nervous system.pptx

Nervous system By Dr/ Abeer Madkour Mahmoud Lecturer of Human Anatomy and Embryology  NERVOUS SYSTEM Made up of nervous tissue (neurons & glia) It receives sensations; analyses/integrates the information; and makes actions. A nerve cell (neuron) is the functio...

Nervous system By Dr/ Abeer Madkour Mahmoud Lecturer of Human Anatomy and Embryology  NERVOUS SYSTEM Made up of nervous tissue (neurons & glia) It receives sensations; analyses/integrates the information; and makes actions. A nerve cell (neuron) is the functional unit of the nervous system found in the CNS and PNS. It is specialized for conducting nerve impulses. Nerves generate electrical signals and pass them on to other nerve or muscle cells. A- Structural classification: I- Central nervous system (CNS), which consists of the brain and spinal cord. II- Peripheral nervous system (PNS), which consists of 12 pairs of cranial nerves, and 31 pairs of spinal nerves. B- Functional classification: 1- The somatic nervous system controls voluntary functions such as contraction of skeletal muscles. 2- The autonomic (visceral) nervous system controls involuntary functions such as gland secretion. Central Nervous System (CNS): includes the brain and spinal cord. The brain is formed of: a. Cerebrum b. Cerebellum c. Diencephalon d. Brain stem The brain stem is formed of 3 parts: (1) Midbrain (2) Pons (3) Medulla Oblongata  Cerebrum Formed of 2 cerebral hemispheres connected by fibers called corpus callosum  Each cerebral hemisphere is formed of: 1. Outer gray matter (cerebral cortex). 2. Inner white matter formed mainly of nerve fibers. Within the white matter masses of gray matter form the basal ganglia  Each cerebral hemisphere is divided into 4 lobes: 1. Frontal lobe 2. Parietal lobe 3. Occipital lobe 4. Temporal lobe Circulation of CSF  The Cerebellum Cerebellum consists of 2 cerebellar hemispheres; one on each side connected together by a median part called vermis.  Cerebellar - Cerebellum consists of 2 cerebellar Vermi s hemisphere hemispheres; one on each side connected together by a median part called vermis. - It has outer cortex (gray matter) andCerebellar cortex inner medulla (white matter). - The cerebellar white matter contains Dentate nucleus masses of gray matter called nuclei Cerebellar white Brain stem (foli a) Connects cerebrum with spinal cord - Formed of 3 parts: 1.Midbrain-connects cerebrum with pons. 2.Pons-connects midbrain with medulla oblongata. 3.Medulla Oblongata- connects pons with spinal cord.  Spinal Cord - Is continuation of medulla oblongata Enclosed by meninges inside upper part of vertebral canal Divided into 31 segments, each gives rise to a pair of spinal nerves Spinal Cord Spinal Cord Spinal cord is formed of outer layerwhite matter and inner layer gray matter. The gray matter is H – shaped : 2 anterior horns contain motor cells 2 posterior horns contain sensory cells Features of the spinal cord Peripheral Nervous System Consists of 1- Cranial nerves —12 pairs that exit the skull through the foramina 2- Spinal nerves—31 pairs that exit the vertebral column through the intervertebral foramina Spinal nerves— 31 pairs 8 Cervical 12 Thoracic 5 Lumbar 5 Sacral 1 Coccygeal Cranial nerves —12 pairs  Autonomic Nervous System Innervates involuntary structures as heart, smooth muscles and glands Formed of peripheral nerves (motor) with central connection · Divided into two parts:  Sympathetic system  Parasympathetic system  Parasympathetic: Cranio-sacral Cranial nerves: Sympathetic: 3,7,9,10 Thoraco-lumbar (T1 – L3 segments) Prepares body for emergency Sacral segments: 2,3,4 Conserves & restores body energy How many segments form the spinal cord? A- 28 segments. B- 30 segments. C- 31 segments. D- 32 segments. The most outer layer of the meninges is: A- Dura mater. B- Pia mater C-Arachnoid mater. D- Periosteum.