Clinical Anatomy 3.1 Skull(Bones, Joints, & Scalp)

The Viscerocranium is made up of what bones?

"15 Irregular Bones" 1. 3 Singular, Centrally-located bones - Mandible - Vomer - Ethmoid 2. 6 Bilateral Pairs - Maxillae - Inferior Nasal Conchae - Zygomatic - Palatine - Nasal - Lacrimal Bones

What is the Orbitomeatal Plane of the skull?

"Along the Zygomatic Arch" In anatomical position: 1.Inferior Margin of bony Orbit 2.Superior Margin of External Acoustic Opening

✚ Fractures to the Viscerocranium: What is a Le Fort Fracture?

"Fractures of Midface" 1.Involves part, or all, of separation of maxillae from Skull

✚ Fractures to the Viscerocranium:What is a Le Fort III?(Craniofacial Disjunction)

*"Horizontal "W" Fracture"* Most Serious 1.Passing through • Superior Orbital Fissures • Ethmoid bones • Nasal Bones 2.Extends laterally thru: • Greater Wings • Frontozygomatic Sutures - Separate Fracture of: • Zygomatic Arch *Zygomatic Bones & entire Maxillae separate from Cranium*

✚ Fractures to the Viscerocranium:What is a Le Fort I?

*"Horizontal Fracture"* 1.Superior to Alveolar Processes (Maxilla) 2.Crossing Bone Nasal Septum 3.Pterygoid Plate of Sphenoid bone (possibly) 4.*Teeth of Upper Jaw separated from cranium*

✚ Fractures to the Viscerocranium:What is a Le Fort II?

*"Pyramidal Fracture"*- 3 demential 1.*From* Posterolateral region of Maxillary sinuses 2.*To* Superomedially through : • Infra-orbital Foramina • Lacrimal Bones • Ethmoid bones • Bridge of Nose 3.*Entire central bones of face separated from skull* • Including hard palate & upper jaw

✚ Hemifacial Microsomia ("Lateral Facial Dysplasia"):Characteristics

*Unilateral underdevelopment of lower half of face* - Always includes maldeveloped ear & mandible - May cause hearing problems - Weakness in facial muscles - TMJ problems

The Cranium(Neurocranium) is formed of what *8 bones*?

1.*4 Singular bones* centrally arranged -* Frontal, Ethmoid, Sphenoid, Occipital* 2. *2 pairs bilaterally* - *2 Parietal* - *2 Temporal*

Fetal Skull Characteristics 2

1.*Bones Underdeveloped* - Soft, and more pliant - More bones to skull - Joined by large sutures 2.*Anterior Fontanelle* - At future *Bregma* 3.*Posterior Fontanelle* - At future *Lambda* 3.*During passage through birth canal* - *Parietal bones* slightly overlap - Two *Frontal bone* flattens - *Occipital Bones* drawn out posterior, and superior

The Viscerocranium is considered the ________________ and is made up of what types of bones and formed by what type of ossification?

1.*Facial Skeleton* 2.*15 Irregular Bones* that form the *Anterior Cranium*: - *Mouth*-Upper & Lower Jaw - *Nose & Nasal Cavity*-With cartilage - *Most of Bony Orbits* 3.Formed by Intramembranous ossification, Endochondral ossification, or both

What bones of the skull are Pneumatized Bones?

1.*Mastoid* Air-Cells (Mc) 2.*Ethmoid* Air-Cells (E) 3.*Maxillary* Sinus (M) 4.*Frontal* Sinus (F) 5.*Sphenoidal* Sinus (S)

What are the aspects of the Cranium?(Temporal Fossa)

1.Bilateral "Squamous" areas of cranium 2.Bordered superiorly by the *Sup. & Inf. Temporal Lines* 3. Corresponds with Inferior limit to *cerebral hemispheres*

What are Pneumatized Bones of the Cranium?

1.Bones of the Cranium with sinuses or air-cells(small sinus). 2.Lighten Skull Bones 3.Space increases with age(Internal/External Tables Separate with age)

The Cranium(Neurocranium) encases what structures?

1.Case for Brain & Meninges 2.Proximal CN-Branch from brainstem 3.Brain Vasculature-Branches of "Circle of Willis"

The Mandible of the Viscerocranium has what importance?

1.Forms lower facial skeleton 2.It is moveable anchor for teeth 3.Upper & Lower Facial bones meet at the TMJ

What are the Craniometric Points of the aspects of the skull?

1.Glabella - Anterior-most prominence - Larger in males 2.Nasion - Intersection of internasal & frontonasal sutures - Distinct depression 3.Bregma - Junction of Sagittal & Coronal Suture

The Maxillae of the Viscerocranium has what importance?

1.Greatest contributor to upper facial skeleton 2.It is *immovable* anchor for upper teeth

✚ Hemifacial Microsomia ("Lateral Facial Dysplasia"):Population

1.More common in males 2.More often on right side 3.2nd most common facial birth defect

P.L.E.S. Feed My Zebra stands for what bones and locate them on the skull.

1.Palatine Bone 2.Lacrimal Bone 3.Ethmoid Bone 4.Sphenoid Bone 5.Frontal Bone 6.Maxillary Bone 7.Zygomatic Bone

What are the major compartments of the skull?

1.The Cranium(Neurocranium & Vicerocranium) 2.Ears~2 3.Bony Orbits~2 4.Nasal Cavities~2 5.Oral Cavity

What are the Craniometric Points of the aspects of the skull?2

4,*Lambda (Greek Λ)* - Junction of Sagittal & Lambdoidal suture 5.*Vertex* - Most superior-point of cranium (top-of-the-head) • In anatomical position • Oriented to *Orbitomeatal Plane*

What are the Craniometric Points of the aspects of the skull?3

6. *Asterion* - Junction of *Lambdoidal, Parietomastoid & Occipitomastoid Suture* 7.*Inion* (Back-of-the-head) - Posterior tip of external occipital protuberance 8.*Pterion* - Junction of parietal, sphenoid, temporal, frontal bones - *Clinically Significant*

What are the aspects of the Cranium?(Frontal Eminence)

Bilateral prominent area above each orbit

✚ Hemifacial Microsomia ("Lateral Facial Dysplasia"):Causes

Cause: - Unknown - Possibly damaged or disturbed blood supply to branchial arches • First 6-8 weeks of pregnancy

Fetal Skull Characteristics

Characteristics: 1.Large Cranium • ~1/4 of skeleton • Due to precocious growth of brain and eyes 2.Small Viscerocranium • No teeth, sinuses • Small maxillae, mandible, small nose 3.No Diploë • Bones are unilaminar at birth(Single plate of compact bone) 4.Prominent Frontal & Parietal Eminence • Give head round shape

The Vicerocranium contains what?

Facial skeleton

✚ Fractures to the Viscerocranium:What are they?

Maxillae Fracture Variations ("Le Fort Fractures")

✚ Hemifacial Microsomia ("Lateral Facial Dysplasia"):Treatment

Multiple Surgeries • Improve facial symmetry • Ear reconstruction

What are the aspects of the Cranium?(Parietal Eminence)

Point of maximum width

What is the Cranial Base(Basicranium) of the Neurocranium?

• "Floor" of the neurocranium • Irregular bones contributing to base develop through *Endochondral Ossification*, or *both*. - Sphenoid & Occipital united by hyaline cartilage

The Oral Cavity compartments contain what?

• *Opening of Digest. System* • Inferior to Nasal Cavity • Separated by *Hard & Soft Palate* • Muscle to control opening & closing

The 2 Nasal Cavitiy compartments contain what?

• *Opening of Resp. System* • Between Orbits • Surrounding Paranasal Sinuses • *External Nares* • Continuously Opened

The Neurocranium contains what?

• Brain/Meninges

The 2 Bony Orbit compartments contain what?

• Cone-shaped bony cavities • Contain *Eyes*, Muscle, fat, BV, Nerves, lids

What is the Calvaria of the Neurocranium?

• Dome-shaped "top" that covers the brain • "Skull-Cap" • Mainly flat-bones developed by *Intramembranous Ossification*

The 2 ear compartments contain what?

• Internal ear embedded within bone of cranial wall -* Petrous Portion of Temporal Bone*

What are Buttresses of the skull?

• Thicker areas of bone • Directs pressure attributed to: - Muscles of Mastication - Postural Muscle of the vertebral Column • Prevents compressive forces from being directed over *orbits & nasal cavity*