Jhia Anjela D. Rivera1,2

1Department of Biology, College of Science, Polytechnic University of the Philippines

2Department of Biological Sciences, School of Science and Technology, Centro Escolar University

NERVOUS SYSTEM

NERVOUS SYSTEM

Functions:• Sensory input - Sensory receptors monitor numerous external and internal

stimuli

• Integration - processing sensory input and initiating responses

• Control of muscles and glands - controls the major movements of the body through the control of skeletal muscle, internal gland movements

• Homeostasis - regulatory and coordinating activities

• Mental activity - brain is the center of mental activities, including consciousness, thinking, memory, and emotions

DIVISIONS OF THE NERVOUS SYSTEM

DIVISIONS OF THE NERVOUS SYSTEM

NERVOUS SYSTEM

CENTRALNERVOUS SYSTEM

PERIPHERALNERVOUS SYSTEM

SENSORY DIVISION

MOTOR DIVISION AUTONOMIC MNS

SOMATIC MNSSYMPATHETIC

PARASYMPATHETIC

ENTERIC

DIVISIONS OF THE NERVOUS SYSTEM

SOMATIC VS AUTONOMIC

CENTRAL NERVOUS SYSTEM

• composed of the brain and spinal cord

• develop from the neural tube in the embryo

• brain is located within the skull, and the spinal cord is located within the vertebral canal, formed by the vertebrae

PERIPHERAL NERVOUS SYSTEM

• composed of all nervous structures outside the CNS that connect the CNS to the body

• consists of the spinal and cranial nerves, visceral nerves and plexuses, and the enteric system

CENTRAL NERVOUS SYSTEM

CENTRAL NERVOUS SYSTEM

a. Brainb. The Meningesc. The Hemispheresd. The Interior of the Cerebrume. The Inter-Brainf. The Midbraing. The Structure of the Cerebrumh. The Cerebellumi. The Pons Varollij. The Medulla Oblongata

BRAIN

Parts of the brain during development (rostral (cranial) to caudal):

1. Telencephalon (cerebrum)

2. Diencephalon

3. Mesencephalon (midbrain)

4. Metencephalon

5. Myencephalon (medulla oblongata)

TELENCEPHALON (CEREBRUM)

• becomes the large cerebral hemispheres

• surface of these hemispheres consists of elevations (gyri) and depressions (sulci)

• hemispheres are partially separated by a deep longitudinal fissure

• fills the area of the skull above the tentorium cerebelli and is subdivided into lobes based on position

DIENCEPHALON (CEREBRUM)

• hidden from view in the adult brain by the cerebral hemispheres

• consists of the thalamus, hypothalamus, and other related structures

• classically is considered to be the most rostral part of the brainstem

MESENCEPHALON (MIDBRAIN)

• first part of the brainstem

• located at the junction between and in both the middle and posterior cranial fossae

METENCEPHALON

• gives rise to the cerebellum (consisting of two lateral hemispheres and a midline part in the posterior cranial fossa below the tentorium cerebelli) and the pons (anterior to the cerebellum, and is a bulging part of the brainstem in the most anterior part of the posterior cranial fossa against the clivus and dorsum sellae)

MYELENCEPHALON (MEDULLA OBLONGATA)

• caudalmost part of the brainstem, ends at the foramen magnum or the uppermost rootlets of the first cervical nerve and to which cranial nerves VI to XII are attached

MENINGES

• three layers of membranes that surround the brain and the spinal cord

• a tough, outer layer (the dura mater), a delicate, middle layer (the arachnoid mater), and an inner layer firmly attached to the surface of the brain (the pia mater).

CRANIAL MENINGES

• CRANIAL DURA MATER - thick, tough, outer covering of the brain; consists of an outer periosteal layer and an inner meningeal layer• Periosteal layer - firmly attached to the skull; periosteum of the cranial cavity,

contains the meningeal arteries, and is continuous with the periosteum on the outer surface of the skull at the foramen magnum and other intracranial foramina

• Meningeal layer - close contact with the arachnoid mater and is continuous with the spinal dura mater through the foramen magnum

MENINGES

CRANIAL MENINGES

• ARACHNOID MATER - a thin, avascular membrane that lines, but is not adherent to, the inner surface of the dura mater; its inner surface thin processes or trabeculae extend downward, cross the subarachnoid space, and become continuous with the pia mater.

CRANIAL MENINGES

• PIA MATER - a thin, delicate membrane that closely invests the surface of the brain; follows the contours of the brain, entering the grooves and fissures on its surface, and is closely applied to the roots of the cranial nerves at their origins

HEMISPHERES

• LEFT HEMISPHERE• Does all the talking

• Repository of language

• Processes many aspects of language: syntax, semantics, etc.

• Does the job for analytical skills, math, logic

• RIGHT HEMISPHERE• mainly concerned with visuospatial tasks

• nonverbal communication: interprets more subtle aspects of language - metaphor, allegory, ambiguity

• also concerned with emotions, intuition

• global holistic aspects of sensory processing

HEMISPHERES

CEREBRUM

• largest part of the brain

• divided into left and right hemispheres by longitudinal fissure

• Has (gyri) numerous folds, which increase the surface area of the cortex and intervening grooves (sulci)

LOBES OF THE BRAIN

• FRONTAL LOBE• Personality, behavior, emotions, judgment, planning, problem solving, speech

(speaking and writing (Broca’s Area), body movement (motor strip), intelligence, concentration and self-awareness

• PARIETAL LOBE• Interprets language, words, sense of touch, pain, temperature (sensory strip),

interprets signals from vision, hearing, motor, sensory and memory, spatial and visual perception

• OCCIPITAL LOBE• Interprets vision (color, light, movement)

• TEMPORAL LOBE• Understanding language (Wernick’s Area), memory, hearing and sequencing and

organization

CEREBRUM

INTER-BRAIN• Hypothalamus

• Located in the floor of the third ventricle and is the master control of the autonomic system; plays a role in controlling behaviors such as hunger, thirst, sleep and sexual response, regulates body temperature, blood pressure, emotions, secretion of hormones

• Pituitary Gland• Lies in a small pocket of bone at the skull base called sella turcica; connected to the hypothalamus of the

brain by pituitary stalk; known as “master gland”; controls other endocrine glands; secretes hormones that control sexual development, promote bone and muscle growth, respond to stress and fight disease

• Pineal Gland• Located behind the third ventricle; regulate the body’s internal clock and circadian rhythms by secreting

melatonin, has some role for sexual development

• Thalamus• Serves as a relay station for almost all information that comes and goes to the cortex; plays a role in pain

sensation, attention, alertness and memory

• Basal ganglia• Includes the caudate, putamen and globus pallidus,

• Limbic system• Center of our emotions, learning and memory; includes cingulate gyri, hypothalamus, amygdala (emotional

reactions) and hippocampus (memory)

INTER-BRAIN

INTER-BRAIN

INTER-BRAIN

MIDBRAIN• smallest region of the brainstem

• located just superior to the pons and contains the nuclei of cranial nerves III (oculomotor), IV (trochlear), and V (trigeminal)

• COLLICULI – dorsal part of the midbrain (4 mounds)• SUPERIOR COLLICULI - involved in visual reflexes, and receive touch input

• INFERIOR COLLICULI - involved in hearing and are an integral part of the auditory pathways in the CNS

MIDBRAIN

CEREBELLUM• Little brain

• attached to the brainstem posterior to the pons by several large connections called cerebellar peduncles

• Coordinate muscle movements, maintain posture and balance

• CEREBELLAR PEDUNCLES – connections that provide routes o f communication between the cerebellum and other parts of the CNS

PONS VAROLLI• part of the brainstem just superior to the medulla oblongata

MEDULLA OBLANGATA• most inferior part of the brainstem

• continuous inferiorly with the spinal cord

• contains sensory and motor tracts; cranial nerve nuclei; other, related nuclei; and part of the reticular formation

PERIPHERAL NERVOUS SYSTEM

PERIPHERAL NERVOUS SYSTEM• a vast network of spinal and cranial nerves that are linked to the

brain and the spinal cord

• contains sensory receptors which help in processing changes in the internal and external environment

• subdivided into the autonomic nervous system and the somatic nervous system (autonomic has involuntary control of internal organs, blood vessels, smooth and cardiac muscles & somatic has voluntary control of skin, bones, joints, and skeletal muscle)

SPINAL NERVES• connected to the spinal cord by posterior and anterior roots

• POSTERIOR ROOT - contains the processes of sensory neurons carrying information to the CNS - the cell bodies of the sensory neurons, which are derived embryologically from neural crest cells, are clustered in a spinal ganglion at the distal end of the posterior root, usually in the intervertebral foramen

• ANTERIOR ROOT - contains motor nerve fibers, which carry signals away from the CNS—the cell bodies of the primary motor neurons are in anterior regions of the spinal cord.

SPINAL NERVES

SPINAL NERVES

SPINAL NERVES NOMENCLATURE• eight cervical nerves—C1 to C8

• twelve thoracic nerves—T1 to T12

• five lumbar nerves—L1 to L5

• five sacral nerves—S1 to S5

• one coccygeal nerve—Co.

SPINAL NERVES

SPINAL NERVES

PLEXUS• Intertwining of nerves, where nerves come together and then separate

• Cervical plexus (originates from C1-C4) – innervate several muscles attached to the hyoid bone, skin of the neck and posterior portion of the head [phrenic nerve:diaphragm]

• Brachial plexus (originates from C5-T1) – innervate upper limb and shoulder [axillarynerve: innervates the deltoid and teres minor muscles & radial nerve:muscles &skin of posterior arm & forearm & ulnar nerve: muscles &skin of anterior arm & forearm & median nerve: muscles &skin of anterior arm & forearm and intrinsic hand muscles]

• Lumbosacral plexus (originates from L1-S4) – innervates the lower limb [obturatornerve: muscles of the medial thigh and the skin over the same region & femoral nerve: innervates anterior thigh muscles and the skin over the anterior thigh and medial side of the leg & tibial nerve: innervates the posterior thigh muscles & common fibular nerve: innervates the muscles of the lateral thigh and leg and some intrinsic foot muscles (tibial+fibular) sciatic nerve

CERVICAL PLEXUS• (originates from C1-C4) – innervate several muscles attached to the hyoid

bone, skin of the neck and posterior portion of the head [phrenic nerve:diaphragm]

BRACHIAL PLEXUS• (originates from C5-T1) – innervate upper limb and shoulder [axillary nerve:

innervates the deltoid and teres minor muscles & radial nerve:muscles &skin of posterior arm & forearm & ulnar nerve: muscles &skin of anterior arm & forearm & median nerve: muscles &skin of anterior arm & forearm and intrinsic hand muscles]

LUMBOSACRAL PLEXUS • (originates from L1-S4) – innervates the lower limb [obturator nerve: muscles

of the medial thigh and the skin over the same region & femoral nerve: innervates anterior thigh muscles and the skin over the anterior thigh and medial side of the leg & tibial nerve: innervates the posterior thigh muscles & common fibular nerve: innervates the muscles of the lateral thigh and leg and some intrinsic foot muscles (tibial+fibular) sciatic nerve

CRANIAL NERVES• 12 pairs of cranial nerves pass through foramina or fissures in the

cranial cavity

• All nerves except one, the accessory nerve [XI], originate from the brain

CRANIAL NERVES COMPONENTS

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)

CRANIAL NERVES (FUNCTIONS)