HSDH2120 Head & Neck Anatomy Lecture Notes Fall 2024 PDF

HSDH2120 Head & Neck Anatomy Lesson#10: Nerve Innervation Objectives: 6.1- 6.5 Week 12. Fall 2024 Dr. Jafar Alabdullah 1  6.0 Nerve Innervation Learning Objectives: 6.1 Nervous System 6.1.1 Describ...

HSDH2120 Head & Neck Anatomy Lesson#10: Nerve Innervation Objectives: 6.1- 6.5 Week 12. Fall 2024 Dr. Jafar Alabdullah 1  6.0 Nerve Innervation Learning Objectives: 6.1 Nervous System 6.1.1 Describe basic function of the central nervous system 6.1.2 Describe basic function of the peripheral nervous system 6.1.3 Describe the basic function of the autonomic nervous system 6.2 Cranial nerves 6.2.1 Describe the 12 cranial nerves 6.2.2 Describe the general function of each nerve 6.2.3 Trigeminal nerve 6.2.3.1 Describe the course of the trigeminal nerve 6.2.3.2 Identify each branch of the trigeminal nerve 6.2.3.3 Describe the function of each branch of the trigeminal nerve 6.2.3.4 Distinguish between motor and sensory branches of the trigeminal nerve 2  Learning resources Illustrated anatomy of the head and neck text book, Chapter 8: Nervous system P. 165- 175 3 Nervous System Overview 4  Nervous System Overview The nervous system is an extensive, complex network of neural structures that activates, coordinates, and controls all functions of the body. 5  Function of the Nervous System 1. Causes muscles to contract resulting in facial expressions and even joint movements, such as those involved in mastication and speech. 2. Stimulates glands to secrete and regulates many other systems of the body such as the vascular system and digestive system. 3. Allows sensation to be perceived, such as pain and touch during dental treatment. 6 Nervous System Overview The nervous system has two main divisions: central and peripheral. 7 8  Nervous System Overview The neuron is the cellular component of the nervous system and is composed of a cell body and neural processes. A nerve is a bundle of neural processes outside the central nervous system and in the peripheral nervous system. 9  Nervous System Overview A synapse is the junction between two neurons or between a neuron and an organ, where neural impulses are transmitted. 10  Nervous System Overview In order to function, most tissue, structures, and organs have innervation, a supply of nerves to the body part. A nerve allows information to be carried to and from the brain, which is the central information center. 11  Nervous System Overview An accumulation of neuron cell bodies outside the central nervous system is a ganglion (plural, ganglia) such as the trigmeninal ganglion. 12  Nervous System Overview: Afferent and Efferent Nerves Nerves are of two types: afferent and efferent. An afferent nerve or sensory nerve carries information from the periphery of the body to the brain (or spinal cord). Thus an afferent nerve carries sensory information such as taste, pain to the brain. 13  Nervous System Overview: Afferent and Efferent Nerves An efferent nerve or motor nerve carries information away from the brain (or spinal cord) to the periphery of the body. Thus an efferent nerve carries information to the muscles in order to activate them, often in response to information received by way of the afferent nerves. 14  Nervous System Overview: Afferent and Efferent Nerves 15  Activity A student ask another student a question. 16  Nervous System Central Nervous System (CNS) 17  Central Nervous System One of the major divisions of the nervous system, the central nervous system (CNS) includes both the brain and spinal cord. 18  I. Brain The major divisions of the brain include: 1. Cerebrum 2. Cerebellum 3. Brainstem 4. Diencephalon 19 20  1. Cerebrum 2. Cerebellum The cerebrum is the largest division of the brain and consists of two cerebral hemispheres. The cerebellum is the second largest division of the brain, after the cerebrum. 21  3. Brain Stem The brainstem has a number of divisions including: A. Medulla B. Pons C. Midbrain 22 23 24  4. Diencephalon Superior to the brainstem, the diencephalon primarily includes: A. The thalamus. B. The hypothalamus. 25  II. Spinal Cord The other component of the CNS, the spinal cord, runs along the dorsal side of the body and links the brain to the rest of the body. 26  Nervous System Peripheral Nervous System (PNS) 27  Peripheral Nervous System The other major division of the nervous system, the peripheral nervous system (PNS), is composed of all the nerves stretching their pathways among the CNS and the receptors, muscles, and glands. 28 29  Peripheral Nervous System The PNS is further divided into: I. Afferent nervous system or sensory nervous system, which carries information from receptors to the brain or spinal cord II. Efferent nervous system or motor nervous system, which carries information from the brain or spinal cord to muscles or glands. 30  Peripheral Nervous System I. A nerve cell leading from the eye to the brain and carrying visual information is a part of the afferent nervous system. II. A nerve cell leading from the brain to the muscles controlling the eye’s movement is a part of the efferent nervous system. 31  Activity A student ask another student a question. 32 2. Autonomic Nervous System The ANS itself has two nervous system subdivisions: A. Sympathetic B. Parasympathetic. 33  A. Sympathetic Nervous System The sympathetic nervous system is involved in “fight- or-flight responses” such as the shutdown of salivary gland secretion. 34 A. Sympathetic Nervous System 35  B. Parasympathetic Nervous System The parasympathetic Rest & Digest nervous system is involved in “rest-or- digest” responses such as the stimulation of salivary gland secretions. 36 37  Activity A student ask another student a question. 38  10 Minutes Break 39 Nervous System Cranial Nerves 40  Cranial Nerves The cranial nerves are an important part of the PNS. All 12 paired cranial nerves are connected to the brain at its base and pass through the skull by way of fissures or foramina. 41  Cranial Nerves Some cranial nerves are either afferent or efferent, and others have both types of neural processes. Both Roman numerals (I to XII) and anatomic terms are used to designate the cranial nerves. 42 To remember the names of the nerves: Oh Once One Takes The Anatomy Final, Very Good Vacations Are Heavenly OR Oh, Oh, Oh, To Take A Family Vacation! Go Vegas After Hours The mnemonics to remember the types of cranial nerves can be chosen from: S = Sensory M = Motor B = Both (sensory + motor) Some Say Money Matters, But My Beloved Says Being Beloved Matters More." 43 44 45 46 47 48 49  Cranial Nerve I: Olfactory The first (I) cranial or olfactory nerve transmits smell from the nasal mucosa to the brain and thus functions as an afferent nerve. The nerve enters the skull through the perforations in the cribriform plate of the ethmoid bone to join the olfactory bulb in the brain. 50  Cranial Nerve II: Optic The second (II) cranial or optic nerve transmits sight from the retina of the eye to the brain and thus functions as an afferent nerve. 51  Cranial Nerve III: Oculomotor The third (III) cranial or oculomotor nerve serves as an efferent nerve to some of the eye muscles that move the eyeball. 52  Cranial Nerve V: Trigeminal The fifth (V) cranial or trigeminal nerve has both an efferent component for the muscles of mastication, as well as some other cranial muscles, and an afferent component for the teeth, tongue, and oral cavity, as well as most of the skin of the face and head. 53  Cranial Nerve V: Trigeminal The trigeminal nerve is the most important cranial nerve to the dental professional because it innervates relevant tissue, structures, and organs of the head and neck. It has three branches: 1. Ophthalmic nerve 2. Maxillary nerve 3. Mandibular nerve 54  Cranial Nerve VII: Facial The seventh (VII) cranial or facial nerve carries both efferent and afferent components. The nerve carries an efferent component for: 1. Muscles of facial expression 2. Lacrimal gland 3. Submandibular and sublingual salivary glands. 55  Cranial Nerve VII: Facial This nerve is also important to dental professionals because it innervates relevant tissue of the head and neck and travels through the parotid gland. 56  Cranial Nerve IX: Glossopharyngeal The ninth (IX) cranial or glossopharyngeal nerve carries an efferent component for: 1. pharyngeal muscles 2. stylopharyngeus muscle 3. parotid salivary gland The nerve also carries an afferent component for: 1. taste and general sensation from the base of the tongue 2. afferent limb of the gag reflex. 57  Cranial Nerve XI: Accessory The eleventh (XI) cranial or accessory nerve functions as an efferent nerve for: 1. Trapezius 2. Sternocleidomastoid 58  Cranial Nerve XII: Hypoglossal The twelfth (XII) cranial or hypoglossal nerve functions as an efferent nerve for both the intrinsic and extrinsic muscles of the tongue. The hypoglossal nerve is important to dental professionals because it innervates the tongue. 59  References Fehrenbach, M. J. and Herring S. W. (2007). Illustrated anatomy of the head and neck, (3rd ed.). Philadelphia: Saunders Elsevier. ISBN- 10: 141603403X ISBN-13:9781416034032 Brand, Richard W. and Isselhard, Donald E. (2003). Anatomy of Orofacial Structures, (7th ed.). Philadelphia: Mosby, Inc. ISBN- 13: 978- 0-323-01954-5, ISBN-10: 0-323-01954-4 60