Basic Anatomical Structures: Skin and Fascia PDF

Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ BASIC ANATOMICAL STRUCTURES Skin Fascia...

Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ BASIC ANATOMICAL STRUCTURES Skin Fascia Muscle Cartilage ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ Bones Joints Ligaments Bursa Synovial membrane Blood vessels Lymph 2023/2024 2023/2024 2023/2024 Nervous system Mucous membranes Serous membranes SKIN Definition: - It is the structure that covers the body and protects it from the environment. It is formed of two layers: 1. Epidermis (the superficial layer) 2. Dermis (the deep layer) 2  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ - Epidermis: 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. - In other areas of the body, for example, on the anterior surface of the arm and forearm, it is thin. Dermis: ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ - The dermis contains many blood vessels, lymphatic vessels, and nerves. - It shows considerable variation in thickness in different parts of the body, tending to be thinner on the anterior than on the posterior surface. - It is thinner in women than in men. - The dermis of the skin is connected to the underlying deep fascia or bones by the superficial fascia, otherwise known as subcutaneous tissue. Skin Lines: 2023/2024 2023/2024 2023/2024 1. Flexure lines (Skin creases): - They are folds of the skin over joints. - At these sites, the skin is thinner than elsewhere and is firmly tethered to underlying structures by strong bands of fibrous tissue. 2. Papillary ridges: - They are confined to palms and soles and the flexor surfaces of the digits. - They form narrow ridges separated by fine parallel grooves. 3. Wrinkle lines: - They are lines caused by contraction of the underlying muscles. - On the face they are known as lines of expression which become permanent with aging due to loss of skin elasticity. 4. Langer (tension) lines: 3  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ - They represent skin tension in rigor mortis and correspond to the orientation of collagen in the dermis. - Surgical incisions made parallel to them heal with a minimum of scar tissue. Functions of the skin: 1. Protection of the deep structures of the body against micro-organisms ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ and external injury. 2. Prevention of fluid loss. 3. Regulation of body temperature by secretion of sweat glands. 4. Sensation (pain, touch, temperature) by nerve endings. 5. Moistening of skin by secretion of fat from sebaceous glands. Skin appendages: - They are skin associated structures. 2023/2024 2023/2024 2023/2024 - They include nails, hair follicles, sebaceous glands and sweat glands. 1. Nails Nails are keratinized plates on the dorsal surfaces of the tips of the fingers and toes. Root of the nail is the proximal edge of the plate. Nail folds are folds of skin that surround the nail except the distal edge of the plate. Nail bed is the surface of skin covered by the nail. 2. Hairs and Hair follicles Hair is a derivative of the epidermis which consists of two distinct parts: the hair follicle and the hair shaft. Hair follicle is a sac from which a hair grows and into which the sebaceous glands open. It anchors each hair into the skin. 4  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Hair shaft consists of a cortex and cuticle cells, and a medulla for some types of hairs. Hair bulb is the concave base of the hair follicle, and the concavity is occupied by vascular hair papilla. Sites with no hair 1. Lips. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ 2. The palms of the hands. 3. The sides of the fingers. 4. The glans penis and clitoris. 5. The labia minora and the internal surface of the labia majora. 6. The soles and sides of the feet and the sides of the toes. 3. Sebaceous glands They pour their secretion, the sebum, onto the shafts of the hairs as they 2023/2024 2023/2024 2023/2024 pass up through the necks of the follicles. They are situated on the sloping undersurface of the follicles and lie within the dermis. Sebum is an oily material that helps preservation of the flexibility of the emerging hair. It also oils the surface epidermis around the mouth of the follicle. 4. Sweat glands. They are long, spiral, tubular glands distributed over the surface of the body. These glands extend through the full thickness of the dermis, and their extremities may lie in the superficial fascia. The sweat glands are therefore the most deeply penetrating structures of all the epidermal appendages. 5  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Sites with no sweat glands: 1. The red margins of the lips. 2. The nail beds. 3. The glans penis and clitoris. FASCIA Definition: It is a band or sheet of connective tissue, primarily collagen, ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs 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. Superficial fascia, or subcutaneous tissue: It is a mixture of loose areolar and adipose tissue that unites the dermis 2023/2024 2023/2024 2023/2024 of the skin to the underlying deep fascia. In the scalp, the back of the neck, the palms of the hands, and the soles of the feet, it contains numerous bundles of collagen fibers that hold the skin firmly to the deeper structures. In the eyelids, auricle of the ear, penis and scrotum, and clitoris, it is devoid of adipose tissue. In the anterior abdominal wall, it is differentiated into superficial fatty layer and deep membranous layer. Functions of superficial fascia: 1. It gives certain parts of the body their specific contour as in buttock and breast. 2. It acts as heat insulator by preventing excess heat loss. 3. It is a source of energy. 6  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ 4. It acts as a medium for the passage of cutaneous nerves and vessels. Deep Fascia: It is a membranous layer of connective tissue that invests the muscles and other deep structures. Different names and forms of the deep fascia: ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ In the neck, it forms well-defined layers that may play an important role in determining the path taken by pathogenic organisms during the spread of infection. In the thorax and abdomen, it is merely a thin film of areolar tissue covering the muscles and aponeuroses. In the limbs, it forms a definite sheath around the muscles and other structures, holding them in place. Fibrous septa extend from the deep 2023/2024 2023/2024 2023/2024 surface of the membrane, between the groups of muscles, and in many places divides the interior of the limbs into compartments. In the region of joints, the deep fascia may be considerably thickened to form restraining bands called retinacula. Functions of the deep fascia: 1. It holds underlying tendons in position or serves as pulleys around which the tendons may move. 2. It invests the deep structures to bone. 3. It gives the origin and insertion of some muscles. 4. It sends septa to bone forming compartments. 5. It forms retinacula to hold the long tendons. 6. It protects the palm and sole by forming palmar and plantar aponeuroses. 7  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ MUSCULAR SYSTEM The muscular system is concerned with the production of movement of the body as a whole and of the internal organs. There are three types of muscles in the human body (Skeletal, smooth, and cardiac). ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ Each type is concerned with a different type of movement. 1. Skeletal muscle Skeletal muscles are attached to their origins and insertions by white fibrous tissue forming rounded cord- like tendons or flattened strong sheet- like aponeurosis. The end of the muscle which remains fixed during contraction is the origin while the end which moves is the 2023/2024 insertion. 2023/2024 2023/2024 Under varying circumstances, the degree of mobility of the attachments may be reversed; therefore, the terms origin and insertion are interchangeable. The fleshy part of the muscle is called belly. Raphe is an interdigitation of the tendinous ends of fibers of flat muscles. It is controlled by voluntary part of the nervous system. 1. Parts of skeletal muscle: Each skeletal muscle is formed of three parts: 1. Origin: it is the proximal part 2. Insertion: it is the distal movable part 3. Belly: it is the intermediate fleshy part 9  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ 2. Visceral (smooth) muscle Visceral muscles are found in the walls of the visceral organs and blood vessels. It is controlled by the involuntary part of the nervous system. In the tubes of the body as digestive tract, it provides the motive power for propelling the contents through the lumen (peristalsis). ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ In storage organs such as the urinary bladder and the uterus, the 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 serves to modify the caliber of the lumen. 3. Cardiac muscle It is only found in the heart (myocardium). 2023/2024 2023/2024 2023/2024 It is controlled by the autonomic nervous system. Specialized cardiac muscle fibers form the conducting system of the heart. SKELETAL MUSCLES Forms of skeletal muscles: It forms the main bulk of the body (about 40% of the body weight). The total number is 620 muscles. There is a wide variation in the size, shape and form of attachments of muscles. Each is well adapted to meet the requirements at the articulations over which it passes. Muscles may be grouped according to the direction of their fibers which may be parallel, oblique or spiral. 10  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ A. Muscles with fibers parallel to the line of pull: These are strap or ribbon - like. They give a wide range of movement, but a less force of pull. Examples: Rectus abdominis and extrinsic muscles of the eye. B. Muscles with fibers oblique to the line of pull: 1. Triangular (fan-like) ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ The fibers converge from the origin to insertion with variable obliquity to the line of pull. Example: Temporalis muscle. 2. Pennate muscles (feather-like) ▪ Unipennate muscles: The tendon forms along one margin of the muscle and the entire fibers slope into one side of the tendon, giving a pattern like 2023/2024 2023/2024 2023/2024 half of a feather. Example: Flexor pollicis longus. ▪ Bipennate muscles: The tendon is situated centrally and the muscle fibers slope into the two sides of the central tendon, like an ordinary feather. Example: Rectus femoris ▪ Multipennate muscles They may be of the following variants: a) Flat type In this type, spaces between parallel tendinous septa are filled with oblique muscle fibers. Example: Middle fibers of the deltoid. 11  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ b) Circumpennate: In which sloping fibers of a muscle converge, from all sides, into a central tendon. Example: Tibialis anterior. 3. Spiral muscles: There is a twist between two groups of muscle fibers gaining two ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ attachment sites. Example: Trapezius, pectoralis major Summary of the forms of skeletal muscles A. Muscles with fibers parallel to the line of pull B. Muscle with fibers oblique to the line of pull: a) Triangular: fan shape, 2023/2024 b) Pennate muscle: feather like: unipennate, 2023/2024 2023/2024 bipennate, multipennate C. Spiral muscles Types of muscle action: All movements are the result of the coordinated action of many muscles. However, to understand a muscle's action it is necessary to study it individually. A muscle may work in the following four ways. 1. Prime movers: - 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. 12  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ 2. Antagonists: - 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 a prime mover can contract, the antagonist muscle must be ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ equally relaxed; this is brought about by nervous reflex inhibition. 3. Fixators: - 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 so that it can act efficiently. - For example, the muscles attaching the shoulder girdle to the trunk 2023/2024 2023/2024 2023/2024 contract as fixators to allow the deltoid to act on the shoulder joint. 4. Synergic muscles: - 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 carpal bones contract to fix the wrist joint, and this allows the long flexor and extensor muscles of the fingers to work efficiently. 5. Action of paradox: 13  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ - Muscles opposing the movement aided by gravity (paying out a rope), against the force of gravity. - Example: contraction of biceps to control the passive extension of the elbow by gravity. ▪ Maintaining the posture: Muscle tone is a state of partial contraction to prepare the muscle for ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ immediate action. Nerve supply of muscles: - The nerve trunk to a muscle is a mixed nerve. - About 60% is motor and 40% is sensory, and it also contains some sympathetic autonomic fibers. - The nerve enters the muscle at about the midpoint on its deep surface, often near the margin. 2023/2024 2023/2024 2023/2024 - This place of entrance is known as the motor point which allows the muscle to move with minimum interference with the nerve trunk. - Hilton's law: The motor nerve to a muscle tends to give a branch of supply to the joint which the muscle moves and another branch to the skin over the joint. 14  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ SKELETAL SYSTEM Skeleton: is the bony built that characterizes the shape of human being. It is composed of two types of tissues: cartilage and bone. Cartilage: It is the temporary skeleton of the developing fetus that is gradually and ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ almost replaced by bone by the process of ossification. It is softer, less rigid and slightly elastic in comparison with bone. In certain sites of the body, it persists throughout life as in. 1. The articular surfaces of most of the bones. 2. Costal cartilage. 3. Air passages as the nasal, laryngeal, tracheal and bronchial cartilages. 2023/2024 2023/2024 2023/2024 4. External ear. Bones: They are modified types of connective tissue being consist of cells (osteocytes), fibers and matrix. They have hard consistency due to calcification of its extracellular matrix. They are classified according to their forms (structure), development, shape, or site in the body. Forms of bones: Bones exist in two forms: A. Compact (hard or ivory) bones: They are hard, dense and form the surface layer of all bones and the tubular shafts of long bones. 16  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ They consist of a number of cylindrical units that form the Haversian system. B. Spongy, trabecular (cancellous) bone: They look like a sponge which are usually filled with red bone marrow. They are formed of spicules or trabeculae. They are located inside the hard bone and form the ends of long bones ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ and the body of all other types of bone. Development of bones: Bones develop by two processes: 1. Membranous ossification: It occurs in bones required quickly for support or protection of essential organs as those of the vault of skull and face. 2023/2024 2023/2024 2023/2024 2. Cartilaginous ossification: At first a model of the future bone is formed from cartilage and then ossified in two steps: a) Primary centres of ossification: Appear during the fetal life in the middle of shaft of bone. As ossification propagates the shaft is transformed to the diaphysis, leaving the ends cartilaginous. b) Secondary centre of ossification: Appear in the ends of bones after birth forming the epiphysis which ossifies leaving: 1. A plate of epiphyseal cartilage between the epiphysis and diaphysis. 2. Articular cartilage covering the ends of the bone. Note: the metaphysis is the more recently developed part of the bone added to the diaphysis adjacent to the epiphyseal plate. 17  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ TYPES (CLASSIFICATION) OF BONES Bones are classified according to their shape, structure or development as follows: I. According to shape (morphological classification): 1. Long bones: They have two ends and shafts, e.g. long bones of upper and ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ lower limbs; femur, tibia, fibula, humerus, radius and ulna. 2. Short bones: they are cubical in shape, e.g. carpal bones of hand and tarsal bones of foot. 3. Flat bones: thin plate of bones, as vault of skull and scapula. 4. Irregular bones: They have no definite shape as vertebrae and bones of base of skull. 5. Pneumatic bones: they are bones containing air as paranasal sinuses of skull. 2023/2024 2023/2024 2023/2024 6. Sesamoid bones: they are nodules of bones lying inside tendons of some muscles as patella. 7. Sutural bones: small bones lying inside sutures of skull. II. According to development (embryological classification): 1. Membranous bones: develop from mesodermal membrane. It occurs in the bones required urgently for support or protection of essential organs as those of the vault of skull and face. 2. Cartilaginous bones: they are developed from cartilage and then ossified in two steps: III. According to structure (structural classification): 1. Compact (Hard or Ivory) bones: it is the outer hard mass covering the surface of all bones. 18  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ 2. Cancellous (spongy) bones: it is a network of trabeculae lying inside the compact bones especially at the ends of long bones. In between these trabeculae there are numerous spaces filled with red bone marrow. Parts and structure of long bones: 1. Each end of long bone is called epiphysis which is formed of spongy bone and ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ covered by a thin layer of hyaline cartilage called articular cartilage. 2. The epiphysis is followed by a thin plate of cartilage called epiphyseal cartilage which is responsible for bone growth. It ossifies at the age of 15-22 years. 3. The diaphysis (shaft) is a cylindrical mass of compact bone enclosing a medullary cavity that contains the bone marrow. It is surrounded by a fibrous 2023/2024 membrane called periosteum. 2023/2024 2023/2024 4. The periosteum surrounds the bone surface except at its articular sites. 5. The periosteum supplies the bone with nerve and blood supply. 6. The part of the shaft that lies distal to the epiphyseal plate is called metaphysis. Arterial blood supply of bones is derived from the following arteries, 1. Epiphyseal arteries supplying the epiphysis. 2. Metaphyseal arteries supplying the metaphysis. 3. Nutrient artery supplying the bone marrow of the shaft. 4. Periosteal arteries supplying the compact bone of the shaft (arising from a nearby main artery or from muscular arteries). 19  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Nerve supply of bones: The bone itself is insensitive to pain but the periosteum is responsible for pain sensation. It is highly innervated by: 1. Sensory nerves derived from the periosteal nerves. 2. Vasomotor nerves, accompanying the blood vessels. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ SKELETON It is the frame of the body. It is built of 206 bones, 34 of them are single (unpaired) and 86 are paired. Functions of the skeleton: 1. Provides the characteristic shape of the human body. 2. Supports the soft parts of the2023/2024 2023/2024 body. 2023/2024 3. Gives attachments for muscles and ligaments. 4. Acts as levers that help in muscle contractions. 5. Protects the important structures such as the brain, heart and lungs. 6. Reservoir for calcium and phosphorus. 7. Production of red blood cells from the bone marrow. Parts of the skeleton: It is formed of two parts; Axial skeleton and Appendicular skeleton. Axial skeleton (80 bones): ▪ Skull: (28), Cranium 8 bones; face 14 bones; and auditory ossicles 6 bones ▪ Hyoid bone: (1) ▪ Vertebral column: 33 vertebrae (7 cervical; 12 thoracic; 5 lumbar; 5 sacral & 4 coccygeal); the sacral and coccygeal bones are fused into 2 masses (26) 20  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ Sternum: 3 pieces (1) ▪ Ribs: 12 pairs (24) Appendicular skeleton (126 bones): Upper limb (64 bones): ▪ Shoulder girdle: 2 scapulae and 2 clavicles (4) ▪ Arm bones: 1humerus in each side (2) ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ Forearm bones: 1 ulna & 1 radius in each (4) ▪ Wrist bones: 8 carpal bones in each wrist (16) ▪ Hand bones: 5 metacarpals in each hand (10) ▪ Fingers bones: 14 phalanges in each hand; 2 in each thumb and 3 in each of other fingers (28). Lower limb (62 bones): ▪ Hip girdle: each hip bone is formed of an ilium, ischium and pubis (2) 2023/2024 2023/2024 2023/2024 ▪ Thigh bone: 1 femur in each thigh. (2) ▪ Leg bones: 1tibia &1 fibula in each leg. (4) ▪ Patella: (2) ▪ Ankle & foot bones: 7 tarsals & 5 metatarsals in each foot. (24) ▪ Toes bones: 14 phalanges in each foot, 2 in the big toe and 3 in each of other toes (28). Parts of the skeleton SKULL The skull consists of two parts, the cranium or brain box and the face. Cranium: 21  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ It is a complex box formed by the following bones: Single bones: ▪ Occipital bone; at the back of the skull. ▪ Frontal bone; forming the front part of the skull roof, the forehead and the upper parts of orbits. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ Sphenoid bone; at the base of the cranium with wings on either side forming the temples. ▪ Ethmoid bone; between the frontal and the sphenoid, forming the roof of the nasal cavities. Paired bones: ▪ Parietal bones: forming the2023/2024 2023/2024 hind part of the roof of the2023/2024 skull. ▪ Temporal bones: at the sides, above the ears. Bones of face: Is formed of 14 bones. Single bones: ▪ Vomer; forming part of the nasal septum. ▪ Mandible; forming the lower jaw. Paired bones: ▪ Zygomatic; or malar bones in the cheeks. ▪ Maxilla; forming the upper jaw, most of the side walls of the nose and front part of the hard palate. 22  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ Palatine bones; forming the rest of the hard palate and part of the side walls of the nose. ▪ Lacrimal bones; one in each eye socket or orbit. ▪ Nasal bones; form the bridge of the nose. ▪ Inferior conchae; inside the nose ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ External features of the skull: Superior Aspect: It is the vault of the skull being formed of: ▪ Frontal, 2 parietal and occipital bones. ▪ Coronal, sagittal and lambdoid sutures. 2023/2024 2023/2024 2023/2024 Anterior Aspect: ▪ Frontal, nasal and maxillary bones. ▪ The orbital cavity. ▪ Anterior nasal aperture. Lateral Aspect: ▪ The frontal, parietal, occipital, temporal & sphenoid bones and zygomatic arch. ▪ Mastoid process ▪ External auditory meatus. Posterior Aspect: It shows: ▪ Occipital bone. 23  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ Occipital protuberance. ▪ Nuchal lines. Inferior Aspect: It is the base of the skull and shows: ▪ Hard palate which is formed from the palatine bone posteriorly and ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ the maxilla anteriorly. ▪ Base of vomer (part of the nasal septum) ▪ Bodies of the sphenoid & occipital bones. ▪ Occipital condyles. ▪ Styloid and mastoid processes. 2023/2024 2023/2024 2023/2024 It also shows multiple foramina with the largest one called foramen magnum. Cranial cavity: ▪ It is the base of the skull from inside which can be seen when the vault of the skull is removed. ▪ It is divided into three big areas: the anterior, middle and posterior cranial fossae. Mandible: It is the bone which forms the lower jaw. It is formed of two parts: 1. Body: 24  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Carries the lower set of teeth in their sockets. 2. Ramus: ▪ It is wide, thin and directed upwards. ▪ It forms the coronoid process anteriorly and the condyloid process posteriorly for articulation with the skull. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ Characters of the skull of newly born infant ▪ Large in proportion to other parts of the skeleton with huge cranium and wide orbital openings. ▪ The bones are smooth, and their ossification is incomplete. Membranous areas are still unossified at the meeting of bones forming the fontanelles. 2023/2024 2023/2024 2023/2024 ▪ 6 fontanelles are present in the fetal skull, ▪ the most important of which are: Anterior and posterior fontanelles. Anterior fontanelle: ▪ The larger of the two fontanelles lies at the junction of the sagittal, coronal, and frontal sutures. ▪ Diamond shaped measuring about 4 x 2.5 cm. It is closed by the age of 18 months. 25  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Posterior fontanelle: ▪ It is triangular and situated at the junction of the sagittal & Lambdoid sutures. ▪ It is closed by the age of 6 months. Importance of the fontanelles: ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ 1. Allow molding and overriding of the skull bones during labour. 2. Give space for the growth of brain & skull bones. 3. They are of importance in evaluating the baby’s growth and health as it helps in diagnosis of some disorders as dehydration and hydrocephalus. VERTEBRAL COLUMN 2023/2024 2023/2024 2023/2024 ▪ The vertebral column or the spine is composed of 33 vertebrae, some of which are fused, so that the real number is 26 bones. ▪ The vertebrae are connected by intervertebral discs. ▪ The vertebral column has the following regions: Cervical region in the neck 7 vertebrae Thoracic or dorsal region 12 vertebrae Lumbar region in the back 5 vertebrae Sacral region in the pelvis 5 vertebrae fused into 1 sacrum Coccygeal region 4 vertebrae fused into 1 coccyx ▪ The adult vertebral column viewed from the side shows 4 curves. 26  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ The thoracic and sacral curves are concave ventrally (primary curves) while the cervical and lumbar curves are convex ventrally (secondary curves). Intervertebral discs: ▪ They are plates of varying thickness that bind two adjacent vertebral bodies together. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ They permit a slight movement between any two vertebrae. ▪ They act as shock absorbers. ▪ Each disc is composed of two parts: The anulus fibrosus: It is the firmer outer portion which2023/2024 2023/2024 is composed of concentrically 2023/2024 arranged fibro-cartilaginous fibres. The nucleus pulposus: It is the softer, compressible central part which is formed of mucoid material. General characters of vertebrae: ▪ The vertebrae vary in size and in other characteristics from one region to another. ▪ Generally, they show a gradual increase in size downwards, an expression of the increasing load. 27  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Parts of typical vertebra: 1. Body: Cylindrical anterior portion, with flattened upper and lower surfaces. 2. vertebral arch: Formed of two pedicles and two flattened laminae. It forms the posterior ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ portion and surrounds the vertebral canal. 3. Processes: ▪ One spinous process ▪ Two transverse processes ▪ Two superior articular processes 2023/2024 2023/2024 2023/2024 ▪ Two inferior articular processes Characters of vertebrae in different regions A. Cervical vertebrae (7): Typical cervical vertebrae (from 3 to 6) Characterized by: ▪ Small body. ▪ Short bifid spinous process. ▪ Foramen transversarium in each transverse process. 28  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Atypical cervical vertebrae: First cervical (Atlas) ▪ Has no body ▪ Has no spinous process. Second cervical (Axis) ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ Shows the large projecting odontoid process. Seventh cervical ▪ Has a long, thick, not bifid, prominent, and horizontal spine, called the vertebral prominence. B. Thoracic vertebrae (12) 2023/2024 2023/2024 2023/2024 Typical vertebrae (from 2 to 8) - Has heart shaped body. - Has costal facets on the body and the transverse processes to articulate with the ribs. - Has long oblique dorsal spine. C. Lumbar vertebrae (5) Typical vertebrae (1- 4) ▪ Body is large and kidney shaped. ▪ Spinous process is short, almost horizontal and quadrangular in shape. D. Sacrum: ▪ It is triangular in shape and formed of fused 5 sacral vertebrae. 29  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ The spinal foramina of the sacral vertebrae form the sacral canal, the upper opening of which is seen on the base and the lower opening is an inverted U-shaped gap, called the sacral hiatus. THORACIC CAGE ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ It is a framework within which lie the important organs of respiration and circulation. Formation: ▪ Sternum anteriorly ▪ 12 thoracic vertebrae and intervertebral discs. ▪ 12 pairs of ribs and costal cartilages 2023/2024 2023/2024 2023/2024 Shape: ▪ It is a truncated cone. ▪ It has an inlet superiorly which slopes downwards and forwards and an outlet inferiorly which slope downwards and backwards. STERNUM It has 3 parts: manubrium, body & xiphoid process. Manubrium: ▪ It is broader above and narrower below. ▪ Its upper border presents the suprasternal notch. 30  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ Its lower border articulates with the body of sternum. This articulation makes an angle called the sternal angle, or angle of Louis which can be easily palpated. Angle of Louis lies: ▪ Opposite the 2nd costal cartilage. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ At the level of the lower border of 4th thoracic vertebra. Body: Has two lateral borders with costal notches for articulation with the lower 1/2 of the 2nd and from the 3rd to the 7th costal cartilages. Xiphoid process: ▪ A plate of hyaline cartilage that 2023/2024 ossifies with aging. 2023/2024 2023/2024 RIBS ▪ There are 12 pairs of ribs. ▪ Posteriorly, all are attached to the thoracic vertebrae. ▪ Anteriorly, each rib ends by joining a costal cartilage. ▪ The anterior attachments of the costal cartilages differ as follows: True ribs: The upper 7 ribs reach the sternum and are attached to it by their costal cartilage. 31  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ False ribs: 8th, 9th &10th ribs do not reach the sternum and their costal cartilages are attached to each other anteriorly forming the costal margin on each side which encloses the infra-sternal (subcostal angle). Floating ribs: ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ 11th &12th ribs have no anterior attachment. Typical rib: Each rib has: Head: With 2 facets Neck: Constricted part between the head and tubercle. Tubercle 2023/2024 2023/2024 2023/2024 Angle: Where the rib bend forward. Shaft: Flat with a rounded superior borders and sharp inferior border. Anterior end: Expanded for the attachment of the costal cartilage. 32  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ BONES OF THE UPPER LIMB Shoulder girdle It consists of two scapulae and two clavicles. CLAVICLE ▪ This bone is easily seen and felt. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ It is a long bone with two ends and a shaft. ▪ The medial end articulates with the manubrium while the lateral articulates with the acromion of the scapula. SCAPULA ▪ It is a flat triangular bone which lies on the posterior wall of the 2023/2024 thorax between the 2nd & 7th2023/2024 rib. 2023/2024 ▪ It has 3 borders, 3 angles, 2 surfaces & 2 processes. Borders: Lateral, medial & superior. Angles: Superior, Inferior & Lateral. Surfaces: Costal surface: form the floor of the subscapular fossa. Dorsal surface: Divided by the spine into small supraspinous fossa and large infraspinous fossa. Processes: Acromion; is the lateral extension of its spine. Coracoid; arises from the lateral end of the superior border. 33  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ BONES OF THE ARM HUMERUS It is a long bone having 2 ends and a shaft. Upper end: Head: ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ Articulates with the glenoid cavity of the scapula to form the shoulder joint. Neck: ▪ Anatomical neck: it is the margin of the head. ▪ Surgical neck: It lies between the upper end and the shaft. Fractures 2023/2024 commonly occur here. 2023/2024 2023/2024 Tuberosities: ▪ Lesser and greater tuberosities with a groove in between called (bicipital groove). Shaft: ▪ It is triangular in cross section having 3 borders and 3 surfaces. Lower end shows: ▪ Medial epicondyle: (lodges the ulnar nerve behind. ▪ Lateral epicondyle 34  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ Trochlea ▪ Capitulum BONES OF FOREARM RADIUS ▪ It is the lateral bone. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ It is a long bone having two ends and a shaft. Upper end: ▪ Head: disc like, articulates with the capitulum of the humerus and the radial notch of the ulna. ▪ The neck; is the constricted part below the head. 2023/2024 2023/2024 2023/2024 ▪ Tuberosity; on the medial side below neck. Shaft: ▪ It is wider below than above. ▪ It is triangular in cross section and has 3 borders and 3 surfaces. Lower end: ▪ Expands from the lower end of the shaft and carries a styloid process laterally. ULNA ▪ Is the medial bone of the forearm. ▪ It is a long bone having two ends and a shaft. Upper end: 35  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ Has two projections (olecranon & coronoid) with a saddle - shaped trochlear notch between them which grip the trochlea of the humerus. Shaft: ▪ Is triangular in cross section. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ It has 3 borders and 3 surfaces. Lower end: ▪ Comprises a small, rounded head and short styloid process. BONES OF THE HAND Carpal Bones: There are 8 carpal bones arranged in two rows; proximal and distal. 2023/2024 2023/2024 2023/2024 Metacarpals: They are 5 bones; each one has two ends and a shaft. Phalanges: There are three phalanges for each of the fingers except the thumb which show two only. BONES OF THE LOWER LIMB PELVIC GIRDLE The pelvic girdle consists of two hip bones. HIP BONE The hip bone is formed by the fusion of three bones, ilium, ischium and pubis in a Y shaped epiphysis at the acetabulum which becomes completely closed by the 15 the year of age. Ilium: 36  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ It is the flattened bone above the acetabulum. ▪ Its upper border Is called Iliac crest. ▪ Its outer surface is called gluteal surface while its inner surface is called iliac fossa. Ischium: ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ L shaped having 2 portions: Body; It carries the ischial tuberosity which supports the sitting weight. Ramus; is the lower thin part which is continuous with the inferior pubic ramus. Pubis: Has 3 parts: 2023/2024 2023/2024 2023/2024 1. Body 2. Superior ramus 3. Inferior ramus BONE OF THE THIGH FEMUR It is a long bone having two ends and a shaft. Upper end: it carries the following structures. Head ▪ Looks upwards and medially to articulate with the acetabulum. 37  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Neck ▪ Make an angle of 125 degrees with the shafts. ▪ At the junction of the neck with the shaft there are: - Greater trochanter, laterally. - Lesser trochanter, medially. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ Shaft: ▪ It shows forward convexity. ▪ It widens appreciably downwards to form the triangular popliteal fossa posteriorly. Lower end: 2023/2024 2023/2024 2023/2024 ▪ Has lateral and medial condyles. ▪ They are separated posteriorly by the inter- condylar notch and are joined anteriorly for articulation with the patella. PATELLA Is a triangular sesamoid bone which lies within the quadriceps tendon. BONES OF THE LEG TIBIA Is the largest medial bone of the leg. it carries the following structures. Upper end: 38  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ ▪ Shows the medial and lateral condyles with an intercondylar eminence between the two. ▪ The tibial tuberosity lies anteriorly. Shaft: ▪ Triangular in cross section with 3 borders & 3 surfaces. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ ▪ Lower end: ▪ Medially, it has a big bony prominence called the medial malleolus. ▪ Laterally, it has a wide depression for the fibula. FIBULA Is the slender lateral bone of the leg. 2023/2024 2023/2024 2023/2024 Upper end carries: ▪ Head. ▪ Styloid process. ▪ Constricted neck. Shaft: ▪ Has 3 borders & 3 surfaces. Lower end: Shows the triangular lateral malleolus. BONES OF THE FOOT Tarsal Bones: ▪ Seven bones arranged in three rows. 39  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Metatarsal Bones & Phalanges: ▪ Resemble the metacarpals and phalanges of the hand. ▪ The big toe has 2 phalanges while the others possess 3 for each. ARCHES OF THE FOOT The tarsal and metatarsal bones are arranged in such a way to form 2 ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ longitudinal and 1 transverse arches. Functions of the arches: ▪ Distribution of the body weight ▪ They act as a powerful lever on which the body weight can be elevated. ▪ They perform a spring like and 2023/2024 shock absorber action. 2023/2024 2023/2024 ▪ Protection of the structures in the sole of the foot. 40  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ JOINTS Definition A joint is the site where two or more bones are articulated. Classification Joints can be classified according to the tissue that lies between the bones ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ into 3 types: fibrous, cartilaginous and synovial. FIBROUS JOINTS ▪ The bony surfaces are joined by fibrous tissue. ▪ The bones are fixed together, or a very little movement is allowed. 2023/2024 2023/2024 2023/2024 ▪ They are of 3 types: 1. Sutures: - They are limited to the flat bones of the skull where the margins of bones are serrated and articulate with one another with a ligament in-between. 2. Syndesmosis: - The opposed bony surfaces are connected by interosseous ligament, e.g. Inferior tibiofibular joint. 3. Gomphosis: - Peg & socket joint; they are restricted to the fixation of teeth in the mandible and maxilla. 42  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ CARTILAGENOUS JOINTS ▪ The bones are united by intervening cartilage. ▪ They are slightly mobile. ▪ They are of 2 types: 1. Primary cartilaginous joint: ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ - It is the joint where the bones are united by a plate or bar of hyaline cartilage. - They are quite immobile. - They are very strong. - Example: 2023/2024 2023/2024 2023/2024 a) Costochondral junctions b) Epiphyseal plate of cartilage 2. Secondary cartilaginous joint: - It is a union between bones whose articular surfaces are covered with a thin lamina of hyaline cartilage. - These cartilaginous laminae are united by a plate of fibrocartilage. - A limited degree of movement is possible. - Examples: a) Symphysis pubis b) Manubriosternal joint c) Intervertebral disc 43  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ SYNOVIAL JOINTS ▪ The bones involved are linked together by a fibrous capsule which is lined by synovial membrane. ▪ They are freely mobile. Characteristics of Synovial Joints: ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ 1. The articular surfaces are in contact but not in continuity. 2. They are covered by a thin layer of hyaline cartilage to decrease the friction. 3. The joint is surrounded by a strong fibrous capsule which is attached around the articular margins. 4. The capsule encloses the joint 2023/2024 completely except for the 2023/2024 bursae where 2023/2024 its continuity is interrupted by protrusions of the synovial membrane. 5. The joint is strengthened by a variable number of ligaments outside and inside the capsule. 6. The fibrous capsule is lined by a synovial membrane. 7. The synovial membrane secretes synovial fluid and engulfs the products of wear & tear and the debris resulted from friction in the joint. 8. Synovial fluid is viscid and acts like a lubricant to make the articular surfaces slippery and also it is important for the nutrition of the cells of the articular cartilages which contain no blood vessels. 9. Some intra-articular structures can be recognized in different joints, the most important are: 44  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ - Tendons of muscles - Menisci, which are incomplete discs as those found in the knee joint which act as shock absorbers, facilitate combined movement and distribute the weight. - Labrum; which is a fibro-cartilaginous annular lip attached to the margins of articular surface as that of the glenoid cavity of the ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ scapula and that of the acetabulum. These deepens the corresponding sockets. - Fat pads, which form flexible cushions which fill the potential spaces and irregularities in the joint cavity. Classification of Synovial Joints: The synovial joints can be classified 2023/2024 according to the arrangement 2023/2024 2023/2024of the articular surfaces and the types of movement allowed into: ▪ Plane joints: - They allow simple gliding or sliding movement between two flat surfaces. - Examples: a) Vertebral articular processes b) Proximal tibiofibular joint. c) Acromioclavicular& sternoclavicular joints. d) intercarpal& intermetacarpal joints. ▪ Uniaxial joints: 45  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ - The movement is only around one axis. This may be: Hinge joint: - It resembles the hinge on a door. - It has a transverse axis. - The movements are only flexion and extension. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ - Example: Elbow joint Pivot joint: - A central bony pivot is surrounded by a bony-ligamentous ring. - It has a vertical axis. 2023/2024 2023/2024 2023/2024 - The movement is only rotation. - Examples: a) Atlanto-axial joint (Saying No) b) Superior & inferior radio-ulnar joints. ▪ Biaxial Joints: - The movement is around two axes. This may be: Condyloid joint: - Two distinct convex surfaces articulate with two concave surfaces. - Movement occurs in two directions at right angles to each other. 46  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ - It allows flexion, extension, abduction and adduction. - Minimal degree of rotation can also occur. - Examples: a) Metacarpo-phalyngeal joints. b) Metatarso-phalyngeal joints. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ Ellipsoid joint: - It is a variation of the condyloid type. - An elliptical biconcave surface articulates with an elliptical biconvex one. - The same movement as condyloid but no rotation 2023/2024 is allowed. 2023/2024 2023/2024 - Examples: a) Wrist joint b) Atlanto-occipital joint Saddle joint: - The articulating surfaces are concavo-convex in one bone which fits in a convexo- concave surface in the other; resemble a saddle on horse’s back. - The movements occur around two axes. - This joint permit flexion, extension, abduction, adduction, and rotation. 47  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ - Example: Carpo-metacarpal joint of the thumb. ▪ Poly- axial Joint (Ball & socket) - Movements are free, nearly in all directions around more than two axes. - The articulating surfaces are usually a hemispherical head (ball) ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ which fits into a cup shaped surface (socket). - This arrangement permits free movements, including flexion, extension, abduction, adduction, medial rotation, lateral rotation, and circumduction. - Examples: a) Shoulder joint 2023/2024 2023/2024 2023/2024 b) Hip joint. ▪ Joint Stability : depends on Shape, size and arrangement of the articular surfaces: Hip joint (ball& socket) is a good example of how the shape of articular surfaces plays an important role in joint stability. On the other hand, acromioclavicular joint is an example in which the shape of bones plays little no role to the stability. Ligaments fixing the joint: Fibrous ligaments prevent excessive movement in a joint and they become stretched if stress persists for a long period. Elastic ligaments return to their original length after stretching. 48  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ Tone of muscles around the joint: Muscle tone is the major factor controlling joint stability as the tone of muscles around shoulder and knee joints. ▪ Nerve Supply of the joint : The capsule and ligaments have abundant nerve supply. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ Hilton's law: The motor nerve to a muscle tends to give a branch of supply to the joint which the muscle moves and another branch to the skin over the joint. 2023/2024 2023/2024 2023/2024 49  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ RESPIRATORY SYSTEM Respiration: is the process by which oxygen is obtained and CO2 is removed from the body. The respiratory system: consists of the upper respiratory system (nose, pharynx and larynx) and lower respiratory system (trachea, ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ bronchi and lungs). The conducting zone of the respiratory system consists of those passages that serve only for airflow, essentially from the nostrils through the major bronchioles. The respiratory zone consists of the alveoli and other gas exchange regions of the distal airway. NOSE 2023/2024 2023/2024 2023/2024 It consists of an external nose and nasal cavity. A. The external nose: - It consists mainly of the nasal bones and hyaline cartilage supported in the middle line by the cartilaginous part of the nasal septum. B. The nasal cavity: - It extends from a pair of anterior openings called the nostrils, or nares, to a pair of posterior openings called the posterior nasal apertures, or choanae. - The roof of the cavity is formed of the base of the skull and the floor is formed of the hard palate. 50  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ - It is divided into right and left halves by the nasal septum which is composed of bone and hyaline cartilage. - The lateral wall of the nasal cavity shows 3 nasal projections called conchae (superior, middle and inferior) and receives the openings of the para-nasal sinuses. - The respiratory mucous membrane lines most of the nasal cavity and ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ continues with that of the paranasal sinuses. It is concerned with cleaning, moistening and warming of the inspired air. Para-nasal sinuses: - They are air filled extensions of the nasal cavity into the following cranial bones: frontal, ethmoid, sphenoid and maxilla. - They are named according to the 2023/2024 bones in which they are 2023/2024 2023/2024 located. - All these sinuses opened into the lateral wall of the nasal cavity. PHARYNX It is a tube of about 13 cm long which extends from the base of the skull to the level of the 6thcervical vertebra where it becomes continuous with the esophagus. It is divided into 3 parts: 1. Nasopharynx: - It is the part which lies behind the nasal cavity above the level of the soft palate. 2. Oropharynx: 51  Principles of Human Body Structure Module (Anatomy) ______________________________________________________________ - It is the part which lies behind the mouth cavity. - It extends from the soft palate superiorly to the epiglottis inferiorly. 3. Laryngopharynx: - It is the part which lies behind the larynx. ‫ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪﺍﻟﻔﺘﺎﺡ ﺳﻌﻔﺎﻥ‬ - It extends from the epiglottis superiorly to the cricoid cartilage inferiorly. LARYNX It is an organ that provides a protective sphincter at the inlet of the air passages and is responsible for voice production. It is about 4 cm in length and 2023/2024 extends from the root of 2023/2024 2023/2024 the tongue and epiglottis to the beginning of the trachea. The framework of the larynx is formed of cartilages that are held together by ligaments and membranes, moved by muscles, and lined by mucous membranes. It is formed of a box made by 2 thyroid cartilages which meet in the midline in the prominent Adam's apple. The 2 thyroid cartilages are attached inferiorly to the cricoid cartilage, which has a signet ring appearance, by a membrane. These two cartilages articulate with several other small cartilages, the