Skeletal System -Axial System Chapter 7 Part A Skeleton Learn: Names of the bones. Identify specific landmarks that allow: Bones to fit into each other, Organs to fit into the bone cavities, Muscles to attach, Blood vessels and nerves to pass. Practice…Practice…Practice…Practice…Practice!! Functions: Skeleton forms the framework of the body. Along with muscles, it helps in movement of the body and body parts. It protect many internal organs. Skeleton - Divisions Divided into two major subdivisions: Axial system….blue Appendicular system….tan Axial system: Composed of bones that form the longitudinal axis of the body/ bones that make up the head and trunk. 80 bones. Appendicular system: Composed of bones that form The limbs. The bones that attach the limbs to the axial. 126 bones. Total number of bones in adult human body: 206 Axial Skeleton Axial system: 1) Skull 22 bones 2) Bones associated with skull: Hyoid 1 bone Auditory ossicles 6 bones 3) Vertebral column: Vertebrae 24 bones Sacrum 1 bone Coccyx 1 bone 4) Thorax: Sternum 1 bone Ribs 24 bones 80 bones auditory ossicles U-shaped bone in the neck that supports the tongue Skull Skull – Cranial Bones Horizontal section Posterior Roof Anterior Floor Lateral Cranial bones form a box…cranial cavity to hold the brain: Roof of the cranium Floor of the cranium Anterior, posterior and lateral walls of the cranium Skull Ethmoid bone Sphenoid bone Skull – Cranial Bones-Frontal bone Frontal bone Frontal bone (1): Supraorbital foramen Form the forehead, part of the roof of cranium and orbital cavity. Two bones at birth fuse by age 6-8 years. Supraorbital margin- thickened portion Lateral view that forms the superior margin of the orbital cavity. Frontal bone Supraorbital Supraorbital foramen- a hole in the margin foramen Supraorbital blood vessels and nerves enter the margin bone. Skull – Cranial Bones-Frontal bone Frontal bone Frontal sinus- air filled space in the bone. Supraorbital Mucus from sinus helps flush the nasal foramen cavity. Makes the skull lighter. Lateral view Frontal sinus Sagittal section Anterior view Skull – Cranial Bones-Parietal bones Parietal Frontal Sphenoid bone Parietal bones (2): Temporal Form part of the roof, lateral wall and posterior wall of the cranium. Occipital Articulations- Parietal bones articulate with one another by sagittal suture. Lateral view Parietal bones also articulate with frontal, temporal, sphenoid and occipital bone. Q. A fracture in the right superior lateral surface of cranium. Which bone? Superior view Skull – Cranial Bones-Temporal bones Temporal bones (2): Form the lateral wall and floor of the cranium. Lateral view External auditory/acoustic meatus: a tube- Frontal like opening forms the external ear to Parietal direct sound into the ear. Temporal Zygomatic process: a projection of the bone temporal bone that connects with the cheek External acoustic Occipital bone (zygomatic bone) form zygomatic meatus arch (cheek arch). Zygomatic process Zygomatic of temporal bone arch Temporal process of zygomatic bone Zygomatic arch Temporal Temporal Horizontal section Inferior view Skull – Cranial Bones-Temporal bones Lateral view Mandibular fossa: two depressions to fit lower jaw (mandible). *Pearson-slide 12 Temporal bone Mastoid process: Site for attachment of muscles that can rotate/extend head Mastoid process Styloid process: - Attached to ligaments that support the hyoid bone. Styloid process - Attached to tendon of several muscles associated with hyoid bone, tongue and pharynx Zygomatic arch Mandibular fossa Styloid process U-shaped bone in the neck Mastoid process that supports the tongue Inferior view Skull – Cranial Bones-Occipital bone Lateral view Occipital bone (1): Forms the floor and posterior wall of the cranium. External occipital protuberance: a bump for attachment of ligaments from cervical vertebrae to support head. Occipital Superior and inferior nuchal lines: lines bone extending from protuberance for attachment of muscles and ligaments to support head. Foramen magnum: a big hole for spinal cord to exit. Occipital condyles: curved surfaces lateral to foramen magnum to articulate with 1st cervical vertebra. *Pearson-slide 11 Occipital condyle Occipital Superior nuchal line bone Foramen magnum External Occipital protuberance Inferior nuchal line External Occipital protuberance Inferior view Posterior view Skull – Cranial Bones-Sphenoid bone Horizontal section Sphenoid bone (1): Forms the floor of the cranium. Articulates with all other cranial bones… to hold Sella turcica them together…”keystone”. Lesser wing Sella turcica: a depression to accommodate Greater wing pituitary gland. Lesser wings: Extend horizontally anteriorly to sella turcica. Greater wings: Extend laterally from body and forms floor of cranium. Sphenoidal sinuses: drains mucus into nasal cavity. *Pearson- Slide 7 Sella turcica Sphenoidal sinus Sagittal section Skull – Cranial Bones-Sphenoid bone a) Foramen ovale-jaws (slide 23) b) Foramen spinosum-cranial cavity membranes (slide 23) c) Foramen rotundum-face (slide 8) d) Superior orbital fissure-orbit (slide 8) e) Optic canal-optic nerve (slide 8) Superior orbital Optic canal fissure Skull – Cranial Bones-Ethmoid bone Horizontal section Ethmoid bone (1): Cribriform Sponge-like bone…vertically placed in the center of plate the skull. Cribriform plate: forms the roof of the nasal cavity and floor of the cranium. Has perforations-Olfactory foramina- to allow olfactory nerves-provides sense of smell. Crista galli-ridge of bone that projects from the cribriform plate. Allows the attachment of a membrane that stabilizes the position of the brain. Olfactory foramina Cribriform plate Sagittal section Skull – Cranial Bones-Ethmoid bone Ethmoid bone (1): Perpendicular plate: forms part of the nasal septum. Superior and middle nasal conchae: projections in the nasal cavity cause turbulence of the inhaled air…filter, Middle moisten and warm the air. nasal concha Ethmoidal sinuses: drains mucus into nasal cavity. Skull – Sutures Coronal suture Frontal Parietal bone bone Squamous suture Temporal Lambdoid bone Sutures: suture - Seam-lines that connect cranial and facial Occipital bone bones to each other…dense fibrous connective tissue. - Characterized by zigzag appearance Lateral view Squamous suture: Temporal Parietal. Coronal suture: Frontal Parietals. Sagittal suture: Parietal Parietal. Lambdoid suture: Occipital Parietals. Superior view Review Cranial Bones ! Lateral Anterior Inferior view view view ? Frontal ? Frontal Parietal ? Parietal ? ? Temporal ? Sphenoid Temporal ? ? Occipital Cranial ? Occipital floor Frontal ? Ethmoid ? Posterior Superior ? Occipital Sphenoid view Parietal bone view ? ? ? ? ? Temporal Occipital Parietal Temporal ? ? ? Occipital Frontal Review Cranial Landmarks ! Lateral Anterior Inferior view view Coronal suture view ? Squamous Supraorbital Zygomatic arch suture ? foramen Supraorbital ? margin ? ? ? Zygomatic process Lamboid suture of temporal bone Mandibular fossa ? External ? Occipital condyle auditory meatus? ? ? ? Mastoid ? ? process Styloid ? Foramen magnum process Mastoid process Cranial floor ? Cribriform plate ? Posterior Superior Greater wing ? view view ? Sella turcica ? Sagittal suture Superior nuchal line ? ? External occipital ? Inferior nuchal line Foramen protuberance ? magnum Skull – Fontanelles Sphenoidal fontanelle Posterior fontanelle Mastoid fontanelle Anterior fontanelle Lateral view Superior view Fontanelles: - Soft spots - Non-ossified areas between cranial bones-made of tough fibrous membrane - Allows the brain and skull to expand - Enable the bony plates of the skull to flex at birth Craniostenosis: premature closure of one or more fontanelles distortion of the skull can affect proper growth of the brain. Skull Facial bones form the face….cheeks, jaws, nose, orbital Cranial bones surround and cavity, and protect/support protect the brain. the entrances to the digestive and respiratory tracts. Frontal Nasal bone bone Parietal bone Lacrimal bone Vomer Temporal Zygomatic bone bone Ethmoid Maxilla Sphenoid Occipital Mandible bone Skull – Facial Bones-Nasal bones Nasal bones (2): Nasal bone - Forms only the superior part of nose bridge….connected to cartilage that forms the distal portion of the bone. - Articulates with one another, with ethmoid, with frontal bone and maxilla. Lateral view Nasal bone Anterior view Skull – Facial Bones-Zygomatic bones Lateral view Zygomatic Zygomatic bones (2): bone Cheek bones. - Temporal process: a projection of the zygomatic bone that connects with the temporal bone form zygomatic arch (cheek arch). Zygomatic process Zygomatic of temporal bone arch Temporal process of zygomatic bone Zygomatic arch Inferior view Skull – Facial Bones-Maxillae Maxillae (2): - Form the upper jaw. - Two bones fuse before birth. - Largest facial bone. Infraorbital Maxillary sinuses: spaces that secrete mucus and foramen drain into the nasal cavity. Maxilla Alveolar processes: projecting ridge on body of maxilla form alveolar sockets to accommodate teeth. Anterior view Infraorbital foramen: hone for blood vessel and Palatine process of nerve to enter maxilla. maxilla Alveolar process Inferior view Skull – Facial Bones-Maxillae Palatine process of Palatine process of maxilla: horizontal maxilla part that forms the anterior part of the hard palate (roof of oral cavity). *Slide 11-Rotate Cleft palate: birth defect when maxillae fail to meet along the midline of the hard palate oral and nasal cavities are continuous; lips are split; difficulty