Chapter 14: 4 Major Regions of the Brain

Chapter 14 4 Major Regions of the Brain: ① Cerebrum ② Cerebellum ③ Diencephalon ④ Brainstem Cerebrum · largest portion of the brain · covered by superficial layer of grey matter called cerebral cortex · processes sensory and motor output · responsible for conscious thought, complex movements, memory, and intellect · gyri: rounded elevations in the brain · sulcus: deep grooves in the brain · separated by longitudinal fissure White Matter of the Cerebrum · Association fibers ↳ connect areas within the same hemisphere ↳ includes arcuate and longitudinal fibers · Commissural fibers ↳ connects the two hemispheres ↳ corpus callosum & anterior commissure · Projection fibers ↳ connects cerebrum to spinal cord and other regions of the brain ↳ "internal capsule" The Basal Nuclei · basal nuclei: masses of grey matter embedded in the white matter · subconscious control of skeletal muscle tone and learned movements · alter motor commands from cerebral cortex via feedback loop · inhibited by dopamine (parkinsons disease) Specialized Areas · primary motor cortex and primary somatosensory cortex is separated by central sulcus · association areas coordinate incoming and outgoing information · cortex of one hemisphere receives and sends into to opposite side (decussation) Language Areas · Wernicke’s area ↳ associated with language comprehension ↳ in temporal lobe · Broca's area ↳ associated with speech production ↳ in frontal lobe · aphasia: language disorder due to damage to these areas Cerebellum · second largest part of the brain · covered by grey matter with cerebellar cortex · Functions: ↳ adjusting postural muscles ↳ coordinating and adjusting complex motor patterns · purkinje cell layer · arbor vitae "tree of life" Diencephalon · surrounds 3rd ventricle · superior part of walls is thalamus · inferior part of walls & floor is hypothalamus · Thalamus ↳ final relay point for sensory information going to cerebral cortex ↳ filters conscious awareness ↳ coordinates activities of the basal nuclei · Hypothalamus ↳ secretion of hormones -antidiuretic hormone (ADH) -oxytocin ↳ regulates body temperature ↳ control of autonomic functions ↳ coordination between voluntary and autonomic functions ↳ coordination of nervous and endocrine systems ↳ regulation of circadian rhythms ↳ subconscious control of skeletal muscle contractions ↳ production of emotional and behavioural drives The Limbic System · functional grouping many different parts/pieces · functions: ↳ establishing emotional states ↳ links conscious intellectual info with unconscious and autonomic info ↳ memory storage and retrieval · "motivational system" Brainstem · contains midbrain, pons, and medulla oblongata · midbrain ↳ visual + auditory info ↳ refexes ↳ maintains consciousness + alertness · pons ↳ relay station to cerebellum and thalamus · medulla oblongata ↳ relays sensory info to thalamus + brainstem ↳ critical autonomic functions (BP, HR, digestion) Ventricles · each cerebral hemisphere contains a lateral ventricle · ventricles are tubes that grow during development ↳ filled with CSF (lined with ependymal cells) · cerebral aqueduct Support and Protection of the Brain · Bones of the skull ↳ parietal, frontal, occipital, and temporal bones · Cranial meninges ↳ dura mater, arachnoid mater, and pia mater · Cerebrospinal fluid Cranial Meninges · Blood-brain barrier (BBB) · Dura Mater ↳ fused with periosteum of cranial bones ↳ dural folds ↳ dural sinuses · Arachnoid Mater ↳ arachnoid trebeculae ↳ subarachnoid space · Pia Mater ↳ lines the brain ↳ anchored by astrocyte projections · continuous with spinal meninges · no epidural space (fused) Cerebrospinal Fluid (CSF) Functions: Formation: · cushions the brain and spinal cord · actively transport nutrients, vitamins, and ions into the CSF · supports the brain · produced by the ependymal cells of the choroid plexus · transports nutrients, chemical · actively removes waste from CSF messengers, and wastes Blood Brain Barrier (BBB) · isolates the CNS from general circulation · 3 protective segments ↳ endothelial cells with tight junctions ↳ basement membrane ↳ astrocytes · transport across the barrier is HIGHLY selective · intact throughout CNS, with exception of circumventricular organs with fenestrated capillaries that allow necessary link for neuroendocrine functions Cranial Nerves (CN) · 12 pairs of cranial nerves · 10 cranial nerves originate in brainstem ↳ olfactory nerve (CN I) attaches to cerebrum ↳ optic nerve (CN II) attaches to diencephalon