The Skeletal System: Bone Tissue and the Skull (BDS104) PDF

THE SKELETAL SYSTEM: BONE TISSUE AND THE SKULL Integrated Biological Sciences – I BDS104 Dr. Jayaraj Ajman University 8-Sep-24...

THE SKELETAL SYSTEM: BONE TISSUE AND THE SKULL Integrated Biological Sciences – I BDS104 Dr. Jayaraj Ajman University 8-Sep-24 1  LEARNING OUTCOMES ▪ Name the major regions of the skeleton and describe their relative functions ▪ Classify bones based on their shape or location ▪ Describe the functions of bones ▪ Describe the gross anatomy of a typical flat bone and a long bone ▪ Indicate the locations and functions of red and yellow marrow, articular cartilage, periosteum, and endosteum ▪ Indicate the functional importance of bone markings ▪ Name, describe and Identify the cranial and facial bones ▪ Describe the major functions of the cranium and the facial skeleton ▪ Identify the important markings of the cranial and facial bones ▪ Describe the sutures and cavities of the skull Ajman University 8-Sep-24 2  Skeletal System ❑ Skeleton system Consists of 206 named bones Most of which are paired ▪ Bones of the adult skeleton divided into Axial skeleton Includes the bones of the skull, vertebral column, and rib cage ✓ Bones protect, support, or carry other body parts Appendicular skeleton Consists of the bones of the upper and lower limbs and the girdles ✓ Responsible for the locomotion of the body Ajman University 8-Sep-24 3  Divisions of the Skeletal System ❑ Axial skeleton Consists of 80 bones Skull Cranium — 8 bones Face — 14 bones Hyoid bone — 1 bone Auditory ossicles — 6 bones Vertebral column — 26 bones Thorax Sternum — 1 bone Ribs — 24 bones Ajman University 8-Sep-24 4  Divisions of the Skeletal System ❑ Appendicular skeleton ▪ Consists of 126 bones Pectoral (shoulder) girdles Pelvic (hip) girdle Clavicle — 2 Pelvic or coxal — 2 Scapula — 2 Lower limbs Upper limbs Femur — 2 Humerus — 2 Patella — 2 Ulna — 2 Fibula — 2 Radius — 2 Tibia — 2 Carpals — 16 Tarsals — 14 Metacarpals — 10 Metatarsals — 10 Phalanges — 28 Phalanges — 28 Ajman University 8-Sep-24 5  Types of Bones Long bones Long bones Have greater length than width Consist of a shaft plus two ends which are often expanded E.g. All limb bones except patella, wrist and ankle bones Short bones Roughly cube shaped Nearly equal in length and width E.g. Bones of the wrist and ankle Flat bones Flat bones Short bones Thin, flattened, and usually a bit curved E.g. Sternum, Scapulae, ribs, and most skull bones Ajman University 8-Sep-24 6  Types of Bones Irregular bones Have complex shapes E.g. Vertebrae and the hip bones Sesamoid bones Special type of short bone that form in a Irregular bones tendon Vary in size and number in different individuals E.g. Patella, pisiform Sutural bones Small bones located in sutures (joints) between certain cranial bones Ajman University 8-Sep-24 7  Gross Anatomy: Bone Textures ❑ Every bone has two layers Compact bone Dense outer layer that looks smooth and solid to the naked eye Spongy bone Internal layer Consists of small needle-like or flat pieces called trabeculae ▪ In living bone The spaces between the trabeculae are filled with red or yellow bone marrow Ajman University 8-Sep-24 8  Structure of A Typical Long Bone Diaphysis Is the bone’s shaft or body Long, cylindrical, main portion of the bone Epiphysis Proximal and distal ends of the bone Metaphysis Regions between the diaphysis and the epiphyses Articular cartilage Thin layer of hyaline cartilage Covering the part of the epiphysis ✓ Reduces friction at movable joints Ajman University 8-Sep-24 9  Structure of A Typical Long Bone Periosteum Tough connective tissue sheath Associated with blood supply ✓ Protects the bone, assists in fracture repair, helps nourish bone tissue, and an attachment point for ligaments and tendons Medullary cavity or marrow cavity Hollow, cylindrical space within the diaphysis Contains fat yellow bone marrow and blood vessels Endosteum Thin membrane lines the medullary cavity Contains a single layer of bone-forming cells And a small amount of connective tissue Ajman University 8-Sep-24 10  Structure of Short, Irregular, and Flat Bones ❑ Short, irregular, and flat bones ▪ Share a simple design Outer thin plate of compact bone Periosteum covering the compact bone Inner spongy bone Endosteum covering the spongy bone Lack of diaphysis and epiphyses Lack of medullary cavity ▪ Spongy bone of a typical flat bone is called the diploë Ajman University 8-Sep-24 11  Bone Surface Markings Projections Heads, trochanter, spine, tubercle, crest, line, tuberosity, condyle, ramus Depressions Fossae, fissure, groove Openings Foramina, sinus, meatus. Ajman University 8-Sep-24 12  Bone Surface Markings ▪ Bones have characteristic surface markings Structural features adapted for specific functions ▪ Two major types of surface markings Depressions and openings Allow the passage of soft tissues (blood vessels, nerves, ligaments, and tendons) Form joints Processes, projections or outgrowths Help to form joints Serve as attachment points for connective tissue (ligaments and tendons) Ajman University 8-Sep-24 13  Location of Hematopoietic Tissue Red bone marrow Hematopoietic tissue of bone marrow Found within the red marrow cavities Trabecular cavities of spongy bone of long bones And in the diploë of flat bones ▪ In newborn infants Red bone marrow located medullary cavity and spongy bone cavities ▪ In adult long bones Fat-containing medullary cavity extends well Little red marrow is present in the spongy bone cavities Hemopoiesis occurs only at heads of the femur and humerus, diploë of flat bones and in some irregular bones Ajman University 8-Sep-24 14  Functions of Bones ❑ Functions of bones Support ✓ Provide a structural framework that supports the body ✓ Provide attachment points for the tendons of the muscles o E.g. Bones of lower limbs act as pillar o Rib cage supports the thoracic wall Protection ✓ Protects the internal organs from injury o E.g. Cranial bones protect the brain o Rib cage protects the heart and lungs Ajman University 8-Sep-24 15  Functions of Bones Assistance in movement Skeletal muscles attach to bones by tendons ✓ Use bones as levers to move the body and its parts o E.g. Walking , grasping and breathing Mineral homeostasis (storage and release) ✓ Reservoir for minerals (calcium and phosphate) ✓ Stored minerals are released into the bloodstream ✓ And maintain critical mineral balances Blood cell production ✓ Blood cell formation (hemopoiesis) occurs in the red marrow of certain bones Ajman University 8-Sep-24 16  Functions of Bones Triglyceride (fat) storage ✓ Yellow bone marrow store triglycerides ✓ Is stored in bone cavities Triglycerides are a potential energy reserve Hormone production ✓ Bones produce osteocalcin Helps regulate bone formation Protects against obesity, glucose intolerance Ajman University 8-Sep-24 17  The Skull ❑ Skull Bony framework of the head Rests on the superior end of the vertebral column Cranial bones Form the cranial cavity Encloses and protects the brain Provides attachments for muscles of head and neck Facial Bones Form the framework of the face Contain cavities for the special sense organs Provide openings for air and food passages Secure the teeth Anchor the facial muscles of expression Ajman University 8-Sep-24 18  Cranial Bones ❑ Paired cranial bones Parietal bones Form superior and lateral aspects of the skull Temporal bones Form inferolateral aspects of the skull and part of the cranial floor Zygomatic process forms the prominence of the cheek ❑ Unpaired cranial bones Occipital bone Frontal bone Forms posterior aspect and base of Forms the forehead, roofs of the orbits and the skull the part of the cranial floor Foramen magnum allows passage Supraorbital foramina allow the passage of of the spinal cord 8-Sep-24 arteries and nerves Ajman University 19  Cranial Bones Sphenoid bone Forms posterior aspect and base of the skull Called the keystone of the cranial floor because it articulates with all the other cranial bones, holding them together. Contributes to the middle cranial fossa and orbits Ethmoid bone Delicate bone forms anterior aspect and base of the skull Major superior supporting structure of the nasal cavity and forms an extensive surface area in the nasal cavity Helps to form the anterior cranial fossa Ajman University 8-Sep-24 20  Important Markings of the Skull Bones Temporal bones Occipital bone Zygomatic process Foramen magnum Mandibular fossa Hypoglossal canal External acoustic meatus Occipital condyles Ethmoid bone Styloid process Sphenoid bone Crista galli Mastoid process Sella turcica Cribriform plates Stylomastoid foramen Superior orbital Superior and middle Jugular foramen fissures nasal conchae Carotid canal Foramen rotundum Frontal bone Foramen ovale Supraorbital foramina Foramen spinosum Ajman University 8-Sep-24 21  Facial Bones ❑ Unpaired facial bones Mandible (lower jawbone) Largest, strongest facial bone The only movable skull bone (other than the auditory ossicles) Articulates with the temporal bone to form the temporomandibular joint (TMJ) Vomer Roughly triangular bone on the floor of the nasal cavity It forms the inferior portion of the bony nasal septum Ajman University 8-Sep-24 22  Facial Bones ❑ Paired facial bones: Maxilla (upper jawbone) The paired maxillae form the upper jaw and parts of the hard palate, orbits, and nasal cavity wall Articulate with every bone of the face except the mandible Zygomatic bones (cheekbones) Form the prominences cheeks and part of the orbits Temporal process of the zygomatic bone articulates with the zygomatic process of the temporal bone to form the zygomatic arch Ajman University 8-Sep-24 23  Facial Bones Nasal bones Small, flattened, rectangular-shaped bones Form the bridge of the nose Lacrimal bones Thin and roughly resemble a fingernail Smallest bones of the face Form part of the medial orbit walls Contain a lacrimal fossa Palatine bones L-shaped palatine bones Inferior nasal concha Form posterior part of the hard palate and Scroll-like bones form part of the a small part of nasal cavity and orbit walls lateral walls of the nasal cavity Ajman University 8-Sep-24 24  Important Markings of the Facial Bones Mandible Maxilla Coronoid processes Dental alveoli Condylar processes Zygomatic processes Mandibular symphysis Palatine processes Dental alveoli Frontal process Mandibular foramina Incisive fossa Mental foramina Inferior orbital fissure Lacrimal bones Infraorbital foramen Lacrimal fossa Median palatine suture Ajman University 8-Sep-24 25  Cavities of Skull ❑ Orbits Cone-shaped bony cavity and houses the eyes Contains muscles for eye movement Contains the lacrimal glands, vessels and nerves ▪ Formed by parts of seven bones Frontal Sphenoid Zygomatic Maxilla Palatine Lacrimal Ethmoid bones Ajman University 8-Sep-24 26  Cavities of Skull ❑ Nasal cavity Constructed of bone and hyaline cartilage Contains olfactory epithelium Provides passage for the air ▪ Nasal cavity is formed by Ethmoid Palatine bones Maxillae Inferior nasal conchae ▪ Nasal cavity is divided into right and left parts by the nasal septum Ajman University 8-Sep-24 27  Cavities of Skull ❑ Paranasal sinuses Cavities near the nasal cavity ▪ Air-filled cavities in the Frontal Sphenoid Ethmoid Maxillary bones ▪ Lined with mucous membranes ▪ Warm and humidify the air ▪ Resonance to voice ▪ Drain into the nasal cavity Ajman University 8-Sep-24 28  Cavities of Skull ❑ Middle Ear ▪ 3 Tiny bones ~ transmit the sound waves Malleus Incus Stapes (Smallest bone in the body) Ajman University 8-Sep-24 29  Sutures of the Skull ❑ Sutures Immovable joint that holds skull bones together Coronal suture 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 sutures Unite the parietal and temporal bones on the lateral aspects of the skull Ajman University 8-Sep-24 30  Sutures of the Skull Ajman University 8-Sep-24 31  Mobile Joint of the Skull ❑ Temporomandibular joint Only mobile joint in the skull ▪ Present between the mandibular condyle and mandibular fossa of temporal bone mandible Ajman University 8-Sep-24 32  Openings of the Skull ▪ The skull has about 85 named openings Foramina, fissures, canals, ….etc ❑ Foramen of the skull Openings for blood vessels, nerves, or ligaments ▪ Foramen Magnum ▪ Provides passageway for Spinal cord Major brain vessels Cranial nerves Ajman University 8-Sep-24 33  Ajman University 8-Sep-24 34