Anatomy of the Skull and Cranial Bones

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of the skull in relation to the brain?

To provide sensory support

To aid in respiratory function

To enhance cognitive abilities

To cover and protect the brain (correct)

How many cranial bones are present in the human skull?

8 (correct)

Which of the following bones is classified as a facial bone?

Sphenoid

Parietal

Vomer (correct)

Occipital

Which suture is the junction of the sagittal and coronal sutures?

Bregma Signup and view all the answers

In the context of the temporal bones, what is the function of the mastoid process?

It serves as an attachment for neck muscles Signup and view all the answers

Which structure marks the intersection of the sagittal and lambdoid sutures?

Lambda Signup and view all the answers

What is the main characteristic of the temporal squama of the temporal bone?

Thin and flat Signup and view all the answers

Which of the following bones is located at the base of the skull between the sphenoid and occipital bones?

Temporal Signup and view all the answers

Which of the following bones forms part of the superior portion of the nasal septum?

Perpendicular plate of the ethmoid bone Signup and view all the answers

What structure is located at the anterior part of the cranial floor and is spongelike in appearance?

Ethmoid bone Signup and view all the answers

Which foramina are known to transmit the middle meningeal blood vessels?

Foramen spinosum Signup and view all the answers

The lateral masses of the ethmoid bone separate which two cavities?

Nasal cavity and orbits Signup and view all the answers

Which of the following paired bones form part of the medial wall of the orbit?

Lacrimal bones Signup and view all the answers

Which bone is unpaired and triangular, articulating with the perpendicular plate of the ethmoid bone?

Vomer Signup and view all the answers

What is the function of the cribriform plate in the ethmoid bone?

Forms the roof of the nasal cavity Signup and view all the answers

Which bone contributes to the formation of the hard palate?

Maxilla Signup and view all the answers

What structure passes through the foramen magnum?

Medulla oblongata Signup and view all the answers

Which nerve is associated with the internal auditory meatus?

Facial nerve (VII) Signup and view all the answers

What is the primary function of the sella turcica?

Encloses the pituitary gland Signup and view all the answers

Which of the following best describes the sphenoid bone?

It resembles a butterfly and acts as a keystone of the cranial floor. Signup and view all the answers

What are the external occipital protuberance and nuchal lines associated with?

The posterior surface of the occipital bone. Signup and view all the answers

Where does the sphenoidal sinus drain?

Superiorly into the nasal cavity Signup and view all the answers

What are the two processes located on either side of the foramen magnum?

Occipital condyles Signup and view all the answers

Which structure is located anterior to the sella turcica?

Optic foramen Signup and view all the answers

Which structure articulates with the mandibular fossa?

Condyle of the mandible Signup and view all the answers

What is the function of the infraorbital foramen?

Transmits blood vessels and nerves Signup and view all the answers

Which of the following accurately describes the palatine process?

Horizontal projection forming part of the hard palate Signup and view all the answers

What characterizes the mental foramen in the mandible?

Inferior to the second premolar tooth Signup and view all the answers

Which of the following is true regarding the zygomatic bones?

They contribute to the lateral wall and floor of each orbit Signup and view all the answers

Which bony structure is involved in the attachment of the temporalis muscle?

Coronoid process Signup and view all the answers

What differentiates the alveolar process in the maxilla from that in the mandible?

The maxilla only supports upper teeth. Signup and view all the answers

What is found between the greater wing of the sphenoid and the maxilla?

Inferior orbital fissure Signup and view all the answers

Study Notes

Skull

The skull, the superior part of the axial skeleton, comprises 22 bones:
- 8 cranial bones (brain box)
- 14 facial bones
The skull covers and protects the brain and provides the facial skeleton, shaping the face.

Cranial Bones

Frontal Bone:
- thick, plate-like frontal squama (forehead)
- supraorbital margin
- supraorbital foramen
- forms the roof of the orbit
- contains frontal sinuses
Parietal Bones:
- quadrilateral shaped
- inferior border is bevelled
- other borders are denticulate
- external surface is convex
- internal surface is concave
Temporal Bones:
- thin, flat temporal squama
- zygomatic process
- tympanic process
- mastoid process: rounded projection posterior to the external auditory meatus
- styloid process: projects inferiorly from the temporal bone
- mandibular fossa: socket on the zygomatic process
- articular tubercle: rounded elevation anterior to the mandibular fossa
- stylomastoid foramen: facial nerve (VII) and stylomastoid artery pass through
- Petrous portion: pyramidal, located at the base of the skull between the sphenoid and occipital bones
  - contains the internal and middle ear
  - carotid foramen
  - jugular foramen: posterior to the carotid foramen and anterior to the occipital bone
- internal auditory meatus: facial (VII) and vestibulocochlear (VIII) nerves pass through
Occipital Bone: - foramen magnum: allows passage of the medulla oblongata, vertebral arteries, spinal arteries, and accessory nerve (XI) - occipital condyles: oval processes with convex surfaces, located on either side of the foramen magnum - external occipital protuberance: prominent midline projection superior to the foramen magnum - superior and inferior nuchal lines - hypoglossal canal: superior to each occipital condyle, allows passage of the hypoglossal nerve (XII)
Sphenoid Bone:
- located in the middle part of the base of the skull
- keystone of the cranial floor
- butterfly-shaped
- body: hollow, cube-like medial portion
- sphenoidal sinus: drains into the nasal cavity
- sella turcica: bony, saddle-shaped structure
  - tuberculum sellae (anterior ridge)
  - hypophyseal fossa: depression containing the pituitary gland
  - dorsum sellae: forms the back of the sella turcica
- greater wings: project laterally from the body
- lesser wings: anterior and superior to the greater wings
- optic foramen: anterior to the sella turcica, allows passage of the optic nerve (II) and ophthalmic artery
- superior orbital fissure: triangular slit lateral to the body, allows passage of nerves and blood vessels to the orbit
- pterygoid processes: extend from the inferior part of the sphenoid bone
- foramen rotundum: junction of anterior and medial parts of the sphenoid bone, transmits the maxillary branch of the trigeminal nerve (V)
- foramen ovale: base of the lateral pterygoid process, transmits the mandibular branch of the trigeminal (V)
- foramen spinosum: lies at the posterior angle of the sphenoid, transmits the middle meningeal blood vessels
- foramen lacerum: bounded anteriorly by the sphenoid, transmits nerves and blood vessels
Ethmoid Bone:
- delicate bone located in the anterior cranial floor
- sponge-like appearance
- forms:
  - part of the cranial floor
  - medial wall of the orbits
  - superior portion of the nasal septum
  - superior sidewalls of the nasal cavity
- lateral masses: wall between the nasal cavity and the orbits
- perpendicular plate: forms the superior portion of the nasal septum
- cribriform plate: horizontal, forms the roof of the nasal cavity and contains olfactory foramina allowing passage of olfactory nerves (I)
- crista galli: triangular process, attachment point for the falx cerebri
- superior and middle nasal conchae

Facial Bones

Nasal Bones:
- paired, small, flattened, rectangular-shaped bones forming the bridge of the nose
Lacrimal Bones:
- paired, thin, fingernail-sized bones forming part of the medical wall of the orbit
- lacrimal fossa: vertical tunnel with the maxilla, contains the lacrimal sac
Palatine Bones:
- paired bones forming the posterior portion of the hard palate
- horizontal plates separate the nasal cavity from the oral cavity
Inferior Nasal Conchae:
- inferior to the middle nasal conchae of the ethmoid bone
Vomer:
- unpaired triangular bone
- articulations:
  - Superiorly: with the perpendicular plate of the ethmoid and the sphenoid bone
  - Inferiorly: with the maxillae and palatine bones, forming the inferior portion of the nasal septum
Maxillae:
- paired bones forming:
  - part of the floor of the orbits
  - lateral walls and floor of the nasal cavity
  - most of the hard palate
- maxillary sinus: central to the body
- alveolar process: contains the alveoli
- palatine process: forms the anterior three-quarters of the hard palate
- infraorbital foramen
- inferior orbital fissure: between the greater wing of the sphenoid and the posterior aspect of the maxilla
Zygomatic Bones:
- form the lateral wall and floor of each orbit.
- temporal process: articulates with the temporal bone forming the zygomatic arch.
- zygomaticofacial foramen: transmits zygomaticofacial nerve and vessels.
Mandible:
- largest, strongest facial bone
- only movable bone in the skull
- body: curved, horizontal portion
- rami: two perpendicular portions
- condylar process: articulates with the mandibular fossa and articular tubercle of the temporal bone
- angle: where the body meets the ramus
- coronoid process: temporalis muscle attachment
- mandibular notch: depression between coronoid and condylar processes
- alveolar process: contains alveoli for the mandibular teeth
- mandibular foramen: on the medial surface of the ramus
- mental foramen: inferior to the second premolar tooth
- mental spines
- mylohyoid line: from the mental spines to an area behind the third molar tooth
- submandibular fossa
- sublingual fossa
- digastric fossa
- lingula: attachment point for the sphenomandibular ligament

Cranial Vault

Three sutures:
- Coronal suture: between the frontal and parietal bones
- Sagittal suture: between the parietal bones
- Lambdoid suture: between the parietal and occipital bones
Important landmarks:
- Bregma: intersection of sagittal and coronal sutures
- Vertix: superior, topmost point of the cranium
- Lambda: intersection of sagittal and lambdoid sutures
- Pterion: superior to the midpoint of the zygomatic arch
  - marked by H-shaped sutures
  - a very dangerous area due to its thinness and the location of major blood vessels
Anterior Cranial Fossa:
- contains:
  - crista galli: attachment for the falx cerebri
  - anterior clinoid process: attachment point for the tentorium cerebelli
Middle Cranial Fossa: - contains: - part of the sphenoid bone and temporal bones - sella turcica - pituitary gland

Orbit

The orbit is the bony cavity that houses the eyeball.
It is formed by:
- Roof: frontal and sphenoid bones
- Lateral wall: zygomatic and sphenoid bones
- Floor: maxilla, zygomatic, and palatine bones

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the anatomy of the skull, detailing its 22 bones, including 8 cranial and 14 facial bones. Understand the structure and function of each cranial bone, including the frontal, parietal, and temporal bones. Test your knowledge on the protective role of the skull and its impact on facial structure.