10.21.11+-+Skull


 * 1a. Define the term "neurocranium"**

The neurocranium is the portion of the skull that surrounds the brain (derived from head mesoderm).


 * 1b. Name which 8 skull bones are associated with the neurocranium.**

Occipital, 2 Parietal, 2 Temporal, Frontal, Ethmoid, Sphenoid


 * 1c. Name the neurocranium bones that contribute to the calvarium and which contribute to the cranial base.**

The calvarium is the part of the neurocranium that forms the skull cap. The bones that contribute are the occipital, frontal, and the two parietals and two temporals. The cranial base is the part of the neurocranium that comes underneath the brain. The bones that contribute are the sphenoid and ethmoid.


 * 1d. Describe the clivus, and name the two bones that contribute to this internal osteological feature.**

The clivus is formed by the occipital and sphenoid bones. It forms the anterior wall of the foramen magnum. It is actually Latin for slope. That is exactly what it is - a steep slope on the anterior side of the foramen magnum.


 * 2a. Define the term "viscerocranium"**

The viscerocranium is the portion of the skull that forms the bones of the face (derived from neural crest cells).


 * 2b. Name the 15 bones associated with it.**

Mandible, Ethmoid, and Vomer 2 each of maxilla, inferior nasal cocha, zygomatic, palatine, nasal, and lacrimal


 * 2c. Name the bones that contribute to the surfaces of the nasal cavity and the oral cavity.**

Nasal Cavity: Anterior Lateral Wall and Nasal Septum - Maxillary Middle Lateral Wall - Lacrimal Inferior Lateral Wall - Inferior Nasal Conchae Superior Lateral Wall and Nasal Septum - Ethmoid Posterior Lateral Wall and Nasal Septum - Palatine Nasal Septum - Vomer

Oral Cavity: Anterior 2/3 of hard palate - Maxillary Lower Jaw - Mandible Posterior 1/3 of hard palate - Palatine


 * 3. Define the following topographic features of the adult skull. Name the bone (or bones) associated with each of these features:**

Vertex - The top of the skull; formed by the left and right parietals, frontal, and occipital bones Lambda - The point of juncture of the two parietal bones and the occipital bone. Nasion - Where the two nasal bones meet with the frontal bone Inferior Temporal Line - Ridge on external surface of frontal and parietal bones. Continuous at front and back with zygomatic arch External Occipital Protuberance - Bump on the inferior/posterior surface of the occipital bone. External. Mastoid Process - Bump on temporal bone, just posterior to external acoustic meatus Lambdoid Suture - Suture joining occipital and parietal bones Bregma - The point of juncture of the two parietal bones and the frontal bone Inion - The most superior portion of the external occipital protuberance Pterion - On the lateral external surface of the skull. Composed of two three-bone juncture points and the line between them: superior/anterior juncture (frontal, sphenoid, parietal) and inferior/posterior juncture (sphenoid, parietal, temporal) and the line (parietal, sphenoid) Supraciliary Ridge - The most anterior prominences of the frontal bone (eyebrow ridge) Zygoma - The prominence of the zygomatic bone (cheek bone) Coronal Suture - Suture joining frontal and parietal bones (source of name for coronal plane) Glabella - The hollow of the frontal bone in-between the supraciliary ridges Asterion - The point of juncture of the occipital bone, (left or right) parietal bone, and temporal bone Superior Temporal Line - Ridge on external surface of frontal and parietal bones. Continuous at front and back with zygomatic arch (superior border of temporal fossa) Pharyngeal Tubercle - Anterior to the foramen magnum, on the inferior surface of the base of the skull. On the occipital bone Styloid Process - Pointy protrusion of the temporal bone, inferior to external acoustic meatus. Point of connection for two ligaments (stylohyoid, stylomandibular) and three muscles (styloglossus, stylohyoid, stylopharyngeus) Sagittal Suture - Suture joining the right and left parietal bones


 * 4. Describe the landmarks used to define the orbitomeatal plane:**

He doesn't use it in his slides, but it seems to be very similar to the calvarium (skullcap). It is the part of the skull that encloses the cranium. The line dividing it from the rest of the body runs from the infraorbital ridge through the superior border of the external acoustic meatus to the midpoint of the occipital bone.


 * 5. State which of the above topographic features correspond to the following fontanelles of the neonatal skull:**


 * Anterior fontanelle:** Bregma
 * Posterior fontanelle:** Lambda
 * Mastoid fontanelle:** Asterion
 * Sphenoidal fontanelle:** Pterion


 * 6. Describe what is meant by the term "paranasal sinus," and name the 3 unpaired and 1 set of paired bones that contain these structures.**

The spaces created lateral and superior to the nasal cavities: 2 maxillary sinuses, 2 frontal sinuses, multiple ethmoidal sinuses, and 2 sphenoidal sinus.

Maxillary sinus is within the maxillary bone, just deep to the maxilla and lateral to the nasal cavities (huge and gets bigger with age). Frontal sinus is within the frontal bone, just deep to the supraciliary ridges (gets bigger with age). Ethmoidal sinuses are within the ethmoid bone (with lateral/frontal contributions from the frontal, lacrimal, maxilla, sphenoid, and palatine bones). Divided into anterior, middle, and posterior. Superior to the nasal cavities. Sphenoid sinus is within the sphenoid bone. It is within the bony shell and located anterior and lateral to body of sphenoidal bone. It is posterior and superior to nasal cavities.


 * 7. Describe (in general terms) the following spaces within, and on the surface of the skull. State which spaces are paired, and which ones are unpaired.**


 * Anterior cranial fossae** - Internal anterior surface of calvarium. Paired if divided by midline. Formed by frontal bone and sphenoid bone.
 * Posterior cranial fossa** - Internal posterior/inferior surface of calvarium. Paired if divided by midline. Formed by occipital bone.
 * Cranial vault** - The space inside the skull, specifically the calvarium. Unpaired.
 * Infratemporal fossae** - N5 P6. External. Inferior to the temporal fossa. Superior border is infra temporal crest. Deep to mandible and zygomatic arch. Anterior to mastoid process. Posterior to zygomatic bone. Formed from surfaces of maxilla and sphenoid bones. Paired.
 * Middle cranial fossae** - Internal middle surface of calvarium. Paired if divided by midline. Formed by parietal bones.
 * Temporal fossae** - External wall of neurocranium. Formed by frontal, parietal, temporal, and sphenoidal bones. Encircled by superior temporal line and zygomatic arch. Paired.
 * Hypophysial fossa** - Also called the sella turcica. It is the divot dorsal to the center of the lesser wing of the sphenoid bone. Houses the pituitary gland. Best visualized on COA: 832 and N5: P49. The notes are unclear as to whether this space also describes the larger region of the center of the sphenoid bone (the body) best visualized on N5: P46, 49, and 83. This larger space is medial. It is bounded laterally by the orbits/superior orbital fissure and superiorly/inferiorly by the greater and lesser wings of sphenoid bone. It contains the sphenoid sinuses and the pituitary gland house. Unpaired.
 * Pterygopalatine fossae** - The medial extension of the infra temporal fossae. Bounded by the sphenoid and maxillary bones. Inferior to the orbit. Paired.
 * Oral cavity** - Within the viscerocranium. Teeth, tongue. Unpaired.
 * Nasal cavities** - Divided by the nasal septum (ethmoid). Many bones contribute. Paired. Medial to orbits and maxillary sinuses. Inferior to brain. Superior to oral cavity.
 * Orbits** - Eyes. Paired.


 * 8a. Describe the osteological features of the mandible.**

Mental protuberance - chin Mental spines - internal side of chin Coronoid process - more anterior Condylar process - more posterior Ramus of the mandible - the superior part Horizontal process Angle of the mandible Mental foramen - external Inferior alveolor foramen - internal on angle of mandible


 * 8b. Describe the temporomandibular joint, as well as the movements of the jaw associated with this synovial joint.**

"The temporomandbiular joint is a modified hinge type of synovial joint, permitting gliding [protrusion and retrusion] and a small degree of rotation [lateral movements] in addition to flexion and extension movements typical for hinge joints." COA p916

The four primary muscles of movement are the temporalis, masseter, medial pterygoid, and lateral pterygoid. Three of the muscles (temporalis, masseter, and medial pterygoid) do elevation. Depression is mostly done by gravity, but lateral pterygoid and hyoid muscles also contribute. Protrusion is primarily done by lateral pterygoid, but masseter and medial pterygoid help.


 * || Masseter || Temporalis || Medial Pterygoid || Lateral Pterygoid ||
 * Elevation || X || X || X ||  ||
 * Depression ||  ||   ||   || X ||
 * Protrusion ||  ||   ||   || X ||
 * Retrusion || X || X ||  ||   ||
 * Lateral Movements || X || X ||  ||   ||


 * 8c. Name the ligaments that limit depression of the jaw.**

The stylomandibular and sphenomandibular ligaments are extrinsic ligaments that limit depression.


 * 9. State which bone (or bones) contain the following foramen, and state which foramen are paired and which ones are unpaired**


 * Foramen || Bone || Paired ||
 * Superior orbital foramen (fissure) || Sphenoid || Yes ||
 * Foramen rotundum || Sphenoid || Yes ||
 * Foramen spinosum || Sphenoid || Yes ||
 * Foramen ovale || Sphenoid || Yes ||
 * Optic canal || Sphenoid || Yes ||
 * Foramen lacerum || Sphenoid, temporal, occipital || Yes ||
 * Jugular foramen || Temporal || Yes ||
 * Foramen magnum || Occipital || No ||