Category: Bones

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Anatomy & Physiology: Bones—Skull, Occipital Bone.

Structure.

• Forms the back of the head, most of the cranial floor and foramin magnum (where the medulla oblongata connects with the spinal cord; vertebral and spinal arteries also pass through this hole).
• The occipital condyles are ovalish convex “stumps” that articulate with C1 (atlas; remember in Greek mythology that Atlas held up the sky or in this case, the skull). This articulation allows the head to nod (like when a person nods “yes”).
• Hypoglosssal canal: a foramen interior of the skull, superior to the occipital condyles, allowing for the hypoglossal nerve to pass through that controls tongue movement.
• External occipital protuberance: inferior to the lambdoid suture, the external occipital protuberance may feel like a “bump”. From a midsagittal cross-sectional view, it looks like a “gentle hill”; it is not sharp nor pointy. It is the thickest area of the occipital.
• Superior nuchal line: extending bilaterally from the external occipital protuberance, a horizontal “line”. Provides attachment points for muscles.
• Inferior nuchal line: similar to the superior nuchal line but inferior to it; extends bilaterally from the external occipital protuberance, a horizontal “line”. Provides attachment points for muscles.

Function.

Clinical Significance.

Occipital. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.

Download these notes.

Anatomy & Physiology: Bones—Skull, Nasal Bones.

Structure.

• The pair of nasal bones are small, flat and rectangular. They form the nose bridge.
• They protect the entry to the nasal cavity and serve as attachment points.

Function.

Clinical Significance.

Nasal bones. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.

Download these notes.

Anatomy & Physiology: Bones—Skull, Maxilla.

Structure.

• The pair of maxillae form the upper jawbone.
• The maxillae articulate with every facial bone except the lower jawbone, the mandible.
• Forms the floor of the orbits, part of the lateral and inferior nasal walls, and a large portion of the hard palate.
• Hard palate: bony roof of mouth. The palantine processes of the maxillae form most of the hard palate along with horizontal plates of the palantine bones (separate from the maxillae). The hard palate separates the nasal and oral cavities.
• Maxillary sinus empties into nasal cavity.
• Alveolar processes: ridge that contains the sockets (alveoli) for the upper teeth.
• Palantine processes: horizontal projection forming anterior of hard palate.
• Infraorbital foramen: passageway for facial nerve.
• Incisive foramen: allows passageway for nerve and blood vessels to the hard palate.
• Inferior orbital fissure: passateway for nerves and vessels to the face.

Function.

• Upper jaw bone helps to break down food when eating.

Clinical Significance.

Maxilla. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.

Download these notes.

Anatomy & Physiology: Bones—Skull, Mandible.

Structure.

• Lower jawbone is the largest and strongest of the facial bones.
• The only freely moving skull bone.
• Consists of: the body and rami (perpendicular portions).
• Mandibular angle: where the ramus meets the mandibular body.
• Condylar process: of each rami; articulates with mandibular fossa of temporal bone. Forms the temporomandibular joint (TMJ).
• Coronoid process: where temporalis (muscle) attaches.
• Mandibular notch: a depression between the condylar process and coronoid process.
• Alveolar process: is a slightly raised arch (more like a very small ridge) which contains the sockets (alveoli) for teeth in the lower jaw bone.
• Mental foramen: “ment” = chin. This is where dentists inject anesthesia.
• Mandibular foramen: located on the interior surface; inferior and between the condylar process and coronoid process. This is where dentists inject anesthesia. This foramen is a passageway for nerve and blood vessels supplying the teeth in the lower jaw bone.

Function.

• To break down food when eating.

Clinical Significance.

Mandible. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.

Download these notes.

Anatomy & Physiology: Bones—Skull, Lacrimal Bone.

Structure.

• The name “lacrimal” means tear or tear-drop
• The pair of bones that are about the size of a fingernail on either side of the the nasal bones, forming part of the medial orbital wall.
• Lacrimal fossa: a vertical passageway (also formed with the maxilla) for tears to pass into the nasal cavity.

Function.

Clinical Significance.

Lacrimal. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.

Download these notes.

Anatomy & Physiology: Bones—Skull, Inferior Nasal Conchae.

Structure.

• Pair of bones that are separate from the middle and superior nasal conchae on the ethmoid bone.

Function.

• Helps to swirl, warm and moisten the air, trap particles via the mucous.

Clinical Significance.

Inferior nasal concha. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.

Download these notes.

Anatomy & Physiology: Bones—Skull, Frontal Bone.

Structure.

• Forms the forehead; eyebrow ridge (supraorbital margin); and the roofs of the eye socket/orbits; and part of the cranial cavity floor.
• Metopic suture: formed when left and right halves join soon after birth; disappears when child is 6-8 yrs old.
• Supraorbital margin: brow ridge. Bone is thicker in this area.
• Supraorbital foramen: hole for the nerves of the eyebrow and eyelid.
• Frontal sinuses: deep to the frontal bone.
• Forms part of the coronal suture.

Function.

Clinical Significance.

Frontal. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.

Download these notes.

Anatomy & Physiology: Bones—Skull, Fontanels.

Structure.

• The skull of developing embryo through birth is not fully developed.
• Gaps between skull bones are cartilage and mesenchme which will be ossified later.
• These gaps are called fontanels (i.e. the “soft spots”).
• Anterior fontanel: midline between the two parietal bones and frontal bone. Closes 18-24 months after birth.
• Posterior fontanel: midline between the two parietal bones and the occipital. Closes 2 months after birth.
• Anterolateral fontanel: between the frontal, parietal, occipital, and temporal bones. Closes 3 months after birth.
• Posterolateral fontanels: bilaterally, between the parietal, occipital, and temporal bones. Closes 12 months after birth.

Function.

Clinical Significance.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.

Download these notes.

Anatomy & Physiology: Bones—Skull, Ethmoid Bone.

Structure.

• Forms part of the anterior cranial floor and is a slender bone “wedged” midsagittally between the orbits (forms the medial wall of the orbits); transversely between the frontal and sphenoid bones; and posterior to the nasal bones thus forming part of the nasal septum and the nasal side walls.
• The name “ethmoid” means a sieve, sponge-like.
• Cribriform plate: forms the roof of the nasal cavity and contains the olfactory foramina where scents/smells get transmitted to the brain.
• Crista galli: superior to the cribriform plate, triangular shaped. It is an important landmark because it is an attachment point for membranes separating the two halves of the brain.
• Perpendicular plate: inferior to the cribriform plate, and forms the upper part of the nasal septum.
• The ethmoid contains 3-18 “air spaces”. These are called the ethmoidal sinuses.

Function.

• Superior and middle nasal concha: scroll-like formations on either side of the ethmoid. The concha increase surface area and helps “swirl” the air (create currents); warm and moisten the air; and helps to “clean” the air as foreign particles might stick to the mucous.

Clinical Significance.

Ethmoid. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.

Download these notes.

Anatomy & Physiology: Bones—Skull.

Structure.

Cranial bones: frontal bone, 2 parietal bones, 2 temporal bones, occipital bone, sphenoid bone, ethmoid bone.

Facial bones: 2 nasal bones, 2 maxillae, 2 zygomatic bones, mandible, 2 lacrimal bones, 2 palatine bones, 2 inferior nasal conchae, vomer.

• Except for the auditory ossicles, the mandible is the only moveable bone of the skull.
• Sutures: immoveable joints that hold the skull together.

Function.

• Protects, supports, and stabilizes brain, sense organs, nerves, and vessels.
• Serves as attachment sites for muscles and membranes (meninges).

Clinical Significance.

Skull. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.