Chapter 7 & 8 Notes PDF

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Chapter 7: The Skeletal System: The Axial Skeleton 

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The axile skeleton and Homeostasis o The bones of the axial skeleton contribute to homeostasis by protecting many of the body’s organs such as the brain, spinal cord, heart, and lungs. They are also important in support and calcium storage and release. Division of the Skeletal System o Musculoskeletal system: Together, the bones, muscles, and joints form an integrated system o Orthopedics: The branch of medical science concerned with the prevention or correction of disorders of the musculoskeletal system o Axial skeleton: consisting of the bones that lie around the longitudinal axis of the human body, an imaginary vertical line that runs through the body’s center of gravity from the head to the space between the feet: skull bones, auditory ossicles (ear bones), hyoid bone, ribs, sternum (breastbone), and bones of the vertebral column. o Appendicular Skeleton: consists of the bones of the upper and lower limbs (extremities or appendages), plus the bones forming the girdles that connect the limbs to the axial skeleton.  Functionally, the auditory ossicles in the middle ear, which vibrate in response to sound waves that strike the eardrum, are not part of either the axial or appendicular skeleton, but they are grouped with the axial skeleton for convenience  Malleus, incus, stapes- considered as auditory ossicles in axial skeletal.

Blue indicate Axile Skeleton

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Types of Bones o Short Bones: are somewhat cube-shaped and are nearly equal in length and width. They consist of spongy bone tissue except at the surface, which has a thin layer of compact bone tissue.  Examples: trapezoid, carpals (wrist), and tarsals (ankle). o Flat bones: generally thin and composed of two nearly parallel plates of compact bone tissue enclosing a layer of spongy bone tissue.  Example: the cranial bones, which protect the brain; the sternum (breastbone) and ribs, which protect organs in the thorax; and the scapulae (shoulder blades). o Irregular Bones: have complex shapes and cannot be grouped into any of the previous categories. They vary in the amount of spongy and compact bone present.  Example: Vertebrae (backbones), hip bones, certain facial bones, and the calcaneus. o Sesamoid Bones: shapes like a sesame seed, develop in certain tendons where is considerable friction, tension, and physical stress such as the palms and soles.  Example: patella and kneecap

o Long Bones: have greater length than width, consist of a shaft and a variable number of extremities or epiphysis (ends), and are slightly curved for strength.  Examples: hemerus, femur, tabia, fibula, flanges, ulna, and radius. o Sutural Bones: classified by location rather than shape. These are small bones located in sutures (joints) between certain cranial bones. o Sutures: are the jointed areas where flat bones come together    

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Coronal suture: is connecting the frontal bone to the parietal bones. Sagittal suture: connects the two parietal bones together Squamous suture: connects the parietal bones to the temporal bones Lambdoid suture: connects the occipital bone to the parietal bone

Surface markings o Bones have characteristics surface markings- structural features adapted for specific functions. o Two Major types of surface markings  Depressions and Openings: which allow the passage of soft tissues such as blood vessels, nerves, ligaments and tendons or form joints.  Fissure: (parietal bone) narrow slit between bones for passage of blood vessels or nerves  Foramen: (occipital bone) hole for passage of blood vessels, nerves, or ligaments.  Fossa: (jawbone or mandibular fossa) shallow depression

Sulcus: (arm bone or intertubercular sulcus of the hemerus) furrow on bone for passage of blood vessel, nerve or tendon.  Meatus: found in our temporal bone it is a tube like opening at external auditory meatus. Processes: which are projections or outgrowths that either help form joints or serves as attachment points for connective tissue such as ligaments and tendons. 

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Under processes that Form joints o Condyle: it is rounded projection with a smooth articular surface. Ex: lateral condyle of femur o Facet: is smooth, flat, slightly concave articular surface. Ex: associated with vertebrae o Head: Usually round articular process supported on a neck. Ex: also found on the head of femur Processes that form attachment points for connective tissue o Crest: is prominent ridge or elongated process. Ex: iliac crest of hip bone o Epicondyle: usually roughened projection on a condyle. Ex: medial epicondyle of femur o Line: it is long, narrow ridge or border (less prominent than a crest). Ex: linea aspera of femur o Spinous process: Sharp, slender projection: Ex: spinoid process of vertebra o Trochanter: it is a large projection found ONLY on the femur. Ex: greater trochanter of femur o Tubercle: Variably sized rounded projection. Ex: greater tubercle of hemerus o Tuberosity: Variably sixed projection with rough, bumpy surface. Ex: ischial tuberosity of hip bone.

Skull: An Overview o Components of Skull  Skull: bony framework of the head. Contains 22 bones and rests on the superior end of the vertebral column.  Cranial bones: forms the cranial cavity, which encloses and protects the brain  Facial bones: forms the face: 2 nasal bones, 2 maxillae, 2 zygomatic bones, the mandible, two lacrimal bones, 2 palatine bones, 2 inferior nasal conchae, and the vomer.

o Cranial bones: Frontal bone  Forms the forehead the anterior part of the cranium, the roots of the orbits and most of the anterior part of the cranial floor. o Cranial bones: Parietal bones

Forms the greater portion of the sides and roof of the cranial cavity. The internal surfaces od the parietal bones contain many protrusions and depression that accommodate the blood vessels supplying the dura mater, the superficial connective tissue covering of the brain. o Cranial bones: Temporal Bones  Form the inferior lateral aspects of the cranium and part of the cranial floor. o Cranial bones: occipital bone  Forms the posterior part and most of the base of the cranium. Skull: Sphenoid Bone o It lies at the middle part of the base of the skull. This bone is called the keystone of the cranial floor because it articulates with all the other cranial bones, holding them together. Skull: Ethmoid Bone o Is a delicate bone located in the anterior part of the cranial flood medial to the orbits and is spongelike in appearance. Skull: Facial bones o Vomer: a roughly triangular bone on the floor of the nasal cavity that articulates superiorly with the perpendicular plate of the nasal ethmoid gone and sphenoid bone and inferiorly with both the maxillae and palatine bones along the midline. o Maxillae: unite to form the upper jawbone. o Zygomatic Bones: commonly called cheekbones, form the prominence of the cheeks and part of the lateral wall and floor of each orbit o Mandible: or lower jawbone, is the largest and strongest facial bone and is the only moveable skull bone. 

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Unique features of the skull o Sutures: a suture is an immoveable joint  Found in the skull holding bones, such as the temporal and parietal together  Four types of sutures  Coronal suture: it unites the frontal bone and both parietal bones.  Sagittal suture: unites the two parietal bones on the superior midline of the skull.  Lambdoid suture: unites the two parietal bones to the occipital bone.  Squamous suture: flat like the flat overlapping scales of a snakes, it unites parietal and temporal bones on the lateral aspects of the skull.  Paranasal sinuses: mucous membrane-lined cavities in the frontal, maxillary, sphenoid and ethmoid bones  Used as resonating chambers to enhance the voice

Increase the surface area of the nasal mucosa and help to moisten it as well. Fontanes: areas of a fetus/baby where unossified mesenchyme develop into dense connective tissue  They close through intramembranous ossification by 2 years of age  Four types of fontanel o Anterior fontanel: the largest and located at the midline among the two parietal bones and the frontal bone. Usually closes 18 to 24 months after birth o Posterior fontanel: located at the midline among the two parietal bones and the occipital bone. Generally, closes about 2 months after birth o Anterolateral fontanels: located laterally among the frontal, parietal, temporal and sphenoid bone. Normally closes about 3 months after birth o Posterolateral fontanels: located laterally among the parietal occipital and temporal bones and are irregularly shapes. They begin to close 1 to 2 months after birth, but closure is generally not complete until 12 months. 

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Hyoid Bone o is a unique component of the axial skeleton because it does not articulate with any other bone. o It supports the tongue and provides an attachment site for some muscles of the neck and pharynx The vertebral column

o Is called the spine or backbone and makes up about 2/5 of your total heigh and is composed of a series of bones called vertebrae. o composed of 26 vertebrae divided into 5 regions o protects the spinal cord tissues mitosis label the cell and organelles passive and active transport tonicity- in medical when giving IV you want isotonic...