Ch 3 + 4 - Bones and Joints

Functions of the skull

Protective cavity of the brain

Cavities to house sensory organs

Openings for air and food passage

Mastication

How many bones are in the skull

22

Sutures

Immovable joints in bones

What bone of the skull is the only bone not joined by sutures

Mandible

How many cranial bones are there?

8

Occipital, Parietal (x2), Temporal (x2), Frontal, Ethmoid, Sphenoid

Structures on the occipital bone

Foramen magnum

External occipital protruberance

Internal occipital protruberance

Superior nuchal line

Inferior nuchal line

Occipital condyles

Basilar part

Clivus

External occipital protruberance

AKA occiput

Large prominent eminence on the posterior midline of the occipital bone

What is the superior surface of the basilar part of the occipital bone called

Clivus

Parietalis

Pertaining to walls

Supraorbital margin

Part of the frontal bone that forms the superior border of the orbit

Structures on the frontal bone

Supraorbital margin

Supraorbital notch/foramen

Squamous part

Frontal sinus

Where is the supraorbital notch/foramen found?

At the medial 1/3 of the supraorbital margin

Frontal sinus

Space that lies between the orbital and the squamous parts of the frontal bone

What is the weakest cranial bone

Temporal bone

Structures on the temporal bone

Squamous part

Zygomatic process

Zygomatic arch (part of it)

Mandibular fossa

Mastoid process

External auditory meatus

Styloid process

Petrous portion

What forms the zygomatic arch

Temporal process of the zygomatic bone + zygomatic process of temporal bone

Zygoma

Yoke or bar connecting 2 parts

What articulates with the mandibular fossa

The condyloid process of the mandible

Mastoid process

Breast shaped projection extending inferiorly from the posterior aspect of the mastoid part

Styloid process

Long, slender pencil like process anteromedial to the external auditory meatus that extends inferiorly

Petrous portion of temporal bone

Hard wedge shaped portion between the occipital and sphenoid bones that houses the middle and inner ear

Sphenoid

Named because it is located/wedged between the cranial and facial bones

Forms the base of the cranium anterior to temporal and occipital bones, and also forms part of the floor and lateral walls of the orbit

Structures on the sphenoid bone

Body

Sphenoid air sinuses

Sella turcica

Dorsum sellae

Hypophyseal fossa

Greater wings

Lesser wings

Foramen rotundum

Foramen ovale

Foramen spinosum

Pterygoid process

Medial pterygoid plate

Lateral pterygoid plate

Where are sphenoid air sinuses found

In the hollowed out body of the sphenoid

Sella turcica

Saddle with a high back

Deep depression on the superior aspect of the sphenoid body

Hypophyseal fossa

Contained in the sella turcica

Houses the pituitary gland

Would be covered with the diaphragma sellae

What structures are found in the greater wings

Foramen rotundum

Foramen ovale

Foramen spinosum

Lesser wings

Thin triangular projections that extend into posterior wall of the orbit and form the anterior aspect of the superior surface of the body

Pterygoid process

Extends inferiorly from the junction of the greater wing and the body

Consists of medial and lateral pterygoid plates, which are separated posteriorly by an oval fossa - pterygoid fossa

What lies lateral to the choanae

Medial pterygoid plate

Ethmoid

Sievelike bone at the anterior base of the cranium between the 2 orbits

Structures found on the ethmoid bone

Cribriform plate

Crista galli

Perpendicular plate

Lateral mass

Ethmoid sinuses

Middle nasal concha (tubinate)

Superior nasal concha (tubinate)

What surrounds the crista galli

The cribriform plate

Perpendicular plate

Extends inferiorly from the cribriform plate to form the superior aspect of the nasal septum

What part of the ethmoid forms part of the orbit

The lateral mass of the ethmoid bone

Which turbinate is not part of the ethmoid bone

Inferior nasal concha/turbinate

Which turbinate/concha can’t be seen from an anterior view of the skull

Superior nasal concha/turbinate

How many bones of the skeleton make up the face

14

Maxilla (x2), Mandible, Zygomatic (x2), Nasal (x2), Lacrimal (x2), Inferior nasal concha (x2), Palatine (x2), Vomer

What are the only 2 non-paired bones of the face

Mandible + Vomer

Maxilla

Upper jaw

What bones have sinuses

Frontal

Maxilla

Sphenoid

Ethmoid

Structures of the maxilla

Body

Maxillary sinus

Alveolar process

Palatine process

Infraorbital foramen

Alveolar process

Arch on the inferior border of the maxilla bears cavities into which the teeth of the upper jaw are set

OR

Arch on superior body of mandible into which teeth of lower jaw are set

What forms the hard palate

The horizonal palatine processes of both maxilla bones anteriorly + palatine bones posteriorly

Mandible

Lower jaw

Mando = chew

Horseshoe-shaped bone

Structures on the mandible

Body

Rami

Alveolar process

Mental foramen

Angle

Condyloid process

Neck

Coronoid process

Mandibular foramen

Mental foramen

On lateral aspect of the body inferior to the second premolar tooth

What forms the angle of the mandible

The intersection of the ramus and the body

Neck of mandible

Constricted area of the ramus inferior to the head

Mandibular foramen

Large central foramen on the medial surface of the ramus

Nasal bones

Form the anterior superior aspect of the nose (the bridge) inferior to the frontal bone

Which nasal wall has the concha branching off of it

Lateral nasal wall superior to the hard palate

Palatine bones

Irregular bones that form the posterior portion of the hard palate posterior to the maxilla

Vomer

= to vomit

Vertical irregular bone in the median plane extends between the hard palate inferiorly and the sphenoid and ethmoid superiorly

Sagittal suture

Articulation of 2 parietal bones in the median plane of the skull

Frontal (coronal) suture

Articulation of the parietal bones with the frontal bone

Lambdoid suture

Articulation of parietal bones with the occipital bone

Squamous suture

Articulation of the parietal and temporal bones

Articular disc

Prominent intraarticular ligament in the TMJ

An oval plate of fibrous tissue that sometimes contains patches of fibrocartilage

Divides the joint cavity into 2 separate compartments:

• Superior compartment

• Inferior compartment

Superior compartment of TMJ

Between articular disc and mandibular fossa

Inferior compartment of TMJ

Between articular disc and condyloid process of mandible

Hinge movements of the jaw

Depression

Elevation

Planar movements of the jaw

Protraction

Retraction

Lateral movement

Fontanelles

6 major unossified, membranous areas between the cranial bones in the fetal skull:

• Anterior

• Posterior

• Anterolateral (x2)

• Posterolateral (x2)

Anterior fontanelle

Largest of the fontanelles

Located at junction of coronal and sagittal sutures

In adults, this is the location of the bregma

Posterior fontanelle

Located at the junction of the lambdoid and sagittal sutures

In adults, this is the location of the lambda

Anterolateral fontanelles

AKA sphenoid fontanelles

Small, irregular fontanelles at the junction of the frontal, parietal, sphenoid, and temporal bones

Posterolateral fontanelles

AKA mastoid fontanelles

Small, irregular fontanelles at the junction of occipital, parietal, and temporal bones

What does the anterior fontanelle help physicians assess

• Position of fetal head in utero

• Development of the skull - this is the “soft spot”, which becomes bony at 2 years of age

• Extent of pathological intracranial pressure