Structures and Function of the Brain stem• Brain stem structure/definition- is part of the brain containing the midbrain, pons, and medulla oblongata.• -Function of the brain stem – performs sensory, motor, and reflex functions
Structure and function of the Cerebellum• function of the cerebellum –performs with 3 general functions, all of which have to do with the control of skeletal muscles:• -1 acts with the cerebral cortex to produce skilled movements by coordinating the activities of groups of muscles• -2 helps control posture it functions below level of consciousness to make movements smooth instead of jerky, steady instead of trembling , and efficient and coordinated instead of ineffective, awkward, and uncoordinated .• -3 controls skeletal muscles to maintain balance.
Identifying and Describing Cranial Nerves• -structure/definition: any of the twelve pairs of nerves that attach to the undersurface of the brain and conduct impulses between the brain and structures in the head, neck, and thorax• olfactory nerve- helps you smell• optic nerve- helps you see• oculomotor nerve- helps with eye movements• trochlear nerve- responsible for eye movements• trigeminal nerve- responsible for chewing movements, head and face movements.
Cranial Nerves continued…• Abducens nerve- responsible for abduction of eye or movements• Facial nerve- responsible for facial expressions, secretion, of saliva and tears , taste• Vestibulocochlear nerve- responsible for hearing and equilibrium.• Glossopharyngeal- responsible for the sensations of the tongue, swallowing movements, secretion of saliva, aid in reflex control of blood pressure and respiration.• Vagus- responsible for sensations and movements of organs supplied e.g. slows heart, increases peristalsis and contracts muscles for voice production.• Accessory nerve- responsible for shoulder movements, turning movements of head, movements of viscera, voice production.• Hypoglossal nerve- responsible for your tongue movements.
• Made of strong white fibrous tissue • Outer layer of the meninges • Inner periosteum of the cranial bones • Protects inner layers including brain• Delicate cob-web like• Between Dura matter and Pia matter• Adheres to outer surface of meninges• Transparent• Adheres to outer surface of the brain and spinal cord• Contains blood vessels
Cervical Plexus Cervical Plexus (C1 through C4) (C1 through C4) Brachial Plexus (C5 through T1) Lumbar PlexusSacral PlexusL4 and L5 throughS1 and S4
• Innervate the muscles and skin of the neck, upper shoulders, and part of the head• Exiting the plexus, phrenic nerve, which innervates the diaphragm• Deep within shoulder• Passes from ventral rami of spinal nerves C5 through T1• Beneath clavicle• Toward upper arm• Innervates the lower part of the shoulder and entire arm
• Made from intermingling fibers from the first four lumbar nerves• Lumbar region of back• Divides into many branches supplying the thighs and legs• Formed fibers from the fourth and fifth lumbar nerves and the first four sacral nerves• Lies in pelvic cavity on the anterior surface of the piriformis muscle• Forms the sciatic nerve• Through buttocks and back of thigh• Supplies all leg skin
• Within spinal cavity• From foramen magnum to the lower border of the first lumbar vertebra• Averages about 18 inches• Conducts information to and from brain• Reflex center for all spinal reflexes
Function of the DiencephalonThalmus: Plays two parts in -Plays a part in Plays an indirect butthe mechanism responsible the arousal/ essential role innfor sensations alerting maintaining waterA. Impulses from mechanism balance appropriate receptors, on -Plays a part in -Helps control function reaching the thalmus, the mechanism of every cell in the body produce conscious that produces -Maintains the waking recognition of the crude, complex reflex state less critical sensations for movements -Regulates appetite pain, temperature and -Maintains normal body touch temperatueB. Neurons whose Hypothalmus: dendrites and cell bodies Helps control and lie in certain nuclei of the integrate the thalamus relay all kinds responses made of sensory impulses, by visceral affects-Responsible for emotions by all over the bodyassociating sensory impulses -The link betweenwith feelings of pleasant and the cerebralunpleasant cortex and the lower centers
Function of CSF• CSF (Cerebrospinal fluid)• Provides a supportive, protective cushion• A reservoir of circulating fluid that gets monitored by the brain for changes in the internal environment.
Somatic Sensory Pathways in CNS• A relay of neurons that send impulses to the sensory area’s• Primary Sensory Neurons: Conduct from Periphery to central nervous system• Secondary Sensory Neurons: Conduct from cord and brainstem up to thalamus• Tertiary Sensory Neurons: Conduct from the thalamus to the post central gyrus of the parietal lobe
Cerebral Cortex• Cerebrum – largest and uppermost division of the brain and has 2 divisions• The cortex has six layers that each has millions of axon terminals• Each area of the cerebrum represents a gyrus• The cerebrum contains the frontal lobe, parietal lobe, occipital lobe, and the temporal lobe
Somatic Motor Pathways• Pyramidal tracts are those who fibers come together in the medulla to form pyramids• Extrapyramidal tracts consist of all motor tracts from the brain to the spinal cord• Sets of coordinated muscle commands the control muscle activity is called a motor program
Dermatomes and Myotomes• Each skin area supplied by sensory fibers is called dermatome• A myotome is a skeletal muscle or group that receives motor axons from a given spinal nerve• There is a overlap among myotomes thus some skeletal muscle organs may be innervated by motor axons