Osteology of The Head and Neck Flashcards
What are the functions of the skull?
Protects the brain, brainstem, cranial nerves and vasculature
Provides attachment for muscles
Provides a framework for the head
Gives us our identity
How are the different types of bones formed?
Flat - intramembranous ossification
Irregular - endochondral ossification
What are pneumatised bones and what are their purpose?
Bones with air spaces (air cells or sinuses)
Reduces skull weight and adds resonance to the voice
Give examples of pneumatised bones
Frontal
Temporal
Sphenoid
Ethmoid
What does the neurocranium include?
Bony case of the brain, cranial meninges, with a dome-like roof - calvaria, and floor - cranial base
What does the viscerocranium include?
Facial skeleton - anterior part of cranium consisting of bones surrounding the oral cavity, nasal cavity and most of the orbit
What are the bones of the neurocranium?
Frontal
Parietal x2
Occipital
Sphenoid
Temporal x2
Ethmoid
What are the bones of the viscerocranium?
Palatine x2
Lacrimal x2
Nasal x2
Zygomatic x2
Inferior Nasal Concha x2
Maxilla x2
Mandible
Vomer
What are the different views of the skull
Lateral - Norma lateralis
Above - Norma verticalis
Below - Norma basalis
Behind - Norma occipitalis
In front - Norma frontalis
What features of the skull can be seen laterally?
Neurocranium - external acoustic meatus, styloid and mastoid processes and temporal fossa
Viscerocranium - zygomatic arch, mandible and infratemporal fossa
What are the borders of the temporal fossa?
Superior and posterior - superior and inferior temporal lines
Anterior - frontal process of zygomatic bone and zygomatic process of frontal bone
Inferior - infratemporal crest deep to zygomatic arch
Give examples of landmarks in the neurocranium
Asterion
Inion
Lambda
Vertex
Bregma
Pterion
Glabella
Nasion
What is the pterion?
H-shaped junction of sutures - frontal, parietal, temporal and greater wing of sphenoid bone
Structurally weak area of the skull and vulnerable to injury
Why should pterion injury be taken seriously?
Overlies anterior branch of middle meningeal artery which if damaged can lead to extradural (epidural) hematoma
How can the pterion be located?
4cm superior to midpoint of zygomatic arch
3cm posterior to frontal process of zygomatic bone
What is the lambda?
The intersection of the sagittal and lambdoid suture
What are Wormian bones and where are they found?
Small islands of bone that may be seen within a cranial suture
Most commonly seen in the lambdoid suture
What are fontanelles?
Fibrous membranes that fuse in post natal life
Name the different fontanelles?
Frontal
Parietal
Sphenoid
Mastoid
Name the different paranasal sinuses
Frontal sinuses
Ethmoidal cells
Maxillary sinuses
Give examples of landmarks found from the Norma basalis view of the skull
Carotid canal
Jugular foramen
Foramen magnum
Incisive fossa
Greater palatine foramen
Foramen lacerum
Foramen ovale
Foramen spinosum
Hypoglossal canal
Where is the ligamentum nuchae found?
Attaches the external occipital protuberance and foramen magnum to the spinous processes of the cervical vertebrae
What is the purpose of the ligamentum nuchae?
Supports the head and resists flexion
Attachment point for muscles
Which cervical vertebrae are bifid?
C2 - C6
What are the names of the atypical spinal vertebrae?
C1 - atlas
C2 - axis
C7 - vertebra prominens
Name the features found in typical cervical vertebrae
Transverse process - foramen transversarium - posterior tubercle and anterior tubercle
Body
Spinous process
Vertebral arch
Vertebral foramen
Lamina
Articular facets
Describe C7
Spinous process elongated but not bifid - site of attachment for the ligamentum nuchae
Smaller foramen a transversaria as the vertebral artery does not need to pass through it
Where does articulation occur?
At the articular facets where the superior facet articulates with the inferior facet of the preceding vertebra
Describe C1
Has anterior and posterior arches
No body
Anterior arch has articular facet for the dens of C2
Has superior articular facet for occipital condyle
Has transverse process and transverse foramina
Describe C2
Has a body
Has a bifid spinous process
Has transverse process and transverse foramina
Has dens or odontoid process which acts as an axis for the atlas and atlanto-occipital joint
Has large superior articular facets
Where is the atlanto-occipital joint found and what does it allow?
Between the skull and C1
Allows flexion and extension of the condyloid joint (nodding)
Where is the lateral atlanto-axial joint and what does it allow?
Between C1 and C2
Allows rotation of head (side to side)
Assisted by transverse ligament of atlas holding the dens in position
What does the lateral atlanto-axial joint replace?
An intervertebral disc between C1 and C2
What are alar ligaments?
Ligaments that prevent excessive rotation of the head and neck
They connect the dens to the occipital condyles
Describe the hyoid bone
U shaped bone found at C3 level of neck
Does not articulate with any skeletal elements, suspended by muscles and ligaments
Connects oral cavity with pharynx posteriorly and larynx inferiorly- helping to keep airway open
Site of attachment for suprahyoid and infrahyoid muscles
What are the purpose of the lesser horns of the hyoid bone?
Form the site of attachment for the stylohyoid ligament which connects the hyoid to the styloid process of the skull
