The pineal gland produces melatonin, a serotonin derived hormone which modulates sleep patterns in both circadian and seasonal cycles. The shape of the gland resembles a pine cone, hence its name.
orpus callosum consists of about 200 millon axons that interconnect the two hemispheres. The primary function of the corpus callosum is to integrate motor, sensory, and cognitive performances between the cerebral cortex on one side of the brain to the same region on the other side.
layers of the meninges in order
dura mater arachnoid mater pia mater
what makes up the brain stem
pons medulla oblongata midbrain
posterior - vertebro-basilar artery system
subclavian -> vertebral artery -> basilar artery -> posterior cerebral artery superior cerebellar artery
anterior circulation - carotid
common carotid - > bifurcates into internal/external carotid -> internal carotid anterior communicating artery anterior cerebral artery middle cerebral artery
vulnerable to anoxia, watershed infarcts area where end vessels from MCA and ACA meet
major divisions of the CNS
cerebrum cerebellum brainstem spinal cord
caudate nucleus putamen globus pallidus
Brainstem • Many fiber tracts carrying motor and sensory information travel through the brainstem; other fiber tracts begin or end within the brainstem. • Brainstem contains important groups of neurons that control equilibrium, cardiovascular activity, respiration, and other functions.
• Consists of two large cerebellar hemispheres and a midline vermis. • Attached to the posterior brainstem by large bundles of fibers called peduncles. – Superior, middle, and inferior peduncles join the midbrain, pons, and medulla with the cerebellum. • Main function is to coordinate movements.
receives and integrates all* sensory information; important for regulation of consciousness, arousal, memory
Important in maintaining homeostasis, emotional expression, regulation of circadian rhythm, endocrine regulation of growth, metabolism and reproductive organs
includes Pineal gland which helps regulate circadian rhythms and influences secretions of the pituitary gland, adrenal and parathyroid glands
• Cutaneous receptors – Mechanoreceptors – Chemoreceptors – Thermoreceptors *nociceptors • Proprioceptors – Muscle spindle – Golgi Tendon Organ – Joint receptors
• Cutaneous receptors respond to touch, pressure, vibration, stretch, noxious stimuli, and temperature. • Touch – Fine (discriminative) touch includes a variety of receptors – Crude (non-discriminative) touch is mediated by free endings throughout the skin.
Muscle spindle (proprioceptors)
• Respond to quick and prolonged stretches of the muscle. • Important to adjust muscle tone
Golgi tendon organs
• GTO respond to force generated by the muscle contraction
• Joint receptors respond to mechanical deformation of joint capsules and ligaments.
dorsal column/medial lemniscus pathway
– Discriminative touch – Conscious proprioception – Vibration • 3 neurons in line – 1st cell body in ipsilateral dorsal root ganglion – 2nd cell body in ipsilateral sensory nuclei at medulla – 3rd cell body in contra-lateral thalamus decussates caudal medulla
• Composed of both sensation and the emotional response to the sensation. • Nociceptors: free nerve endings that receive information about stimuli that damage or threaten to damage tissue. – Fast pain (Anterolateral/ spinothalamic pain) is the initial and immediate sharp sensation that helps us localize the injury – Slow pain (spinolimbic pain) is the dull, throbbing ache following fast pain that is not well localized that assists us with our behavioral response to injury • Sensation depends on several aspects including emotional state, cultural background etc
anterolateral, spinothalamic tract
decussates at the spinal level – Fast pain – Temperature – Crude touch • 3 neurons in line – 1st cell body in ipsilateral dorsal root ganglion – 2nd cell body in ipsilateral dorsal horn – 3rd cell body in contra-lateral thalamus
medial pain (slow)
• Dull, aching, throbbing pain • C fibres • Diffuse signals to several brain structures including the limbic system and brainstem • Can generate a widespread response involving the whole body, modulate the sensitivity of the receptors and other parts of the pathway • Helps us with understanding the impact, activates a decision making process and a response
sensory contribution to movement
• Feedforward refers to the anticipatory use of sensory information to prepare for movement. • Feedback refers to the use of sensory information during or after movement to make corrections either to the ongoing movement or to future movements.