Bones of the Head and Neck

Bones of the Head and Neck

Anterior View

• Bones visible from the anterior view include:
  • Ethmoid
  • Frontal
  • Inferior conchae
  • Lacrimal
  • Mandible
  • Maxilla
  • Nasal
  • Parietal
  • Sphenoid
  • Temporal
  • Vomer
  • Zygomatic

Skull Bones

• Skull bones are divided into cranial and facial bones.
• Cranial Bones (Neurocranium):
  • Number: 8
  • Frontal bone: Single
  • Parietal bone: Paired
  • Temporal bone: Paired
  • Occipital bone: Single
  • Sphenoid bone: Single
  • Ethmoid bone: Single
• Facial Bones (Viscerocranium):
  • Number: 14
  • Inferior nasal conchae: Paired
  • Lacrimal bones: Paired
  • Nasal bones: Paired
  • Vomer: Single
  • Zygomatic bones: Paired
  • Maxilla: Paired
  • Mandible: Single
  • Palatine bones: Paired

Cranial Bones

• Landmarks:
  • Supraorbital ridge of the frontal bone.
  • Mastoid process of the temporal bone.
• Cranial bones form the dome-like roof (calvaria) and the floor (cranial base) of the skull.

Neurocranium

• Provides:
  1. Framework for the cranial cavity and orbital cavities.
  2. Protection for the brain.
  3. Attachment sites for muscles.

Viscerocranium

• Provides:
  1. Skeletal framework for facial features, orbital, nasal, and oral cavities.
  2. Attachment sites for muscles.
  3. Accommodates the teeth and sensory structures for sight, hearing, smell, and taste.

Cranial Bones - Anterior View

• Cranial bones visible from the anterior view include:
  • Frontal
  • Parts of the sphenoid
  • Parts of the ethmoid
  • Parts of the parietal & temporal
  • Facial bones

Cranial Bones - Superior View

• Bones visible from the superior view include:
  • Frontal
  • Parietal
  • Occipital
  • Nasal
  • Zygomatic
• Sutures: Immovable articulations where bones are connected with dense fibrous tissue.
  • Coronal suture: Connects the frontal and parietal bones.
  • Sagittal suture: Divides the right and left sections, connecting the right and left parietal bones.
  • Lambdoid suture

Cranial Bones - Lateral View

• Bones visible from the lateral view include:
  • Frontal
  • Parietal
  • Part of the sphenoid
  • Temporal
  • Part of the ethmoid
  • Occipital
• Sutures:
  • Squamosal: Side of skull, connects temporal and parietal bones.
  • Temporozygomatic: Connects the temporal and zygomatic bones.
  • Lambdoidal: Connects the occipital and parietal bones.

Cranial Bones - Posterior View

• Bones visible from the posterior view include:
  • Parietal
  • Occipital
  • Temporal
  • Mandible
• Sutures:
  • Sagittal: Divides the right and left parietal bones.
  • Lambdoidal: Connects the occipital and parietal bones.

Cranial Bones - Inferior View

• Bones visible from the inferior view include:
  • Occipital
  • Temporal
  • Sphenoid
  • Frontal
  • Maxilla
  • Palatine
  • Parietal
  • Vomer
  • Zygomatic
• Landmarks: Styloid process, Stylomastoid foramen

Skull at Birth

• Skull is large in comparison to the body.
• Cranial portion is larger than the facial portion.
• Fontanelles:
  • Sphenoid fontanelle
  • Posterior fontanelle
  • Mastoid fontanelle
  • Anterior fontanelle

Facial Bones

• There are 14 facial bones:
  • Nasal bones (2)
  • Lacrimal bones (2)
  • Inferior nasal concha (2)
  • Vomer (1)
  • Zygomatic (2)
  • Maxilla (2)
  • Mandible (1)
  • Palatine (2)

Sutures

• Median palatine suture: Joins the right and left palatine bones.
• Transverse palatine suture: Connects the maxilla and palatine bones.

Orbital Walls

• Combination of bones that make up the orbital walls:
  • Ethmoid bone
  • Lacrimal bone
  • Maxilla
  • Frontal bone
  • Sphenoid bone (greater wing)
  • Zygomatic bone

Orbital Apex

• The orbital apex is the deepest part of the orbit.
• Composed of the lesser wing of the sphenoid bone (the base) and the palatine bone (a small inferior part).

Orbital Walls Composition

• Frontal bone: Roof or superior wall.
• Zygomatic & Sphenoid: Lateral wall.
• Maxilla: Floor.
• Lacrimal & Ethmoid: Medial wall.

Orbital Landmarks

• Supraorbital notch
• Supraorbital rim
• Lesser wing of sphenoid bone
• Optic canal
• Superior orbital fissure
• Greater wing of sphenoid bone
• Inferior orbital fissure
• Maxilla
• Infraorbital rim
• Zygomaticomaxillary suture

Definitions: Prominences

• Arch: Prominent bridge-like bony structure.
• Condyle: Oval, bony prominence typically located at articulations.
• Cornu: Small, hornlike prominence.
• Crest: Roughened border or ridge on the bone surface.
• Eminence or Tubercle: Tubercle or rounded elevation on a bony surface.
• Line: Straight, small ridge of bone.
• Head: Rounded surface from a bone by a neck.
• Process: General term for any prominence on a bony surface.
• Protuberance: A protrusion from something else.
• Spine: Abrupt, small prominence of bone.
• Tuberosity: Large, often rough prominence on the surface of a bone.

Definitions: Openings

• Canal: Long, narrow, tube-like opening in a bone.
• Fissure: Narrow, cleft-like opening in a bone.
• Foramen: Short, window-like opening in a bone (plural: foramina).
• Meatus: Type of canal, usually leading from inside to outside.

Definitions: Depressions

• Fossa: Deeper depression or concavity in a bone.
• Fovea: Small pit or depression.
• Notch: Indentation at the edge of a bone.
• Sulcus: Shallow depression or groove (for blood vessels or nerves).
• Plate: Flat structure of a bone.

Definitions: Articulation

• Articulation: Where bones are joined together by:
  • Suture: Union of bones joined by fibrous tissue, appears as a jagged line.
  • Joint: Site of union of two or more bones.

Frontal Bone

• Single bone.
• Forms the forehead & roof of the orbit.
• Articulates with:
  • Parietal
  • Sphenoid
  • Lacrimal bones
  • Nasal bones
  • Ethmoid bone
  • Zygomatic bones
  • Maxillae

Frontal Bone Landmarks

• Prominences:
  • Forehead/frontal eminence
  • Supraorbital ridges
  • Supraorbital notches
  • Glabella: Smooth, elevated area between eyebrows
  • Zygomatic process: Articulates with Zygomatic bone

Frontal Bone - Inferior View

• Depression:
  • Lacrimal fossa: Contains the lacrimal gland which produces tears (lacrimal fluid).

Parietal Bones

• Paired bone.
• Articulates at the sagittal suture; forms the greater part of the walls and roof of the skull (protective brain case).
• Articulates with:
  • Occipital
  • Frontal
  • Temporal
  • Sphenoid

Parietal Bones Landmarks

• Prominences:
  • Superior temporal line
  • Inferior temporal line

Temporal Bones

• Paired bone.
• Forms the lateral walls of the skull.
• Houses hearing and equilibrium.
• Composed of 3 portions.
• Articulates with:
  • Zygomatic bone
  • Parietal bone
  • Occipital bone
  • Sphenoid bone(s)
  • Mandible

Temporal Bones: Squamous Portion

• Large, fan-shaped, flat portion.
• Forms the lateral wall of the skull.
• Landmarks:
  • Zygomatic process: Will become part of the zygomatic arch with the temporal process of the zygomatic bone.

Temporal Bones: Squamous Portion (continued)

• Landmarks, cont.
  • Articular eminence (anterior)
  • Post-glenoid process (posterior)
• Depression:
  • Articular fossa or mandibular fossa
    • Articulation with the TMJ (temporomandibular joint)

Temporal Bones: Tympanic Portion

• Landmarks
• Openings:
  • External acoustic (auditory) meatus: Short canal leading to the tympanic cavity.

Temporal Bones: Petrous Portion

• Landmarks:
  • Mastoid process: Filled air spaces that help with equilibrium.
  • Mastoid notch
  • Styloid process: Attachment for tongue & pharyngeal muscles.
  • Stylomastoid foramen
  • Carotid canal: Passageway for internal carotid artery.
  • Internal acoustic meatus
  • Jugular notch: With the occipital bone, forms jugular foramen.

Sphenoid Bone

• Single midline, cranial bone; links all bones in the neurocranium.
• Internally wedged in the anterior cranium;