Final Exam (Exam 3 stuff) Flashcards
Functions: i.Sensory 1. Somatic sensory (Se) 2. Special sensory (SS) 3. Visceral sensory (SV) ii.Motor 1. Somatic/Branchial motor (Mo) 2. Parasympathetic motor (MP)
Foramen Magnum
- exit for spinal cord
- by far the biggest hole in skull (point of herniation)
External carotids feeds what?
-the face, skull, and meninges
Pterion
- weakest poing in skull
- immediately overlies middle meningeal artery
- bleeding outside meninges can cause epidural hematoma (EDH)
Meninges (layers?)
- pia mater
- arachnoid mater
- dura mater
- spinal cord vs brain
- in spinal cord, subarachnoid space is enlarged.
Cranial arteries (location and cause of what?)
- in subarachnoid space
- cause of subarachnoid hemorrhage (SAH)
Cranial Vasculature: Anterior circulation
Internal Carotid Artery (ICA)
splits into anterior and middle cerebral arteries
Anterior Cerebral Artery (ACA)
- provides blood supply to medial brain
- most noticeable function is sensory/motor for legs
Middle cerebral artery (MCA)
- Lenticulostriate branches feed basal ganglia and internal capsule
- Distal branches feed sensory/motor to arms/face and many language areas (on dominant side, usually left)
Cranial Vasculature: Posterior circulation
-Vertebral arteries (posterior cerebral artery)
Posterior Cerebral Artery (PCA)
- visual cortex
- visual association areas
Cranial Vasculature: Veins
- Dura mater sinuses
- Cortical veins
- Bridging veins
Bridging veins cause what?
-cause subdural hematoma (SDH)
Stroke terminology
- Ischemic (blockage)
- Hemorrhagic (bleeding)
Hemorrhagic (ICH and SAH)
ICH = intracerebral hemorrhage SAH = subarachnoid hemorrhage
Blood Brain Barrier (BBB)
Passive::
1) tight junctions btwn endothelial cells
2) astrocyte foot processes
Active::
1) astrocytes pump chemical back into blood
Cerebrospinal fluid (CSF): Ventricular system
1) continuous circulation from inside ventricles down spinal cord
2) product of the inside of the original neural tube
Cerebrospinal fluid (CSF): production
1) Choroid plexus
2) Ependymal cells on inside of ventricles
Cerebrospinal fluid (CSF): Absorption
1) Arachnoid granulations
- pushes CSF back into dural sinuses (venous blood)
Monro-Kellie doctrine
- 3 things in brain (blood, brain, and CSF)
- an increase in the size of one (i.e., tumor) leads to a decrease in one of the others out the foramen magnum (i.e., blood or brain tissue)
Cushing’s triad - response to increased ICP
- Bradycardia (slow heart rate)
- Hypertension (increase blood pressure)
- Irregular breathing (hyperventilation)
Herniation
- final outcome of uncontrolled ICP
- brain herniates out foramen magnum, leading to compression of brain stem, and death
Causes of increased ICP
1) Hydrocephalus
- clogged CSF circulation leading to backup in brain
- very dangerous
2) turmors
3) cerebral edema (from trauma)
Brainstem divisions
Midbrain
Pons
Medulla
Cranial nerve: Surface anatomy
CN 1-2 on underside of brain CN 3-4 around midbrain CN 5 from side of pons CN 6-8 from under pons CN 9-12 in medulla
CN 1 - Olfactory Nerve
1) Function: Smell (Special sense)
2) Test: different scents
3) Pathways:
- olfactory bulb, olfactory cortex, Amygdala
4) clinical correlates:
- anosmia (loss of smell) in trauma
- Emotional link to scents
CN II - Optic Nerve
1) Function: vision (special sensory)
2) Test: Visual acuity
3) pathways
- lateral geniculate nucleus = conscious vision
- superior colliculus - coordinate eye movement
4) clinical correlates:
- pituitary/hypothalamus tumors affected by vision
- stroke localization (peripheral vs. central lesions)
CN III - Oculomotor nerve
1) Func:
- motor for eye movement (Mo)
- eyelid retraction (Mo)
- pupil constriction (MP)
2) test
- move eye in cardinal directions. up down and in?
3) Palsy: “Down and out” eye is lateral and inferior facing
- Parasympathetic fibers are on outside of nerve, so benign vascular pathologies (like diabetes) tend to spare the pupil, while dangerous pathologies (like an aneurysm) tend to “blow” the pupil
CN IV - trochlear nerve
1) Func:
- motor to superior oblique (Mo) = down and inward
2) palsy: nasal upshoot - when eye moves medially, it is superiorly displaced
- bcuz it exits the back of midbrain and curls around brainstem it is commonly injured in trauma
- frequently found to be congenital, but missed for a long period of time bcuz it is easy to miss
CN V - trigeminal nerve
1) Function:
- cutaneous sensation to face (Se)
- muscles of mastication (Mo)
2) test
- light touch to lower face, cheeks, and forehead
CN VI - abducens
1) function
- motor to lateral rectus (Mo) = controls eye movement laterally
2) palsy: cross-eye = unable to move one eye laterally
- frequently happens congenitally
- bcuz 6th nerve exits below pons, it is very sensitive to brain displacement due to increased ICP
CN VII - facial nerve
1) function:
- motor to muscles of facial expression (Mo)
- parasympathetic to salivary glands (MP)
- tast from anterior 2/3rds of tongue (SV)
2) test
- symmetric smile, squeeze eyes shut, wrinkle forehead
CN VIII - vestibulocochlear nerve (auditory)
1) function:
- hearing (SS)
- vestibular sensation (SS)
2) Test
- Rinne, Weber, Tonotopy; tilt table
CN IX - glossopharyngeal nerve
1) function:
- palatal elevation (Mo)
- parotid salivary gland (MP)
- sensation in pharynx (Se)
- tast for posterior 1/3 of tongue (SV)
2) Test
- say “ahhh”, watch for palate elevation
3) palsy:
- impaired elevation of palate on that side, uvula deviates towards unaffected side.
CN X - vagus nerve
1) function:
- swallowing (Mo)
- larynx/voice (Mo)
- parasympathetic to body (MP)
- sensation from pharynx (Se)
2) test
- is their voice hoarse?
CN XI - spinal accessory nerve
1) function:
- sternocleidomastoid and trapezius
2) test:
- turn head, shoulder shrug
CN XII - hypoglossal nerve
1) function:
- tongue movement (Mo)
2) test:
- stick tongue straight out
3) palsy:
- tongue will deviate towards affected side.
Tongue sensation (nerves)
Anterior = trigeminal posterior = glossopharyngeal
Tongue taste (nerves)
anterior = facial posterior = glossopharyngeal
Tongue motor (nerves)
= hypoglossal
Eye anatomy
Retina
Pupil / iris
Cornea
Sclera
Lens and refractive properties
- To form a clear image, light must converge on retina
- Changes in focus (accommodation) performed by ciliary muscles stretching lens
- Myopia, Hyperopia, Presbyopia
Myopia
(nearsighted)
- light focuses anterior to retina
Hyperopia
(farsighted)
- light focuses posterior to retina
Presbyopia
- lens fails to relax, unable to focus on near objects
Retina surface anatomy
- Blood vessels
- Fovea (avascular, dense in high acuity cones)
- Optic disc (blind spot)
Retina development
1) eye forms as direct extension of neural tube (optic vesicle)
2) optic vesicle folds into itself to form optic cup
- distal layer = neural retina
- proximal layer = pigmented epithelium
Retina cellular structure (Layers from back of eye to front)
1) pigmented epithelium
2) Outer nuclear layer
3) outer plexiform layer
4) inner nuclear layer
5) inner plexiform layer
6) Ganglion cell layer
7) nerve fiber layer
Pigmented epithelium
- Provides dark backdrop to reduce light scatter
- Involved in photoreceptor maintenance and pigment turnover
Outer nuclear layer
Photoreceptors (rods and cones)
Photoreceptors: Rods
- Low light - can respond to single photons
- Slow adapting
- Low acuity, highly convergent
- No color content
- Highly sensitive to motion
- Located in periphery
Photoreceptors: Cones
- Need more light, >100 photons
- Fast adapting
- High acuity, low convergence
- Specialized for particular color
- Located on fovea
Outer plexiform layer
Horizontal cells
- integrate across multiple photoreceptors.
Inner nuclear layer
Bipolar cells
-connects outer layer to ganglion layer
inner plexiform layer
Amacrine cells
- located btwn bipolar and ganglion cells
- integrates horizontally