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 feeding.

Inferior view Skull – Facial Bones-Mandible Mandible (1): Lower jaw…the strongest facial bone and the only movable bone of the skull. Develops as 2 bones  fuse before birth. Body: horizontal part of the mandible. Ramus: vertical parts of the mandible. Mandibular/condylar process: rounded projection  fits into mandibular fossa of temporal bone  forms temporomandibular joint (TMJ). Ramus Coronoid process: Insertion point for temporalis muscle. Angle Mandibular notch: Separates the condylar and coronoid processes. Body Anterior view

Lateral view

Coronoid process TMJ Mandibular Alveolar notch process Head

Condylar process Ramus Body

Mandible Angle Skull – Facial Bones-Mandible Anterior view Mandible: TMJ syndrome: malfunction of the joint  headache, referred pain in the ear, muscle pain, noise and reduced movement of the joint  physical therapy, anti-inflammatory drug therapy. Four holes: Mental foramen: Opening (in the body) for nerves that carry sensory information from lips and chin to the brain.

Ramus Mandibular foramen: Opening (in the ramus)-entrance for mandibular canal-serves lower teeth. Angle

Body Mandibular foramen Mental foramen

Mental Ramus foramen Body

Angle Skull – Facial Bones-Lacrimal bones Lateral view Lacrimal bones (2): Smallest facial bone. Lacrimal Resembles a fingernail. bone Part of the medial wall of the orbital cavity.

Lacrimal fossa: houses lacrimal sac

Lacrimal foramen: passage way for lacrimal artery

Lacrimal Lacrimal bone bone

Lacrimal bone

Orbital cavity Anterior view Skull – Facial Bones

Palatine bones (2): Form the posterior part of the hard

Palatine palate…next to palatine process of bones maxilla.

Palatine bone

Inferior view

Orbital cavity Skull – Facial Bones

Vomer (1): A triangular, vertical bone that forms inferior part of the nasal septum. * Pdf file in Learning Web-Position of vomer-incorrect

Vomer

Inferior view Skull – Facial Bones

Inferior nasal conchae (2): The largest of the 3 conchae. (* Superior and middle nasal conchae are part of ethmoid). Functions-Create turbulence in air. - Warms and humidifies internal ear

Inferior nasal concha

Anterior view

Superior and middle nasal conchae of ethmoid bone

Inferior nasal concha

Sagittal section Review Skull Bones !

maxilla zygomatic bone ? ? palatine bone ? nasal bone ? ? vomer ? sphenoid maxilla ?

? ?maxilla ? mandible temporal

? ? mandible occipital

temporal ?

mandible ? Review Skull Landmarks !

Supraorbital foramen Supraorbital ? margin ?

Infraorbital foramen ? Ramus? ? Angle Palatine process-Maxilla ? Zygomatic arch Temporal process ? ? of zygomatic bone ? Mental foramen ? Zygomatic process of temporal bone Lambdoid suture ?

? ? ?Sagittal suture Foramen Occipital magnum condyle ? Coronal suture

? External occipital protuberance Skull – Orbital Cavity

Frontal bone

Sphenoid Optic canal Ethmoid Superior orbital Lacrimal fissure bone Inferior orbital fissure

Zygomatic Palatine bone bone Maxilla

Orbital cavity: space to accommodate eyeball. Formed by a total of 7 cranial and facial bones. Cranial bones- frontal, sphenoid, ethmoid. Facial bones- zygomatic, maxilla, lacrimal, palatine.

Optic canal, superior & inferior orbital fissures – for passage of optic and other nerves. Q. Which bone contains optic canal? Skull – Paranasal Sinuses

Paranasal sinus: space in the bones around the nose…open into the nasal cavities. Examples: Frontal, Ethmoidal, Sphenoidal and Maxillary sinuses. Functions: Make the skull lighter. Have extensive mucous epithelium that secretes mucus into the nasal cavity  provides moisture and traps dust and microorganisms. Sinusitis: viral, bacterial or fungal infection of the sinuses  mucous membrane swells  openings of sinuses (ostia) narrow  mucus accumulates in the sinuses  pressure builds  headache. Antihistamines, vasoconstrictors and painkillers  relieve the pressure and pain. Axial Skeleton-Skull 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 Skull – Associated Bones

Auditory ossicles: Six smallest bones…3 in each ear. Malleus, Incus and Stapes Function: amplify sound stimulus.

Auditory ossicles Hyoid: Single, U-shaped bone. Located between mandible and larynx. Often fractures during strangulation. Does not articulate with any other bone…floats. Body: horizontal part. Greater and lesser horns/cornua: projections Greater for muscle attachment. horn Function: supports tongue and attach some of the neck and tongue muscles. Body Lesser horn

An anterior view of the hyoid bone Axial Skeleton

Axial system:

Skull 22 bones Hyoid 1 bone Auditory ossicles 6 bones Vertebral column 26 bones Thorax: Sternum 1 bone Ribs 24 bones 80 bones