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Academic year 2022-2023 فرع جراحة الفم والوجه والفكين كلية طب االسنان 1st year...
Academic year 2022-2023 فرع جراحة الفم والوجه والفكين كلية طب االسنان 1st year Human Anatomy Lecture 2 Basic Structures : Part 1 Cartilage By:Dr.Nada hashim AL JASSIM Snell R.S. Clinical Anatomy by regions, 9th Edition, Lippincott Williams & Wilkins, For more detailed instructions, any question, cases need help please post to the telegram group of the session Skin The skin is divided into two parts: the superficial part, the epidermis; and the deep part, the dermis. The epidermis is a stratified epithelium, On the palms of the hands and the soles of the feet, the epidermis is extremely thick, to withstand the wear and tear that occurs in these regions. The dermis is composed of dense connective tissue containing many blood vessels, lymphatic vessels, and nerves. The dermis of the skin is connected to the underlying deep fascia or bones by the superficial fascia, otherwise known as subcutaneous tissue. The appendages of the skin are the nails, hair follicles, sebaceous glands, and sweat glands. Fasciae The fasciae of the body can be divided into two types— superficial and deep—and lie between the skin and the underlying muscles and bones. The superficial fascia, or subcutaneous tissue, is a mixture of loose areolar and adipose tissue that unites the dermis of the skin to the underlying deep fascia. The deep fascia is a membranous layer of connective tissue that invests the muscles and other deep structures. In the neck, it forms well- defined layers and in the thorax ,and abdomen, it is usually a thin film. Muscle The three types of muscle are skeletal, smooth, and cardiac. ❖ Skeletal Muscle Skeletal muscles produce the movements of the skeleton; voluntary muscles and are made up of striped muscle fibers. A skeletal muscle has two or more attachments. The attachment that moves the least is referred to as the origin, and the one that moves the most, the insertion.. The fleshy part of the muscle is referred to as its belly. The ends of a muscle are attached to bones, cartilage, or ligaments by cords of fibrous tissue called tendons. flattened muscles are attached by a thin but strong sheet of fibrous tissue called an aponeurosis. A raphe is an interdigitation of the tendinous ends of fibers of flat muscles. Skeletal Muscle Action All movements are the result of the coordinated action of many muscles. A muscle may work in the following four ways: Prime mover: A muscle is a prime mover when it is the chief muscle or member of a chief group of muscles responsible for a particular movement. For example, the quadriceps femoris is a prime mover in the movement of extending the knee joint. Antagonist: Any muscle that opposes the action of the prime mover is an antagonist. For example, the biceps femoris opposes the action of the quadriceps femoris when the knee joint is extended. Before aprime mover can contract, the antagonist muscle must be equally relaxed. Fixator: A fixator contracts isometrically (i.e., contraction increases the tone but does not in itself produce movement)to stabilize the origin of the prime mover. For example, the muscles attaching the shoulder girdle to the trunk contract as fixators to allow the deltoid to act on the shoulder joint. Synergist: In many locations in the body, the prime mover muscle crosses several joints before it reaches the joint at which its main action takes place. To prevent unwanted movements in an intermediate joint, groups of muscles called synergists contract and stabilize the intermediate joints. For example, the flexor and extensor muscles of the carpus contract to fix the wrist joint, and this allows the long flexor and the extensor muscles of the fingers to work efficiently.. Prime mover Antagonist: Synergist: Fixator: ❖ Smooth Muscle Smooth muscle consists of long, spindle-shaped cells closely arranged in bundles or sheets. In the tubes of the body, it provides the motive power for propelling the contents through the lumen. In the digestive system, it also causes the ingested food to be thoroughly mixed with the digestive juices. In storage organs such as the urinary bladder and the uterus, the fibers are irregularly arranged and interlaced with one another. Their contraction is slow and sustained and brings about expulsion of the contents of the organs. In the walls of the blood vessels, the smooth muscle fibers are arranged circularly and serve to modify the caliber of the lumen. ❖ Cardiac Muscle Cardiac muscle consists of striated muscle fibers that branch and unite with each other. It forms the myocardium of the heart. Its fibers tend to be arranged in whorls and spirals, and they have the property of spontaneous and rhythmic contraction Skeletal striated muscle Cardiac striated muscle Striation Nucleus Muscle fiber Intercalated disc Nucleus Striation Satellite cell Muscle fiber Smooth (unstriated or unstriped) muscle Smooth muscle fiber Nucleus Joints A site where two or more bones come together, whether or not movement occurs between them, is called a joint. Joints are classified according to the tissues that lie between the bones: fibrous joints, cartilaginous joints, synovial joints 1-Fibrous Joints The articulating surfaces of the bones are joined by fibrous tissue, and thus very little movement is possible.Example: The sutures of the vault of the skull. 2-Cartilaginous Joints Cartilaginous joints can be divided into two types: primary and secondary. A primary cartilaginous joint is one in which the bones are united by a plate or a bar of hyaline cartilage,like, the union between the 1st rib and the manubrium sterni. No movement is possible. A secondary cartilaginous joint is one in which the bones are united by a plate of fibrocartilage and the articular surfaces of the bones are covered by a thin layer of hyaline cartilage like the joints between the vertebral bodies. A small amount of movement is possible 3-Synovial Joints The articular surfaces of the bones are covered by a thin layer of hyaline cartilage separated by a joint cavity. This arrangement permits a great degree of freedom of movement. The cavity of the joint is lined by synovial membrane, which extends from the margins of one articular surface to those of the other. The synovial membrane is protected on the outside by a tough fibrous membrane referred to as the capsule of the joint. The articular surfaces are lubricated by a viscous fluid called synovial fluid, which is produced by the synovial membrane. In certain synovial joints, for example, in the knee joint Ligament A ligament is a cord or band of connective tissue uniting two structures. Commonly found in association with joints, Bone Bone is a living tissue like other connective tissues, consists of cells, fibers, and matrix. It is hard because of the calcification of its extracellular matrix and possesses a degree of elasticity because of the presence of organic fibers. Bone has a protective function; the skull and vertebral column, for example, protect the brain and spinal cord from injury; the sternum and ribs protect the thoracic and upper abdominal viscera. and as an important storage area for calcium salts. Bone exists in two forms: compact (cortical) solid mass cancellous (spongy). network of trabeculae. Protects the organs within the body cavities against mechanical injury, e.g. the rib cage protects the heart and lungs, the skull protects the brain Contains and protects the red bone marrow, where red blood cells (or erythrocytes), white blood cells (or leukocytes) and lymph cells are formed Classification of Bones Bones may be classified regionally or according to their general shape. - Regional Classification of Bones: ❖ Axial skeleton 80 bones Skull Cranium 8 Face 14 Auditory ossicles 6 Hyoid 1 Vertebrae (including sacrum and coccyx) 26 Thoracic cage Sternum 1 Ribs 24 Appendicular skeleton 126 bones Shoulder (Pectoralgirdle)girdles Scapula 2 Clavicle 2 Upper extremities Humerus 2 Radius 2 Ulna 2 Carpals 16 Metacarpals 10 Phalanges 28 Pelvic girdle Hip bone 2 Lower extremities Femur 2 Patella 2 Fibula 2 Tibia 2 Tarsals 14 Metatarsals 10 Phalanges 28 The adult human body contain 206 bones, 80 in axial. skeleton and 126 in appendicular skeleton - Classification of Bones according to shape: Bones are grouped as follows based on their general shape: long bones, short bones, flat bones, irregular bones, and sesamoid bones. 1. Long Bones: Long bones are found in the limbs (e.g., the humerus, femur,metacarpals, metatarsals, and phalanges). Their length is greater than their breadth. They have a tubular shaft, the diaphysis, and usually an epiphysis at each end which is responsiple for lengthening the bone. The shaft has a central marrow cavity containing bone marrow. The outer part of the shaft is composed of compact bone that is covered by a connective tissue sheath, the periosteum. The ends of long bones are composed of cancellous bone surrounded by a thin layer of compact bone. The articular surfaces of the ends of the bones are covered by hyaline cartilage. 2. Short Bones Short bones are found in the hand and foot (e.g., the scaphoid, lunate, talus, and calcaneum). They are roughly cuboidal in shape and are composed of cancellous bone surrounded by a thin layer of compact bone.. 3. Flat Bones Flat bones are found in the vault of the skull (e.g., the frontal and parietal bones). They are composed of thin inner and outer layers of compact bone, The scapulae, although irregular, are included in this group 4. Irregular Bones Irregular bones include those not assigned to the previous groups (e.g., the bones of the skull, the vertebrae, and the pelvic bones). They are composed of a thin shell of compact bone with an interior made up of cancellous bone. 5. Sesamoid Bones Sesamoid bones are small nodules of bone that are found in certain tendons where they rub over bony surfaces. The greater part of a sesamoid bone is buried in the tendon,and the free surface is covered with cartilage. The largest sesamoid bone is the patella, which is located in the tendon of the quadriceps femoris. The function of a sesamoid bone is to reduce friction on the tendon; THANK YOU
