Anatomy of the Occipital and Frontal Bones

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Questions and Answers

Which part of the occipital bone is located anterior to the foramen magnum?

Condyle part

Squamous part

Lateral part

Basilar part (correct)

What major structure passes through the hypoglossal canal of the occipital bone?

Vagus nerve

Optic nerve

Hypoglossal nerve (correct)

Oculomotor nerve

Which feature of the occipital bone serves as a prominent external landmark and is easily felt?

External occipital protuberance (correct)

Pharyngeal tubercle

Clivus

Superior nuchal line

Which suture is located between the occipital bone and the parietal bones?

Lambdoid suture Signup and view all the answers

What anatomical feature is found on the superior surface of the basilar part of the occipital bone?

Clivus Signup and view all the answers

Which of the following bones are part of the neurocranium?

Temporal bone Signup and view all the answers

Which structure does the occipital condyle articulate with?

First cervical vertebra Signup and view all the answers

What is the primary function of the frontal bone?

Forms the forehead and upper eye orbits Signup and view all the answers

Which part of the occipital bone is positioned posterior to the foramen magnum?

Squamous part Signup and view all the answers

Which suture articulates the frontal bone with the parietal bones?

Coronal suture Signup and view all the answers

Which of the following bones contributes to the lateral surface of the cranium along with the occipital bone?

Parietal bone Signup and view all the answers

What is the primary function of the superciliary arches in the frontal bone?

Support the eyebrows Signup and view all the answers

At what age do the two halves of the frontal bone typically fuse?

5 or 6 years Signup and view all the answers

Which part of the frontal bone forms the superior border of the orbits?

Orbital part Signup and view all the answers

At what stage of development are the frontal sinuses typically fully developed?

After puberty Signup and view all the answers

Which marking on the frontal bone is more pronounced in men?

Glabella Signup and view all the answers

A persistent frontal suture that is visible in the midline of the glabella is known as what?

Metopic suture Signup and view all the answers

Which of the following structures can be found in the frontal bone?

Frontal sinuses Signup and view all the answers

Which of the following functions does the lacrimal fossa serve?

Accommodation for the lacrimal gland Signup and view all the answers

The landmark known as the glabella is located between which of the following features?

Frontal sinuses and superciliary arches Signup and view all the answers

Which cranial bones does the frontal bone articulate with?

Temporal, ethmoidal, and parietal bones Signup and view all the answers

Which structure is found in the frontal bone that is an opening in the supraorbital margin?

Supraorbital notch Signup and view all the answers

What separates the two frontal sinuses?

Frontal septum Signup and view all the answers

What is the nasal border in relation to the frontal bone?

It articulates with the maxillary bone Signup and view all the answers

Study Notes

Introduction to the Skeleton System

The skeleton is a complex bony structure.
The skeleton consists of two major divisions: axial and appendicular.

Divisions of the Skeleton

Axial Skeleton
- Skull
  - 22 bones and 6 auditory ossicles
  - Protects brain and special senses
  - Provides attachment for structures that take air, food, and water.
  - The skull is made up of several cavities.
    - Cranial cavity
    - Nasal cavity
    - Orbits
    - Paranasal sinuses
    - Ears
- Hyoid bone
- Vertebral column
- Thoracic (rib) cage
Appendicular Skeleton
- Limbs
- Girdles

Skull (Axial Skeleton)

22 Bones plus 6 auditory ossicles that function in hearing.
Two portions:
- 1- Neurocranium (brainbox)
  - Surrounds and protects brain
  - Provides muscle attachment
  - Contains sinuses to reduce weight of the skull
- 2- Viscerocranium (facial bones)
  - Shapes the face
  - Protects major sensory organs like eyes, nose, and tongue
  - Provides attachment for muscles of mastication, facial expression, and eye movement
Bone List
- Neurocranium Bones (Cranium):
  - Frontal (1)
  - Parietal (2)
  - Occipital (1)
  - Temporal (2)
  - Ethmoid (1)
  - Sphenoid (1)
- Viscerocranium Bones:
  - Inferior nasal concha (2)
  - Lacrimal (2)
  - Vomer (1)
  - Nasal (2)
  - Zygomatic (2)
  - Palatin (2)
  - Maxilla (2)
  - Mandible (1)
Cranial Bones:
- Thin but remarkably strong for their weight

The Frontal Bone

Forms the anterior portion of the cranium (forehead)
Articulates posteriorly with parietal bones via the coronal suture
Major markings include:
- Supraorbital margins
- Anterior cranial fossa
- Frontal sinuses (internal and lateral to glabella).
Development: Forms in two halves, usually fused by ages 5 or 6
Some adults have a metopic suture
Parts of the frontal bone:
- Squamous part
- Orbital part
- Nasal part
Supraorbital margin: Edge of the frontal part forming the superior border of the orbits
Supraorbital foramen/notch: Opening or notch in the middle of the supraorbital margin
Superciliary arches: Thickened ridges over the supraorbital margins supporting eyebrows
Other features:
- Frontal eminence
- Glabella
- Frontal sinus

The Occipital Bone

Contributes to the posterior, lateral and inferior surfaces of the cranium
Encircled by four parts: basilar, lateral (2), squamous
Foramen magnum: large circular opening for cranial and spinal cavities connection
Clivus(superior surface);slightly concave and sloped upwards in continuity with the sphenoid
Pharyngeal tubercle (inferior surface), site for muscle and raphe attachment
Other features
- External occipital protuberance (inion)
- Superior nuchal line
- Occipital condyle
- Hypoglossal canal

The Parietal Bones

Contribute to the superior and lateral surface of the cranium.
Connected by immovable joints called sutures.
Major Sutures:
- Lambdoid suture: Between occipital and parietal bones.
- Sagittal suture: Between the parietal bones.
- Coronal suture: Between the frontal and parietal bones.
- Squamous suture: Between the parietal and temporal bones.

The Temporal Bones

Form the inferolateral aspects of the skull
The temporal bone is divided into four parts:
- Squamous (flattened plate)
- Tympanic (surrounds external acoustic meatus or ear canal)
- Mastoid (posterior to the external acoustic meatus)
- Petrous (dense portion housing middle and inner ear structures)
Major Features of the temporal bone:
- Zygomatic process:forms the zygomatic arch (cheek bone)
- Mandibular fossa: Forms a joint with the condyle of the mandible
- External acoustic meatus: Ear canal
- Styloid process: Projects inferiorly from the tympanic part.
- Mastoid process: Bony knob behind the earlobe.
- Stylomastoid foramen: Located between mastoid and styloid processes, passage for facial nerve.
- Mastoid foramen: Posterior to the mastoid process
- Other features in Petrous Part:
  - Internal acoustic meatus
  - Carotid canal
  - Jugular foramen

The Sphenoid Bone

Butterfly-shaped bone that spans the width of the middle cranial fossa
Forms the central wedge that articulates with all other cranial bones.
Consists of:
- Body (median portion)
- Two greater wings (lateral portion)
- Two lesser wings (anterior portion)
- Pterygoid processes (directed inferiorly)
Other features:
- Sella turcica: Bony enclosure for the pituitary gland.
- Greater wings: Large, lateral wing-like processes that strengthen the sides of the skull; have openings(foramen rotundum, foramen ovale, and foramen spinosum)
- Lesser wings: small wing-like processes anterior to the sella turcica
- Superior orbital fissure: Irregular slit-like opening between lesser and greater wings.
- Pterygoid processes: Plates that permit muscle attachment
- Pterygoid canals
Major Markings:
- Sella turcica
- Hypophyseal fossa
- Pterygoid processes

The Ethmoid Bone

Lies between the sphenoid and nasal bones.
Forms most of the bony area between nasal cavity and orbits
Composed of:
- Cribriform plate: Perforated plate containing olfactory foramina
- Crista galli: Raised ridge that projects upward
- Perpendicular plate: Forms part of the nasal septum
- Superior and middle nasal conchae: Bony projections that increase surface area for airflow.
- Ethmoid sinuses: Air spaces within the bone

The Facial Bones

The facial bones form the skeleton of the face.
List of Facial Bones:
- Nasal bones (2)
- Lacrimal bones (2)
- Zygomatic bones (2)
- Maxillae (2)
- Palatine bones (2)
- Inferior nasal conchae (2)
- Vomer (1)
- Mandible (1)

The Mandible

Largest and strongest bone of the face. Described as horseshoe shaped
All muscles of mastication attach to the mandible
Has different sections :
- Body
- Ramus
- Head of the mandible
- Neck of the mandible
- Angle of the mandible
- Coronoid process
- Condylar process
- Mandibular notch
- Mental tubercle
- Mental protuberance
- Mental foramen
- Alveolar process (supports mandibular teeth)
- Parts of the Mandible:
  - Mylohyoid line
  - Mylohyoid groove
  - Sublingual fovea
  - Submandibular fovea
  - Mental spine
The alveolar process supports the teeth
Alveolar bone is resorbed when a tooth is lost

The Hyoid Bone

Located at the C3 vertebral level, in front of the neck
Unique as it does not articulate with any bone
Attachment for hyoid muscles
The upper and lower parts of the neck's hyoid muscles attach to this bone

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Description

This quiz covers key aspects of the occipital and frontal bones, including their anatomical features, functions, and relationships with other cranial structures. Test your knowledge on the important landmarks, sutures, and articulations of these cranial bones.