity
Identify the nerves
1- contain inflow/outflow of SPINAL CORD
2
- contain inflow/outflow of BRAIN
- often contain types of neurons that are SIMILAR to types of neurons found in spinal nerves like SENSORY AXONS of SKIN
- contain types of neurons not found in spinal nerves e.g TASTE FIBERS
- contain more than one type of neuron
1- SPINAL NERVES
2- CRANIAL NERVES
**there is a system of classification of types of neurons used to analyze types of neurons in diff cranial nerves
In order to analyze and remember the types of neurons found in different cranial nerves, there is a system of classification of types of neurons. Why is this?
*how many types of neurons
Neurons of same type will form columns of nuclei in the brain stem
7 types of neurons
There are 7 types of neurons found in the cranial nerves. 4 of which are same types as spinal nerves. The other 3 are only found in cranial nerves.
Identify the 7
A. Same as in spinal nerves
- SOMATIC MOTOR (GSE); voluntary SKELETAL muscles (derived from somites)
- SOMATIC SENSORY (GSA); Sensation is PRECISE to skin joints, muscle, tendon receptors (in head, also nasal and oral cavities)
- VISCERAL MOTOR (GVE-efferents) = AUTONOMICS -SMOOTH muscles (including arrector Pilae muscles of skin), blood vessels; secretomotor to target glands
- VISCERAL SENSORY (GVA); Sensation is IMPRECISE from gut, blood vessels, glands, internal organs (in head, pharynx which is rostral end of gut)
B. Only in cranial nerves
- SPECIAL SENSES (SSA) - vision, hearing (auditory), balance (vestibular apparatus)
- CHEMICAL SENSES (SVA)- taste and smell
- BRANCHIOMOTOR (SVE)- voluntary skeletal muscles from branchial arches
Name the cranial nerves and innervation
I. OLFACTORY ; smell
II. OPTIC; vision
III. OCCULOMOTOR; eye movement, also parasympathetic to eye smooth muscle
IV. TROCHLEAR ; eye movement
V. TRIGEMINAL ; SENSORY nerve to skin, oral and nasal cavities, outer ear
VI. ABDUCENS ; eye movement
VII. FACIAL; muscles of facial expression, also taste, parasympathetic e.t.c
VIII. Vestibule-cochlear (stato-acoustic); hearing and balance
IX. GLOSSOPHARYNGEAL; SENSORY to pharynx, back of tongue (gag reflex)
X. VAGUS ; MOTOR to pharynx (most), larynx (voice box), soft palate, many others
XI. ACCESSORY (Spinal accessory) ; MOTOR to sternocleidomastoid, trapezius
XII. HYPOGLOSSAL ; MOTOR to muscles of tongue
Identify the neuron type
- considered VOLUNTARY, CONSCIOUS part of nervous system
- control skeletal muscle
- VOLUNTARY activities (e.g limb or eye movements, walking)
- conscious actions
SOMATIC MOTOR (Efferents)
Motor axons to skeletal muscles e.g muscles of hand
**This neuron type found in cranial nerves is similar to those found in spinal cord (INNERVATE VOLUNTARY SKELETAL muscles derived from somites)
- somatic motor in head is limited to 2 GROUPS
1. EYE (extraocular muscles that move eye and lift upper eyelid) - derived from pre-otic somites, innervated by - Occulomotor III ; to superior, inferior and medial RECTUS, Inferior oblique and LEVATOR palpebrae SUPERIORIS (skeletal part)
- TROCHLEAR IV ; to Superior oblique muscle
- ABDUCENS VI; lateral RECTUS muscle
- Intrinsic and Extrinsic muscles of TONGUE - derived from OCCIPITAL SOMITES - all innervated by XII (HYPOGLOSSAL)
Identify the neuron type
- considered VOLUNTARY, CONSCIOUS part of nervous system
- sensory neurons that innervate skin joints
- provide PRECISE CONSCIOUS SENSATION of touch, pressure, pain etc. to skin
- also provide SENSE OF BODY POSITION (prioception)
SOMATIC SENSORY (Afferents)
Sensory axons to skin; also joints, body position
- innervate SKIN OF HEAD, ORAL cavity, NASAL cavity, joints, muscles;
- sensory cell bodies in sensory ganglia attached to cranial nerves as they enter central nervous system, similar to DRG (dorsal root ganglia)
- All of face, forehead, temporal region, ORAL CAVITY, temporo-mandibular joint
innervated by V (TRIGEMINAL); Note: cell bodies in TRIGEMINAL GANGLION (similar to dorsal root ganglia of spinal nerves). - Exception: skin of outer ear, external auditory meatus is innervated by V
(TRIGEMINAL), plus branches of VII (FACIAL), IX (Glossopharyngeal) and X (VAGUS). (note: sensory cell bodies of VII in sensory ganglion called GENICULATE GANGLION)
Note: In Bell’s Palsy (paralysis of VII) patients can complain of EAR ACHE due to PRECISE sensory innervation of outer ear by FACIAL NERVE.
Identify the neuron type
- INVOLUNTARY, unconscious part of nervous system
- control SMOOTH and cardiac muscle, glands and internal organs
- largely UNCONSCIOUS ACTIONS (autonomic means self-regulating or automatic)
VISCERAL MOTOR (PARASYMPATHETIC and sympathetic efferents)
- SYMPATHETIC innervation (THORACOLUMBAR OUTFLOW) - NOT in cranial nerves
A. FIRST NEURON arises from spinal cord levels T1, T2; axons exits via ventral roots and white communicating rami, ascends in paravertebral sympathetic chain to synapse in superior cervical ganglion
B. SECOND NEURON in SUPERIOR CERVICAL GANGLION; axon joins plexuses associated with branches of internal and external carotid arteries; these give off branches in 2 ways; i) small unnamed branches close to target ; II) small named branches that come off arterial plexuses and join other nerves (e.g deep petrosal nerve)
- PARASYMPATHETIC innervation (CRANIOSACRAL OUTFLOW) - in cranial nerves - FIRST NEURON (PREGANGLIONIC) in brainstem; axon goes out with cranial nerve to synapse in named ganglion located close to target; SECOND NEURON (POSTGANGLIONIC) innervates target
- *Sympathetic - ganglia close to vertebrae
- *Parasympathetic - ganglia close to target organ
Identify the neuron type
- INVOLUNTARY, unconscious part of nervous system
- SENSORY neurons that innervate internal organs, blood vessels
- only provide IMPRECISE LOCALIZATION OF SENSATION and dull sense of pressure, pain etc
VISCERAL SENSORY (afferents)
- distributed with both parasympathetic and sympathetic innervation; imprecise sensation, poorly localized
1. Sensory axons with sympathetic - sensory to blood vessels, pharynx and its derivatives; cell bodies in dorsal root ganglia of spinal cord; axons travel with sympathetic efferents
2. Sensory axons with parasympathetic - more localized, specific
What are the 4 nerves of visceral motor, their respective ganglion and innervation?
III (OCULOMOTOR)
- CILIARY ganglion - innervates pupillary sphincter/constrictor muscle, ciliary muscle
VII (Facial)
- PTERYGOPALATINE ganglion - lacrimal gland, mucous glands of nose palate
- SUBMANDIBULAR ganglion - submandibular, sublingual salivary glands
IX (GLOSSOPHARYNGEAL)
- OTIC ganglion - parotid gland
X (Vagus) - Many ganglia in thorax, abdomen - provides parasympathetic innervation to many organs in thorax and abdomen
What are the 3 nerves of the visceral sensory nerves and their respective innervation
- Nasopharynx
- sensation to laryngopharynx, larynx in head
- Sensation to posterior third of tongue
VII (facial) - innervates NASOPHARYNX
IX (GLOSSOPHARYNGEAL) - sensation (touch, pressure) to posterior third of tongue, OROPHARYNX, tympanic cavity and auditory tube, carotid sinus
X (Vagus) - Sensation to LARYNGOPHARYNX, larynx in head (also innervates many organs in thorax and abdomen)
**Imprecise localization in CHOKING on food; middle ear infections
There are 7 neurons in the cranial nerve. Identify the neuron type
- INNERVATE; Vision, hearing, balance
- ASSOCIATED CN;
- II (Optic nerve)
- VIII (VESTIBUOCOCHLEAR nerve)
SPECIAL SENSES
- II (Optic nerve)
- vision (actually a brain tract);
- primary receptors (rods and cones) in retina;
- axons of ganglion cells of retina from optic nerve;
- half of axons cross over to opposite side of optic chiasm
**VIII (Vestibulocochlear nerve) - auditory and vestibular sensation; cell bodies in cochlear and vestibular apparatus
There are 7 neurons in the cranial nerve. Identify the neuron type
INNERVATION -Smell and taste
ASSOCIATED CN
- I (Olfactory nerve) for smell
- VII, IX, X for taste (what parts of the tongue?)
CHEMICAL SENSES
- Smell - I (Olfactory nerve) - cell bodies in olfactory epithelium, axons project through fila olfactoria to olfactory bulb
- Taste - more complex - distributed over several cranial nerves
VII (facial) - ANTERIOR 2/3rd of TONGUE
IX (GLOSSOPHARYNGEAL - POSTERIOR 1/3RD of tongue
X (Vagus) - POSTERIOR tongue, immediately anterior to epiglottis
**Damage produces loss of taste in region of innervation
There are 7 neurons in the cranial nerve. Identify the neuron type
-VOLUNTARY MOTOR to SKELETAL MUSCLES of face, ear, pharynx and neck that are derived from BRANCHIAL ARCHES
What are the 5 nerves and what do they innervate Tensor palati Stapedius Stylopharyngeus Muscles of larynx Trapezius
BRANCHIOMOTOR
V (Trigeminal) all in V3 - muscles of mastication, mylohyoid, tensor tympani, tensor palati, anterior belly of digastric
VII (Facial) - muscles of facial expression, stylohyoid, posterior belly of digastric, stapedius
IX (GLOSSOPHARYNGEAL) - stylopharyngeus
X (Vagus) - all muscles of pharynx (except stylopharyngeus), muscles of larynx, all muscles of palate (except tensor palati)
XI (Accessory) - sternocleidomastoid, trapezius
What are the neuron components of CN III (OCULOMOTOR)
- Somatic motor (GSE)
2. Visceral motor (GVE)
What are the cranial nerves that only contain somatic motor neurons (GSE)?
IV - TROCHLEAR
VI - ABDUCENS
XII - Hypoglossal
**III is also somatic motor but also visceral motor
What cranial nerve contains both BRANCHIOMOTOR (SVE) and SOMATIC SENSORY (GSA) neurons?
CN V (trigeminal) VII IX X
**XI is in BRANCHIOMOTOR but not in somatic sensory
What are the neurons contained in CN VII (facial), IX (GLOSSOPHARYNGEAL), X (vagus)
- BRANCHIOMOTOR (SVE)
- VISCERAL MOTOR (GVE)
- SOMATIC SENSORY (GSA)
- VISCERAL SENSORY (GVA)
- CHEMICAL SENSE (SVA)
**All neurons except special senses (SSA) and somatic motor (GSE)
What is the neuron present in CN I
CHEMICAL SENSES (SVA)
**Other neurons in chemical senses I - smell VII - anterior 2/3rd of tongue IX - posterior 1/3rd of tongue X- anterior to epiglottis
WHAT NEURON IS PRESENT IN CN II (optic) AND VIII (vestibulococchlear)
SPECIAL SENSES (SSA)
*II - vision
VIII- hearing and balance
The 7 types of neurons can be classified in the 3 letter system
- G/S
- S/V
- A/E
- G - general (types of neurons found BOTH in spinal nerves and cranial nerves)
S - special (types of neurons ONLY FOUND in CRANIAL NERVES not spinal nerves) - S - Somatic - types of neurons innervation gets structures derived from somites (myotomes)
V - Visceral - types of neurons innervating gut, structures derived from or associated with GUT and BRANCHIAL ARCHES, also vascular system, smooth muscle, internal organs and glands - A - afferent - sensory neurons
E - Efferent - motor neurons to skeletal and smooth muscle, also secretomotor neurons to glands
Vision is composed of eye that senses and transmits information about shape, color and movement of objects. What are the other components/structures responsible for vision (4)
3 chambers
3 layers
- Internal space has 3 chambers
- anterior (located btw cornea, iris and lens)
- posterior (small space btw iris, ciliary process, ZONULAR fibers and lens)
- vitreous (large posterior space behind lens and ZONULAR fibers, surrounded by retina) - Lens
- Optic nerve - (visual images are conveyed from eye to brain via optic nerve)
- Eye wall structure has 3 layers
- sclera, cornea
- uveal tract (densely pigmented posterior portion is CHOROID, anterior portion is CILIARY BODY, third portion is IRIS)
- retina (innermost lining of posterior chamber in contact with choroid. Posterior three quarters is Photosensitive region consists of rods, cones and various interneurons - cells that are stimulated by and respond to light). Retina terminates anteriorly at ORA SERRATA -nonphotosensitive part of retina
What connects the lens to the ciliary body?
What is the function of the eye? Where is eye located?
Contents of the eye?
SUSPENSORY LIGAMENT / ZONULAR FIBERS
**The eye is a highly specialized organ for PERCEPTION of form, LIGHT and COLOR
-The eye is located in protective cavities within the skull called ORBITS
-Each eye contains;
+PROTECTIVE COVER to maintain its shape
+A LENS for focusing
+PHOTOSENSITIVE CELLS that respond to light stimuli
+NUMEROUS CELLS that process visual information
(The visual impulses from the photosensitive cells are then conveyed to the brain via the axons that leave the eye in the OPTIC NERVE)
Each eyeball is surrounded by 3 distinct layers
Identify the structure of the eye wall
-outer white layer
-DENSE connective tissue
+ collagen and elastic fibers
+ point of attachment of extraocular muscles
-ANTERIOR portion is the CORNEA (light rays enter eye through here)
-Inner layer is located adjacent to the CHOROID (contains diff types of CT fibers and cells, including macrophages and melanocytes, have many blood vessels that give nutrient to photoreceptor cells)
SCLERA
- (maintains the RIGIDITY of the eyeball and is the WHITE of the eye)
- choroid and ciliary body are adjacent to sclera
3 layers of eyeball
- Outer fibrous layer; cornea and sclera
- Middle layer; vascular layer (UVEA)- CHOROID, ciliary body, iris
- Inner layer; sensory retina
Each eyeball is surrounded by 3 distinct layers. The outer fibrous layer, middle layer and inner layer. The outer fibrous layer consist of cornea and sclera.
- In the layers of the eye, the transition btw sclera and cornea is what?
- In the posterior region, what does the sclera merge with?
LIMBUS
**In the posterior region, the sclera merges with the dura mater where the optic nerve exits the eye
(The posterior five sixths of the sclera is an OPAQUE outer layer of DENSE CT that extends from the cornea to the optic nerve)
Each eyeball is surrounded by 3 distinct layers. The outer fibrous layer, middle layer and inner layer. The outer fibrous layer consist of cornea and sclera.
Identify this
- Transparent and thick
- no blood vessels
- many nerve endings
- has 5 layers
What are the layers
CORNEA (on the ANTERIOR SIXTH of the eyeball, the fibrous sclera is modified into a transparent cornea through which light rays enter the eye)
- Corneal epithelium
- Bowman’s layer
- Stroma
- Descemet’s membrane
- Corneal endothelium
There are 5 layers of cornea. Identify this layer
- superficial cells have microvilli (helps to maintain moisture by retaining tears)
- basal cells connect to Bowman’s membrane by hemidesmosomes
CORNEAL EPITHELIUM
**Epithelium is stratified squamous non-keratinizing
There are 5 layers of cornea. Identify this layer
- transparent, randomly oriented collagen TYPE 1 fibers
- protects against trauma and bacteria
BOWMAN’S LAYER
There are 5 layers of cornea. Identify this layer
- COLLAGEN I and V
- fibers in thin layers arranged in parallel bundles that run at various angles
- FIBROBLASTS btw layers
- rich in PROTEOGLYCANS
- nerves pass through stroma to epithelium
STROMA
There are 5 layers of cornea. Identify this layer
-THICK basement membrane ( endothelial cells attach here)
DESCEMET’S MEMBRANE
There are 5 layers of cornea. Identify this layer
- SIMPLE SQUAMOUS CELLS facing the anterior chamber
- IMPERMEABLE to fluid from anterior chamber
ENDOTHELIUM
Each eyeball is surrounded by 3 distinct layers. The outer fibrous layer, middle layer and inner layer. The outer fibrous layer consist of cornea and sclera. The middle layer is the uveal tract and inner layer is retina.
Identify the structure of the eye wall
- found btw sclera and light sensitive retina
- contains melanocytes and blood vessels (give blood supply to eye)
- highly pigmented DARK BROWN layer that contains diff types of CT fibers and cells, including macrophages and melanocytes
- have many blood vessels that give nutrient to photoreceptor cells in the retina and structures of the eyeball
POSTERIOR PORTION OF UVEAL TRACT : CHOROID
3 layers
- Suprachoroid lamina/layer ; CT fibers and numerous melanocytes
- Vascular layer; blood vessels and melanocytes
- Choriocapillaris layer; capillaries with large lumina
- Innermost layer of choroid is glassy membrane and lies adjacent to pigment cells
- Pigment cells separate choroid from retina and perform important functions ; phagocytosis, store VIT A and form visual pigments for rods and cones
The anterior portion of the eye is made of what 3 parts
- what part help with accommodation
- what is continuation of ciliary body in front of lens
- Ciliary body and processes
- projection of choroid and retina
- FUNCTIONS; accommodation and production of aqueous humor - Iris
- continuation of CILIARY BODY in front of lens
- partially covers the lens and is the colored part of the eye
- radial smooth muscle forms an opening in the iris called the PUPIL - Lens
Name the structure of the eye wall
- Primarily contains smooth muscle arranged in longitudinal, circular and radial directions
- contraction changes shape of lens - Ciliary processes
-attach to lens by SUSPENSORY LIGAMENTS
-covered with 2 layers of epithelial cells
+superficial not pigmented
+deep cells are pigmented
ANTERIOR PORTION OF THE UVEAL TRACT ; CILIARY BODY
Ciliary process
- Pigmented; continuous with retinal pigmented epithelium
- Non-pigmented; continuous with sensory retina
**Posterior side of Iris has 2 layers of pigmented cells
Identify
- watery secretion formed by the EPITHELIUM of the CILIARY PROCESS located behind the iris in the posterior CHAMBER.
- bathes and supplies the non-vascular cornea and lens with nutrients and oxygen
- flows from posterior to ANTERIOR chamber and out trabecular mesh work into CANAL OF SCHELMM to circulation
**WHAT is the other content of the eye chambers?
AQUEOUS HUMOR
**The large vitreous CHAMBER is filled with a transparent gelatinous substance, called the VITREOUS BODY. The contents of the vitreous body are primarily water with some soluble proteins. The fluid component of the vitreous body is called the VITREOUS HUMOR.
Identify the part of eye
- extension of CILIARY BODY
- controls amount of light entering eye
- ANTERIOR SURFACE has no epithelial cells
- POSTERIOR SURFACE has 2 layers of pigmented cuboidal epithelial cells
- stroma contains melanocytes, fibroblasts, myoepithelial cells (dilator muscle) and blood vessels
IRIS f
Identify the part of eye
- focuses light on the retina
- ZONULAR fibers attach lens to ciliary body
- AVASCULAR
- Outer capsule (similar to a basement membrane)
- Simple cuboidal layer of lens epithelial cells ( only on the ANTERIOR SURFACE of lens)
LENS
**Len fibers
-derived from lens epithelium
-concentric layers of cells
+Lose nuclei and organelles toward center of lens
-packed with crystallins
Identify the posterior structures of the eye
- Vitreous chamber (posterior cavity)
- Ora serata
- Optic disc
- Macula lutea
Which posterior structure of the eye is this
- extends from lens to retina
- contains GEL-LIKE SUBSTANCE composed of water, hyaluronic acid and collagen fibers
VITREOUS CHAMBER
Gel-like substance is vitreous BODY (consists of mainly water);
- Fluid component of the vitreous body is the vitreous humor
- BODY contains small amounts of hyaluronic acid, very thin collagen fibers, glycosaminoglycans and some proteins
- BODY transmits incoming light, is nonrefractive with respect to the lens, contributes to the intraocular pressure and shape of the eyeball
- holds retina in place against the pigmented layer of the eyeball
Which posterior structure of the eye is this
- ANTERIOR BOUNDARY of the photosensitive portion of the retina
- Non-photosensitive portion of retina continues anteriorly to cover the ciliary body
ORA SERATA
Which posterior structure of the eye is this
- entry/exit point for the optic nerve and blood vessels
- No photoreceptors - BLIND SPOT (NO VISION)
OPTIC DISC
Which posterior structure of the eye is this
-Yellow spot on the posterior retina
-Fovea centralis
+ central depression
+ SHARPEST VISION in this region (high conc of cones)
-Immediately adjacent to and surrounding the depression fovea
-small area that appears yellow in retina due to the presence and accumulation of the yellow pigment XANTHOPHYLL in the laterallly located ganglion cells of the fovea
MACULA LUTEA
- *In the center of the macula lutea is FOVEA (shallow depression in the retina where blood vessels do not pass over the photosensitive cells).
- The FOVEA is devoid of photoreceptive rods and blood vessels. Instead it contains a DENSE conc of photosensitive CONES)
- The visual axis of the eye directly pass through the fovea, this is why the fovea in the eye produce the GREATEST VISUAL ACUITY and the SHARPEST COLOR DISCRIMINATION)
The retina has 8 layers. Name all
What are the 3 types of neurons found in the retina
- choroid
1. Pigment epithelium
2. Photoreceptor layer -rods and cones (Sensitive to light)
3. Outer nuclear layer - outer limiting membrane
4. Outer plexiform layer
5. Inner nuclear layer
6. Inner plexiform layer
7. Ganglion cell layer
8. Nerve fiber layer (optic nerve fiber layer) - Inner omitting membrane
3 NEURONS (Distributed in diff layers)
- Photoreceptive RODS and CONES (essential for vision, synapse with the bipolar cells which then connect the receptor neurons with the ganglion cells)
- BIPOLAR CELLS
- GANGLION CELLS (The afferent axons that leave the ganglion cells converge POSTERIORLY in the eye at the OPTIC PAPILLA/DISK and leave the eye as the OPTIC NERVE)
**OPTIC PAPILLA also called BLIND SPOT (no rods or cones, just axons)
The retina has 8 layer which has different cells per layer. Identify the layer and cell types
FUNCTION;- maintains viability of sensory retina
- transport nutrients to outer portion of sensory retina
- remove waste products
- phagocytosis and recycling of photoreceptor disks
- metabolism of retinol
- PIGMENTED EPITHELIAL CELLS
- Non-sensory
- Simple cuboidal cells
- Extends from optic disc to ora serrata then continues as PIGMENTED LAYER OF ciliary epithelium
- Melanin granules in apical cytoplasm
- Apical microvilli surround outer segments of photoreceptors
- Synthesize BRUCH’S MEMBRANE
(Basement membrane that attaches the retina to the choroid)
Identify the layers where photoreceptor cells are found
- RODS - Peripheral and night vision
* highly sensitive to light and function best in dim or LOW LIGHT (dusk/night)
* In the dark, a visual pigment (RHODOPSIN) is synthesized and accumulates in the rod cells which nitrates the visual stimulus when it interacts with the light - CONES - Distinguish color and detail
* Less sensitive to low light, respond best to BRIGHT LIGHT
* FOR HIGH VISUAL ACUITY and color vision
* Contain visual pigment (IODOPSIN) that responds maximally to the colors red, green or blue of color spectrums that trigger a visual response
***Absoption and interaction of light rays with these pigments cause transformations in the pigment molecules. This action excites the rods and/or cones and produces a nerve impulse for vision.
- PHOTORECEPTOR LAYER
- Outer segment (Disks of photo pigment)
- Inner segment (Organelles) - OUTER NUCLEAR LAYER - Nuclei of photoreceptor cells
- OUTER PLEXIFORM LAYER - Synapses with bipolar neurons and horizontal cells
What are the secretions/tears of the eyes
- Each eyeball is covered with an EYELID, which contains sebaceous glands and sweat glands (of Moll)
- Above each eyeball is the LACRIMAL GLAND, which produces lacrimal secretions or tears
- MYOEPITHELIAL CELLS surround secretory acini in lacrimal gland
- Tears contain mucus, salts and antibacterial enzyme LYSOZYME
- Sebaceous (tarsal) gland secretions form an oily layer on the surface of tear film
Identify the cell type found in retina
- separate types interact with rods and cones in outer plexiform layer
- nuclei are found in the inner nuclear layer
- axons contact ganglion cells in inner plexiform layer
BIPOLAR CELLS
**Because the rods and cones are situated adjacent to the CHOROD LAYER of the retina, LIGHT RAYS must first pass through the GANGLION and BIPOLAR CELL layers to reach and activate the photosensitive rods and cones
- *The RETINAL PIGMENTED LAYER of the choroid next to the retina ;
- ABSORBS LIGHT RAYS and prevents them from reflecting back through the retina and producing glare.
- These cells also phagocytosis worn-out outer components of both rods and cones, which is continually shed in renewal processes.
- The retinal pigment layer store VITAMIN A, a rhodopsin precursor that initiates visual stimulation
- Retinal pigment epithelial cells use the VITAMIN A to form visual pigment molecules for both rods and cones
Identify the cell type found in retina
- Nuclei in inner nuclear layer
- Contact rods and cones in outer plexiform layer
HORIZONTAL CELLS
Identify the cell type found in retina
- Nuclei are at inner edge of inner nuclear layer
- contact bipolar neurons and ganglion cells in inner plexiform layer
AMACRINE CELLS
Identify the cell type found in retina
- Glial cells
- nuclei are in inner nuclear layer
- processes extend throughout retina
- inner limiting membrane is the basal lamina of the muller cells (separates retina from vitreous chamber)
MULLER CELLS
*Outer limiting membrane formed by processes from muller cells surrounding outer segments of photoreceptors cells
Identify the cell type found in retina
- Dendrites in inner plexiform layer have synapses with bipolar cells
- Axons from the optic nerve fiber layer
- Fibers converge in optic disc to form the optic nerve
GANGLION CELLS
When does eye development begin and continues till?
- what forms lens placode
- what form optic vesicle
- what do both lens placode and optic vesicle form
- Eye development BEGINS abound DAY 22 and continues AFTER BIRTH
- Grooves in the lateral wall of the forebrain (NEURAL ECTODERM) from OPTIC VESICLE
- Contact SURFACE ECTODERM which forms LENS PLACODE
- Lens placode and vesicle invaginate to form OPTIC CUP
During development of the eye, what forms the double walled optic cup?
What is function of choroid fissure
- INVAGINATION OF OPTIC VESICLE forms the double walled optic cup
- choroid fissure ALLOWS ARTERY to reach INNER CHAMBER of the eye
How does lens placode separates out during eye development?
- Lens placode separates from surface ectoderm
- Lens sits in the mouth of the optic vesicle
- Inner layer of optic vesicle forms neural retina
- Outer layer forms pigmented epithelium
During the eye development, what forms the lip of the optic cup
- IRIS AND CILIARY BODY develop from the lip of the optic cup
- Pigmented and non-pigmented cells are continuous with the neural and pigmented retina
- Muscle cells of the iris come from pigmented epithelial cells
- *Lens is from SURFACE ECTODERM
- *Retina is from NEURAL ECTODERM
DURING eye development, what forms choroid and sclera ?
What is the entire developing eye surrounded by?
- Entire developing eye is surrounded by MESENCHYME derived from neural crest
- INNER LAYER forms CHOROID
- OUTER LAYER forms SCLERA
WHAT happens during the last stages of eye development
- what form the optic nerve
- what form the central artery
- choroid fissure of the optic stalk closes
- INCREASING number of NERVE FIBERS form the OPTIC NERVE
- DISTAL PORTION of the hyaloid artery degenerates reining portion forms the CENTRAL ARTERY
WHAT are the 2 functions of the ear
- Receive and transmit sound (COCHLEA)
- Balance
- Utricle, saccule and semicircular canals
Ear is a specialized region that contains structures responsible for hearing, balance and maintenance of equilibrium
The structure of the ear (auditory system) is made of what 3 parts
Which parts have ;
- pinna
- eustachain tube
- cochlea
- External ear
- PINNA/auricle (gathers sound waves form the external environment and directs the through the external auditory canal interiorly to the eardrum or TYMPANIC MEMBRANE, from which sound is directed to middle ear)
- external auditory canal - Middle ear
- tympanic cavity (small air filled space located and protected by the temporal bone of the skull)
* TYMPANIC MEMBRANE separates the external auditory canal from the middle ear
- auditory ossicles (3 little bones- staples, incus and malleus; attached to the tympanic membrane and to the cochlea of the inner ear)
- Eustachian tube (the sound waves vibrate the tympanic membrane and are then transmitted through the auditory ossicle bones to the inner ear)
* The cavity of the middle ear communicates with the nasopharynx region of the head via the auditory tube (presence of the tube allows for equalization of air pressure on both sides of tympanic membrane during SWALLOWING or blowing the nose) - Inner ear (deep in the temporal bone of the skull)
- semicircular canals
- vestibule
- cochlea (transmits sound, sensation of balance and movement)
* *All collectively called OSSEOUS or BONY LABYRINTH (filled with perilymph)
The ear structure has 3 parts; external, middle and inner ear. Identify the part of external ear
1
- structure composed of ELASTIC CARTILAGE covered with THIN SKIN (sebaceous glands and hair)
- Caputures sound and directs it down auditory canal to tympanic membrane
How is it diff from other part of external ear?
PINNA
Other part is AUDITORY CANAL
- Outer portion is cartilage
- Inner portion is bone
- Both covered by stratified squamous epithelium
- cereminuos glands produce cerumen (earwax)
Identify the 3 structures in auditory ossicles of the middle ear
MALLEUS, INCUS, STAPES
- MALLEUS - attaches to tympanic membrane
- converts sound to mechanical motion - INCUS - connects malleus and stapes
- STAPES - attached to oval window (in vestibule, outside the cochlea)
- amplifies sound by putting pressure on oval window
Identify the structure in middle ear
- connects to nasopharynx
- maintains PRESSURE BALANCE btw tympanic cavity and external environment
- Bony portion changes to cartilage
- Lined with simple columnar to PSEUDOSTRATIFIED ciliated epithelium with mucous glands (as it gets closer to lasopharynx)
EUSTACHIAN TUBE
*partly supported by bone and partly by cartilage
Identify the 2 systems in the inner ear
- Cochlea, auditory nerve
- Vestibule, 3 semicircular canals
- AUDITORY SYSTEM
- Cochlea (receives and transmits sound)
- Auditory nerve - VESTIBULAR SYSTEM
- Vestibule (Utricle, saccule)
- 3 semicircular canals (superior, posterior and horizontal) run in different planes
Identify the following in inner ear structure
1. Space between bone and membranous labyrinth contains perilymph (sensory structures)
- Contains endolymph
- OSSEOUS LABYRINTH (all sensory structures sit here)
- MEMBRANOUS LABYRINTH
- *PERILYMPH is a fluid that is rich in sodium and similar in composition to the CSF of the central nervous system
- *ENDOLYMPH is fluid in series of interconnected, thin-walled compartments Calle membranous labyrinth
Identify the structure
- spiral structure within temporal bone (resemble SNAIL’S SHELL)
- MODIOLUS is central portion containing spiral ganglion
- bipolar neurons in spiral ganglion make contact with hair cells in the basilar membrane
*
-specialized for receiving and transmitting sound found in the inner ear
What are the diff parts of cochlea (4)
COCHLEA
3 channel;
1. Vestibular duct aka SCALA VESTIBULI STARTS at the oval window and sits above organ of corgi (filled with PERILYMPH)
- Cochlea duct aka SCALA MEDIA contains the organ of corti which are specialized receptor cells on the basilar membrane that help DETECT SOUND (filled with ENDOLYMPH)
- Tympanic duct aka SCALLA TYMPANI ENDS at the round window and sits below the organ of corti (filled with PERILYMPH)
- HELICOTREMA at apex of cochlea connects SCALA vestibuli and SCALA tympani
Identify the structure in the cochlea of inner ear
- 1 INNER and 3 OUTER hair cells and supporting cells
- movement of perilymph causes up and down movement of basilar membrane
- hair cells move against TECTORIAL MEMBRANE which causes them to transmit signals to bipolar nerve terminals (What helps this movement?)
ORGAN OF CORTI (auditory sensory structure of inner ear)
**Tectorial membrane sit above hair cells, movement of hair cells by CILIA create signal for bipolar neuron
- ORGAN of corti consist of numerous hair cells and supporting cells that respond to diff sound frequencies
- Hair cells contain long, stiff STEREOCILIA and project into the fluid-filled cochlear duct
- The auditory stimuli/sounds are carried away from the receptor hair cells via afferent axons of the COCHLEAR NERVE to the brain for interpretation
- A TECTORIAL MEMBRANE overlies the organ of corti
Identify the structure
-ridge in the ampulla of the semicircular canals
- sensory epithelium
+Hair cells (sensory); stereocilial, single kinocilium
+ supporting cells
- covered by cupula of gelatinous material
-movement of cupula deflects stereocilia which transmits information about position and movement
**what does the vestibular apparatus consist of ?
CRISTA AMPULLARIS
(One of the 2 vestibular sensory structures of inner ear)
*other is macula in the saccule and utricle
VESTIBULAR APPARATUS
- Consist of utricle, saccule and semicircular canals
- these sensitive organs respond to linear or angular accelerations or movements of the head
- sensory inputs from the vestibular apparatus initiate the complex pathways that activate specific skeletal muscles that correct balance and equilibrium and restore the body to its normal position
IDENTIFY
- multiple stereocilia with actin core
- single kinocilium with microtubules
VESTIBULAR HAIR CELLS
There are 3 sensory structures in the inner ear. The vestibular structure has crista ampullaris and macula. In the macula of saccule and utricle, Hair cells is covered by what membrane
Supporting cells rest on what membrane
- HAIR CELLS covered by OTOLIITHIC MEMBRANE
+Gelatinous matrix covered with otoliths
+Single kinocilium and numerous stereocilia
+stereocilia move in response to movement of otolithic membrane and endolymph
+Transmits movements of head to nerve endings
-SUPPORTING CELLS rest on the BASEMENT MEMBRANE
+ Hair cells are embedded in the supporting cells
In the inner ear structure, what are the 3 sensory structures?
- Auditory
- organ of corti in the cochlea - Vestibular
- crista ampullaris in the ampullae of the semicircular canals
- macula in the saccule and utricle
**Sensory cells are hair cells
What are the special senses located in the head (4)
What innervates this structures?
- Ear - HEARING, equilibrium
* Ear transmits sound to tympanic cavity, cochlea for hearing - Oral cavity (tongue) - TASTE
* space below skull surrounded by mandible - Eyes - VISION
- Nasal cavity - SMELL
**These structures are innervated by CRANIAL NERVES
What rigidly connects skull bones to protect the brain and also provide attachment to move eyes precisely?
What is used to estimate the age of skull?
SUTURES
**Connective tissue joints between bones (look like cracks)
**Sutures progressively FUSE with AGE, EXTENT OF SUTURE FUSION can be used to estimate age of skull (sutures disappear with age)
What is the skull cap called and what does it consist of?
CALVARIUM
- Consists of bones linked by sutures
1. Frontal
2. Sphenoid
3. Occipital
4. Temporal
5. Parietal
Identify the named fibrous joints that connects the bones of the calvarium;
- Between frontal and parietal bones
- Between parietal bones
- Between parietal and occipital bones
What are the mid points of the sutures called?
- CORONAL SUTURE
* *MIDPOINT of suture is called BREGMA - SAGITTAL SUTURE
- LAMBDOIDAL SUTURE
* *MIDPOINT of suture is called LAMBDA
What is the area of junction of; Sphenoid, Temporal, Parietal and Frontal bones
*Why is this clinically important?
PTERION
**SKULL FRACTURES in region of PTERION clinically important (EPIDURAL HEMATOMA)
In infants, bones are further apart and joined by specific membranes.
1. What are the membranes that link bones at birth called?
- What do these membranes permit at birth?
- What are the membranes
- at bregma
- at pterion
- at lambda - **Which membrane can be used to access SUPERIOR SAGITTAL SINUS in NEONATES
- FRONTANELLES
- FRONTANELLES (soft spots) permit CRANIAL COMPRESSION at birth - and later CRANIAL GROWTH
- ANTERIOR FRONTANELLE - at bregma
POSTERIOR FRONTANELLE - at lambda
LATERAL FRONTANELLE - at pterion - ANTERIOR FRONTANELLE can be used to access superior SAGITTAL venous sinus in neonates (venous system)
The skull cap is called the CALVARIUM. The internal structure of the CALVARIUM is made of 3 layers.
What are these layers of calvarium and what are they made of
**What courses btw the middle layer and what do they transmit infections
- Outer tables - hard CORTICAL BONE
- Inner tables - hard CORTICAL BONE
- Middle layer - SOFT SPONGY BONE called DIPLOE**
- *The DIPLOIC VEINS course within the diploe and connect both to cranial cavity and surface of skull
- This veins can TRANSMIT INFECTIONS from scalp to brain via EMISSARY VEINS
The middle layer of the calvarium is called the DIPLOE. The diploe contains DIPLOIC VEINS which can transmit infections from scalp to brain via EMISSARY VEINS.
What is the major difference btw emissary and bridging veins
*EMISSARY VEIN
-Scalp to diploe
-scalp to sinus
-diploe to sinus
‘OUTSIDE’ TO SINUS
*BRIDGING VEIN
-surface of brain (cerebral vein) to venous sinus
BRAIN TO SINUS
What is the blood supply to the Calvarium?
- outer surface
- inner surface
**What causes bleeding of meningeal arteries?
- Outer surface - receives branches from ARTERIES to SCALP
- Inner surface - MENINGEAL ARTERIES (coursing immediately below bone)
**SKULL FRACTURE can cause bleeding of meningeal arteries (epidural hematoma)
What are the 5 layers of the SCALP?
- *Infections can readily spread through which layers?
- *what layer of scalp is the origin of emissary veins
- *what layer attaches to scalp muscles (frontalis and occipitalis) and temporalis fascia
- *you remove scalp between which layers?
SCALP
- SKIN - with associated hair follicles, sweat and sebaceous gland
- CONNECTIVE TISSUE - dense fibrous connective tissue SURROUNDing arteries and nerves (origin of emissary veins)
- EPICRANIAL APONEUROSIS - thin tendinous sheet, tightly attached to skin and connective tissue above; moveable anteriorly and POSTERIORLY; laterally attached to temporal fascia; attached to frontalis and occipitalis muscles
- LOOSE AREOLAR TISSUE - loosely connects epicranial aponeurosis to periosteum of skull; crossed by emissary veins
- PERICRANIUM/PERIOSTEUM - CT layer on outer side of calvarium
- *INFECTIONS can readily spread through loose areolar layer deep to epicranial aponeurosis
- *Remove scalp btw 3 and 4
What is the innervation of the scalp?
- Branches of trigeminal nerve (V)
2. Cervical spinal nerves
The scalp is innervated by the branches of trigeminal nerve and cervical spinal nerves.
**What are the branches of the trigeminal nerve respectively
**What parts of scalp is innervated?
V1 - SUPRAORBITAL N., SUPRATROCHLEAR N.
(Anterior scalp)
V2 - Zygomaticotemporal N.
(Lateral scalp)
V3 - Auriculotemporal N.
(Lateral scalp)
The scalp is innervated by the branches of trigeminal nerve and cervical spinal nerves.
**What are the types of the cervical spinal nerves
**What part of scalp does the nerves innervate?
- Lesser Occipital N. - C2 VENTRAL RAMUS
(Lateral scalp) - Greater Occipital N. - C2 DORSAL RAMUS
(Posterior scalp)
**Innervated lateral and posterior scalp
The arteries of the scalp have a rich supply from what branches (2)?
**Why would scalp wound bleed profusely from both sides of cut?
- Branches of OPHTHALMIC ARTERY (from ICA);
- SUPRATROCHLEAR and - SUPRAORBITAL arteries.
(Anterior scalp) - Branches of EXTERNAL CAROTID;
- Superficial temporal artery (to lateral scalp)
- Posterior auricular artery (scalp above and posterior to external ear)
- Occipital artery (posterior scalp)
**There are EXTENSIVE ANASTOMOSES btw arteries to scalp; scalp wounds can bleed profusely from both sides of cut
What is the venous drainage of the scalp?
**How do Infections spread?
- Venous drainage is by veins with same names as arteries
- They also drain VIA EMISSARY VEINS to DIPLOIC VEINS in DIPLOE
**Infections can spread via EMISSARY VEINS from scalp to brain
NOTE
- DIPLOIC veins are located inside the bones of the calvarium (skull cap)
- Emissary veins are different; they pass from the scalp (or DIPLOIC veins) into venous sinuses inside the skull
The brain is bilaterally symmetrical;
- cortex is connected to spinal cord by BRAINSTEM
- outflow/inflow of brain is via CRANIAL NERVES
**Name the cranial nerves and innervations
I. OLFACTORY NERVE - sense of smell
II. OPTIC NERVE - vision
III. OCULOMOTOR NERVE - eye muscles
IV. TROCHLEAR - eye muscles
V. TRIGEMINAL - SENSORY to skin, MOTOR to muscles of mastication (chewing) etc
VI. ABDUCENS - eye muscles
VII. FACIAL - MOTOR to muscles of facial expression etc; taste to anterior 2/3 tongue
VIII. VESTIBULOCOCHLEAR - hearing and balance (vestibular apparatus)
IX. GLOSSOPHARYNGEAL - sensory to pharynx +more (motor to stylopharyngeus)
X. VAGUS - SENSORY and MOTOR to larynx (voice box), pharynx and rest of body
XI. ACCESSORY NERVE - MOTOR to trapezius, sternocleidomastoid
XII. HYPOGLOSSAL - MOTOR to muscles of tongue (no sensory)
What are the 6 bones in the FRONT view of the skull
- *where is the infraorbital foramen found?
- *where is the mental foramen found?
- Frontal bone (1) - forms forehead, upper margin and roof of orbit
- Orbit - eye socket
- Zygomatic bone (2) - forms cheeks
- Maxillary bone (2) - has sockets for upper teeth (alveolar processes); INFRAORBITAL FORAMEN (below orbit)
- Nasal apertures (Choanae) - covered superiorly by nasal bones
- Mandible (1) - separate bone; alveolar processes for lower teeth; MENTAL FORAMEN (below second pre-molar tooth)
What are the 4 items in the LATERAL view of the skull
- *what bones do zygomatic arch consist of
- *what are the parts (4) of temporal bone
- Zygomatic ARCH -
+ Zygomatic bone
+ Maxillary bone (zygomatic process)
+ Temporal bone (zygomatic process) - Temporomandibular joint - joint btw head of mandible (upper end of RAMUS) and temporal bone
- Temporal bone (4 parts)
+ Mastoid process (hard bone inferiorly)
+ Squamous (flat) part laterally
+ Tympanic part - forms anterior side of external auditory meatus (opening of ear)
+ Petrous part - inside skull - Parietal, temporal, frontal and sphenoid bones from lateral side of cranial cavity
* *Greater wing of sphenoid - lateral side of skull
What bone is in the POSTERIOR view of the skull
**What is found here
OCCIPITAL BONE
- Superior and Inferior NUCHAL LINES
- External Occipital protuberance (inion) is raised bump in middle of superior nuchal line
What bones are found in the complex BASE of the skull (3)
- what has styloid process
- what has foramen magnum and occipital condyles
- what has palatine bones
- Temporal bone - has styloid process for muscle attachment
- Occipital bone - has;
- Foramen magnum; for spinal cord and vertebral arteries
- Occipital condyles; articulate with vertebra C1 (Atlas) - Hard palate - palatine bones and palatine process of maxillary bones
Identify the individual bone of skull
- CORE of skull
- forms part of orbit, lateral side of skull, base of skull and parts of all three cranial fossa
- *What are the 6 parts of the bone
- what part is for muscle attachment?
- for ligament attachment?
- where is pituitary gland located?
- what landmarks are important in neurology?
SPHENOID BONE.
- Medial and lateral PTERYGOID PLATES - processes for muscle attachment
- Spine of sphenoid - on inferior side of sphenoid for ligament attachment
- Lesser wing of sphenoid - in interior of skull, ABOVE superior orbital fissure
- Greater wing of sphenoid - extends BELOW superior orbital fissure (also on lateral side of skull)
- SELLA TURCICA (Turkish saddle) - depression above body of sphenoid (central part) btw anterior and posterior clinoid processes
* *LOCATION OF PITUITARY GLAND - Clivus - central part of sphenoid and occipital bones that extends from posterior edge of sella turcica (dorsum sellae) down to posterior cranial fossa
**PARTS OF SPHENOID (Sella turcica, Dorsum sellae) are important landmarks in neurology (ex. MENINGIOMA AT CLIVUS) **many symptoms
What is divided into depressions/fossae that are functionally related to parts of brain and facial skeleton
**What are the 3 fossa (and contents)
CRANIAL CAVITY
- Anterior cranial fossa (roof of nasal cavity, orbit)
- Middle cranial fossa (orbit, nasal cavity, face)
- Posterior cranial fossa (face, oral cavity, neck)
The cranial cavity is divided into depressions or fossae that are functionally related to parts of brain and facial skeleton.
There are 3 fossae
Identify this
- related to roof of nasal cavity (also forms roof of orbit)
- *Identify the bones, contents and foramina
ANTERIOR CRANIAL FOSSA
- BONES - Frontal, Ethmoid and Sphenoid bones
- CONTENTS - CNI (cribriform plate), Olfactory bulbs and frontal lobes of cortex
- FORAMINA - In cribriform plate of ethmoid bone conduct branches (fila olfactoria) of OLFACTORY NERVE CNI
The cranial cavity is divided into depressions or fossae that are functionally related to parts of brain and facial skeleton.
There are 3 fossae
Identify this
-related to orbit, nasal cavity and face
BONES - sphenoid, temporal, parietal
CONTENTS - pituitary gland, temporal lobes of cortex and cranial nerves from rostral brainstem
FORAMINA - for nerves to orbit (Optic nerve and nerves to eye muscles), nasal cavity and face CN II-VI
MIDDLE CRANIAL FOSSA
The cranial cavity is divided into depressions or fossae that are functionally related to parts of brain and facial skeleton.
There are 3 fossae
Identify this
-related to face oral cavity, neck
BONES; sphenoid, temporal, parietal and occipital bones
POSTERIOR CRANIAL FOSSA
- BONES; sphenoid, temporal, parietal and occipital bones
- CONTENTS; lower brainstem and cerebellum; petrous part of temporal bone contains cochlea (hearing) and semicircular canals (gravity)
- FORAMINA ; for nerves to face, oral cavity (also taste), muscles of tongue and neck CN VII - XII; foramen magnum transmit spinal cord and vertebral arteries
The arterial supply of the brain is derived from 2 sources.
Identify
- Common carotid artery arises from
- brachiocephalic artery on right,
- arch of aorta on left
* bifurcates at level of upper border of thyroid cartilage into internal and external carotid arteries
- Internal carotid ascends to enter skull via carotid canal to middle cranial fossa - Arises from SUBCLAVIAN ARTERY, ascends through FORAMINA TRANSVERSARIA of vertebrae C1-C6; enters skull via foramen magnum
- INTERNAL CAROTID ARTERY
- enters skull via carotid canal and foramen lacerum
- Passes through CAVERNOUS SINUS
* *Carotid siphon; c-shaped turn of internal carotid artery - VERTEBRAL ARTERY
- enters skull via foramen magnum
The meninges of brain have 3 layers as in spinal cord
*what is the difference?
- Dura mater (tough mother)
- Arachnoid (spider like)
- Pia mater (tender mother)
**Dura mater is tightly attached to inner side of cranial cavity and has extensions/reflections into the cranial cavity
**The cranial cavity is enclosed by bone so there is no room for expansion inside the skull
**HEMATOMA - abnormal mass of blood outside blood vessel
There are 3 layers of the meninges of the brain.
Identify this
- tough connective tissue layer
- composed of 2 layers
**Why is there no epidural space in the skull?
**what support and stabilize the brain and contain venous sinus
DURA MATER
2 layers
- Inner membrane layer (true dura)
- Outer endosteum layer - periosteum on inner side of calvarium
- *The 2 layers are fused in most places and tightly attached to inner surface of calvarium and cranial cavity (No epidural space)
- *Layers of dura separate to form inward folds called DURAL REFLECTIONS
- *Dural reflections support and stabilize the brain and contain VENOUS SINUSES
**There is NO EPIDURAL SPACE in skull as DURA IS FUSED TO BONE
The layers of the dura separate to form inward folds called DURAL REFLECTIONS. These dural reflections support and stabilize the brain and contain venous sinuses. There are 4 total dural reflections
Identify this
- sickle shaped fold btw cerebral hemispheres
- attached anteriorly to crista galli of ethmoid bone
- POSTERIORLY blends into tentorium cerebelli
FALX CEREBRI
The layers of the dura separate to form inward folds called DURAL REFLECTIONS. These dural reflections support and stabilize the brain and contain venous sinuses. There are 4 total dural reflections
-small sickle-shaped fold that projects anteriorly from posterior wall of posterior cranial fossa btw cerebellar hemispheres
FALX CEREBELLI
The layers of the dura separate to form inward folds called DURAL REFLECTIONS. These dural reflections support and stabilize the brain and contain venous sinuses. There are 4 total dural reflections
- CRESCENT shaped fold
- forms roof over posterior cranial fossa
- anteriorly has gap called tentorial notch for passage of brainstem
TENTORIUM CEREBELLI
**tentorial notch for passage of brainstem
The layers of the dura separate to form inward folds called DURAL REFLECTIONS. These dural reflections support and stabilize the brain and contain venous sinuses. There are 4 total dural reflections
-Small circular fold of dura mater over sella turcica (has opening for stalk of pituitary)
DIAPHRAGMA SELLA
Identify the layers of meninges
- Layer attached to INNER SURFACE of DURA (separated form dura by potential space, sub dural space)
- separated from pia mater by subarachnoid space which contains CSF fluid - Thin layer closely adherent to BRAIN
- surrounds arteries and veins that course on surface of brain
- ARACHNOID (spider like)
2. PIA MATER (tender mother)
