Osteology and Radiology (Skull) Flashcards
What 2 bones make up the skull?
Cranium + Mandible
In an adult what is the only movable joint?
Temporomandibular Joint
The points of interlocking bone in the skull are known as what? What type of joint is this?
Fibrous joints called sutures
Give 3 functions of the skull
1) Encloses and protects the brain and the special sense organs (eyes, ears, tongue, nose)
2) Creates specialised environment in which the brain thrives
3) Site for attachments of muscles (externally) and meninges (internally- periosteal layer of dura mater)
The thickness of cranium is variable, give 2 thick areas and 1 thin area
Thick areas: Occipital and frontal bones
Thin areas: Pterion
What is the Pterion?
Which important artery is found below the Pterion and why is this important?
Pterion: parital, frontal, temporal and sphenoid
Artery found beneath pterion is the MMA and can be damaged during head injury leading to a extradural haematoma
The cranium has a tri-lamina bony structure, what are the 3 layers?
Give 2 features of each
2 plates of compact bone (thick plates):
- Outer and Inner plate
- Resilient
1 middle layer of spongy bone:
- Diploe layer (cancellous bony tissue)
- Reduces weight of cranium
Label the bones of the skull
Label the image of the skull below
The Mandible is a bilateral bony structure, what are the 2 parts and how are they joined?
Formed by the union of R & L mandibles
Joined by a midline fibrous joint → Mental Symphisis
Label the following parts of the mandible:
- Condylar Process
- Coronoid Process
- Ramus
- Angle
- Body
- Mental foramen
- Alveolar arch
Which part of the mandible is the portion that
a) articulates with skull
b) non-articulating portion
c) located at the internal ridge
d) where nerves exit into chin to supply the skin of the face
a) condylar Process → articulates with skull
b) coronoid Process → non-articulating portion
c) alveolar Process → internal ridge
d) mental foramen
What feature of the bony edges of the skull aid in interlocking
Bony edges are serrated which allows the bones to interlock, making it less likely for them to easily unlock when force is applied one direction
List the 4 sutures of the skull and label them on the image below
What are the 3 sections where the sutures join? Label 2 of them on the image below
Sutures: Coronal, Sagittal, Lambdoid, Squamous
Join: Bregma, Lambda, Pterion
How can the cranial floor (cranial fossa) be divided?
Each division contains unique openings , list which CN exits through each
Divided into 3 fossae
1) Anterior Fossa: CN I and II (CN II foramen is on the junction between anterior and middle fossa)
2) Middle Fossa: CN II - VI
3) Posterior Fossa: CNs VII- XII
Cranial Nerves are numbered?
CNI – CN XII: from how they exit the cranial base from an anterior to posterior direction
What 3 bones make up the anterior cranial fossa?
What 2 ‘holes’ are found here and what CN passes here?
Bones:
- Frontal
- Ethmoid
- Sphenoid
Holes:
- Olfactory foramina in cribriform plate (CNI)
- Optic canal (CNII)
What 2 bones make up the Middle Cranial Fossa?
What 4 ‘holes’ are found here and what CN passes here?
Bones:
- Sphenoid
- Temporal
Holes:
- Superior orbital fissure (CN III, IV, VI, V1)
- Foramen rotundum (CN V2) (part of trigeminal nerve)
- Foramen ovale (CN V3) (other part of trigeminal nerve)
- Foramen spinosum (MMA)
What 4 bones make up the Posterior Cranial Fossa?
What 4 ‘holes’ are found here and what CN passes here?
Bones:
- Temporal
- Occipital
- Bits of the Sphenoid
- Bits of the Parietal
Holes:
- Foramen magnum
- Internal acoustic meatus (CN VII, VIII)
- Jugular foramen (CN IX,X,XI)
- Hypoglossalcanal (CN XII)
Label the bones below
Palatine plate
Sphenoid
Temporal
Occipital
What is the major opening of the skull?
Foramen magnum
Through what structure does the facial nerve exit the skull?
Stylomastoid Foramen
Give 2 functions of the foramina of the cranial base
1) Decrease weight of skull
2) Passageway for structures to enter/exit skull
Give 3 things that may enter/exit the skull through the cranial base (2 normal, 1 pathological)
1) Nerves:
- sensory (enter)/motor (exit)
- SNS fibres (enters)/PNS outflow (exits)
2) Blood vessels:
- arterial supply to brain and meninges (enter)
- venous blood (enters/exits)
3) Infections (enters/exits)
