Lecture 20 - External anatomy of the Brain Flashcards
What do mammalian brains have more of?
Convolutions
What are convolutions related to?
Overall size, NOT ability
What do the convolutions do?
Keep neurons with similar or related functions together spatially
What does the forebrain partake in?
Sensory processing, decision making, and relay to/from body
What does the brain stem have within it?
Midbrain, pons, cerebellum, and medulla
What does the brain stem have within it dealing with the CN?
Cranial nerve nuclei
What does the brain stem do?
Conduit of function between spinal cord and forebrain
What are the two structures of the brain?
Telencephalon/Cerebrum
– and –
Diencephalon/Thalamus
What are the landmarks in the cerebrum? (basic)
Hemisphere (right and left)
Gyri (Ridges)
Sulci (Grooves) - cruciate
Fissures (longitudinal and transverse)
What are the five cerebral lobes?
Parietal, frontal, olfactory, temporal, and occipital
What is the corpus callosum?
Axonal tract that allows communication between lobes on right and left side
What are the commissural fibers?
Interconnect corresponding structures between hemispheres
What are association fibers?
Interconnect different areas of cortex in same hemisphere
What are the two kinds of projection fibers?
Corticopetal and Corticofugal
What is the corticopetal?
Fibers entering cortex
What is the corticofugal?
Fibers exiting the cortex
Where are the motor and motor planning portions of the brain generally located?
Frontal and parietal lobes
Where are the primary sensory cortices found?
MANY PLACES
Where is the visual cortex?
Occipital lobe
Where is the somatosensory cortex?
Parietal lobe
Where is the auditory cortex?
Temporal lobe
What is the diencephalon?
Thalamic nuclei
What are the two parts of the thalamic nuclei?
Thalamus and Hypothalmus
What is the thalamus?
Selectively routes motor and sensory info to portions of the cortex
What is the hypothalamus?
Autonomics, appetities, temperature, circadian rhythm
What CN nuclei are contained in the midbrain?
CN III and IV
What CN nuclei are contained in the pons?
CN V and VI
What CN nuclei are contained in the medulla?
CN VII, VIII, IX, X, XI, XII
What do you have to worry about when there is damage to the brain stem?
Cranial nerve function and innervation of the body
What protects the brain?
Meninges
What are the three layers of meninges?
Dura mater - arachnoid mater - pia mater
What is between the skull and the dura mater?
Epidural space
What is within the epidural space?
Fat and veins
What is between the dura mater and the arachnoid mater?
Subdural space
What is within the subdural space?
Very small amounts of lymphatic fluid
What is between arachnoid space and the pia mater?
Subarachnoid space
What is within the subarachnoid space?
Cerebrospinal fluid
What are the three dural reflections?
Falx cerebi - Falx cerebelli - Tentorium cerebelli
What are sinuses, structurally?
Small gaps between folds of dura and skull
What is the function of the sinuses?
Receive venous blood draining from the brain
Where does the blood from the sinuses go?
Vertebral and internal jugular vein
Where are the dura folds located?
Cerebral hemispheres and cerebellum
How many ventricles are there?
4 total - 2 lateral, third and fourth
What is the function of the ventricles?
Spaces in the brain within which CSF is produced and circulates
What are choroid plexuses?
Vascular tufts into ventricles that release CSF
What is CSF made from?
Ultrafiltrate of blood plasma
What is the function of CSF?
Protect the brain
Transports nutrients
Flushes away waste products
Medium for diffusion of neuroendocrine and NT’s
How often is CSF produced in dogs?
Continuous, ~30 mL per hour
What is the path of the CSF?
Choroid plexus - Subarachnoid space - Arachnoid granulation
What are arachnoid granulations, functionally?
Where the CSF can enter the venous system
What are the arachnoid granulations, structurally?
Outpockets from the subarachnoid space into dural venous sinus
What two main arteries contribute to the circulus arteriosis cerebri?
Internal carotid aa. and vertebral aa..
What branches in the circulus arteriosis cerebri come off the internal carotid aa.?
Rostral cerebral aa.
Middle cerebral aa.
Caudal cerebral aa.
What branches in the circulus arteriosis cerebri come of the vertebral aa.?
Basilar a.
Rostral cerebellar aa.
Caudal cerebellar aa.
What does the rostral cerebral aa. supply?
Medial portions of the cerebral hemispheres
What does the middle cerebral aa. supply?
Lateral portions of the cerebral hemispheres
What does the caudal cerebral aa. supply?
Posterior portions of the cerebral hemispheres and midbrain
What does the basilar a. supply?
Pons
What does the caudal cerebellar a. supply?
Caudal cerebellum
What does the rostral cerebellar aa. supply?
Midbrain, pons, rostral cerebellum
