University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2024
Views:

240

Pages:

27
Author:

behend6abs

The Nervous System 1 Overview   The nervous system is the system that controls the various functions of the body by the means of electrical impulses (action potential) In comparison, the endocrine system controls various functions of the body by means of chemical substances (hormones) Divisions of the nervous system 1. Central Nervous System (CNS) 2. Peripheral Nervous System (PNS) 2 3 Histology Of The Nervous System  1. 2.    The nervous tissue is formed of two types of cells: The nerve cell – Neurons Supporting cells –Neuroglia or Glia cells In the nervous tissue there is no extracellular matrix The space between the cells is called neuropil and is formed of the processes of both neurons and glia cells and some fluid Mature neurons cannot divide. A damaged neurons cannot be repaired and is replaced by fibrous tissue 4 5 Types of Neurons: Functional Classification 1. Sensory or afferent neurons: convey action potentials into the CNS through cranial or spinal nerves. 2. Motor or efferent neurons: convey action potentials away from the CNS to effectors (muscles and glands) 3. Interneurons or association neurons: mainly located within the CNS between sensory and motor neurons. Neuroglia (Glia) cells Cell Location Schwann cells PNS Oligodendrocytes CNS Function Form myelin sheath Form myelin sheath 6 The Central Nervous System The Brain  The brain is the part of the nervous system present within the skull. The brain is formed of two halves which are similar to each other grossly. The two halves are connected with each by a number of nerve bundles The brain is formed of: 1) The Cerebrum 2) The Diencephalon 3) The Brainstem (midbrain and pons and medulla oblongata) 4) The Cerebellum 7 8 The Cerebrum    Central sulcus Lateral sulcus All motor commands issue from the cerebrum. All sensations are perceived here. In addition, this part is responsible for emotions, behavior and memory Each cerebrum is formed of four lobes: frontal lobe, parietal lobe, temporal lobe and Parietooccipital sulcus. occipital lobe. by the presence of fissures, sulci and It’s characterized protrusions called gyri. The cavity within it is the lateral ventricle 9  The outer layer of the cerebrum is called the cerebral cortex. It’s formed mainly of the body of neurons and therefore it’s called the gray matter. Inside it, we have the white matter formed mainly of nerve fibers (called tracts in CNS) (three types). corpus callosum 10 10 -1 1 left 44 - 45 1-2 4 -3 Important Sulci and Gyri 4 39- 0 17 11 The Diencephalon  This part of the brain is located on the medial aspect of the cerebrum. The cavity here is the 3rd ventricle  It’s formed of the: Thalamus Hypothalamus Epithalamus 1. 2. 3. 12 The Diencephalon Part Thalamus Main Function Relay station for most sensation to cerebral cortex. Hypothalamus 1. Controls and integrates activities of Related to ANS (anterior and 2. Controls hormone secretions of all posterior endocrine glands in the body (maestro pituitary gland gland) lobes) 3. Controls body temperature (thermostat) 4. Controls eating and drinking Pineal gland of Secrete melatonin hormone which regulates the epithalamus sleep 13 The Cerebellum    Second largest part of the brain. The central constricted area is the vermis. On each side of the vermis, we have the expanded cerebellar hemispheres The function of the cerebellum is the coordination of movement and the maintaining of balance on the same side of the body. 1. Smooths and coordinates contractions of skeletal muscles 2. Regulates posture and balance. 4th ventricle White matter Gray matter 14 14 The Brainstem  Connects the diencephalon with the spinal cord  Has 3 parts: midbrain, pons and the medulla oblongata Contains several important Control centers and the Origin of several cranial nerves (nuclei) & Several sensory and motor tracts  Part Midbrain Pons Medulla oblongata Important Centers  Substantia nigra  Red nucleus  Pontine nuclei  Tracts Notes The cavity here is the cerebral aqueduct  Cardiovascular center  Respiratory center  Pyramids: site of decussation of motor tract Exits the skull through the foramen magnum to become continuous with the spinal cord 15 Relays between cerebrum and cerebellum 16 17 The Central Nervous System The Spinal Cord • A grayish-white cylindrical structure • Starts at the foramen magnum and ends at lower border of L1 in adults. In children, it ends at L3  The spinal cord is divided into segments: 8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral and 1 Coccygeal. From each segment arise a pair of spinal nerves. Thus, we have a total of 31 pairs of spinal nerves The Peripheral Nervous System The Cranial Nerves Central Attachment Main Functions I – Olfactory Cerebrum Olfaction (Smelling) II – Optic Cerebrum Vision (sight) III – Oculomotor (autonomic) Midbrain Supply intrinsic and extrinsic muscles of eye. Pons 1. Carry sensation from scalp and face (teeth) 2. Supply muscles of mastication Between Pons and Medulla Supply extrinsic muscle of eye Cranial Nerve IV – Trochlear SO4 V – Trigeminal largest 3 Divisions VI – Abducent LR6 19 Cranial Nerve VII – Facial (autonomic) VIII Vestibulocochlear IX – Glossopharyngeal (autonomic) X – Vagus (autonomic) XI – Accessory XII – Hypoglossal Central Attachment Main Functions 1. Supply muscles of facial expression Between Pons 2. Carry taste sensations from and medulla anterior 2/3 of tongue 3. Secretions of tears and saliva Between Pons Hearing and equilibrium and medulla 1. Supply some muscles 2. Carry taste sensation from posterior 1/3 of tongue Medulla 3. Secretions of parotid saliva 1. Supply various muscles 2. Carry various sensation Supply the sternocleidomastoid and trapezius muscles Medulla Supply all intrinsic muscles of the tongue (except palatoglossus) 20 21 The Peripheral Nervous System The Spinal Nerves      31 pairs; mixed nerves (sensory and motor) Cervical (C1-C8), thoracic (T1-T12), lumbar (L1L5), sacral (S1-S5) and coccygeal (C0). A spinal nerve gives off two main branches: anterior ramus and posterior ramus Anterior rami of spinal nerves usually arranged in groups called plexuses. These include: Cervical, Brachial, Lumbar and Sacral plexuses 22 Cervical Plexus    Present in the neck Formed of anterior rami of C1-C4 The Phrenic nerve C-3,4,5 is an important nerve arising from this plexus. It supplies the diaphragm 23 Brachial Plexus  Formed by the anterior rami of C5,6,7,8 & T1.  Supplies the shoulders and upper limbs.  Important nerves arising from the brachial plexus are: 1. Axillary 2. Musculocutaneous 3. Radial 4. Median 5. Ulnar 24 Parts of the Brachial Plexus 25 Lumbar Plexus   Formed by the anterior rami of L1-L4. Femoral and obturator nerves arise from this plexus 26 Sacral Plexus    Formed by the anterior rami of L4-L5 and S1S4. Supplies the buttocks, perineum, and lower limbs. Gives rise to the largest nerve in the body- the sciatic nerve. ica: Pain along the distribution of sciatic nerve The end --- Good Luck 27

Nervous System

of 27

Description

Free up your schedule!

Take 5 seconds to unlock