Neuroanatomy review Flashcards
Nervous system functions
Sensory input- sensory receptors present in the skin and organs respond to external and internal simuli by generating nerve impulses that to send to the CNS
Integration- the brain and spinal cord of the CNS combine and sum up all the data received from the body and send out nerve impulses
motor output- the nerve impulses from the CNS go to the effectors (muscles and glands) muscle contractions and gland secretions are responses to stimuli recieved by sensory receptos
CNS
the CNS consists of the spinal cord and brain, the spinal cord connect to the brain via the brainstem
Brain stem- medulla pond and midbrain
Cerebral hemispheres
Four major lobes
Occipital, parietal, temporal (medial part contain the hippocampus), frontal
the outer layer of the cerebral hemisphere is the cerebral cortex,
Deep nuclei include structures such as the basal ganglia and the thalamus
meninges
The piamater is separated from the delicate arachnoid membrane by the subarachnoid space, and the dura mater with the subdural space
Neurons
the cell body contains the nucleus and cytoplasm, it is the cells metabolic processes, housing mito golgi and peroxisomes
The dendrites they are the receiving arms of the cell, they increase the Siface A, for infromation synapses
There is only one axon per neuron
Axolemma is the PM of the axon membrane
Many axons are surrounded by a myein sheath, allows for fast AP propagation, gaps are the nodes of ranvier
Myelin sheath is formed by Schwann cells in the PNS and oligodenrocytes in the CNS
Neuroglial cells of the CNS
astrocytes- small stellate cells, found throughout the CNS, form structural framework for neuronal cells and capillaries, they maintain integrity of BBB, they store and release some NTs, disperse excess ions, important role in development of NS and may have a role in injury recovery, may have a role in presenting antigen to the immune system when CNS and BBB damage
Oligodendrocytes- responsible for myelination of the CNS neurons, large numbers in the white matter, each oligoodendrocyte forms myelin 3-50 fibers –MS destroys this
Ependymal cells- imortant for enabling movement of CSF and interacting with astrocytes to form a barrier separating the ventricles and CSF from neuronal envrionment, they line the central canal in the spinal cord
Microglial cells- phagocytes of the CNS
Schwann cells
found only in the PNS, myelination of peripheral nerves
Spinal cord
Foramen magnum to the first lumbar vertebra,
Enlarged at the cervical and lumbar region
the lower part of the spinal canal has the cauda equina
Sensory nerve fibers enter the spinal cord via the dorsal (posterior roots) the cel bodies for these neurons are situatuated in the dorsal root ganglia
motor and preganglionic autonomic fibers exit via the ventral (Anterior) root
Spinothalamic tract
from dorsal horn Laminae 1, 3, 4 and 5, crosses midline in spinal cord, projects to brain stem and contralateral thalamus - Spine ouch - conveys pain and temperature
Dorsal column medial leminiscal pathway
Afferents from mechanoreceptors, muscle and joint receptors, terminates in dorsal column nuclei of medulla, forms medial lemniscus at the level of medulla, and synapses in ventroposterior nucleus of thalamus, conveys proprioception, light touch and vibration
Spinocerebellar tract-Dorsal SCT relays inferior cerebellar peduncle and VCT relays via superioer cerebellar peduncle to the cerebellum, it conveys proprioceptive information and on going activity in the spinal cord interneurons
Descending motor tracts
corticospinal (pyramidal) tract- from the motor cortex, premotor cortex, and somatosensory cortex, has a sensory processing and fractionated finger movements
Rubrospinal tracts- originates from the magnocellular part of the red nucleus in the brain, it projects toward common structures with the COST, particularly those involved with distal motor control,
Vestibulospinal tract- originates from Deiters nucleus in the medulla and innervates the extensor and axial muscles, it is involved in balance control and posture
Reticulospinal tract- caudal reticular formation in the pons and medulla, provides both excitable and inhibitory effects on the interneurons in the spinal cord, motor neurons, dapends does the spinal cord
CNS blood supply
Arterial blood supply comes from 4 vessels- Right and left internal carotids, and right and left vertebral arteries
Vertebral arteries
arising from subclavian artery these 2 arteries enter the skull through foramen magnum after passing through foramina in the transverse processes of the upper cervical vertebra. they unite in the brainstem to form the basilar artery which ascends to form the 2 posterior cerebral arteries at the superior border of the pons, this is the posterior cerebral hemisphere blood supply including the posterior spinal artery, posteiror inferior cerebral artery and the anterior spinal artery, these constitiute the blood supplu to the upper cervical cord, the PICA supplies the lateral medulla and cerebellum
internal carotid arteries
transverse the skull within the carotid canal and cavernous sinus then they pierce the dura and enter the middle cranial fossatheu become the middle cerebral arteries
Basilar artery
Anterior and inferioer cerebellar aretery
