Osteology Written Exam

Axial skeleton and appendicular skeleton

What are the two major divisions of the skeleton, and what does each include? | Axial skeleton: head, neck, trunk. | Appendicular skeleton: limbs.

Axial skeleton

Is the skull part of the axial or appendicular skeleton?

Axial - torso and head

Appendicular - limbs

Distinguish the axial skeleton from the appendicular skeleton in the image.

Intramembranous ossification

What type of ossification is associated with the cranial vault?

Intramembranous ossification

What type of ossification are the maxilla and mandible grouped under?

Endochondral ossification

What type of ossification is associated with the skull base?

Endochondral ossification

What type of ossification are vertebrae, long bones, and the pelvis grouped under?

“The skull needs to ossify fast!” / “Kids better bounce, not break!”

What memory phrases are paired with intramembranous and endochondral ossification, respectively?

• Cranial Vault

• Maxilla/Mandible

• Clavicle

Which structures are formed by intramembranous ossification?

Long, sesamoid, flat, short, irregular

What five categories are used to classify bones by shape?

• Cranial/skull vault = flat bone

• facial region = irregular bone

What bone-shape classifications are demonstrated in the skull?

Bone-shape categories

Identify the five bone-shape categories shown in the image.

Outer plate → diploë → inner plate

• Outer plate: compact bone

• Diploë: spongy/trabecular bone

• Inner plate: compact bone

What are the three layers of skull bone in the diploë arrangement, from outside to inside? What type of bone are they made of?

Outer plate → periosteum

Inner plate → endosteum

What covers the outer and inner plates of skull bone?

Diploë

What is the central spongy/trabecular bone between the outer and inner compact plates called?

1. Brain protection

2. Reduced weight

3. Bone marrow reservoir

4. Shock absorption

What four functions are listed for the diploë arrangement?

Label this image

Emissary veins pass through small holes in the skull; diploic veins lie within diploic/spongy bone

How are emissary veins and diploic veins positioned relative to the skull?

Frontal, ethmoid, maxillary, sphenoid sinuses

What four paranasal sinuses are shown?

• Frontal = forehead/frontal region

• ethmoid = upper nasal region between the orbits

• maxillary = cheek/maxillary region

• sphenoid = posterior to the nasal cavity

Match each paranasal sinus with its general location.

Paranasal sinuses

Label this image

Neurocranium and viscerocranium

What are the two major parts of the skull?

Neurocranium = cranial/brain-containing portion

viscerocranium = facial skeleton

Which major skull division corresponds to the cranial portion, and which corresponds to the facial skeleton?

How do you divide the neurocranium from the viscerocranium

8 bones: frontal, occipital, ethmoid, sphenoid, 2 parietal, 2 temporal

How many bones make up the neurocranium, and which bones are included?

Single: frontal, occipital, ethmoid, sphenoid

Paired: parietal, temporal

Which neurocranial bones are single vs paired?

15 bones: mandible, vomer, hyoid, nasal (paired), maxilla (paired), zygomatic (paired), palatine (paired), lacrimal (paired), and inferior nasal concha (paired)

How many bones are listed in the viscerocranium group, and which bones are included?

Single: mandible, vomer, hyoid

Paired: nasal, maxilla, zygomatic, palatine, lacrimal, inferior nasal concha

Which bones listed in the viscerocranium group are single vs paired?

Paired skull bones: parietal, temporal, nasal, maxilla, zygomatic, palatine, lacrimal, inferior nasal concha

Which skull bones in these groups are paired?

Solid circle = articulation; open circle = sometimes articulates; triangle = articulating pair; slash = unpaired element

What do the symbols on the skull bone articulation chart mean?

Solid circle = articulation; open circle = sometimes articulates; triangle = articulating pair; slash = unpaired element

Use this chart to study which skull bones articulate with one another.

Gomphosis

What is a tooth in its socket, described as a “peg in a hole”?

Suture (synarthrosis)

What skull articulation consists of bones joined by connective tissue?

Synchondrosis

What articulation consists of bones joined by cartilage?

Gomphosis and suture = fibrous; synchondrosis = cartilaginous; TMJ = synovial

Classify the major skull articulation types shown. (IMAGE?)

Skull articulation types (IMAGE NEEDED — SLIDE 14)

Identify the articulation types shown and classify them as fibrous, cartilaginous, or synovial.

Coronal suture

Which suture is formed by the frontal and parietal bones?

Sagittal suture

Which suture is formed by the right and left parietal bones?

Lambdoid suture

Which suture is formed by the occipital and parietal bones?

Squamosal suture

Which suture is formed by the temporal and parietal bones?

Coronal, sagittal, lambdoid, squamosal sutures (IMAGE NEEDED — SLIDE 15)

Identify the major sutures shown in the image.

Median palatine suture

Which suture is formed by the right and left maxillae?

Transverse palatine suture

Which suture is formed by the maxilla and palatine bone?

Internasal suture

Which suture is formed by the right and left nasal bones?

Metopic/interfrontal suture — formed by right and left frontal bones; usually not present in the adult

Which suture is formed by the right and left frontal bones, and what is notable about it in adults?

Median palatine, transverse palatine, metopic, internasal sutures (IMAGE NEEDED — SLIDE 16)

Identify the sutures shown in the image.

Wormian (intrasutural) bones

What are bones located within skull sutures called?

Lambdoid suture

What is the most common location for Wormian/intrasutural bones?

Wormian/intrasutural bones (IMAGE NEEDED — SLIDE 17)

Identify the Wormian/intrasutural bones in the image.

Closure of the suture so that it becomes bone

What is stenosis of a skull suture as defined here?

Pterion

What landmark is the junction of the greater wing of the sphenoid, squamous portion of the temporal bone, frontal bone, and parietal bone?

Lambda

What landmark is the junction of the lambdoid and sagittal sutures between the occipital and parietal bones?

Bregma

What landmark is the junction of the coronal and sagittal sutures between the frontal and parietal bones?

Vertex

What is the superior point of the cranium in the midline with the skull in anatomical position?

Asterion

What landmark is the junction of the parietomastoid, occipitomastoid, and lambdoid sutures?

Glabella

What is the elevation superior to the root of the nose?

Nasion

What landmark is the junction of the frontonasal and internasal sutures?

Inion

What is the most prominent point of the external occipital protuberance?

Major skull landmarks (IMAGE NEEDED — SLIDE 19)

Identify pterion, lambda, bregma, vertex, asterion, glabella, nasion, and inion in the image.

Major skull landmarks — alternate views (IMAGE NEEDED — SLIDE 20)

Identify the major skull landmarks from these alternate views.

Anterior, middle, and posterior cranial fossae

What are the three cranial fossae?

Posterior border of the lesser wing of the sphenoid + anterior border of the chiasmatic sulcus

What marks the boundary between the anterior and middle cranial fossae?

Ridge of the petrous portion of the temporal bone + posterior border of the sella turcica (dorsum sellae)

What marks the boundary between the middle and posterior cranial fossae?

Cranial fossae and boundaries (IMAGE NEEDED — SLIDE 21)

Identify the anterior, middle, and posterior cranial fossae and their boundaries.

Crista galli; frontal crest; foramen cecum; foramina of cribriform plate; cribriform plate; orbital part of frontal bone; lesser wing of sphenoid; anterior clinoid process; body of sphenoid

What major structures are labeled in the anterior cranial fossa?

Anterior cranial fossa structures (IMAGE NEEDED — SLIDE 22)

Identify the labeled structures of the anterior cranial fossa.

Tuberculum sellae; chiasmatic sulcus; hypophysial fossa; dorsum sellae; posterior clinoid process; middle clinoid process

What central sphenoid/sella structures are labeled in the middle cranial fossa?

Optic canal; superior orbital fissure; foramen rotundum; foramen ovale; foramen spinosum; foramen lacerum; opening of carotid canal

What major openings are labeled in the middle cranial fossa?

Trigeminal impression; grooves/hiatuses for greater and lesser petrosal nerves; tegmen tympani; arcuate eminence; groove for middle meningeal artery

What temporal/petrous-region features are labeled in the middle cranial fossa?

Greater wing of sphenoid

Which sphenoid region forms much of the lateral middle cranial fossa in this diagram?

Middle cranial fossa structures (IMAGE NEEDED — SLIDE 23)

Identify the labeled structures of the middle cranial fossa.

Clivus; foramen magnum; internal occipital protuberance; internal occipital crest

What major midline structures are labeled in the posterior cranial fossa?

Internal acoustic meatus; jugular foramen; hypoglossal canal; jugular tubercle; grooves for sigmoid, transverse, and inferior petrosal sinuses

What openings and grooves are labeled in the posterior cranial fossa?

Superior border/ridge of the petrous portion of the temporal bone

What temporal-bone landmark helps form the anterior boundary of the posterior cranial fossa?

Posterior cranial fossa structures (IMAGE NEEDED — SLIDE 24)

Identify the labeled structures of the posterior cranial fossa.

Head, neck, condyle, trochlea, facet

What surface markings are associated with articulation with other bones?

Tuberosity, tubercle, crest, line, spine

What surface markings are associated with attachment of ligaments, tendons, or fascia?

Depressions: fossa, sulcus. Openings: foramen, canal, fissure.

What depressions and openings are associated with proximity or entry of vessels, nerves, or tendons?

Sinus, antrum, ramus, body, process, notch

What other external/internal bone features are listed?

Supraorbital → infraorbital → mental foramina

Which three facial foramina line up vertically?

Supraorbital, infraorbital, mental foramina (IMAGE NEEDED — SLIDE 26)

Identify the three vertically aligned foramina.

Venous sinuses

What structures create grooves on the internal surface of the skull?

Superior sagittal, inferior sagittal, straight, transverse, sigmoid, occipital, cavernous, intercavernous, sphenoparietal, superior petrosal, inferior petrosal, basilar sinus, confluence of sinuses

What major venous sinuses are labeled in the diagrams?

Venous sinus grooves and locations (IMAGE NEEDED — SLIDE 27)

Identify the named venous sinuses in the image.

Parietal bone (IMAGE NEEDED — SLIDE 29)

Identify the parietal bone in the different skull views shown.

Superior temporal line and inferior temporal line

What two temporal lines are found on the lateral skull/parietal region?

Superior vs inferior temporal lines (IMAGE NEEDED — SLIDE 30)

Identify the superior and inferior temporal lines.

Groove for superior sagittal sinus and depressions for arachnoid granulations

Which internal parietal/skull-vault features are emphasized here?

Internal parietal features (IMAGE NEEDED — SLIDE 31)

Identify the groove for the superior sagittal sinus and the depressions associated with arachnoid granulations.

Emissary veins

What veins are associated with the parietal foramina?

Parietal foramina (IMAGE NEEDED — SLIDE 32)

Identify the parietal foramina.

Frontal bone (IMAGE NEEDED — SLIDE 33)

Identify the frontal bone in the different skull views shown.

Frontal bone external landmarks (IMAGE NEEDED — SLIDE 34)

Identify the labeled external features of the frontal bone, including the squamous portion, metopic/interfrontal suture, supraorbital margin/notch/foramen, and superciliary region.

Trochlear fossa (IMAGE NEEDED — SLIDE 35)

Identify the indicated frontal-bone feature.

Supraorbital notch

The supraorbital foramen may also appear as what?

Supraorbital foramen/notch, nasion, metopic suture (IMAGE NEEDED — SLIDE 36)

Identify the labeled frontal-region structures in the image.

Occipital bone (IMAGE NEEDED — SLIDE 37)

Identify the occipital bone from posterior, inferior, and lateral views.

Basilar part; external occipital crest; external occipital protuberance; superior and inferior nuchal lines; foramen magnum; occipital condyle; pharyngeal tubercle

What major external/inferior features of the occipital bone are emphasized in this view?

External occipital features (IMAGE NEEDED — SLIDE 38)

Identify the major external/inferior occipital structures shown.

OC = occipital condyle → occipital bone; JF = jugular foramen → occipital + temporal bones; CC = carotid canal → temporal bone; arrows = tympanic canaliculus → temporal bone

Match the abbreviations/features with their associated bones.