Skull Bones and Neurocranium Anatomy

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Questions and Answers

The skull is supported by which structure?

  • The spinous process
  • The ribs
  • The sternum
  • The vertebral column (correct)

What is the primary type of joint that immovably articulates the bones of the skull?

  • Hinge joints
  • Cartilaginous joints
  • Sutures (correct)
  • Ball and socket joints

Which of the following skull bones is an exception to the immovable articulation via sutures?

  • Occipital bone
  • Parietal bone
  • Mandible (correct)
  • Frontal bone

What are the two main divisions of the skull?

<p>Neurocranium and splanchnocranium (D)</p> Signup and view all the answers

Which of the following is the primary function of the neurocranium?

<p>Protecting the brain (A)</p> Signup and view all the answers

What is the main function of the splanchnocranium?

<p>Protecting sense organs (A)</p> Signup and view all the answers

Which of the following bones is NOT part of the neurocranium?

<p>Nasal (D)</p> Signup and view all the answers

How many temporal bones are part of the neurocranium?

<p>Two (A)</p> Signup and view all the answers

What bones constitute the NEURCRANIUM?

<p>Occipital, Two Parietals, Frontal, Two Temporals, Sphenoid, Ethmoid (A)</p> Signup and view all the answers

Which of the following bones is part of the splanchnocranium?

<p>Maxilla (A)</p> Signup and view all the answers

What is the name for the bones of the face?

<p>Splanchnocranium (A)</p> Signup and view all the answers

Which of the following pairs of bones are part of the facial skeleton?

<p>Nasal and maxilla (C)</p> Signup and view all the answers

Which of the following best describes the form of the parietal bones?

<p>Irregularly quadrilateral (C)</p> Signup and view all the answers

Which of the following features characterizes each parietal bone?

<p>Two surfaces, four borders, and four angles (C)</p> Signup and view all the answers

What is the name of the flat vertical portion of the frontal bone that corresponds to the forehead?

<p>Squama (B)</p> Signup and view all the answers

Which part of the frontal bone contributes to the formation of the roof of the orbit?

<p>Orbital portion (B)</p> Signup and view all the answers

Where is the occipital bone situated in relation to the cranium?

<p>The postero-inferior part (A)</p> Signup and view all the answers

Which of the following apertures is found in the occipital bone?

<p>Foramen magnum (B)</p> Signup and view all the answers

The upper fossae on the internal surface of the occipital bone primarily lodge which part of the brain?

<p>Cerebrum (D)</p> Signup and view all the answers

What articulates with the atlas on the inferior surface of the occipital bone?

<p>Condyles (A)</p> Signup and view all the answers

Which of the following describes the location of the sphenoid bone?

<p>Base of the skull (C)</p> Signup and view all the answers

Which of the following is a distinctive feature of the sphenoid bone?

<p>Resembles a bat with wings (C)</p> Signup and view all the answers

What is the term for the processes that arise from the body of the sphenoid bone and extend inferiorly?

<p>Pterygoid processes (C)</p> Signup and view all the answers

What is the name of the deep depression on the internal surface of the sphenoid bone that houses the hypophysis?

<p>Sella turcica (C)</p> Signup and view all the answers

The temporal bones are situated at the:

<p>Sides and base of the skull (C)</p> Signup and view all the answers

Which of the following organs is housed within the temporal bone?

<p>Organ of balance (C)</p> Signup and view all the answers

Which of the following is NOT considered a major part of the temporal bone?

<p>Orbital plate (A)</p> Signup and view all the answers

Where is the ethmoid bone situated?

<p>Anterior part of the base of the cranium (C)</p> Signup and view all the answers

What part of the ethmoid bone is perforated by foramina for the passage of the olfactory nerves?

<p>Cribriform plate (B)</p> Signup and view all the answers

Which of the following is constituted by the perpendicular plate of the ethmoid bone?

<p>Part of the nasal septum (B)</p> Signup and view all the answers

What structures are the superior and middle nasal conchae of the ethmoid bone?

<p>Downward extensions (D)</p> Signup and view all the answers

The palatine process of the maxilla contributes significantly to the formation of:

<p>the floor of the nose and the roof of the mouth (B)</p> Signup and view all the answers

What is the primary function of the mandible?

<p>Receiving the lower teeth (B)</p> Signup and view all the answers

The palatine bone is situated between the maxilla and the:

<p>Sphenoid (B)</p> Signup and view all the answers

Which walls of the nasal cavity are contributed to by the palatine bone?

<p>Floor and lateral (B)</p> Signup and view all the answers

What part of the nasal septum contributes to the vomer?

<p>Lower part (C)</p> Signup and view all the answers

What form of articulation is defined by the joining of contiguous margins of bones by a thin layer of fibrous tissue?

<p>Suture (B)</p> Signup and view all the answers

Which bones articulate to form the coronal suture?

<p>Frontal and parietal (C)</p> Signup and view all the answers

Which of the following sutures is located between the occipital and parietal bones?

<p>Lambdoidal suture (B)</p> Signup and view all the answers

The squamosal suture is located between which two bones?

<p>Temporal and parietal (A)</p> Signup and view all the answers

Which of the following best describes the articulation of skull bones, excluding the mandible?

<p>Immovable articulations via sutures (D)</p> Signup and view all the answers

If a patient has a fracture affecting the anterior cranial fossa, which bone is most likely involved?

<p>Frontal bone (D)</p> Signup and view all the answers

Which cranial bone is essential for the stabilization and protection of the brain and many of its associated blood vessels and cranial nerves?

<p>Sphenoid bone (B)</p> Signup and view all the answers

A patient presents with hearing loss and balance issues post-trauma. Which bone is MOST likely affected?

<p>Temporal bone (D)</p> Signup and view all the answers

What is the functional significance of the cribriform plate's perforations found on the ethmoid bone?

<p>Providing a route for olfactory nerve passage (B)</p> Signup and view all the answers

The perpendicular plate of which bone contributes to the formation of the nasal septum?

<p>Ethmoid (A)</p> Signup and view all the answers

If a surgeon needs access to the hypophyseal fossa, which bone must they operate on or through?

<p>Sphenoid (D)</p> Signup and view all the answers

What would be the MOST LIKELY consequence of damage to the cribriform plate?

<p>Loss of smell (A)</p> Signup and view all the answers

Which of the following statements accurately describes the location of the temporal bone within the cranium?

<p>It is positioned at the sides and base of the skull. (C)</p> Signup and view all the answers

Damage to the hypoglossal canal of the occipital bone could MOST DIRECTLY affect which function?

<p>Tongue movement (C)</p> Signup and view all the answers

If a patient exhibits difficulty in the lateral movement of their eyes, which cranial nerve function might be impaired, and which bone is MOST closely associated with its passage?

<p>Abducens nerve (CN VI); Sphenoid bone (C)</p> Signup and view all the answers

A surgeon is planning a procedure that involves accessing the middle cranial fossa. Which bone will provide the MOST direct route?

<p>Temporal bone (B)</p> Signup and view all the answers

Which of the following bones, through its palatine process, significantly contributes to the formation of the hard palate?

<p>Maxilla (B)</p> Signup and view all the answers

Which bone's condyle articulates with the atlas (the first cervical vertebra)?

<p>Occipital bone (C)</p> Signup and view all the answers

Which part of the ethmoid bone contains perforations that allow the passage of olfactory nerves, enabling the sense of smell?

<p>Cribriform plate (A)</p> Signup and view all the answers

Which of the following structures is housed within the temporal bone?

<p>Inner ear (D)</p> Signup and view all the answers

What functional role does the mandible primarily serve?

<p>Providing attachment for muscles of mastication and housing the lower teeth (C)</p> Signup and view all the answers

In a lateral skull radiograph, the pterion is identified as the region where several bones converge. Which bones intersect at the pterion?

<p>Frontal, parietal, sphenoid, and temporal bones (A)</p> Signup and view all the answers

A patient has an injury affecting their ability to move their jaw. Which bone is MOST likely involved?

<p>Mandible (C)</p> Signup and view all the answers

What distinguishes the palatine bone’s location from the other bones that form the nasal cavity?

<p>It is situated at the posterior part of the nasal cavity. (B)</p> Signup and view all the answers

If a patient has difficulty chewing due to a fracture affecting the zygomatic arch, which bone is directly affected?

<p>Zygomatic bone (A)</p> Signup and view all the answers

Which part of the vomer contributes to the nasal septum?

<p>Superior border (C)</p> Signup and view all the answers

A fracture at the lambdoid suture would involve which two bones?

<p>Parietal and occipital (B)</p> Signup and view all the answers

Which bones form the coronal suture?

<p>Frontal and parietal bones (D)</p> Signup and view all the answers

What is the role of the frontal bone's orbital part?

<p>Forms roof of the orbit (B)</p> Signup and view all the answers

Which of the following characteristics describes the parietal bones?

<p>They form the sides and roof of the cranium. (C)</p> Signup and view all the answers

The squamous part of the temporal bone is known for which of the following features?

<p>Articulating with the mandible at the temporomandibular joint (D)</p> Signup and view all the answers

Which of the following skull bones is part of the neurocranium, contributing to the cranial base and housing the pituitary gland?

<p>Sphenoid (D)</p> Signup and view all the answers

What is the primary role of the bones comprising the splanchnocranium in the skull?

<p>To support and protect the sense organs (B)</p> Signup and view all the answers

A patient is diagnosed with a fracture of the anterior nasal spine. Which bone is affected?

<p>Maxilla (C)</p> Signup and view all the answers

What is the 'Glabella' on the frontal bone?

<p>The prominence between the eyebrows. (D)</p> Signup and view all the answers

Which landmark represents the meeting point of the sagittal and lambdoidal sutures?

<p>Lambda (B)</p> Signup and view all the answers

A sunken fontanelle in an infant may indicate which of the following?

<p>Dehydration (B)</p> Signup and view all the answers

The anterior or frontal fontanelle demarcates the junction of which bones in an infant's skull?

<p>Frontal and parietal bones (B)</p> Signup and view all the answers

What is the process called where skull bones are joined at contiguous margins by fibrous tissue?

<p>Sutural articulation (D)</p> Signup and view all the answers

Which specific part of the maxilla is crucial in forming the larger part of the floor of the nasal cavity?

<p>Palatine Process (B)</p> Signup and view all the answers

What bones constitute the SPLANCHNOCRANIUM?

<p>Bones of the face (B)</p> Signup and view all the answers

Which skull structure is crucial for movement and doesn't articulate using sutures?

<p>Mandible (C)</p> Signup and view all the answers

Flashcards

The Skull

Supported by the vertebral column, composed of flattened or irregular bones joined by sutures (immovable joints), the mandible is the only exception.

Two parts of the Skull

The neurocranium encases and protects the brain. The splanchnocranium supports the face and protects sense organs.

Parietal Bones

The Parietal Bones form the sides and roof of the cranium. Each bone is irregularly quadrilateral with two surfaces and four angles.

Frontal Bone

Located at the anterior-superior part of the skull, it has two portions; the squama (forehead) and the orbital or horizontal portion (roof of orbits)

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Occipital Bone

Situated at the postero-inferior part of the cranium. It features a large oval aperture called the foramen magnum.

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Sphenoid Bone

Resembles a bat, situated at the base of the skull, in front of the temporals and the occipital.

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Temporal Bone

Situated at the sides and base of the skull containing the the organ of hearing and equilibrium. Three Parts: Squamous, petrous and mastoid process.

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Ethmoid Bone

The ethmoid bone is situated at the anterior part of the base of the cranium, at the roof of the nose.

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Vomer

Located in between the two nasal cavities, it is thin and roughly triangular in shape, contributing the the lower part of the nasal septum.

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Mandible (Lower Jaw)

The largest, strongest bone of the face. Consists of a curved, horizontal portion (body), hollowed into cavities of the teeth.

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Maxilla

Two maxillae unite to form the upper jaw, assisting the boundaries of three cavities- roof of the mouth, floor/lateral wall of the nose and the floor of the orbit.

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Palatine Bone

The palatine bone is situated at the posterior part of the nasal cavity, between the maxilla and the sphenoid.

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Zygomatic Bone

Situated on the lateral part of the face forming the prominence of the cheek, part of the lateral wall and floor of the orbit

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Lacrimal bone

located on anteromedial wall of the orbit

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nasal bone

Located on the dorsum of the nose

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Sutures

Form of joint articulation where contiguous margins of bones are united by a thin layer of fibrous tissue

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squamosal sutures

Between tempiral and parietal bones

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occipitomastoid sutures

Between the occiptal and temporal bones

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sphenosquamosal sutures

Between the temporal and sphenoid bones

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Anterior Cranial Fossa

The anterior cranial fossa is at the front of the skull

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bregma

The point where the coronal and sagittal sutures intersect

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lambda

The point where the sagittal and lambdoidal sutures

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Nasion

The point of intersection between the nasal sutures

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bregma

the junction between frontal and parietal bones

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lambda

junction between occipital and parietal bones.

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Study Notes

  • The study notes relate to the skull and individual cranial bones

Skull Bones

  • The skull is supported by the vertebral column
  • The skull consists of flattened or irregular bones that articulate immovably
  • These bones connect via joints called sutures
  • The mandible is the only skull bone that does not articulate with sutures

Division of the Skull

  • The skull is divisible into two parts:
    • NEURCRANIUM
    • SPLANCHNOCRANIUM (bones of the face)

Functions of Neurocranium and Splanchnocranium

  • The neurocranium lodges and protects the brain
  • The splanchnocranium protects sense organs

Neurocranium Composition

  • The neurocranium consists of eight bones:
    • Occipital
    • Two Parietals
    • Frontal
    • Two Temporals
    • Sphenoid
    • Ethmoid

Parietal Bone

  • Parietal bones form the sides and roof of the cranium
  • Each parietal bone has two surfaces, four borders, and four angles

Frontal Bone

  • The frontal bone is located on the anterior-superior part of the skull
  • Consists of the flat vertical squama portion corresponding to the forehead
  • An orbital or horizontal portion contributes to the roof of the orbit

Occipital Bone

  • The occipital bone is situated at the postero-inferior part of the cranium
  • It features a large oval aperture called the foramen magnum
  • The foramen magnum allows the cranial cavity to communicate with the vertebral canal
  • The internal surface of the occipital bone is concave and divided into two fossae
    • The upper fossae lodge the cerebrum
    • The lower fossae accommodate the cerebellum
  • The inferior surface features condyles that articulate with the atlas (first cervical vertebra)

Sphenoid Bone

  • Located at the base of the skull
  • Positioned in front of the temporals and the occipital bones
  • Resembles a bat with a body in the middle and wings on the sides
  • Features two pterygoid processes that arise from the body and extend inferiorly
  • The internal surface of the body has a deep depression called the sella turcica
  • The deepest part of the sella turcica houses the hypophysis and is known as the hypophysial fossa

Temporal Bone

  • The temporal bones are situated at the sides and base of the skull
  • They contain the organs of hearing and equilibrium
  • The temporal bone has three major parts:
    • Squamous part
    • Petrous part
    • Mastoid process
  • The temporomandibular joint is located between the temporal bone and the mandible

Ethmoid Bone

  • Situated on the anterior part of the base of the cranium, at the roof of the nose
  • Features a horizontal part, or cribriform plate, forming anterior part of the base of the cranium
  • Perforated by foramina for the passage of olfactory nerves
  • The perpendicular plate constitutes part of the nasal septum
  • Superior and middle nasal conchae extend downwards on the sides of the septum

Vomer

  • Situated between the two nasal cavities
  • Thin and roughly triangular in shape
  • Contributes to the lower part of the nasal septum

Mandible

  • Represents the largest and strongest bone of the face
  • Receives the lower teeth
  • Consists of a curved, horizontal portion, referred to as the body
  • There are two perpendicular portions, know as rami
  • The superior border of the body is hollowed into cavities housing sixteen teeth
  • Each condyle presents an articular surface for articulation with the temporal bone

Maxilla

  • Two maxillae unite to form the upper jaw
  • Each maxilla assists in forming the boundaries of three cavities
    • The roof of the mouth
    • The floor and lateral wall of the nose
    • The floor of the orbit
  • The body is pyramidal in shape and contains a large cavity, the maxillary sinus
  • The palatine process forms a considerable part of the floor of the nose and the roof of the mouth (palate)

Palatine Bone

  • Situated at the posterior part of the nasal cavity, between the maxilla and the sphenoid
  • Contributes to the walls of two cavities:
    • The floor and lateral wall of the nasal cavity
    • The roof of the mouth (palate)

Zygomatic Bone

  • Situated on the lateral part of the face
  • Forms the prominence of the cheek
  • Forms part of the lateral wall and floor of the orbit

Nasal Bone

  • Located on the dorsum of the nose

Lacrimal Bone

  • Located on the anteromedial wall of the orbit

Sutures

  • The suture is defined as the form of articulation where contiguous margins of bones unite
  • The bones are united by a layer of fibrous tissue
  • Only found in the skull

Types of Sutures

  • Coronal: Parietal bones articulate with the frontal bone in their front
  • Lambdoidal: Parietal bones articulate with the occipital in their behind
  • Sagittal: Parietal bone articulates with its the opposite side
  • Squamosal: Between the temporal and parietal bones
  • Occipitomastoid: Between the occipital and temporal bones
  • Sphenosquamosal: Between the temporal and sphenoid bones

Important Skull Landmarks

  • Bregma: The midline point where the coronal and sagittal sutures intersect
  • Lambda: The midline point where the sagittal and lambdoidal sutures intersect
  • Glabella: The slight elevation in the midline of the forehead, between the superciliary arches and above the nasofrontal suture
  • Pterion: The point of intersection between the frontal, sphenoid, parietal, and temporal bones
  • Nasion: The point of intersection between the frontonasal suture and the midsagittal plane
  • Gnathion: The most anterior and lowest median point on the border of the mandible

Fontanelles

  • The junction between the frontal bone and the two parietal bones is called the bregma
  • In newborns, ossification is incomplete, so the region can be felt as a soft spot called the anterior fontanelle
  • The anterior fontanelle is the biggest fontanelle
  • By palpating the anterior fontanelle, bone development and hydration status of the infant can be measured
    • Dehydration is indicated by a sunken fontanelle
    • Increased intracranial pressure is indicated by a tense and bulging fontanelle
  • Occipital bone and two parietal bones junction is called lambda
  • In newborns, ossification is incomplete, so the region can be felt as a soft spot called the posterior fontanelle.

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