Axial Skeleton (Part I): The Head

How many bones is the axial skeleton comprised of?

206 bones!

Identify the three (3) main skeletal regions associated with the axial skeleton.

• Skull

• Thoracic cage

• Vertebral column

Identify the eight (8) facial bones.

1. Maxillae

2. Palatine bones

3. Nasal bones

4. Inferior nasal conchae

5. Zygomatic bones

6. Lacrimal bones

7. Vomer

8. Mandible

Identify the six (6) cranial bones.

1. Occipital bone

2. Frontal bone

3. Parietal bones

4. Temporal bone

5. Sphenoid

6. Ethmoid

Describe the purpose of the cranial bones.

The cranial bones enclose the cranial cavity containing the brain:

• The cranium provides an extensive area for muscle attachment.

• Responsible for head, eyes, and jaw movement.

What is a suture?

A suture is a dense, fibrous connective tissue that joins the flat bones of the skull.

Identify the four (4) cranial sutures.

1. Lambdoid

2. Sagittal

3. Coronal

4. Squamous

What cranial bones are associated with the lambdoid suture?

The occipital and parietal bones.

The lambdoid suture is the horizontal suture located on the back of the head.

What cranial bones are associated with the sagittal suture?

Between the parietal bones.

The sagittal suture is the vertical suture that separates the left and right regions of the brain.

What cranial bones are associated with the coronal suture?

The parietal and frontal bones.

The coronal suture is the closest one to the face.

What cranial bones are associated with the squamous suture?

The parietal and temporal bones.

The squamous suture is the region where all of the temporal bones are located.

Identify the suture associated with [1].

Lambdoid

Identify the suture associated with [2].

Sagittal

Identify the suture associated with [3].

Coronal

Identify the suture associated with [4].

Squamous

Is there a facial suture?

Yes. The face has one associated suture called the frontonasal suture.

What type of bone is this?

This is the occipital bone:

• The occipital bone is located on the posterior, lateral, and inferior surface of the cranium.

• Only one (1) bone is associated with the occipital bone.

What bones do the temporal bones articulate with?

• Zygomatic

• Parietal

• Occipital

• Sphenoid

• Mandible

What is the function of the temporal bones?

The temporal bones form an attachment area for muscles responsible for head and jaw movement, and also play an essential role in protecting the organs of the internal ear.

Identify the three (3) regions/parts of the temporal bone.

1. Petrous part

2. Tympanic part

3. Squamous part

What is the function of the mastoid process?

The mastoid process is the attachment site of muscles responsible for rotating the head.

What is the function of the styloid process?

The styloid process is an attachment site for muscles associated with the:

• Hyoid

• Tongue

• Pharynx

• Larynx

What is the function of the stylomastoid foramen?

This foramen houses a facial nerve.

What is the function of the carotid canal?

The carotid canal houses the carotid artery, which supplies blood to the brain.

What is the external acoustic meatus?

The acoustic meatus is a passageway that ends at the eardrum, i.e., the tympanic membrane.

What is the function of the internal acoustic meatus?

The internal acoustic meatus houses blood vessels and nerves in the internal ear.

What is the function of the sphenoid?

The sphenoid is the bone that unites ALL of the facial and cranial bones together.

This means that it articulates with EVERY bone in there:

• Frontal

• Parietal

• Occipital

• Ethmoid

• Temporal

• Palatine

• Maxilla

• Mandible

• Vomer

What is the function of foramina?

Foramina are small holes that enable the entrance of blood and nerve supply to the bones.

What is the function of the pterygoid process?

The pterygoid process is a sphenoid structure that functions as the attachment site for muscles that move the lower jaw and soft palate.

What structures does the ethmoid form part of?

• Orbital wall

• Floor of cranium and nasal cavity

• Part of the nasal septum

What is a nasal septum?

A nasal septum is the midline wall that divides the nasal cavity into left and right sides.

What structures are associated with the nasal septum?

• Perpendicular plate of the ethmoid

• Vomer (behind the perpendicular plate)

• Hyaline cartilage

What structures are associated with the anterior cranial fossae?

• Frontal bone

• Ethmoid

• Lesser wing of sphenoid

What structures are associated with the middle cranial fossae?

• Sphenoid

• Temporal

• Parietal

What structures are associated with the posterior cranial fossae?

• Occipital

• Part of temporal

• Part of parietal

What are fontanelles?

Fontanelles are fibrous regions of connective tissue that connect the cranial bones in infants.

• Fontanelles allow cranial expansion and distortion at birth.

What bone does the maxillae not articulate with?

The maxillae do not articulate with cranial bones and the mandible.

• The mandible articulates with the temporal bones.

What is the palatine process?

The palatine process is a maxillary bone that forms the hard palate of the root of your mouth.

What are lacrimal bones?

Lacrimal bones (2) are small, L-shaped bones.

What structure(s) does the horizontal plate articulate with?

The horizontal plate articulates with the maxillae to form the posterior portion of the bony plate.

What structure(s) do the perpendicular plates articulate with?

• Maxillae

• Sphenoid

• Ethmoid

• Inferior nasal concha

What structure(s) does the nasal crest articulate with?

Vomer

What is the vomer?

The vomer is a singular bone that forms the inferior portion of the nasal septum.

• Located posterior to the perpendicular plate.

• Articulates with ethmoid and sphenoid

What structure(s) do the nasal bones articulate with?

The maxilla

What is the inferior nasal conchae?

The inferior nasal conchae are scroll-like bones located laterally on each side of the nasal septum.

• Form the lateral wall of the nasal cavity.

What is the smallest facial bone?

Lacrimal

What are the smallest bones in the skull?

Ossicles

Where do temporal muscles attach?

Coronoid process

What structures are associated with the mandibular foramen?

Lower teeth nerves

What structure(s) is associated with the submandibular fossa?

Salivary glands

What structure(s) is associated with the mylohyoid line?

Muscles of the tongue and floor of mouth

What structures form the orbit?

• Frontal bone

• Zygomatic bone

• Maxillae

• Ethmoid bone

• Palatine bone

How many bones form the nasal complex.

Seven:

1. Frontal bones

2. Nasal bones

3. Maxillae

4. Palatine bones

5. Ethmoid

6. Sphenoid

7. Inferior nasal conchae

What bones form the paranasal sinuses?

• Frontal (frontal sinus)

• Ethmoid (ethmoidal air cells)

• Sphenoid (sphenoidal sinus)

• Maxillae (maxillary sinus

What are the functions of the paranasal sinuses?

Paranasal sinuses are air-filled chambers that open into the nasal cavities. These sinues help to lighten the skull, produce mucus, and produce sounds.

What is the hyoid bone?

The hyoid bone lies inferior to the skull, suspended by styloid ligaments.

• The hyoid bone DOES NOT articulate with any other bone.

• Moveable base for the tongue