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Questions and Answers
What defines the inferior limit of the neck posteriorly?
What defines the inferior limit of the neck posteriorly?
Where is the superior limit of the neck located posteriorly?
Where is the superior limit of the neck located posteriorly?
Which structure is suspended by muscles connecting it to several bones, including the mandible and scapula?
Which structure is suspended by muscles connecting it to several bones, including the mandible and scapula?
Eagle syndrome is associated with which anatomical feature?
Eagle syndrome is associated with which anatomical feature?
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Which ligament extends from the anterior aspect of the foramen magnum to the pelvic surface of the sacrum?
Which ligament extends from the anterior aspect of the foramen magnum to the pelvic surface of the sacrum?
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What is the role of the posterior longitudinal ligament?
What is the role of the posterior longitudinal ligament?
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What type of joints are the zygapophysial joints?
What type of joints are the zygapophysial joints?
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Which statement accurately describes the IV discs?
Which statement accurately describes the IV discs?
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What is the main function of the ligamenta flava?
What is the main function of the ligamenta flava?
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Which structure provides attachment sites for muscles and extends from the occipital protuberance to the cervical spinous processes?
Which structure provides attachment sites for muscles and extends from the occipital protuberance to the cervical spinous processes?
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What type of joint is the atlanto-occipital joint, and what movement does it primarily allow?
What type of joint is the atlanto-occipital joint, and what movement does it primarily allow?
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What is the role of the anterior atlanto-occipital membrane?
What is the role of the anterior atlanto-occipital membrane?
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What characteristic defines the lateral atlanto-axial joints?
What characteristic defines the lateral atlanto-axial joints?
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What function does the posterior atlanto-occipital membrane serve?
What function does the posterior atlanto-occipital membrane serve?
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Which ligaments are known to limit flexion and separation of vertebral laminae?
Which ligaments are known to limit flexion and separation of vertebral laminae?
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Which of the following best describes the interspinous ligaments?
Which of the following best describes the interspinous ligaments?
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What is the function of the check ligaments in the median atlanto-axial joint?
What is the function of the check ligaments in the median atlanto-axial joint?
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Which ligament extends from the dens of C2 to the lateral margin of the foramen magnum?
Which ligament extends from the dens of C2 to the lateral margin of the foramen magnum?
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Which of the following movements is NOT associated with the cervical portion of the vertebral column?
Which of the following movements is NOT associated with the cervical portion of the vertebral column?
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What type of joint is the temporomandibular joint (TMJ)?
What type of joint is the temporomandibular joint (TMJ)?
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Which ligament is a continuation of the posterior longitudinal ligament?
Which ligament is a continuation of the posterior longitudinal ligament?
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What is the role of the articular disc in the TMJ?
What is the role of the articular disc in the TMJ?
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Which ligament attaches from the spine of the sphenoid bone to the lingula of the mandible?
Which ligament attaches from the spine of the sphenoid bone to the lingula of the mandible?
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Which ligament of the TMJ is intrinsic and helps to prevent posterior dislocation?
Which ligament of the TMJ is intrinsic and helps to prevent posterior dislocation?
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What movement is allowed at the median atlanto-axial joint?
What movement is allowed at the median atlanto-axial joint?
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Which of the following describes the neurocranium?
Which of the following describes the neurocranium?
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What is the primary function of the fontanel in an infant's cranium?
What is the primary function of the fontanel in an infant's cranium?
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Which bone forms the prominence of the cheeks?
Which bone forms the prominence of the cheeks?
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Which structure is located in the superior wall of the orbit?
Which structure is located in the superior wall of the orbit?
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What is the significance of the mandibular notch in the mandible?
What is the significance of the mandibular notch in the mandible?
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Which of the following bones contributes to the nasal septum?
Which of the following bones contributes to the nasal septum?
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What do the external occipital protuberance and the superior nuchal line mark?
What do the external occipital protuberance and the superior nuchal line mark?
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Which bone houses the external auditory meatus?
Which bone houses the external auditory meatus?
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Which of the following definitions best describes the calvaria?
Which of the following definitions best describes the calvaria?
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What anatomical feature is the condylar process part of?
What anatomical feature is the condylar process part of?
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Which suture separates the parietal bones from the occipital bone?
Which suture separates the parietal bones from the occipital bone?
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What is the primary role of the foramen magnum?
What is the primary role of the foramen magnum?
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Which foramen is related to the mandibular nerve?
Which foramen is related to the mandibular nerve?
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What is the primary function of the greater palatine foramen?
What is the primary function of the greater palatine foramen?
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Which bone is located inferior to the frontal bone of the cranial base?
Which bone is located inferior to the frontal bone of the cranial base?
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Which structure is the primary boundary of the hypophyseal fossa?
Which structure is the primary boundary of the hypophyseal fossa?
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What connects the occipital bone to the cervical vertebrae?
What connects the occipital bone to the cervical vertebrae?
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What feature distinguishes the Atlas (C1) vertebra from others?
What feature distinguishes the Atlas (C1) vertebra from others?
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What is the primary role of the lateral masses of the Atlas (C1)?
What is the primary role of the lateral masses of the Atlas (C1)?
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Which foramen allows the passage of the vertebral arteries?
Which foramen allows the passage of the vertebral arteries?
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Which feature is unique to the Axis (C2) vertebra?
Which feature is unique to the Axis (C2) vertebra?
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What is the purpose of the cribriform plate of the ethmoid bone?
What is the purpose of the cribriform plate of the ethmoid bone?
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Which cranial fossa houses the cerebellum, pons, and medulla?
Which cranial fossa houses the cerebellum, pons, and medulla?
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What is the significance of fontanels in an infant's skull?
What is the significance of fontanels in an infant's skull?
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What defines the boundaries of the middle cranial fossa?
What defines the boundaries of the middle cranial fossa?
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Which cervical vertebra is responsible for the greatest range of movement?
Which cervical vertebra is responsible for the greatest range of movement?
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What is the role of the pterion in the adult skull?
What is the role of the pterion in the adult skull?
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Study Notes
Posterior to Palatine Bone
- Choanae: posterior openings of the nasal cavity
- Palatine bone: anterior to the vomer and posterior to the maxilla, located at the root of the mouth
- Greater palatine foramen: posterolateral to the palatine bone
- Lesser palatine foramina: posterior to the greater palatine foramen
- Maxilla
- Palatine process
- Incisive fossa: posterior to incisive teeth
Internal Surface of Cranial Base
- Anterior cranial fossa: formed by the frontal, ethmoid, and sphenoid bones
- Frontal bone orbital part
- Frontal crest: median bony extension
- Foramen cecum: at the base of the frontal crest
- Ethmoid
- Crista galli: thick, median ridge posterior to the foramen cecum
- Cribriform plate: sieve-like structure on each side of the crista galli
- Frontal bone orbital part
Middle Cranial Fossa
- Sphenoid
- Body
- Greater wings
- Lesser wings
- Optic canal: located through the lesser wing
- Sphenoidal crest: formed by the lesser wings overhanging the middle fossa anteriorly and ends medially in the anterior clinoid process
- Anterior clinoid process: guards the hypophyseal fossa anteriorly
- Sella turcica (Turkish saddle)
- Tuberculum sellae: elevation of bone, forming the anterior boundary of the hypophyseal fossa
- Hypophyseal fossa (pituitary fossa): median depression between tuberculum and dorsum sellae, houses the pituitary gland
- Dorsum sellae: elevation of bone, forming the posterior boundary of the hypophyseal fossa, and ends laterally in the posterior clinoid processes
- Posterior clinoid process: guards the hypophyseal fossa posteriorly
- Superior orbital fissure: between the greater and lesser wings of the sphenoid, and goes into the orbit
- Foramen rotundum: posterior to the medial end of the superior orbital fissure
- Foramen ovale: posterolateral to the foramen rotundum
- Foramen spinosum: posterolateral to the foramen ovale
- Foramen lacerum: posterolateral to dorsum sellae
Posterior Cranial Fossa
- Lodges the Cerebellum, Pons, and Medulla
- Temporal
- Petrous part of the temporal bone: divides the middle cranial fossa from the posterior cranial fossa and looks like a mountain range
- Internal auditory meatus: on the medial side of the posterior cranial fossa
- Jugular foramen: posteroinferior to the internal auditory meatus
- Occipital
- Clivus: extends posteriorly from the dorsum sellae to the foramen magnum
- Basilar part: extends anteriorly from the foramen magnum until the posterior end of the sphenoid bone
- Hypoglossal canal: on the lateral wall of the foramen magnum
- Foramen magnum
- Internal occipital protuberance: in the posterior part of the occipital bone, related to the confluence of sinuses
- Internal occipital crest: extends anteriorly from the internal occipital protuberance
Development of Cranium
- Unerupted teeth (no teeth)
- Small face area compared to cranial cavity: face is approximately ⅛ the size of cranial portion, about ⅓ in adults
- Mandible: no ramus at birth
- Mastoid and styloid processes: underdeveloped
- Frontal bone halves are separated
- Fontanels or soft spots: the last area where the bones are lay in the cranium
- Anterior fontanel: between frontal and parietal bones
- Posterior fontanel: between parietal and occipital bones
- Mastoid fontanel: where temporal, parietal, and occipital bones converge
- Sphenoid fontanel: where sphenoid, frontal, parietal, and temporal bones converge
- Pterion: one of the last areas in the skull to develop, area where majority of bones intersect
Neck Osteology
- Bones of neck
- Cervical vertebrae
- Hyoid bone
- General characteristics of vertebrae
- Body: cylindrical, anterior part that supports body weight
- Vertebral arch: posterior to the vertebral body
- Pedicles (2): short, cylindrical projecting posteriorly from the body
- Laminae (2): flat plates continuous with pedicles that join posteriorly in the midline
- Vertebral foramen: formed by the vertebral arch and the posterior surface of the vertebral body
- The succession of vertebral foramina forms the vertebral canal
- Vertebral notches (2): superior and inferior to each pedicle
- Superior and inferior notches of adjacent vertebrae form the intervertebral foramina (exit for spinal nerves and accompanying vessels)
- Processes (7)
- Spinous process: median and posterior
- Transverse processes (2): project posterolaterally from the junction of pedicles and laminae
- Articular processes (4): 2 superior & 2 inferior, project from the junction of pedicles and laminae
- Each bears an articular surface (or facet)
Cervical Vertebrae
- Located between the cranium and the thoracic vertebrae
- Smallest of the moveable vertebrae (bear less weight)
- Greatest range and variety of movement of all vertebral regions
- Relative thickness of discs compared to the vertebral bodies
- Nearly horizontal orientation of facets
- Small amount of surrounding body mass
C1 = Atlas (Atypical Vertebra)
- Carries the cranium
- No body
- Anterior arch
- Anterior tubercle
- Articular facet for dens: on the posterior surface of the anterior arch
- Lateral masses: bear the weight of the cranium
- Transverse process: project laterally, and are relatively flat
- Transverse foramen: passage for vertebral arteries and accompanying veins
- Superior articular facet: articulates with the occipital condyle
- Inferior articular facet: articulates with axis (C2)
- Tubercle for transverse ligament of Atlas: the ligament helps to hold the dens of C2 in place
- Posterior arch
- Posterior tubercle
- Groove for vertebral artery: allows passage for vertebral artery into the cranium
C2 = Axis (Atypical Vertebra)
- Strongest of the cervical vertebrae
- Atlas (C1) carries the cranium and rotates on the Axis (C2)
- Body
- Dens: projects superiorly from the body, and articulates with the posterior surface of the anterior arch of the Atlas, forming a synovial joint
- Embryologically, the dens represent the remnant of the body of the Atlas
- Anterior articular facet: articulates with the posterior surface of the anterior arch of Atlas (C1)
- Posterior articular facet: where the dens is supported by the transverse ligament of the atlas
- Pedicles
- Lateral masses
- Superior articular facet: where the atlas (C1) rotates
- Inferior articular facet: articulates with C3
- Transverse process: extends lateroinferior
- Transverse foramen: passage for vertebral arteries and accompanying veins
- Laminae
- Spinous process: bifurcated in whites, but not as common in blacks or females
C3-C7 (Typical Vertebrae)
- Body
- Transverse process
- Transverse foramina: vertebral artery goes through C3 – C6, but not C7
- Anterior tubercle: muscle attachment
- Posterior tubercle: muscle attachment
- Pedicles
- Lamina
- Superior articulate facet: more transverse plane to allow more articulation, gliding movement
- Inferior articulate facet: more transverse plane to allow more articulation, gliding movement
- Vertebral foramen: triangular and large, contains large portion of spinal cord
- Uncus of body: raised lateral margins of the superior surface of cervical vertebrae C3 – C7
- Spinous process: bifurcated in whites, but not as common in blacks or females
- C7 (vertebra prominens): defines the inferior limit of the neck posteriorly
Hyoid Bone
- Located anteriorly in the neck, at the level of C3
- Suspended by muscles that connect it to the mandible, styloid process, thyroid cartilage, manubrium, and scapula
- U-shaped
- Body
- Lesser horn
- Greater horn
- Stylohyoid ligament: it is a fibrous cord, which is attached to the top of the styloid process of the temporal bone and the lesser cornu (lesser horn) of the hyoid bone
Eagle Syndrome
- Elongation of the styloid process or mineralization of the stylohyoid ligament complex
- Radiographic features: can be seen on panoramic or lateral-jaw radiographs
- Symptoms: patient will present with pain when speaking, headaches, and limited range of motion
- Treatment: can be corrected with surgery
Joints of Vertebral Bodies
- Intervertebral discs: cartilaginous joints, connecting articulating surfaces of adjacent vertebral bodies
- Ligaments (support)
- Anterior longitudinal ligament (ALL): strong, broad fibrous band covering and connecting the anterolateral aspects of vertebral bodies and IV disks
- Extends from anterior aspect of the foramen magnum to the pelvic surface of the sacrum
- Limits extension
- Posterior longitudinal ligament: weaker, narrower band than ALL
- Runs within the vertebral canal along the posterior aspect of vertebral bodies
- Extends from the body of C2 to the sacrum
- Limits flexion
- Anterior longitudinal ligament (ALL): strong, broad fibrous band covering and connecting the anterolateral aspects of vertebral bodies and IV disks
Joints of Vertebral Arches
- Zygapophysial joints: synovial joint between superior and inferior articular facets of adjacent vertebrae. Allows gliding movements.
- Ligaments (accessory ligaments supporting the vertebral arches)
- Ligamenta flava: broad, pale yellow band of elastic tissue joining the laminae of adjacent vertebrae
- Form the posterior wall of the vertebral canal. Limit flexion and separation of vertebral laminae, protecting intervertebral disks
- Interspinous ligaments: weak ligaments joining adjacent spinous processes
- Inconsequential in the cervical region
- Nuchal ligament: strong, broad, and thickened fibroelastic tissue
- Extends from the occipital protuberance and posterior border of the foramen magnum to the spinous processes of the cervical vertebrae
- Muscle attachment
- Ligamenta flava: broad, pale yellow band of elastic tissue joining the laminae of adjacent vertebrae
Craniovertebral Joints
- Atlanto-occipital joint: synovial joint, with a thin, loose capsule between superior articular facets of the Atlas and the condyles of the occipital bone
- Flexion & extension
- Anatomical equivalent of the zygapophysial joint
- Ligaments
- Anterior atlanto-occipital membrane: extends from anterior arches of Atlas to anterior margin of foramen magnum
- Merges with the anterior longitudinal ligament in the center
- Posterior atlanto-occipital membrane: extends from posterior arches of Atlas to posterior margin of foramen magnum
- Perforated to allow passage for the vertebral artery
- Anterior atlanto-occipital membrane: extends from anterior arches of Atlas to anterior margin of foramen magnum
- Atlanto-axial joints
- Lateral atlanto-axial joints (2): synovial, gliding joint, with thin, loose capsule between inferior articular facets of the Atlas (C1) and the superior articular facets of the Axis (C2).
Atlanto-Axial Joints
-
Types:
- Median Atlanto-Axial joint: Pivot joint between dens of C2 and anterior arch of C1
- Lateral Atlanto-Axial joints: Synovial gliding joints between the articular facets of the atlas (C1) and axis (C2)
-
Ligaments:
- Anterior Atlanto-Axial Membrane: Extends from anterior arches of Atlas to anterior arches of Axis and merges with the anterior longitudinal ligament in the center.
- Posterior Atlanto-Axial Membrane: Extends from posterior arches of Atlas to posterior arches of Axis. It's a superior continuation of the Ligamenta flava but has less elastic fibers.
- Tectorial membrane: Superior continuation of posterior longitudinal ligament from the body of Axis (C2) to the anterior aspect of the foramen magnum.
-
Cruciate ligament:
- Transverse ligament of atlas: Strong band extending between tubercles on lateral masses of C1.
- Superior and inferior longitudinal bands: Span from the transverse ligament to the occipital bone superiorly and to the body of C2 inferiorly.
- Alar ligaments: Extend superolaterally from each side of the dens to the lateral margin of the foramen magnum.
- Check ligaments: Prevent excessive rotation of the joints.
- Ligamentum nuchae: A broad, flat ligament that extends from the external occipital protuberance to the spinous processes of the cervical vertebrae. It supports the head and limits cervical flexion.
Movements of Cervical Vertebrae
- Rotation
- Lateral Bending
- Flexion
- Extension
Temporomandibular Joint (TMJ)
- Type: Modified hinge synovial joint.
- Unique feature: Only moveable joint in the cranium.
- Movements: Allows gliding and slight rotation (protrusion and retrusion), flexion (elevation), and extension (depression).
-
Components:
- Mandibular fossa of the temporal bone: Shallow depression on the temporal bone.
- Articular tubercle of the temporal bone: A bony projection anterior to the mandibular fossa.
- Condylar process of the mandible: A bony projection on the mandible that articulates with the temporal bone.
- Articular disc of the TMJ: Separates the fibrous capsule into superior and inferior articular cavities.
-
Ligaments:
- Lateral ligament: Intrinsic, strengthens the joint laterally and prevents posterior dislocation of the TMJ. Attaches superiorly to the articular tubercle and inferior surface of the zygomatic arch, and inferiorly to the neck of the mandible.
- Sphenomandibular ligament: Extrinsic, attaches superiorly to the spine of the sphenoid bone and inferiorly to the lingula of the mandible.
- Stylomandibular ligament: Extrinsic, attaches superiorly to the styloid process of the temporal bone and inferiorly to the angle of the mandible.
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