Skeletal System Review

Flashcards of Skeletal System terminology and definitions.

Articulations

Areas where bones of the skeleton join together.

Sutures

Most flexible in infants, as much early growth of the skull occurs at the sutural edges of cranial bones

Functions of skull bones (cranial or facial)

Protect the brain, participate in the temporomandibular joint, serve as a base for the dentition, and form the facial features

Number of bones that form the skull (not counting small bones of the middle ear)

22

Number of small bones that form the middle ear

6 auditory ossicles (very small bones)

Skull bones where growth continues during early childhood

All skull bones, except middle ear bones

Locations of growth of the upper face

Sutures between the maxillae and other bones and bony surfaces

Locations of growth in the lower face

Bony surfaces of the mandible and head of the mandibular condyle

Movable skull bones (have moveable articulation)

All skull bones are immovable (and articulate by sutures), except the mandible (which articulates at TMJ)

What does the skull itself have moveable articulation with?

The bony vertebral column in the cervical region

Skull bone not viewable from anterior view of the external skull

Paired palatine bone; not considered a facial bone by anatomists

Divisions of the orbit

Orbital walls (4), orbital apex

Orbital structures/features that connect the orbit with the cranial cavity

Optic canal, superior orbital fissure

Shape of the orbit versus the orbital rim

Pyramid vs. rectangle

Why is the orbital rim generally strong?

To protect orbital contents

When are most structures from inferior view of the external skull visible?

When the mandible is removed

What completely separates the oral cavity from the nasal cavity superiorly?

The paired midline bones (paired palatine process of maxilla, paired horizontal plate of palatine bones)

Function of fovea palatinae

No particular anatomic function

Gives the foramen spinosum its name

The nearby spine of the sphenoid bone

Why can palpitation of supraorbital notch produce transient soreness?

Due to presence of supraorbital nerve

How does the frontal bone help form the root of the nose?

By articulating with nasal bones and frontal processes of maxillae

Where does lacrimal fluid empty into after lubricating the eye?

Nasal cavity via nasolacrimal duct

What separates tympanic part from petrous part of temporal bone?

Petrotympanic fissure

Where is the stylomastoid process of a newborn located?

At the surface of the mastoid bone (since the mastoid process has not yet formed but instead grows to its full extent around the second year after birth)

The more difficult bones of the skull to describe and visualize separately

Sphenoid bone (despite fact that it is observable from various viewpoints); ethmoid bone (more hidden than sphenoid)

Since the sphenoid bone shares a close anatomic relationship with the pituitary gland

The gland can be accessed surgically by having instruments passed through the sphenoid bone and its sinus

What is located between the pterygoid process of the sphenoid bone and the maxillary tuberosity of the maxilla?

Pterygomaxillary fissure

What bones is foramen lacerum formed by?

Sphenoid, temporal, occipital bones

What does the perpendicular plate assist?

Nasal septal cartilage and vomer in forming nasal septum

In general, what is the nasal septum formed by?

oAnterior & Superior part: cartilage (nasal septal cartilage), ethmoid bone (perpendicular plate) o Posterior & Inferior part: vomer

What do facial bones serve as a base for?

The dentition

How many soft tissue structures of the face are shared by many facial bones?

Two or more (ex. frontal bone = forehead + area around eyes)

What are the smallest and most fragile facial bones?

Lacrimal bones

What bone serves as a link between the maxillae and sphenoid bone?

Palatine bones

What is each maxilla’s orbital surface separated from the sphenoid bone by?

Inferior orbital fissure

On alveolar process, what is the root of each tooth covered by?

A prominent facial ridge of bone (more prominent for maxillary arch)

Concerning dental arches, what is less dense and more porous?

Maxillary alveolar process in comparison to mandibular, mandibular anterior alveolar process in comparison to posterior

What are individual alveoli of molars subdivided into?

Septa (to provide space for their multiple roots)

What happens if the alveolar process is edentulous? What can it lead to problems with?

o Maxillary & Mandibular arches: resorption of alveolar process (but not body (instead, thinning of walls)); o Maxillary arch: maxillary sinuses o Mandibular arch: landmarks, ex. mental foramen moves on superior border of mandible (instead of lateral surface) or even disappears entirely (but inferior border is not effected)

What is the strongest facial bone?

Mandible

Symphyses

Midline articulation where bones are joined by fibrocartilage

In what direction does the mandible elongate/grow?

Posteriorly

In what direction does the mandibular ramus elongate/grow? What does this displace?

Superiorly and posteriorly, displacing mental protuberance inferiorly and anteriorly

Which tooth roots are closest to the mandibular canal?

Distal root of mandibular second molar, root of mandibular second premolar

In relation to mylohyoid line, where do roots of mandibular posterior teeth often extend?

Internally inferior to mylohyoid line (internal oblique ridge)

Skeletal System

Consists of bones, associated cartilage and joints

Bones

Mineralized structures protecting internal soft tissue and serving as biomechanic basis for movement (along with muscles, tendons, and ligaments)

Plate

Flat bony structure; neither a prominence nor depression

Process

General term for any prominence on a bony surface

Condyle

Large, convex, oval bony prominence usually involved in joints

Head

Rounded structure projecting from a bony surface by a neck

Tuberosity

Large, often rough bony prominence that typically serves as an attachment site for muscles or tendons

Arch

Bridgelike bony prominence with a bowlike outline

Cornu

Small hornlike bony prominence

Tubercle/Eminence

Small rounded elevation on bony surface

Crest

Prominent roughened border or ridge on bony surface

Line

Small straight ridge of bone

Spine

Abrupt small bony prominence that is either blunt or sharply pointed

Notch

Indentation at edge of bone

Sulcus

Shallow depression or groove that usually marks the course of blood vessels or nerves

Fossa

Deeper depression or concavity on a bony surface that can be part of joints or attachment sites for muscles, etc.

Fovea

Small pit or depression in a bone or other structure

Purpose of bony openings

Provide entrances and exits for main nerves and blood vessels of H&N (e.g. allows cranial nerves to travel to and from brain)

Foramen

Short windowlike opening

Fissure

Narrow and cleftlike opening

Ostium

Smaller opening especially as an entrance into a hollow organ or canal

Aperture

Narrow opening

Canal

Longer narrow, tubelike opening

Meatus

Type of canal; opening or canal

Articulation

Area where bones are joined to each other

Joint

Mjunction or iunion between two or more bones

Suture

Iunion of bones by fibrous tissue (a type of immovable joint)

Skull

Braincase; structure composed of the cranium/cranial bones (outer shell) and facial bones (inner support)

Cranium

Structure formed by cranial bones including frontal, parietal, occipital, temporal, sphenoid, ethmoid (superior and middle nasal conchae)

Cranial Bones

Neurocranium; skull bones forming cranium including frontal, parietal, occipital, temporal, sphenoid, ethmoid (superior and middle nasal conchae)

Facial bones

Viscerocranium; skull bones forming face including nasal bones, maxillae, lacrimal bones, vomer, inferior nasal conchae, zygomatic bones, mandible

Each middle ear contains the following (in order from outer to inner): MIS/HAS

malleus, incus, stapes

Function of auditory ossicles of the middle ear

To transmit and amplify vibrations to inner ear by way of the tympanic membrane (eardrum)

What is viewable from superior view of the external skull?

4 cranial bones, 4 sutures

From superior view of the external skull, which skull suture is more serrated looking than the others?

lambdoidal suture

Frontal bone

single cranial bone anterior skull

Parietal bone

paired cranial bone lateral skull, forms greater part of roof of skull (and lateral walls)

Occipital bone

single cranial bone in most posterior part of skull, forms base of cranium

Coronal suture

paired suture between frontal and parietal bones

Anterior fontanelle

soft spot in newborns; area joining frontal and paired parietal bones

Sagittal suture

single suture between paired parietal bones

Lambdoidal suture

single suture between paired parietal bones and occipital bone

Bones visible from an anterior view of the external skull

13: frontal bone, nasal bones, maxillae, lacrimal bones, ethmoid bone, sphenoid bone, vomer, inferior nasal conchae, zygomatic bones, mandible

Skull sutures visible from an anterior view of the external skull

coronal suture, frontonasal suture, internasal suture, nasomaxillary suture, lacrimomaxillary suture, frontozygomatic suture, temporozygomatic suture, zygomaticomaxillary suture, intermaxillary suture, etc.

What do facial bones form together?

orbit, nasal cavity, facial features

Nasal bone

paired facial bone

What does the lacrimal bone form?

[small part of anterior] medial wall of orbit

Vomer

single midline facial bone

Inferior nasal concha

paired facial bone

Zygomatic bone

paired facial bones forming cheekbones

Honorable mention: Palatine bone

paired bone of skull (not facial bone, not visible from anterior view)

Orbital walls

4 walls of orbit

Orbital apex

deepest part of orbit

Optic canal

canal in orbital apex

Superior orbital fissure

fissure between greater and lesser wings of sphenoid transmitting structures from cranial cavity to orbit