Chapter 8 (2)

• Facial bones are skull bones anterior to the cranial cavity (they do not enclose the brain). There are 14 facial bones. These bones support the teeth, give shape to the face, form part of orbital and nasal cavities, and provide attachments for muscles of facial expression and mastication (chewing). There are 2 maxillae, 2 nasal bones, 2 palatine bones, 2 inferior nasal conchae, 2 zygomatic bones, 1 vomer, 2 lacrimal bones, 1 mandible.
• The maxillae is the largest facial bone and is the roof of the mouth that forms the upper jaw and meets at the median intermaxillary suture. It is made up of the alveolar processes which are bony points between the teeth and the alveolus which are sockets that hold teeth. A cleft palate and cleft lip occur when the two maxillae fail to join at the suture.
• The Maxillae forms the inferomedial wall of the orbit and forms most of the hard palate. The hard palate forms the roof of the mouth and the floor of the nasal cavity. The palate allows us to chew while breathing and consists of the palatine process and the incisive foramen.
• The maxillary sinus fills the maxillae bone. It is larger in volume than the frontal, sphenoid, and ethmoid sinuses.
• The Palatine Bones are L-shaped bones that form the posterior portion of the hard palate they are part of the lateral nasal cavity wall and part of the orbital floor.
• The Zygomatic Bones form angles of cheekbones and are part of each lateral orbital wall. The zygomatic arch is formed from the temporal process of the zygomatic bone and the zygomatic process of the temporal bone.
• The Lacrimal (tear) Bones form part of the medial wall of each orbit (eyeball sockets). The lacrimal bones are the smallest bone of the skull. The lacrimal fossa houses the lacrimal sac and tears collect in the sac and drain into the nasal cavity.
• The nasal bones form the bridge of the nose. They support cartilages that shape the lower portion of the nose. It is unfortunately often fractured.
• The Inferior Nasal Conchae is the largest of the three conchae in the nasal cavity. It is separate from the other conchae which are parts of the ethmoid bone.
• The Vomer is the inferior half of the nasal septum. It is inferior to the perpendicular plate of the ethmoid. It supports the cartilage that forms the anterior part of the nasal septum.
• The mandible is the strongest bone in the skull as well as the only bone in the skull that moves (especially when we talk) It supports lower teeth the alveolar processes are between teeth. The mandible provides attachments for the muscles of expression and mastication (chewing).
• The mandible has 3 major parts; (1)the Body supports the teeth. (2)The Ramus articulates with the cranium. (3)The Angle is where the body meets the ramus. The ramus is made up of the coronoid process for the temporalis muscle, the mandibular notch between processes, and the condylar process with the mandibular condyle that articulates with temporal bone forming TMJ (temporomandibular joint).
• There are three auditory ossicles in each middle-ear cavity, the Malleus, incus, and stapes.
• The hyoid bone is a slender U-shaped bone between the chin and the larynx. It does not articulate (connect) with any other bone as it is suspended from the styloid process of the skull. It has a body and greater and lesser horns (cornua). A fractured hyoid bone is evidence of strangulation.
• Fontanels are spaces between unfused cranial bones that contain fibrous membranes. They allow the shifting of bones during birth and the growth of the brain. There are the anterior, posterior, sphenoid (anterolateral), and mastoid (posterolateral) fontanels. The two frontal bones fuse by the age of 6 forming the metopic suture. The skull then approaches adult size by 8 or 9 years of age.
• The functions of the spine include supporting the skull and trunk and allowing for their movement. It protects the spinal cord, absorbs stresses of movements, and provides attachments for limbs, thoracic cage, and postural muscles. The spine is made up of 33 vertebrae with intervertebral discs between most of them. These discs account for about one-quarter of the spine’s 71 cm length (on average). The discs compress a bit during the day due to the pressure of body weight making us shorter than we were when we woke up.
• There are Five vertebral groups with the spine, 7 cervical (C1-7) in the neck, 12 thoracic (T1-12) in the chest, 5 lumbar (L1-5) in the lower back, 5 fused sacral (S1-5) at the base of the spine, and 4 fused coccygeal.

  
• There are two types of vertebral (spinal) curvature: primary and secondary. In primary curvature: the spine exhibits one continuous C- C-shaped curve at birth (convex). This persists as the curvature of the thoracic and pelvic spine. Secondary curvature is developed in the cervical and lumbar areas (concave) due to crawling and walking as babies. The vertebral column is S-shaped beyond the age of 3 years.

  
• The S-shaped vertebral column has four normal curvatures; Cervical, Thoracic, Lumbar, and Pelvic.