Lexi, Aldana, Syeda, Erycha & Thomas

Flight or Flee?

• 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

Structures and Function of the Brain stem

Brain Stem

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.

Cerebellum

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.

Cranial Nerves

Meninges

Dura Matter• Made of strong white fibrous tissue• Outer layer of the meninges• Inner periosteum of the cranial bones• Protects inner layers including brain

Arachnoid Membrane• Delicate cob-web like• Between Dura matter and Pia matter• Adheres to outer surface of meninges

Pia Matter• Transparent• Adheres to outer surface of the brain and spinal cord• Contains blood vessels

Plexuses

Cervical Plexus(C1 through C4)

Brachial Plexus(C5 through T1)

Lumbar Plexus

Sacral PlexusL4 and L5 throughS1 and S4

Cervical Plexus(C1 through C4)

Cervical Plexus

Brachial Plexus

• 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

Lumbar Plexus

Sacral Plexus

• 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

Spinal Cord

Spinal Cord• 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

Structure of Spinal Nerves

Function of the Diencephalon Thalmus: Plays two parts in the mechanism responsible for sensationsA. Impulses from

appropriate receptors, on reaching the thalmus, produce conscious recognition of the crude, less critical sensations for pain, temperature and touch

B. Neurons whose dendrites and cell bodies lie in certain nuclei of the thalamus relay all kinds of sensory impulses,

-Responsible for emotions by associating sensory impulses with feelings of pleasant and unpleasant

-Plays a part in the arousal/ alerting mechanism-Plays a part in the mechanism that produces complex reflex movements

Hypothalmus: Helps control and integrate the responses made by visceral affects all over the body-The link between the cerebral cortex and the lower centers

Plays an indirect but essential role inn maintaining water balance-Helps control function of every cell in the body-Maintains the waking state-Regulates appetite -Maintains normal body temperatue

Structure of the Diencephalon

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

Lateral Fissure

Frontal Lobe

Central Sulcus

Parietal Lobe

Occipital Lobe

Temporal 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

Cerebrum Midbrain

Pons

Medulla

Spinal Cord

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

Medial Pectoral

Lateral Pectoral

Medial Brachial pectoral

Ulnar

Median Medial Root

Musculocutaneous

Radial

Axillary

Suprascapular

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