Ch. 10: Bones of the Skull

Frontal Bone- location

"Forehead" Located at the anterior and superior aspect of the cranium anterior to the parietal bones. It also forms the roof of the orbits (eye sockets).

(Sphenoid Bone) Sella Turcica

"a saddle with a high back" A deep depression on the superior aspect of the body. Its posterior border is formed by the *dorsum sellae*. It contains the *hypophyseal fossa*, which houses the pituitary gland.

Mandible

"chin bone" - forms the lower jaw bone. The name refers to the function of the mandible, to chew. It is a horseshoe shaped bone consisting of a horizontal *body* and paired *rami* (singular ramus), which are perpendicular to the body. The rami project superiorly from the posterior aspect of the body.

(Sphenoid Bone) Pterygoid Process

"feet of the butterfly" Extends inferiorly from the junction of the greater wing and the body. It consists of a *medial and lateral pterygoid plate*, which are separated posteriorly by an oval fossa, the *pterygoid fossa*.

(Ethmoid Bone) Cribriform Plate

(horizontal plate) Forms the anterior aspect of the cranium and has numerous foramina for the passage of nerve fibers (CN1). It surrounds the base of the vertical *crista galli*.

What are the 7 structures of the Mandible?

1. Alveolar Process 2. Mental Foramen 3. Angle 4. Condyloid Process (head) 5. Neck 6. Coronoid Process 7. Mandibular Foramen

What are the 4 structures of the Maxilla?

1. Body 2. Alveolar Process 3. Palatine Process 4. Infraorbital foramen

What are the 5 structures of the Sphenoid Bone?

1. Body -- sphenoid air sinuses 2. Sella Turcica -- dorsum sellae, hypophyseal fossa 3. Greater Wings -- foramen rotundum, foramen ovale, foramen spinosum 4. Lesser Wings 5. Pterygoid Process -- medial and lateral pterygoid plate, pterygoid fossa

What are the 5 structures on the Ethmoid Bone?

1. Cribriform Plate 2. Perpendicular Plate 3. Lateral Mass 4. Middle Nasal Concha (turbinate) 5. Superior Nasal Concha (turbinate)

What are the 5 structures on the occipital bone?

1. External Occipital Protuberance (occiput) 2. Superior Nuchal Line 3. Inferior Nuchal Line 4. Occipital Condyles 5. Basilar Part

What are the 8 Cranial Bones?

1. Occipital 2/3. Parietal x2 4. Frontal 5/6. Temporal x2 7. Sphenoid 8. Ethmoid

What are the 4 functions of the skull?

1. Protective cavity for the brain 2. Cavities to house sensory organs (eyes, ears, tongue, etc.) 3. Openings for air and food passage 4. Mastication (chewing)

What are the 7 structures on the temporal bone?

1. Squamous Part 2. Zygomatic Process 3. Mandibular Fossa 4. Mastoid Process 5. External Auditory Meatus 6. Styloid Process 7. Petrous Portion of the Temporal Bone

What are the 4 structures on the Frontal Bone?

1. Supraorbital margin 2. Supraorbital notch or foramen 3. Squamous part 4. Frontal sinus

What are the 14 Facial Bones?

1/2. Maxilla 3. Mandible 4/5. Zygomatic 6/7. Nasal 8/9. Lacrimal 10/11. Inferior Nasal Conchae (turbinate) 12/13. Palatine 14. Vomer

How many Facial Bones are there?

14 bones make up the skeleton of the face.

How many bones are in the skull?

22 --> cranial bones and facial bones both paired and unpaired

How many Cranial Bones are there?

8 bones that encase and protect the brain. the superior portion of the cranium is also referred to as the *calvaria*.

(Occipital Bone) Inferior Nuchal Line

A curved ridge that parallels the superior nuchal line and extends laterally from the occiput.

Occipital Bone- location

A flat bone at the posterior inferior aspect of the cranium. The *foramen magnum* is a large foramen at the base of the skull near the anterior aspect of the occipital bone through which the spinal cord enters the cranium.

(Frontal Bone) Supraorbital Notch or Foramen

A small notch or hole, respectively, is found at the medial third of the supraorbital margin. The supraorbital nerve, artery, and vein pass through it.

(Ethmoid Bone) Lateral Mass

Consists of lateral aspects of the ethmoid made of large air cells (*ethmoid sinuses*). It forms part of the orbit.

(Occipital Bone) Superior Nuchal Line

Curved ridge extending laterally from the occiput.

(Mandible) Angle

Formed by the intersection of the ramus and the body.

(Frontal Bone) Squamous Part

Forms the forehead

(Mandible) Coronoid Process

Found on the superior border of the ramus.

Palatine + Palatine Process (of the maxilla) =

Hard Palate

(Maxilla) Palatine Process

Horizontal process that extends medially to articulate with the contralateral maxilla, forming the hard palate. anterior portion of the hard palate.

Sphenoid Bone- location

It is located, or wedged, between the cranial and the facial bones. "butterfly shape" It forms the base of the cranium anterior to the temporal and occipital bones. It also forms part of the floor and lateral walls of the orbit.

(Temporal Bone) External Auditory Meatus

Large canal posterior to the mandibular fossa that opens into the ear.

(Mandible) Mandibular Foramen

Large central foramen on the medial surface of the ramus. *dentist anesthetizes the nerve that passes through this.

(Maxilla) Infraorbital Foramen

Large foramen found on the anterior surface of the body inferior to the infraorbital margin. nerve- supplies upper lip, nose, cheek

(Occipital Bone) External Occipital Protuberance (occiput)

Large, prominent eminence on the posterior midline of the occipital bone. (you can feel the "bump" on the back of your head)

(Occipital Bone) Basilar Part

Lies anterior to the foramen magnum and articulates with the sphenoid bone.

(Temporal Bone) Styloid Process

Long, slender, pencil like process anteromedial to the external auditory meatus that extends inferiorly. attachment to a styloid ligament

(Temporal Bone) Zygomatic Process

Long, thin process that extends anteriorly from the anteroinferior aspect of the squamous part to articulate with the zygomatic bone. The arch formed by these two bones (temporal bone and zygomatic bone) is called the *zygomatic arch*.

(Mandible) Mental Foramen

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

Parietal Bone- location

PAIRED x2 Forms a large part of the (lateral) walls of the skull. The two parietal bones are located at the lateral and superior aspects of the cranium.

Temporal Bone- location

PAIRED x2 The two temporal bones (left and right), lie at the lateral aspects of the cranium inferior to the parietal bones. *Weakest* cranial bone, it is thin. Named because the hair of this region turns gray first, revealing the effects of age and time.

What cranial bones are paired?

Parietal and Temporal

(Frontal Bone) Supraorbital Margin

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

(Occipital Bone) Occipital Condyles

Prominent oval projections at the anterolateral aspects of the foramen magnum that articulate with the first cervical vertebrae.

(Maxilla) Body

Pyramidal in shape, contains a large air sinus, the *maxillary sinus*.

Ethmoid Bone- location

Sievelike bone at the anterior base of the cranium between the two orbits.

(Frontal Bone) Frontal Sinus

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

(Maxilla) Alveolar Process

The arch on the inferior border of the maxilla; it bears cavities into which the teeth of the upper jaw are set.

(Mandible) Alveolar Process

The arch on the superior border of the body into which the teeth of the lower jaw are set.

(Temporal Bone) Mastoid Process

The breast shaped projection extending inferiorly from the posterior aspect of the mastoid part.

(Mandible) Neck

The constricted area of the ramus inferior to the head. Narrow.

(Sphenoid Bone) Body

The cubical portion of the sphenoid in the midline of the base of the cranium anterior to the occipital bone. It is hollowed out to form two *sphenoid air sinuses*.

(Ethmoid Bone) Middle Nasal Concha (turbinate)

The free, convoluted inferior margin of the medial plate of the lateral mass.

(Temporal Bone) Petrous Portion of the Temporal Bone

The hard (like a rock) wedge shaped portion between the occipital and the sphenoid bones that houses the middle and inner ear.

(Temporal Bone) Mandibular Fossa

The oval depression for articularlation with the mandible, specifically the *condyloid process* of the mandible. This is the location of the *temporomandibular joint*.

(Ethmoid Bone) Superior Nasal Concha (turbinate)

The part of the lateral mass superior to the middle nasal concha. This is difficult to see from an anterior view of the skull.

(Mandible) Condyloid Process (head)

The posterior condyloid process on the superior border of the ramus articulates with the mandibular fossa of the temporal bone. (TMJ?)

(Temporal Bone) Squamous Part

The thin, scalelike superior expansion of the temporal bone forming part of the lateral cranial wall.

Vomer

The vomer is fancied to resemble an ancient plow that "threw up" on earth. The vertical irregular bone in the median plan extends between the hard palate inferiorly to the sphenoid and the ethmoid superiorly. Coanae space lying lateral to it. Makes up the medial portion of the nasal septum.

(Ethmoid Bone) Perpendicular Plate

Thin plate that is perpendicular to and extends inferiorly from the cribriform plate to form the superior aspect of the nasal septum. Makes up the upper part of the nasal septum.

(Sphenoid Bone) Lesser Wings

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

(Sphenoid Bone) Greater Wings

Two broad lateral extensions from the body. The Greater wing contains the openings including the *foramen rotundum and foramen ovale*. It also contains the *foramen spinosum* through which the middle meningeal artery will pass.

Maxilla

X2 "jaw bone" - forms the upper jaw.

Palatine

X2 Irregular palatine bones form the posterior portion of the hard palate posterior to the maxilla. Makes up the posterior portion of the hard palate

Lacrimal

X2 Near the tear ducts. These small, thin, irregular bones form the anterior portion of the medial wall of the orbit. Contains the nasal lacrimal duct.

Nasal Bone

X2 The nasal bones help form the nose. The two small bones form the anterior superior aspect of the nose (the so called bridge) inferior to the frontal bone.

Zygomatic Bone (cheek bone)

X2 The zygomatic bones help form the zygomatic arch that connects the zygomatic and temporal bones. These irregular bones also form part of the lateral wall and floor of the orbit.

Inferior Nasal Conchae (turbinate)

X2 "bone of its own" A concha is a small, curved, irregular, shell like bone that extends horizontally along the lateral nasal wall superior to the hard palate. Allows us to warm and humidify the air.

piriform aperture

anterior opening of the nasal cavity, large and triangular

Temporal Process of the Zygomatic Bone

articulates with the zygomatic process of the temporal bone.

(Occipital Bone) What is the superior surface of the basilar part?

clivus

medial pterygoid plate

lies lateral to the choanae.

sutures

most of the bones are joined at immovable joints called sutures. except the mandible (jaw bone), which presents at a synovial (moveable) joint.

Zygomatic Arch

suture in-between the anterior and posterior portion of the temporal process of the zygomatic bone, to form the arch.