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DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Overview Of Muscle Tissues CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Overview Of Muscle Tissues using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic The three types of muscle tissue are skeletal, cardiac, and smooth. SKELETAL MUSCLE Overview Of Muscle Tissues CONNECTIVE TISSUE SHEATHS Epimysium. An overcoat of dense irregular connective tissue surrounds the whole muscle. ATTACHMENTS Muscle attachments, whether origin or insertion, may be direct or indirect. SMOOTH MUSCLE Smooth muscle lacks the coarse connective tissue sheaths seen in skeletal muscle. CARDIAC MUSCLE NERVOUS TISSUE NEUROGLIA Neuroglia in the CNS include astrocytes, microglia, ependymal cells, and oligodendrocytes. NEURONS 1. They have extreme longevity. Given good nutrition, neurons can function optimally for a lifetime (over 100 years). OVERVIEW OF MUSCLE AND NERVOUS TISSUES The three types of muscle tissue are skeletal, cardiac, and smooth. First, skeletal and smooth muscle cells (but not cardiac muscle cells) are elongated and, for this reason, are called muscle fibers. Second, muscle contraction depends on two kinds of myofilaments, which are the muscle equivalents of the actin- or myosin-containing microfilaments. These two proteins play a role in motility and shape changes in virtually every cell in the body, but this property reaches its highest development in the contractile muscle fibers. Third, whenever you see the prefixes myo or mys or sarco (flesh), the reference is to muscle SKELETAL MUSCLE Each skeletal muscle is a discrete organ, made up of several kinds of tissues. Although skeletal muscle fibers predominate, blood vessels, nerve fibers, and substantial amounts of connective tissue are also present. A skeletal muscle’s shape and its attachments in the body can be examined easily without the help of a microscope. Overview Of Muscle Tissues In general, each muscle is served by one nerve, an artery, and by one or more veins, all of which enter or exit near the central part of the muscle and branch profusely through its connective tissue sheaths. Unlike cells of cardiac and smooth muscle tissues, which can contract in the absence of nerve stimulation, each skeletal muscle fiber is supplied with a nerve ending that controls its activity. Overview Of Muscle Tissues Contracting muscle fibers use huge amounts of energy, a situation that requires more or less continuous delivery of oxygen and nutrients via the arteries. Muscle cells also give off large amounts of metabolic wastes that must be removed through veins if contraction is to remain efficient. Muscle capillaries, the smallest of the body’s blood vessels, are long and winding and have numerous cross-links, features that accommodate changes in muscle length. CONNECTIVE TISSUE SHEATHS In an intact muscle, the individual muscle fibers are wrapped and held together by several different connective tissue sheaths. Together these connective tissue sheaths support each cell and reinforce the muscle as a whole, preventing the bulging muscles from bursting during exceptionally strong contractions. Overview Of Muscle Tissues Endomysium. Each individual muscle fiber is surrounded by a fine sheath of connective tissue consisting of areolar and reticular fibers. Perimysium and fascicles. Within each skeletal muscle, the endomysium-wrapped muscle fibers are grouped into fascicles that resemble bundles of sticks. Surrounding each fascicle is a layer of fibrous connective tissue called perimysium. Epimysium. An overcoat of dense irregular connective tissue surrounds the whole muscle. This coat is the epimysium, a name that means outside the muscle. Sometimes the epimysium blends with the deep fascia that lies between neighboring muscles or the superficial fascia deep to the skin ATTACHMENTS Most skeletal muscles span joints and are attached to bones (or other structures) in at least two places. When a muscle contracts, the movable bone, the muscle’s insertion, moves toward the immovable or less movable bone, the muscle’s origin. In the muscles of the limbs, the origin typically lies proximal to the insertion Muscle attachments, whether origin or insertion, may be direct or indirect. In direct, or fleshy, attachments, the epimysium of the muscle is fused to the periosteum of a bone or perichondrium of a cartilage. In indirect attachments, the muscle’s connective tissue wrappings extend beyond the muscle either as a ropelike tendon or as a sheetlike aponeurosis. The tendon or aponeurosis anchors the muscle to the connective tissue covering of a skeletal element (bone or cartilage) or to the fascia of other muscles SMOOTH MUSCLE Smooth muscle fibers are spindle-shaped cells, each with one centrally located nucleus. Typically, they have a diameter of 5–10 µm and are 30–200 µm long. Skeletal muscle fibers are some 10 times wider and thousands of times longer. Smooth muscle lacks the coarse connective tissue sheaths seen in skeletal muscle. However, a small amount of fine connective tissue, secreted by the smooth muscles themselves and containing blood vessels and nerves, is found between smooth muscle fibers. Most smooth muscle is organized into sheets of closely apposed fibers. These sheets occur in the walls of all but the smallest blood vessels and in the walls of hollow organs of the respiratory, digestive, urinary, and reproductive tracts CARDIAC MUSCLE like skeletal muscle, is striated, and it contracts by the sliding filament mechanism. However, in contrast to the long, cylindrical, multinucleate skeletal muscle fibers, cardiac cells are short, fat, branched, and interconnected. Each fiber contains one or at most two large, pale, centrally located nuclei. The intercellular spaces are filled with a loose connective tissue matrix (the endomysium) containing numerous capillaries. This delicate matrix is connected to the fibrous skeleton, which acts both as a tendon and as an insertion, giving the cardiac cells something to pull or exert their force against Overview Of Muscle Tissues Large mitochondria account for 25–35% of the volume of cardiac cells and give cardiac cells a high resistance to fatigue. Most of the remaining volume is occupied by myofibrils composed of fairly typical sarcomeres. The sarcomeres have Z discs, A bands, and I bands that reflect the arrangement of the thick (myosin) and thin (actin)

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Nervous Tissue CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Nervous Tissue using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Nervous tissue or nerve tissue: Components of Nervous Tissue A typical Neuron consist of: Types of Neurons Classification of Neurons according to their Functional Roles Neuroglia (Glial Cells) Microglia Glia Cells Found in the Peripheral Nervous System NERVOUS TISSUE Nervous tissue or nerve tissue: Is a complex network of cells that makes up the brain,spinal cord and nerves which are responsible for controlling and coordinating many of body’s activities. It creates two parts of the nervous system,which are; 1.The brain and spinal cord of the Central nervous system (CNS) and 2.The peripheral nerves of the Peripheral nervous system (PNS) Nervous tissue is distributed throughout the body as an integrated communications network. Components of Nervous Tissue Structurally, nerve tissue consists of two classes of cell types. 1.Neurons, Nervous tissue is made up of billions of cells called neurons that are specialized to respond to stimuli and to transmit a signal to activate other cells. 2.Glial cells or neuroglia (non-excitable supporting cells), They participate in neural activity, neural nutritional and defence processes of the central nervous system. A typical Neuron consist of: Cell body, which has many radiating processes called dendrites, which are specialized to receive signals from other neurons. Axon, a single long process, which is capable of generating a nerve impulse and conducting it over a long distance to stimulate other neurons in the CNS, or muscular or secretory cells elsewhere in the body. Neurons usually receive information through dendrites; the information is integrated in the cell body and transmitted onwards via axons. Types of Neurons 1.Unipolar neurons, These neurons have single processes, the axon arising from the cell body.Unipolar neurons have no dendrites. 2.Bipolar neurons, Have two processes (both axons) emerging directly and oppositely from the cell body. Bipolar neurons are found in the cochlear and vestibular ganglia as well as retina and olfactory mucosa. 3.Multipolar neurons, Has one axon and many dozens of dendrites.Most neurons in the CNS are multipolar. 4.Pseudo unipolar neurons, Has a single short process (an axon) with a T-shaped branching, one branch extending towards the CNS, and the other extending to a periphery ending.In typical pseudo unipolar neurons, both branches are axons on both structural and electrophysiological grounds. Classification of Neurons according to their Functional Roles Motor neurons, They are involved in stimulating muscles or glands (effector organs) in the periphery. Sensory neurons, Sensory neurons receive sensory stimuli from the environment or from tissues and organs of the body. Inter-neurons, They maintain connection between neurons in the CNS, forming complex functional chains or circuits Neuroglia (Glial Cells) These are supporting cells found in the central nervous system and peripheral nervous system.There are six types of supporting cells whereas four are found in the CNS and two are found in the PNS. Neuroglia found in central nervous system are; Astrocytes Star-shaped, abundant, and versatile cells which guide the migration of developing neurons, they are found in large numbers adjacent to blood vessels. They form a blood-brain barrier, i.e. the blood is separated from neurones by capillary wall and a layer of astrocytes foot process. Microglia Specialized immune cells that act as the macrophages of the CNS and they derived from monocytes. Ependymal Cells These cells form the epithelial lining of the ventricles of the brain and the central canal of the spinal cord. Oligodendrocytes These are found in clusters around cell bodies.They form and maintain the myelin, having the same functions as schwann cells in peripheral nerves. These cells have clinical importance as most tumours of the brain are arising from them. Glia Cells Found in the Peripheral Nervous System Satellite cells, surround clusters of neuronal cell bodies in the PNS, they are of unknown function Schwann cells, form myelin sheaths around the larger nerve fibers in the PNS, they are for neuronal regeneration ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Nervous System CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Nervous System using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Nervous System Division of nervous system: Present in the cranial cavity Don’t get confused about simple anatomy on parts of the brain- fore brain,mid brain and hind brain Brain and spinal cord composed of grey mater and white mater Brain The diencephalon is located at the center of the brain, and its name (Greek for “between-brain”) reflects that. The corpus callosum is the bridge between the left and right sides of the brain The Meninges Ventricular system Ventricles of the Brain lateral ventricles Fourth ventricle It is also found inside the subarachnoid space of the meninges which surrounds both the brain and the spinal chord. Ependymal cell, Composition of CSF PNS Cranial nerve spinal cord Spinal nerves T1–T6 Intercostals and trunk above the waist Brain Present in the cranial cavity. Diencephalon. Hypothalamus. Meninges of the Brain. Peripheral Nervous System. Nervous System Nervous System The nervous system is responsible for controlling much of the body, both through somatic (voluntary) and autonomic (involuntary) functions It is very important in helping to maintain balance of the body Made up of nerve tissue neurones and neuroglia Nervous system enables the body to react to continuous changes in its internal and external environment Division of nervous system: Nervous system is divided Structurally into Central nervous system Peripheral nervous system Functionally into Somatic Autonomic Present in the cranial cavity Surrounded by three layers of meninges Don’t get confused about simple anatomy on parts of the brain- fore brain,mid brain and hind brain brain has 2 hemispheres namely right and left hemisphere has 4 lobes namely occipital lobe,pariental lobe,frontal lobe and temporal lobe Brain and spinal cord composed of grey mater and white mater Grey mater formed by nerve cell bodies White mater formed by interconnecting fibre tract system Brain Forebrain (prosencephalon)-cerebrum,thalamus+hypothalamus form limbic system(regulation of thirst, hunger, mood) and basal ganglia (reward processing, habit formation, movement and learning Midbrain(mesencephalon)-tectum,tegmentum Hind brain (rhombencephalon)- cerebellum,pons,medulla oblangata Applied anatomy:degeneration of basal ganglia cells uncoordinated movements of skeletal muscles e.g in Parkinson’disease NB: midbrain, pons and medulla form the brain stem Development of brain Nervous System v vv The diencephalon is located at the center of the brain, and its name (Greek for “between-brain”) reflects that. It’s surrounded by the brain stem and cerebellum on the bottom and the cerebral cortex on top. The corpus callosum is the bridge between the left and right sides of the brain The corpus callosum (Latin for "tough body") The Meninges The central nervous system consists of the brain and spinal cord. The brain and spinal cord are completely covered by three membranes, the meninges lying between the skull and the brain, and between vertebrae and the spinal cord. o Dura mater o Arachnoid mater o Pia mater Ventricular system Ventricular system is a communicating system of cavities underlined by choroid plexus which produce cerebrospinal fluid and transport it around the cranial cavity. They are lined by ependymal cells. There are ventricles:- Lateral ventricles Third ventricle Fourth ventricle Central Canal. Ventricles of the Brain Within the brain there are four irregular shaped cavities containing cerebrospinal fluid. They are called ventricles, these are o Right and left lateral ventricles o third ventricle and fourth ventricle lateral ventricles lateral ventricles are the two largest cavities of the ventricular system of the human brain and contain cerebrospinal fluid (CSF). Each cerebral hemisphere contains a lateral ventricle, known as the left or right ventricle They open into the 3rd ventricle through the interventricular foramina (of monro). They are separated from each other by a thin membrane, the septum lucidium,and are lined by ciliated epithelium (ependymal cells). 3rd ventrical It is a cavity situated below the lateral ventricles between the two parts of the thalamus. Fourth ventricle It is situated below and behind the third ventricle, between the cerebellum and pons. It communicates with the subarachnoid space by 3 foramina in its roof, and continuous below with central canal of the spinal cord The fourth ventricle contains cerebrospinal fluid. It has a diamond shape and is located in the upper portion of the medulla CEREBRAL SPINAL FLUID It is also found inside the subarachnoid space of the meninges which surrounds both the brain and the spinal chord. In addition, a space inside the spinal chord called the central canal also contains cerebrospinal fluid CSF is produced mainly by a structure called the choroid plexus in the lateral, third and fourth ventricles. A small amount is also produced by ependymal cells. Ependymal cell, type of neuronal support cell (neuroglia) that forms the epithelial lining of the ventricles (cavities) in the brain and the central canal of the spinal cord. Composition of CSF It consists of Water Mineral salts Glucose Plasma proteins: small amount of albumin and globulin Small amount of creatinine, urea A few leukocytes It is slightly alkaline Functions of CSF Applied anatomy Hydrocephalus PNS 12 pairs of cranial nerves—leave the brain and pass through the foramina in the skull 31 pairs of spinal nerves—leave the spinal cord and pass through intervertebral foramina Cranial nerve any of the nerves that arise in pairs from the lower surface of the brain one on each side and pass through openings in the skull to the periphery of the body and that comprise 12 pairs. They can be classified as sensory nerves, motor nerves, or a combination of both, primarily responsible for the sensory and motor functions of the head and neck (one of these nerves targets organs in the thoracic and abdominal cavities as part of the parasympathetic nervous system). spinal cord cervical segments thorathic segments lumbar segments sacral segments coccygeal segements Origin of spinal nerves Spinal nerves Actions of the spinal nerves Level Motor Function C1–C6: Neck flexors C1–T1: Neck extensors C3, C4, C5=Phrenic nerve Supply diaphragm

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Musculoskeletal System CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Musculoskeletal System using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Musculoskeletal System Axial skeleton Outside the bony skull there is a layer with fascia and muscles known as scalp which covers the skull The spine Atlas Axis (C2) Thoracic spine Lumbar spine Sacrum MUSCULOSKELETAL SYSTEM Musculoskeletal System The musculoskeletal system is an interconnected structure of bone, muscle, cartilage, tendons, and other tissues that give our bodies form, support, movement, and the ability to do work. Skeleton is made up of 206 bones that articulates together to form joints that support balance and movement. It is classified into two forms,which are; 1.Axial skeleton 2.Appendicular skeleton Axial skeleton It consists of skull,spine and pelvis bones The Skull Skull is the most superior part of the bodily structure and has total of 22 bones which are divided in two categories,which are; 1.Cranial bones (8 bones) 2.Facial bones (14 bones) Outside the bony skull there is a layer with fascia and muscles known as scalp which covers the skull And inside the skull there is strong layer that protects the brain from trauma is called meninge Meninges has three layers,which are; 1.Dura matter 2.Arachnoid matter 3.Pia matter The space btn dura and arachnoid matter is called subdural space while a space btn arachnoid and pia matter is called subarachnoid space Cranial bones The spine It is fundamental structure in body balance,support,coordination and movement.It consists of 33 vertebral bodies that are divided into 5 categories depending on the position and function. Cervical spine The cervical spine is the first part of the spinal column, consisting of 7 cervical vertebrae, C1-C7. These vertebrae are ring-like bony structures supporting the weight of the head. The first two bones, C1 and C2, are highly specialized, known as the atlas and axis.It is found at the neck posteriorly surrounded by adjacent muscles that support neck movement i.e sternocleiodomastoid Atlas Located at the top of the spine,the atlas forms the articulation with the occipital bone, connecting the skull and spine. Its primary difference from the other vertebrae in the cervical region is the absence of a vertebral body and spinous process. Its lateral masses are connected by the anterior and posterior arches. Axis (C2) It forms the pivot upon which the Atlas rotates (atlanto-axial joint), letting us rotate our head independently of the body. The most identifiable landmark of this bone is the strong odontoid process or dens that rises perpendicularly from the upper surface of the body and articulates with the atlas’ anterior arch. There are also articulations between the axis’s superior articular facets and the atlas’ inferior articular facets. Between two vertebral bodies there is catilagenous roundish pad known as intervertebral disc. Thoracic spine It is below the cervical spine and it is made up of 12 vertebral bodies.Bends posteriorly creating thoracic kyphosis. Has articulating facets both superiorly and inferiorly for rib attachment thus involved in creating thoracic cage posteriorly Lumbar spine Has 5 vertebral bodies joined up by intervertebral discs.They are wide and tough as it creates the base of the spine.It is tightly hold up by psoas and iliopsoas muscles.It bend anteriorly resulting into lumnar lordosis. Sacrum It consist of 5 fused vertebra with 4 paired sacral foramens for passage of spinal nerves.It is involved in creating pelvic brim posteriorly and it is attached to iliac spine by sacroiliac joint in both left and right side Coccyx It consist of 4 fused small vertebral bodies and it is the last segment of the spine.It is known as the spine tail. Pelvis ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Musculoskeletal CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Musculoskeletal using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic BONES AND CARTILAGES Musculoskeletal HYALINE CARTILAGES Skeletal hyaline cartilages include: ELASTIC CARTILAGES FIBROCARTILAGES CLASSIFICATION OF BONES Bones come in many sizes and shapes. 2. Short bones are roughly cube shaped. 3. Flat bones are thin, flattened, and usually a bit curved. FUNCTIONS OF BONES 2. PROTECTION. The fused bones of the skull protect the brain. 4. MINERAL AND GROWTH FACTOR STORAGE. Bone is a reservoir for minerals, most importantly calcium and phosphate. BONE STRUCTURE BONE MARKINGS These bone markings are named in different ways. BONE TEXTURES: COMPACT AND SPONGY BONE DIAPHYSIS EPIPHYSES MEMBRANES Internal bone surfaces are covered with a delicate connective tissue membrane called the endosteum . STRUCTURE OF SHORT, IRREGULAR, AND FLAT BONES LOCATION OF HEMATOPOIETIC TISSUE IN BONES BONE DEVELOPMENT FORMATION OF THE BONY SKELETON BONE HOMEOSTASIS: REMODELING AND REPAIR Spongy bone is replaced every three to four years; compact bone, every ten years. BONE REMODELING Bone deposit occurs wherever bone is injured or added bone strength is required. BONE REPAIR FRACTURES CLASSIFICATION 3. Orientation of the break relative to the long axis of the bone. 4. Whether the bone ends penetrate the skin. A fracture is treated by reduction, the realignment of the broken bone ends. Repair in a simple fracture involves four major stages Fibrocartilaginous callus formation. Bony callus formation. SKELETAL SYSTEM BONES AND CARTILAGES A skeletal cartilage is made of some variety of cartilage tissue, which consists primarily of water. The high water content of cartilage accounts for its resilience, that is, its ability to spring back to its original shape after being compressed. Musculoskeletal The cartilage, which contains no nerves or blood vessels, is surrounded by a layer of dense irregular connective tissue, the perichondrium. The perichondrium acts like a girdle to resist outward expansion when the cartilage is compressed. HYALINE CARTILAGES Which look like frosted glass when freshly exposed, provide support with flexibility and resilience. They are the most abundant skeletal cartilages. When viewed under the microscope, their chondrocytes appear spherical. The only fiber type in their matrix is fine collagen. Skeletal hyaline cartilages include: Articular cartilages, which cover the ends of most bones at movable joints. Costal cartilages, which connect the ribs to the sternum (breastbone) Respiratory cartilages, which form the skeleton of the larynx (voicebox), and reinforce other respiratory passageways. Nasal cartilages, which support the external nose. ELASTIC CARTILAGES Look very much like hyaline cartilages, but they contain more stretchy elastic fibers and so are better able to stand up to repeated bending. They are found in only two skeletal locations the external ear and the epiglottis (the flap that bends to cover the opening of the larynx each time we swallow). FIBROCARTILAGES Are highly compressible and have great tensile strength. The perfect intermediate between hyaline and elastic cartilages, fibrocartilages consist of roughly parallel rows of chondrocytes alternating with thick collagen fibers. Fibrocartilages occur in sites that are subjected to both heavy pressure and stretch, such as the padlike cartilages (menisci) of the knee and the discs between vertebrae CLASSIFICATION OF BONES The 206 named bones of the human skeleton are divided into two groups: axial and appendicular. The axial skeleton forms the long axis of the body and includes the bones of the skull, vertebral column, and rib cage. Generally speaking these bones are most involved in protecting, supporting, or carrying other body parts. Musculoskeletal The appendicular skeleton consists of the bones of the upper and lower limbs and the girdles (shoulder bones and hip bones) that attach the limbs to the axial skeleton. Bones of the limbs help to get from place to place (locomotion) and to manipulate our environment. Bones come in many sizes and shapes. For example, the pisiform bone of the wrist is the size and shape of a pea, whereas the femur (thigh bone) is nearly 2 feet long in some people and has a large ball-shaped head. The unique shape of each bone fulfills a particular need. Musculoskeletal For the most part, bones are classified by their shape as long, short, flat, and irregular . 1. Long bones, as their name suggests, are considerably longer than they are wide. A long bone has a shaft plus two ends. All limb bones except the patella (kneecap) and the wrist and ankle bones are long bones. Notice that these bones are named for their elongated shape, not their overall size. 2. Short bones are roughly cube shaped. The bones of the wrist and ankle are examples. Sesamoid bones are a special type of short bone that form in a tendon (for example, the patella). They vary in size and number in different individuals. 3. Flat bones are thin, flattened, and usually a bit curved. The sternum (breastbone), scapulae (shoulder blades), ribs, and most skull bones are flat bones. Irregular bones have complicated shapes that fit none of the preceding classes. Examples include the vertebrae and the hip bones. FUNCTIONS OF BONES Besides contributing to body shape and form, our bones perform several important functions: SUPPORT. Bones provide a framework that supports the body and cradles its soft organs. For example, bones of lower limbs act as pillars to support the body trunk when we stand, and the rib cage supports the thoracic wall. 2. PROTECTION. The fused bones of the skull protect the brain. The vertebrae surround the spinal cord, and the rib cage helps protect the vital organs of the thorax. Musculoskeletal MOVEMENT. Skeletal muscles, which attach to bones by tendons, use bones as levers to move the body and its parts. As a result, we can walk, grasp objects, and breathe. The design of joints determine the types of movement possible. 4. MINERAL AND GROWTH FACTOR STORAGE. Bone is a reservoir for minerals, most importantly calcium and phosphate. The stored minerals are

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Muscles of the thorax CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Muscles of the thorax using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Learning objectives Muscles of the thoracic wall Other accessory muscles of expiration/Inspiration The intercostal nerves Innervation to diaphragm Blood supply and drainage The muscles of the chest wall, neuro-vascular bundle and lymphatic drainage of the thorax Learning objectives At the end of this session, a student should be able to:- Identify the muscles making the thoracic wall Identify the main and accessory muscles of respiration Identify the neurovascular bundles of the thorax Describe the lymphatic drainage of the thorax Muscles of the thoracic wall External intercostal muscles (accessory m. of Inspiration) Internal intercostal m. (expiration) Diaphragm m. (Major m. of Inspiration) Subcostalis m. ( accessory m of expiration-forced) Transversus thoracis m. (accessory expiration) Other accessory muscles of expiration/Inspiration Serratus anterior m. (inspiration) Rectus abdominis m. (expiration) Sternocleidomastoid m. (inspiration) Scalenius m.(inspiration) Transversus abdominis (expiration) Internal oblique m.(expiration) External oblique (expiration) The diaphragm Innervation of diaphragm The neuro-vascular bundle The intercostal nerves The intercostal nerves arise from the anterior rami of the thoracic spinal nerves from T1 to T11 and are situated between adjacent ribs. Located in the costal groove Supply the intercostal muscles. Occur in the order VAN Innervation to diaphragm The phrenic nerve originates from the anterior rami of the C3,C4 and C5 nerve roots and consists of motor, sensory, and sympathetic nerve fibers. It provides complete motor innervation to the diaphragm and sensation to the central tendon aspect of the diaphragm. Blood supply and drainage The T. wall muscles receives blood from internal thoracic artery (a branch of subclavian artery). Venous drainage is through Azygous and hemiazygous veins into right and left subclavian veins Lymphatic drainage THANK YOU ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Muscle Tissue-Structure And Functions CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Muscle Tissue-Structure And Functions using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Muscle Tissue Skeletal Muscles- 6 Functions of Skeletal Muscles Muscles serve specific functions in moving and positioning the body. How is muscle tissue organized at the tissue level? Organization of Connective Tissues 3. Endomysium Muscle Attachments Nerves What are the characteristics of skeletal muscle fibers? Skeletal Muscle Fibers Organization of Skeletal Muscle Fibers The Sarcolemma Transverse Tubules (T tubules) Muscle Striations Figure 10–6 (1 of 5) Muscle Contraction Skeletal Muscle Contraction The Process of Contraction Structure of Cardiac Tissue 7 Characteristics of Cardiocytes 4 Functions of Cardiac Tissue Role of Smooth Muscle in Body Systems Structure of Smooth Muscle 8 Characteristics of Smooth Muscle Cells Functional Characteristics of Smooth Muscle Muscle Tissue Muscle Tissue One of 4 primary tissue types, divided into: skeletal muscle cardiac muscle smooth muscle Without these muscles, nothing in the body would move and no body movement would occur Skeletal Muscles- Organs of skeletal muscle tissue are attached to the skeletal system and allow us to move Muscular System- Includes only skeletal muscles Skeletal Muscle Structures Muscle tissue (muscle cells or fibers) Connective tissues Nerves Blood vessels 6 Functions of Skeletal Muscles Produce skeletal movement Maintain body position and posture Support soft tissues Guard body openings (entrance/exit) Maintain body temperature Store Nutrient reserves Muscles serve specific functions in moving and positioning the body. The same muscle may act as a prime mover, antagonist, synergist, or fixator under specific conditions. The functions include. A prime mover or agonist is the main muscle responsible for producing a specific movement of the body (e.g. concentric contraction). Fixators steady the proximal parts of a limb while movements are occurring in distal parts. A synergist complements the action of prime mover for example, by preventing movement of the intervening joint when a prime mover passes over more than one joint. An antagonist is a muscle that opposes the action of a prime mover. As a prime mover contracts, the antagonist progressively relax, producing a smooth movement How is muscle tissue organized at the tissue level? Organization of Connective Tissues Figure 10–1 Organization of Connective Tissues Muscles have 3 layers of connective tissues: Epimysium-Exterior collagen layer Connected to deep fascia Separates muscle from surrounding tissue perimysium- Surrounds muscle fiber bundles (fascicles) Contains blood vessel and nerve supply to fascicles endomysium 3. Endomysium Surrounds individual muscle cells (muscle fibers) Contains capillaries and nerve fibers contacting muscle cells Contains satellite cells (myogenic stem cells) that repair damage Muscle Attachments Endomysium, perimysium, and epimysium come together: at ends of muscles to form connective tissue attachment to bone matrix i.e., tendon (bundle) or aponeurosis (sheet) Nerves Skeletal muscles are voluntary muscles, controlled by nerves of the central nervous system Blood Vessels Muscles have extensive vascular systems that: supply large amounts of oxygen supply nutrients carry away wastes What are the characteristics of skeletal muscle fibers? Skeletal muscle cells are called fibers Figure 10–2 Skeletal Muscle Fibers Are very long Develop through fusion of mesodermal cells (myoblasts- embryonic cells)) Become very large Contain hundreds of nuclei –multinucleate Unfused cells are satellite cells- assist in repair after injury Germ layers Structures originating from germ layers Organization of Skeletal Muscle Fibers Figure 10–3 The Sarcolemma The cell membrane of a muscle cell Surrounds the sarcoplasm (cytoplasm of muscle fiber) A change in transmembrane potential begins contractions All regions of the cell must contract simultaneously Transverse Tubules (T tubules) Transmit action potential – impulses through cell Allow entire muscle fiber to contract simultaneously Have same properties as sarcolemma Filled with extracellular fluid Muscle Striations A striped or striated pattern within myofibrils: alternating dark, thick filaments (A bands) and light, thin filaments (I bands) Figure 10–6 (1 of 5) Level 1: Skeletal Muscle Level 2: Muscle Fascicle Muscle Contraction Is caused by interactions of thick and thin filaments Structures of protein molecules (actin and myosin) detemine interactions Skeletal Muscle Contraction Figure 10–9 (Navigator) The Process of Contraction Neural stimulation of sarcolemma: causes excitation–contraction coupling Cisternae of Sarcoplasmic reticulum(SR) release Ca2+: which triggers interaction of thick and thin filaments consuming ATP and producing tension What are the structural and functional differences between skeletal muscle fibers and cardiac muscle cells? Structure of Cardiac Tissue Cardiac muscle is striated-involuntary muscle, found only in the heart Figure 10–22 7 Characteristics of Cardiocytes Unlike skeletal muscle, cardiac muscle cells (cardiocytes): are small have a single nucleus have short, wide T tubules 7 Characteristics of Cardiocytes have no triads have SR with no terminal cisternae are aerobic (high in myoglobin, mitochondria) have intercalated discs 4 Functions of Cardiac Tissue 1. Automaticity: – contraction without neural stimulation controlled Variable contraction tension: – controlled Extended contraction time Prevention of wave summation and tetanic contractions Role of Smooth Muscle in Body Systems Forms around other tissues In blood vessels: regulates blood pressure and flow In reproductive and glandular systems: produces movements In digestive and urinary systems: forms sphincters produces contractions In integumentary system: arrector pili muscles cause goose bumps Structure of Smooth Muscle Nonstriated tissue Figure 10–23 8 Characteristics of Smooth Muscle Cells Long, slender, and spindle shaped Have a single, central nucleus Have no T tubules, myofibrils, or sarcomeres Have no tendons or aponeuroses 8 Characteristics of Smooth Muscle Cells Have scattered myosin fibers Myosin fibers have more heads per thick filament Have thin filaments attached to dense bodies Dense bodies transmit contractions from cell to cell Functional Characteristics of Smooth Muscle Excitation–contraction coupling Length–tension relationships Control of contractions Smooth muscle tone ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? 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DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Male Reproductive System CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Male Reproductive System using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic By the end of this session students are expected to be able to: Composition of Male Reproductive System Male Reproductive System The reproductive glands produce secretions that become part of semen, the fluid that is ejaculated from the urethra. Structures and Functions of Male Reproductive System Structures of the male reproductive system Seminal vesicles Functions of the male reproductive system Epididymis Smooth muscle of the wall of epididymis propels the sperm to dactus deferens Inguinal canal is a natural weak spot where most of hernia is formed in men. Ejaculatory ducts Their secretion contains fructose to provide an energy source for sperm and is alkaline to enhance sperm motility. Prostate gland The glandular tissue of the prostate secretes an alkaline fluid that helps maintain sperm motility. Bulbourethral (Cowper‘s) glands Urethra-penis Spermatogenesis For each primary spermatocyte that undergoes meiosis, four functional sperm cells are produced. The sperm cell and semen Within the middle piece are mitochondria that produce ATP. It is the beating of the flagellum that requires energy from ATP. Semen consists of sperm and the secretions of the seminal vesicles, prostate gland, and bulbourethral glands During ejaculation, approximately 2 to 4 mL of semen is expelled. Key Points Evaluation Structure and Functions of the Male Reproductive System By the end of this session students are expected to be able to: Define Male Reproductive System Explain the Composition of Male Reproductive System Describe Structure and Functions of the Male Reproductive System Explain the Process of Spermatogenesis Composition of Male Reproductive System What is the composition of male reproductive system? Male Reproductive System Male reproductive system: Is the genital system, reproductive system organs and tissues involved in the production and maturation of gametes and in their union and subsequent development as offspring. The male reproductive system consists of the testes and a series of ducts and glands. Male Reproductive System Sperm are produced in the testes by a process of spermatogenesis and are transported through the reproductive ducts: epididymis, ductus deferens, ejaculatory duct, and urethra The reproductive glands produce secretions that become part of semen, the fluid that is ejaculated from the urethra. These glands are the seminal vesicles, prostate gland, and bulbourethral glands. Structures and Functions of Male Reproductive System What are the structures and functions of the male reproductive system? Structures of the male reproductive system Testes Epididymis Dactus deferens (vas deferens) Ejaculatory ducts Seminal vesicles Prostate gland Bulbourethral (Cowper‘s) glands Urethra-penis Functions of the male reproductive system Testes The testes are located in the scrotum, a sac of skin between the upper thighs. Internally is divided in to lobes Each lobe contains several seminiferous tubules where spermatogenesis takes place. Among the produced spermatogonia are Sertoli cells which produce inhibin hormone when stimulated by testosterone Male Reproductive System Between the loops of the seminiferous tubules are interstitial cells called Leydig cells which produce testosterone when stimulated by luteinizing hormone from anterior pituitary gland Testosterone is responsible for maturation of sperm and secondary male characteristics. Epididymis It is a tube about 6m long that is coiled in the posterior surface of each testis. Within it the sperm complete the maturation and their flagella become functional. Smooth muscle of the wall of epididymis propels the sperm to dactus deferens Dactus deferens (vas deferens) Extends from the epididymis in the scrotum on its own side into the abdominal cavity through the inguinal canal Male Reproductive System Spermatic cord is a connective tissue sheath that contains the ductus deferens, testicular blood vessels (arteries+veins), and nerves Inguinal canal is a natural weak spot where most of hernia is formed in men. The smooth muscle layer of the ductus deferens contracts in waves of peristalsis as part of ejaculation Ejaculatory ducts Each of the two ejaculatory ducts receives sperm from the ductus deferens and the secretion of the seminal vesicle on its own side. Both ejaculatory ducts empty into the single urethra Seminal vesicles The paired seminal vesicles are posterior to the urinary bladder Their secretion contains fructose to provide an energy source for sperm and is alkaline to enhance sperm motility. The duct of each seminal vesicle joins the ductus deferens on that side to form the ejaculation duct Prostate gland A muscular gland just below the urinary bladder It surrounds the first inch of the urethra as it emerges from the bladder The glandular tissue of the prostate secretes an alkaline fluid that helps maintain sperm motility. The smooth muscle of the prostate gland contracts during ejaculation to contribute to the expulsion of semen from the urethra Bulbourethral (Cowper‘s) glands They are located below the prostate gland and empties to the urethra Their alkaline secretion coats the interior of the urethra just before ejaculation, which neutralizes any acidic urine that might be present. Urethra-penis The urethra is the last of the ducts through which semen travels, and its longest portion is enclosed within the penis. Male Reproductive System The penis is an external genital organ; its distal end is called the glans penis and is covered with a fold of skin called the prepuce or foreskin which is removed by surgical procedure of circumcision Male Reproductive System Within the penis are three masses of cavernous (erectile) tissue by which the flow of blood to these masses through arteries cause penile erection. Spermatogenesis It is the process of meiosis as it takes place in the testes, the site of sperm production. Within each testis are seminiferous tubules that contain spermatogonia, which are stem cells that generate sperm. Male Reproductive System A spermatogonium divides by mitosis to form two cells, one of which will remain in place as a stem cell, while the other differentiates (specializes) to become a primary spermatocyte that will undergo meiosis. Gamete formation is regulated by

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Lymphatic system and its diseases CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Lymphatic system and its diseases using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic By the end of this session students are expected to be able to: Definition and Organization of Lymphatic System Composition of Lymphatic System Lymphatic system and its diseases Tonsils They are: Thymus Spleen The white pulp is lymphatic tissue consisting mainly of lymphocytes around arteries. Bone marrow Functions of Lymph System Plasma filters into the interstitial spaces from blood flowing through the capillaries. If this would continue over even a brief period of time, the increased interstitial fluid would cause massive oedema. Absorption and transport of dietary fat, Immunity Common Disorder of the Lymphatic System Lymphadenopathy Lymphedema This most commonly occurs in women who have had surgery to remove a breast cancer. Infectious causes of lymphangitis Lymphoma Key Points Evaluation Assignment Structure, Functions and Common Disorders of Lymphatic System By the end of this session students are expected to be able to: Define Lymphatic System Explain the Organization of Lymphatic System the Structures Lymphatic System Describe Functions of Lymph System List the Common Disorders of the Lymphatic System What is lymphatic system? Definition and Organization of Lymphatic System Lymphatic system: A network of tissue, organs, and vessels that help to maintain the body‘s fluid balance, cleanse the body fluid of foreign matter and provide immune cells (lymphocytes) for defence Composition of Lymphatic System Lymph, the fluid corrected by the system from the interstitial spaces of the tissue and returns to the bloodstream. Lymphatic plexuses, networks of small lymphatic vessels, lymphatic capillaries, that originate in the extracellular spaces of most tissues. Lymphatic system and its diseases Lymphatic vessels (lymphatics), a nearly body wide network of thin-walled vessels with valves, originating from lymphatic plexuses along which lymph nodes are located. Lymph nodes, small masses of lymphatic tissue through which lymph is filtered on its way to the venous system. Lymphocytes, circulating cells of the immune system that react against foreign materials/microbes. Lymphatic system and its diseases Lymphoid tissue, sites that produce lymphocytes, such as that found in the walls of the digestive tract; in the spleen, thymus, and lymph nodes; and in myeloid tissue in red bone marrow. Lymphatic system and its diseases The lymphoid tissue is primarily involved in immune responses, and consists of lymphocytes and other white blood cells enmeshed in connective tissue through which the lymph passes. Lymphatic system and its diseases The lymphatic system differs from the circulatory system in the way that, the lymphatic do not form a closed ring or circuit. Instead, it begins blindly in the intercellular spaces of the soft tissues of the body. The Specialized organs of the lymphatic system are tonsils, thymus, bone marrow and spleen. Tonsils Masses of lymphoid tissue located in a protective ring under mucous membranes in the mouth and back of the throat. Help protect against bacteria that may invade tissues in the area around the openings between the oral and nasal cavities. They are: Palatine tonsils; located on each side of the throat. Pharyngeal tonsils; are near the posterior openings of the nasal cavity. Lingual tonsils; located near the base of the tongue Lymphatic system and its diseases The tonsils serve as the first line of defence from the exterior and as such are subject to chronic infection (tonsillitis). Thymus The thymus is located inferior to the thyroid gland. In the foetus and infant, the thymus is large and extends under the sternum Lymphatic system and its diseases The thymus hormones are necessary for immunological competence by enabling the T-cells to participate in the recognition of foreign antigens and provide immunity. This capability of T cells is established early in life and then is perpetuated by the lymphocytes themselves. Lymphatic system and its diseases The new-born‘s immune system is not yet fully mature, and infants are more susceptible to certain infections than are older children and adults. Usually by the age of 2 years, the immune system matures and becomes fully functional Spleen A soft, elongated wedge shaped purple organ Spleen is located in the left hypochondrium directly below the diaphragm, above the left kidney and descending colon, and behind the fundus of the stomach … The white pulp is lymphatic tissue consisting mainly of lymphocytes around arteries. The red pulp consists of venous sinuses filled with blood and cords of lymphatic cells, such as lymphocytes and macrophages. Arteries leading into each compartment are surrounded by dense masses (nodules) of developing lymphocytes Lymphatic system and its diseases Near the outer regions of each compartment is tissue called red pulp made up of fine reticular fibres submerged in blood that comes from nearby arteries. Lymphatic system and its diseases After passing through the reticular meshwork, blood collects in venous sinuses and then returns to the heart through Subclavian veins. Bone marrow Bone marrow is responsible for the production of blood cells: red blood cells, white blood cells, and platelets. Bone marrow stem cells play an important role in immunity as they generate lymphocytes Functions of Lymph System Maintenance of fluid balance in the body It returns excess fluid and proteins from the tissues that cannot be returned through the blood vessels. Lymphatic system and its diseases The fluid is found in tissue spaces and cavities, in the tiny spaces surrounding cells, known as the interstitial spaces. These are reached by the smallest blood and lymph capillaries Proteins that accumulate in the interstitial spaces can return to the blood only via lymphatic vessels. Plasma filters into the interstitial spaces from blood flowing through the capillaries. Much of this interstitial fluid is absorbed by tissue cells or reabsorbed by the blood before it flows out of the tissue. A small amount of interstitial fluid is left behind. Lymphatic system and its diseases Loss of the lymphatic system would be fatal within

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Introduction to Gastrointestinal system CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Introduction to Gastrointestinal system using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Definition and Overview of Gastrointestinal System Introduction to Gastrointestinal system Organs of the digestive tract include: The gastrointestinal tract is made of four layers of tissues: Muscular is thick layer of smooth muscle tissue which consists of inner circular layer and outer longitudinal layer Functions of the Gastrointestinal System Overall, the digestive system performs six basic processes: Structure of the Oral Cavity Structure of the Oral Cavity (The Buccal Cavity) Their ducts open opposite the last molar teeth Teeth Permanent Teeth A typical tooth has the following parts: Structure and Functions of the Tongue The dorsal mucosa is covered by numerous papillae; tiny projections, some of which bear taste buds There are four basic taste sensations Some respond to all four classic categories, others to fewer or only one Salivary Glands and its Constituents The major salivary glands are the paired parotid, submandibular and sublingual glands Mechanism of Swallowing Oral stage (mouth to oropharynx), voluntarily controlled Movement; contractions and gravity moves bolus through oesophagus and into stomach Key points evaluation assignment Introduction to Gastrointestinal System (Digestive system) Definition and Overview of Gastrointestinal System What is digestive system? What are the organs of digestive system? Introduction to Gastrointestinal system Digestive system consists of the digestive tract(alimentary canal) which is a tube extending from the mouth, pass through the thorax, abdomen and pelvis and ends at the anus and its associated accessory organs Organs of the digestive tract include: The mouth or oral cavity, which has salivary glands and tonsils as accessory organs The pharynx, or throat , with tubular mucous glands The oesophagus, with tubular mucous glands The stomach, which contains many tube like glands The small intestine, consisting of the duodenum, jejunum and ileum, with the liver, Gallbladder and pancreas as major accessory organs The large intestine, including the cecum, colon, rectum and anal canal, with mucus glands The anus Introduction to Gastrointestinal system The digestive system also consists of accessory organs which include the teeth, tongue, salivary glands, liver, gallbladder, and pancreas Teeth aid in the physical breakdown of food, and the tongue assists in chewing and swallowing. The other accessory digestive organs produce or store secretions that flow into the GI tract through ducts to aid in the chemical breakdown of food The gastrointestinal tract is made of four layers of tissues: Mucosa is the innermost layer made up of three layers The inner epithelium Lamina propria Muscularis mucosae Submucosa this layer is composed of connective tissue, it contains numerous small glands, blood vessels, and parasympathetic nerves that form the submucosal plexus (Meissner plexus) Muscular is thick layer of smooth muscle tissue which consists of inner circular layer and outer longitudinal layer Between the two layers of muscles there is a nervous plexus called myenteric plexus (Auerbach plexus) Serosa is the outermost layer of made up of loose connective tissue (visceral peritoneum) Layers of the GI tract have various modifications to enable it to perform various functions. Functions of the Gastrointestinal System What are the functions of the digestive tract? Overall, the digestive system performs six basic processes: Ingestion: This process involves taking foods and liquids into the mouth (eating) Secretion: Each day, cells within the walls of the GI tract and accessory digestive organs secrete a total of about 7 litres of water, acid, buffers, and enzymes into the lumen (interior space) of the tract Mixing and propulsion: Alternating contractions and relaxations of smooth muscle in the walls of the GI tract mix food and secretions and propel them toward the anus This capability of the GI tract to mix and move material along its length is called motility Digestion: Mechanical and chemical processes break down ingested food into small molecules Introduction to Gastrointestinal system In mechanical digestion the teeth cut and grind food before it is swallowed, and then smooth muscles of the stomach and small intestine churn the food As a result, food molecules become dissolved and thoroughly mixed with digestive enzymes In chemical digestion the large carbohydrate, lipid, protein, and nucleic acid molecules in food are split into smaller molecules by hydrolysis Digestive enzymes produced by the salivary glands, tongue (lingual lipase), stomach, pancreas, and small intestine catalyse these catabolic reactions. A few substances in food(vitamins, ions, cholesterol, and water) can be absorbed without chemical digestion Absorption. The entrance of ingested and secreted fluids, ions, and the products of digestion into the epithelial cells lining the lumen of the GI tract is called absorption. Defecation. Wastes, indigestible substances, bacteria, cells sloughed from the lining of the GI tract, and digested materials that were not absorbed in their journey through the digestive tract leave the body through the anus in a process called defecation and the materials in form of feaces Structure of the Oral Cavity The oral cavity or mouth is that part of the digestive tract bounded by the lips anteriorly, the fauces throat; opening into the pharynx posteriorly, cheeks laterally, the palate superiorly, and a muscular floor inferiorly The oral cavity is lined throughout with mucus membrane consisting of stratified squamous epithelium containing small mucus secreting glands. The oral cavity is divided into two regions: o The Vestibule; part of the mouth between Gums and Cheeks o The oral cavity proper; which lies medial to the alveolar processes (gums) Muscles of oral cavity Orbicularis oris (kiss muscle) Structure of the Oral Cavity (The Buccal Cavity) Lips: Are muscular structure formed mostly by the orbicularis oris muscles They are covered externally by skin and internally The junction between skin and mucous membrane is highly sensitive When lips are closed, line of contact is oral fissure Cheeks The cheeks are formed in large part by buccinators muscles covered They form the lateral boundaries of the oral cavity,