ANAT-A 225, Lab, Central nervous system (CNS)

general features

- protective bony covering

- meninges

- blood supply to brain

meninges

- three connective tissue membranes that surround the brain and spinal cord

pia mater

- innermost layer

arachnoid mater

- spidery, web-like

- attached to pia mater

subarachnoid space

- contains cerebrospinal fluid

dura mater

- thick, outermost layer

- surrounding and protecting the brain and spinal cord

blood supply to brain

- through internal carotid and vertebral arteries

vertebral arteries

- two pass through the transverse foramen of cervical vertebrae

- enter cranial cavity through foramen magnum

- then join to form a single vessel, the basilar artery

basilar artery

- sends branches to the brain, some join with branches from internal carotid arteries to form a circle of willis

circle of willis

- aka cerebral arterial circle

- provides alternative vascular pathways if one of the major vessels is blocked

dural venous sinuses

- venous drainage of blood from the brain

- located within the dura mater

- drain into internal jugular veins

how many subdivisions of the brain are there?

- six subdivisions: cerebrum, diencephalon, midbrain, cerebellum, pons, and medulla oblongata

what is the cerebrum divided into?

- right cerebral hemisphere and left cerebral hemisphere

cortex

- outer layer

- composed of unmyelinated nerve cell processes and neuron cell bodies (gray matter)

white matter

- tracts of myelinated axons

what are the lobes of the cerebrum?

- frontal, parietal, temporal, occipital, insula

frontal lobe

- initiate voluntary skeletal muscle movement

- motor movements in speech

- intellect, personality, complex decision-making

parietal lobe

- receives and interprets most somatosensory input

occipital lobe

- interpret visual stimuli

temporal lobe

- interpret auditory stimuli

gyri

- rounded ridges on the surface of the cerebrum

precentral gyrus

- primary motor cortex

- initiate skeletal muscle movement

postcentral gyrus

- primary somatosensory cortex

sulci and fissures

- furrows or grooves which separate the gyri and lobes

longitudinal fissure

- deep furrow b/t right and left hemispheres

lateral sulcus

- groove separating the temporal lobe from the frontal and parietal lobes

central sulcus

- a groove that separates the precentral gyrus from the postcentral gyrus, separating the frontal lobe from the parietal lobe

olfactory tract

olfactory bulb

corpus callosum

- white matter made up of myelinated axons passing from one hemisphere to the other

lateral ventricles

- contains CSF

septum pellucidum

- membrane in midline separating the right and left lateral ventricles

diencephalon

- surrounded by cerebral hemispheres

pineal gland

pituitary gland

optic chiasm

optic tracts

third ventricle

- contains CSF

- communicates with each lateral ventricle interventricular foramen

thalamus

- gray matter

- forms lateral walls of third ventricle

hypothalamus

- interior walls and floor of third ventricle

midbrain

cerebral peduncles

- composed of motor axons connecting cerebrum with other regions

cerebral aqueduct

- cavity containing CSF

- in midline, joining third and fourth ventricles

cerebellum

- not part of the brainstem

- coordinates skeletal muscle movement

- helps maintain balance and posture

pons

- anterior: axonal tracts

- posterior: a variety of nuclei (groups of neuron cell bodies) and axonal tracts

middle cerebellar peduncles

- connect pons to cerebellum

superior half of fourth ventricle

- cavity containing CSF

medulla oblongata

pyramids

- two large columns of motor axonal tracts

inferior half of the fourth ventricle

spinal cord

- structure occupying vertebral canal of vertebral column

gray matter

- contains interneurons, cell bodies and nerve cell processes of motor neurons, axons of sensory (afferent) neurons, and glial cells

white matter

- bundles of myelinated axons running along cord

spinal cord structures

- dura mater (on donor)

- arachnoid mater (on donor)

- pia mater

posterior roots

- sensory (afferent) axons

posterior root ganglion

- cell bodies of sensory (afferent) neurons

conus medullaris

- cone-shaped

- ends at level of first lumbar vertebra

cauda equina

- spinal nerve roots

- horse's tail

spinal cord cross sections

dura mater

gray matter

- darker internal portion of the spinal cord

- consists of neuron cell bodies, unmyelinated nerve cell processes, supporting cells, interneurons

posterior horns

- contains interneurons and distal portions of axons of sensory neurons

anterior horns

- contains cell bodies of somatic (voluntary) motor neurons

central canal

- opening in center of gray commissure that contains CSF

what does white matter contain?

- myelinated axons

anterior root

- motor (efferent) axons

spinal nerve

- posterior root and anterior root unite

- contains both motor (efferent) and sensory (afferent) neurons