Thoracic Wall
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Thoracic Wall
The thoracic wall or chest wall is the boundary of the thoracic cavity. Structure The bony skeletal part of the thoracic wall is the rib cage, and the rest is made up of muscle, skin, and fasciae. The chest wall has 10 layers, namely (from superficial to deep) skin (epidermis and dermis), superficial fascia, deep fascia and the invested extrinsic muscles (from the upper limbs), intrinsic muscles associated with the ribs (three layers of intercostal muscles), endothoracic fascia and parietal pleura. However, the extrinsic muscular layers vary according to the region of the chest wall. For example, the front and back sides may include attachments of large upper limb muscles like pectoralis major or latissimus dorsi, while the sides only have serratus anterior. Function Diving reflex When not breathing for long and dangerous periods of time in cold water, a person's body undergoes great temporary changes to try to prevent death. It achieves this through the activation of ...
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Thoracic Cavity
The thoracic cavity (or chest cavity) is the chamber of the body of vertebrates that is protected by the thoracic wall (rib cage and associated skin, muscle, and fascia). The central compartment of the thoracic cavity is the mediastinum. There are two openings of the thoracic cavity, a superior thoracic aperture known as the thoracic inlet and a lower inferior thoracic aperture known as the thoracic outlet. The thoracic cavity includes the tendons as well as the cardiovascular system which could be damaged from injury to the back, spine or the neck. Structure Structures within the thoracic cavity include: * structures of the cardiovascular system, including the heart and great vessels, which include the thoracic aorta, the pulmonary artery and all its branches, the superior and inferior vena cava, the pulmonary veins, and the azygos vein * structures of the respiratory system, including the diaphragm, trachea, bronchi and lungs * structures of the digestive system, including ...
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Upper Limb
The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulder, elbow, wrist and knuckle joints. In humans, each upper limb is divided into the arm, forearm and hand, and is primarily used for climbing, lifting and manipulating objects. Definition In formal usage, the term "arm" only refers to the structures from the shoulder to the elbow, explicitly excluding the forearm, and thus "upper limb" and "arm" are not synonymous. However, in casual usage, the terms are often used interchangeably. The term "upper arm" is redundant in anatomy, but in informal usage is used to distinguish between the two terms. Structure In the human body the muscles of the upper limb can be classified by origin, topography, function, or innervation. While a grouping by innervation reveals embryological and phylogenet ...
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Mammalian Diving Reflex
The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date. It optimizes respiration by preferentially distributing oxygen stores to the heart and brain, enabling submersion for an extended time. The diving reflex is exhibited strongly in aquatic mammals, such as seals, otters, dolphins, and muskrats, and exists as a lesser response in other animals, including human babies up to 6 months old (see infant swimming), and diving birds, such as ducks and penguins. Adult humans generally exhibit a mild response, the dive-hunting Sama-Bajau people being a notable outlier. The diving reflex is triggered specifically by chilling and wetting the nostrils and face while breath-holding, and is sustained via neural processing originating in the carotid chemoreceptors. The most noticeable effects are on the cardio ...
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Serratus Anterior
The serratus anterior is a muscle that originates on the surface of the 1st to 8th ribs at the side of the chest and inserts along the entire anterior length of the medial border of the scapula. The serratus anterior acts to pull the scapula forward around the thorax. The muscle is named from Latin: ''serrare'' = to saw, referring to the shape, ''anterior'' = on the front side of the body. Structure Serratus anterior normally originates by nine or ten muscle slips – branches from either the first to ninth ribs or the first to eighth ribs. Because two slips usually arise from the second rib, the number of slips is greater than the number of ribs from which they originate. The muscle is inserted along the medial border of the scapula between the superior and inferior angles along with being inserted along the thoracic vertebrae. The muscle is divided into three named parts depending on their points of insertions: #the serratus anterior superior is inserted near the superior a ...
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Latissimus Dorsi
The latissimus dorsi () is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. The word latissimus dorsi (plural: ''latissimi dorsorum'') comes from Latin and means "broadest uscleof the back", from "latissimus" ( la, broadest)' and "dorsum" ( la, back). The pair of muscles are commonly known as "lats", especially among bodybuilders. The latissimus dorsi is the largest muscle in the upper body. The latissimus dorsi is responsible for extension, adduction, transverse extension also known as horizontal abduction (or horizontal extension), flexion from an extended position, and (medial) internal rotation of the shoulder joint. It also has a synergistic role in extension and lateral flexion of the lumbar spine. Due to bypassing the scapulothoracic joints and attaching directly to the spine, the actions the latissimi dorsi have on moving the arms can also influence the movement of the sca ...
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Pectoralis Major
The pectoralis major () is a thick, fan-shaped or triangular convergent muscle, situated at the chest of the human body. It makes up the bulk of the chest muscles and lies under the breast. Beneath the pectoralis major is the pectoralis minor, a thin, triangular muscle. The pectoralis major's primary functions are flexion, adduction, and internal rotation of the humerus. The pectoral major may colloquially be referred to as "pecs", "pectoral muscle", or "chest muscle", because it is the largest and most superficial muscle in the chest area. Structure It arises from the anterior surface of the sternal half of the clavicle from breadth of the half of the anterior surface of the sternum, as low down as the attachment of the cartilage of the sixth or seventh rib; from the cartilages of all the true ribs, with the exception, frequently, of the first or seventh, and from the aponeurosis of the abdominal external oblique muscle. From this extensive origin the fibers converge toward the ...
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Parietal Pleura
The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls. The inner pleura, called the visceral pleura, covers the surface of each lung and dips between the lobes of the lung as ''fissures'', and is formed by the invagination of lung buds into each thoracic sac during embryonic development. The outer layer, called the parietal pleura, lines the inner surfaces of the thoracic cavity on each side of the mediastinum, and can be subdivided into ''mediastinal'' (covering the side surfaces of the fibrous pericardium, oesophagus and thoracic aorta), ''diaphragmatic'' (covering the upper surface of the diaphragm), ''costal'' (covering the inside of rib cage) and cervical (covering the underside of the suprapleural membrane) pleurae. The visceral and the mediastinal parietal pleurae are connected at the root of the lung ("hilum") through a smooth fold known as ''pleural reflections'', and ...
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Endothoracic Fascia
The endothoracic fascia is the layer of loose connective tissue deep to the intercostal spaces and ribs, separating these structures from the underlying pleura. This fascial layer is the outermost membrane of the thoracic cavity. The endothoracic fascia contains variable amounts of fat. It becomes more fibrous over the apices of the lungs The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side ... as the suprapleural membrane. It separates the internal thoracic artery from the parietal pleura. References Thorax (human anatomy) Fascia {{musculoskeletal-stub ...
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Intercostal Muscles
Intercostal muscles are many different groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing by helping expand and shrink the size of the chest cavity. Structure There are three principal layers; # External intercostal muscles also known as intercostalis externus aid in quiet and forced inhalation. They originate on ribs 1–11 and have their insertion on ribs 2–12. The external intercostals are responsible for the elevation of the ribs and bending them more open, thus expanding the transverse dimensions of the thoracic cavity. The muscle fibers are directed downwards, forwards and medially in the anterior part. # Internal intercostal muscles also known as intercostalis internus aid in forced expiration (quiet expiration is a passive process). They originate on ribs 2–12 and have their insertions on ribs 1–11.Their fibers pass anterior and supe ...
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Deep Fascia
Deep fascia (or investing fascia) is a fascia, a layer of dense connective tissue that can surround individual muscles and groups of muscles to separate into fascial compartments. This fibrous connective tissue interpenetrates and surrounds the muscles, bones, nerves, and blood vessels of the body. It provides connection and communication in the form of aponeuroses, ligaments, tendons, retinacula, joint capsules, and septa. The deep fasciae envelop all bone (periosteum and endosteum); cartilage (perichondrium), and blood vessels (tunica externa) and become specialized in muscles (epimysium, perimysium, and endomysium) and nerves (epineurium, perineurium, and endoneurium). The high density of collagen fibers gives the deep fascia its strength and integrity. The amount of elastin fiber determines how much extensibility and resilience it will have. Examples Examples include: * Fascia lata * Deep fascia of leg * Brachial fascia * Buck's fascia Fascial dynamics Deep fascia is l ...
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Bone
A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provide structure and support for the body, and enable animal locomotion, mobility. Bones come in a variety of shapes and sizes and have complex internal and external structures. They are lightweight yet strong and hard and serve multiple Function (biology), functions. Bone tissue (osseous tissue), which is also called bone in the mass noun, uncountable sense of that word, is hard tissue, a type of specialized connective tissue. It has a honeycomb-like matrix (biology), matrix internally, which helps to give the bone rigidity. Bone tissue is made up of different types of bone cells. Osteoblasts and osteocytes are involved in the formation and mineralization (biology), mineralization of bone; osteoclasts are involved in the bone resorption, resor ...
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Superficial Fascia
A fascia (; plural fasciae or fascias; adjective fascial; from Latin: "band") is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches to, stabilizes, encloses, and separates muscles and other internal organs. Fascia is classified by layer, as superficial fascia, deep fascia, and ''visceral'' or ''parietal'' fascia, or by its function and anatomical location. Like ligaments, aponeuroses, and tendons, fascia is made up of fibrous connective tissue containing closely packed bundles of collagen fibers oriented in a wavy pattern parallel to the direction of pull. Fascia is consequently flexible and able to resist great unidirectional tension forces until the wavy pattern of fibers has been straightened out by the pulling force. These collagen fibers are produced by fibroblasts located within the fascia. Fasciae are similar to ligaments and tendons as they have collagen as their major component. They differ in their location and function: li ...
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