Axial Skeleton- Skull Flashcards
(90 cards)
1
Q
What is the axial skeleton composed of?
A
- The bones along the central axis of the body, which commonly divide into 3 regions.
1. Skull
2. Vertebral Column
3. Thoracic Cage - There are 80 bones in the axial skeleton.
- The main function of the axial skeleton is to form a - framework that supports and protects the organs
- It also houses special sense organs and provides areas for attachment of skeletal muscles
2
Q
What 2 types of bones make up the skull?
A
- Cranial bones: form the rounded cranium which completely surrounds and encloses the brain (8)
- Provide attachment sites for several jaw, head and neck muscles - Facial bones: form the face (14)
- Protect the entrances to the digestive and respiratory systems
- Provide attachment sites for facial muscles
3
Q
What are the 8 cranial bones?
A
- Frontal bone
- Parietal bones 1 and 2
- Temporal bones 1 and 2
- Occipital bone
- Sphenoid bone
- Ethmoid bone
4
Q
What are the 14 facial bones?
A
- Zygomatic bones 1 and 2
- Lacrimal bones 1 and 2
- Nasal bones 1 and 2
- Vomer bone
- Inferior nasal conchae bones 1 and 2
- Palatine bones 1 and 2
- Maxillae bones 1 and 2
- Mandible bone
5
Q
What are orbits? (anterior view)
A
- Left and right eye sockets
- Are formed from a complex articulation of multiple skull bones
- Superior orbital fissure and inferior orbital fissure are 2 large openings in the orbits
- Superior to the orbits are the superciliary arches (brow ridges)
6
Q
What is the glabella? (anterior view)
A
- Smooth landmark area that is superior to the left and right nasal bones and between the orbits
- Part of the frontal bone sandwiched between superciliary arches
7
Q
What are maxillae? (anterior view)
A
- Left and right facial bones that form most of the upper jaw and lateral boundaries of the nasal cavity
- Also help form the inferior floor of each orbit
- Each inferior portion of maxillae contain alveolar processes that house the upper teeth
8
Q
What are infraorbital foramen? (anterior view)
A
- Within maxillae facial bones
- Inferior to each orbit
- Conducts blood vessels and nerves to the face
9
Q
What is the mandible? (anterior view)
A
- Facial bone which forms the lower jaw
- Prominent “chin” section is called the mental protuberance
- Supports inferior teeth and provides attachment for the muscles of mastication
- 2 vertical-to-oblique ascending posterior regions called ramus
10
Q
What is the anterior nasal spine? (anterior view)
A
- Inferior border of the nasal cavity
- Its the thin ridge of bone that subdivides the nasal cavity into left and right halves
- Helps form the nasal septum
11
Q
What are inferior nasal conchae? (anterior view)
A
- Found along the lateral walls of the nasal cavity
- 2 scroll-shaped bones
12
Q
What is the coronal suture? (superior view)
A
- The articulation between the anterior frontal bone and more posterior parietal bones
- Extends across the superior surface of the skull along a coronal plane
13
Q
What is the sagittal suture? (superior view)
A
- Extends between the superior mid-lines of the coronal and lambdoid sutures
- The midline of the cranium
- Articulation between the right and left parietal bones
14
Q
What is the parietal foramen/ parietal foramina? (superior view)
A
- Along the posterior 1/3 of the sagittal suture
- Either single or paired (number can vary between left and right sides)
- Conduct tiny emissary veins from the veins of the brain to the veins of the scalp
15
Q
What is the lambdoid suture? (superior view)
A
- Extends like an arc across the posterior surface of the skull
- Articulates the parietal bones and the occipital bone
16
Q
What is the external occipital protuberance? (posterior view)
A
- Bump on the back of the head
- Size varies based on genetics and hormonal sex
17
Q
What are the lacrimal bones? (lateral view)
A
- Articulates with the nasal bone anteriorly and with the ethmoid bone posteriorly
- Part of the medial wall of each orbit
- Lacrimal groove is a small depressed inferior opening that provides a passageway for the nasolacrimal duct (drains tears into the nasal cavity)
18
Q
What is the sphenoid bone? (lateral view)
A
- A portion articulates with the frontal, parietal and temporal bones
19
Q
What is the pterion region? (lateral view)
A
- The ‘H’ shaped set of sutures of the frontal, parietal, temporal and sphenoid bone
20
Q
What is the zygomatic arch? (lateral view)
A
- Where the temporal process of the zygomatic bone and the zygomatic process of the temporal bone fuse to form the bony prominences of your cheeks
21
Q
What is the temporomandibular joint? (lateral view)
A
- The articulation point of the mandible and the mandibular fossa of the temporal bone
22
Q
What is the mastoid process? (lateral view)
A
- Posterior to your external acoustic meatus of the skull (underneath the external ear opening)
- The bump you feel posterior to your ear lobe
23
Q
What is the cranial cavity? (sagittal sectional view)
A
- Formed from a complex articulation of the frontal, parietal, temporal, occipital, ethmoid and sphenoid bones
24
Q
What is the frontal sinus? (sagittal sectional view)
A
- A vessel impression on the internal surface of the cranial cavity
- This visible space is found in the frontal bone
25
What is the sphenoid sinus? (sagittal sectional view)
- A vessel impression on the internal surface of the cranial cavity
- This visible space is found in the sphenoid bone
26
What is the nasal septum? (sagittal sectional view)
- Made up of the perpendicular plate (superior) of the ethmoid bone and the vomer (inferior)
27
What is the hard palate? (sagittal sectional view)
- Maxillae and palatine bones form it
| - Acts as both the floor of the nasal cavity and part of the roof of the mouth
28
What is the pterygoid processes? (inferior view)
- On the posterior aspect of either side of the hard palate
- Sphenoid bone processes
- Vertical projections that begin at the boundary between the greater and lesser wings of the sphenoid bone
29
What are choanae? (inferior view)
- Adjacent to pterygoid processes
| - Internal openings of the nasal cavity
30
What are the foramen ovale? (inferior view)
- Closest foramina to the pterygoid processes
31
What are foramen spinosum? (inferior view)
- Posterior and lateral to foramen ovale
| - Slightly smaller foramina
32
What is the jugular foramen? (inferior view)
- Posterior and lateral to foramen spinosum and foramen ovale
- The "throat" foramen in the space between temporal and occipital bones
- Jugular notch is the part of the occipital bone that helps form the jugular foramen
33
What is the largest foramen? (inferior view)
- Literally means "big hole"
| - Through this opening, the spinal cord enters the cranial cavity and becomes continuous with the brainstem
34
What is the cribriform plate? (internal view of cranial base)
- Surrounded by the frontal bone
| - Part of the ethmoid bone
35
What are the wings of the sphenoid bone? (internal view of cranial base)
- Posterior to the frontal bone are the lesser (anterior) and greater (posterior) wings of the sphenoid bone
- Optic canals are located in the lesser wings
36
What are sutures?
- Immovable joints that form the boundaries between the cranial bones
- Dense regular connective tissue seals the bones together at a suture
37
What are the squamous sutures?
- On each side of the skull
- Articulates the temporal bone and the parietal bone of that side
- The squamous (flat) part of the temporal bone typically overlaps the parietal bone
38
What are sutural bones?
- Typically small and ranging in size
- Any suture may have these bones, but they are most common and numerous in the lambdoid suture
- In adulthood, sutures typically disappear as the adjoining bones fuse (starts internally/endocranially)
39
What is the calvaria or skullcap of the cranium?
- Roof of the cranium
| - Composed of the squamous part of the frontal bone, the parietal bones and the squamous part of the occipital bone
40
What is the base of the cranium?
- Composed of portions of the ethmoid, sphenoid, occipital and temporal bones
41
What is the frontal bone?
- Forms part of the calvaria, the forehead and the roof of the orbits
- Has a flat (squamous) part at the front and ends at the supraorbital margins
42
What are the supraorbital margins? (frontal bone)
- Each form the superior ridge of the eye orbits
43
What are the supraorbital foramen? (frontal bone)
- Holes or notches at the midpoint of each supraorbital margin
44
What are superciliary arches? (frontal bone)
- Superior to supraorbital margins
| - Brow ridges (more pronounced in males)
45
What are zygomatic processes? (frontal bone)
- Lateral to each orbital part of the frontal bone
| - Articulates with the frontal process of the zygomatic bone
46
What is the frontal crest? (frontal bone)
- On the internal surface of the frontal bone
- Mid-line elevation of bone that serves as a point of attachment for the falx cerebri (a protective connective tissue sheet that helps support the brain)
47
What are the parietal bones?
- Form the lateral walls and roof of the cranium
| - Each bone is bordered by 4 sutures that unite it to it's neighboring bones
48
What are the superior and inferior temporal lines? (parietal and frontal bones)
- Pair of faint ridges that arc across the surface of the parietal and frontal bones
- Mark the attachment site of the large temporalis muscle that closes the mouth
49
What are the parietal eminences? (parietal bones)
- Superior to the temporal lines
| - Rounded, smooth parietal surfaces
50
What are temporal bones?
- Form the inferior lateral walls and part of the floor of the cranium
- Each temporal bone has a complex has a complex structure composed of 3 parts: petrous, squamous, tympanic
51
What is the petrous part? (temporal bones)
- The thick part of the temporal bone that houses sensory structures of the inner ear that provide information about hearing and balance
52
What is the internal acoustic meatus? (temporal bones)
- Also called internal auditory canal
| - Provides a passageway for nerves and blood vessels to and from the inner ear
53
What is the mastoid process? (temporal bones)
- The prominent bulge on the inferior surface of the temporal bone
- An anchoring site for muscles that move the neck
- Rather than being being solid bone, it is filled with small interconnected air cells that communicate with the middle ear
54
What is the styloid process? (temporal bones)
- Thin, pointed projection of bone
- Serves as an attachment site for several hyoid and tongue muscles
- Foramen lies between the mastoid process and styloid process (facial nerve extends through this foramen to innervate the facial muscles)
55
What is the squamous part of the temporal bones?
- The lateral flat surface of the temporal bone immediately inferior to the squamous suture
56
What is the zygomatic process? (temporal bones)
- Immediately inferior to the squamous part
- Curves laterally and anteriorly to unit with the temporal process of the zygomatic bone
- Union of these processes forms the zygomatic arch
57
What is the mandibular fossa? (temporal bones)
- Each temporal bone articulates with the mandible inferior to the base of both zygomatic processes in a depression called the mandibular fossa
58
What is the articular tubercle? (temporal bones)
- Bump that is anterior to the mandibular fossa
59
What is the tympanic part? (temporal bones)
- Immediately posterolateral to the mandibular fossa
| - A small, bony ring surrounding the entrance to the external acoustic meatus
60
What is the occipital bone?
- Subdivided into a flattened squamous part which forms the posterior region of the skull, and a median basilar part which forms a portion of the base of the cranium
61
What are occipital condyles? (occipital bone)
- Lateral to the foramen magnum
- Smooth knobs at the back of the head
- Skull articulates with the first cervical vertebra at the occipital condyles
- Posterior to each condyle is a condylar canal which transmits a vein
62
What is the hypoglossal canal? (occipital bone)
- At the anteromedial edge of each occipital condyles
| - Through each is a hypoglossal nerve that extends to supply the tongue muscles
63
What is the external occipital crest? (occipital bone)
- Projects in a posterior direction from the foramen magnum, ending in the external occipital protuberance
64
What are the superior and inferior nuchal lines? (occipital bone)
- Intersecting the external occipital crest are these two horizontal ridges
- Attachment sites for ligaments and neck muscles
65
What are the grooves found on the internal surface of the occipital bone?
- Groove for the superior sagittal sinus
- Groove for the transverse sinus
- Portion of the groove for the sigmoid sinus
66
What is the internal occipital protuberance?
- Junction of the left and right internal grooves for the transverse sinuses
- An internal occipital crest extends from this protuberance to the border of the foramen magnum
67
What is the sphenoid bone?
- Has a complex shape resembling a butterfly
- Referred to as a "bridging bone" because it unites the cranial and facial bones
- Articulates with almost every bone of the skull
- Hidden mostly by superficial bones
68
What is the hypophyseal fossa? (sphenoid bone)
- The pituitary gland is suspended inferiorly from the brain into the prominent midline depression between the greater and lesser wings
- This depression is the hypophyseal fossa
- The bony enclosure around this fossa is called the sella turcica (houses the pituitary gland)
69
What are anterior and posterior clinoid processes? (sphenoid bone)
- Projections on the other side of the sella turcica
70
What is the optic groove? (sphenoid bone)
- Anterior to sella turcica
- Shallow, transverse depression that crosses the superior surface of the sphenoid bone
- Optic foramen are located on either end of this groove
71
What are medial and lateral pterygoid plates? (sphenoid bone)
- Each pterygoid process forms a pair of plates
| - Provide the attachment surfaces for some muscles that move the lower jaw and the soft palate
72
What is the ethmoid bone?
- Irregularly shaped bone positioned between the orbits
- Forms the anteromedial floor of the cranium, the roof of the nasal cavity, part of the medial wall of each orbit and part of the nasal septum
73
What is the crista galli? (ethmoid bone)
- On the superior part of the ethmoid bone
| - A thin midsagittal elevation
74
What is the cribriform plate? (ethmoid bone)
- Immediately lateral to each side of the crista galli
- Horizontal plate that has numerous perforations called cribriform foramina (provide passageways for the olfactory nerves)
75
What are ethmoidal labyrinths? (ethmoid bone)
- Paired bones that contain ethmoidal sinuses
- These sinuses open into both sides of the nasal cavity
- The smooth part of each labyrinth is called the orbital plate
- These labyrinths are partially composed of superior and middle nasal conchae
76
What is the perpendicular plate? (ethmoid bone)
- The inferior, midline projection of the ethmoid bone
| - Forms the superior part of the nasal septum
77
What are cranial fossae?
- 3 curved depressions on the floor of the cranial cavity
| - Their surfaces are grooves for blood vessels and numerous foramina
78
What is the anterior cranial fossa?
- The shallowest of the 3 depressions
- Formed by the frontal bone, the ethmoid bone and the lesser wings of the sphenoid bone
- Houses frontal lobes of the cerebral hemispheres
- Ranges from the internal surface of the inferior frontal bone (anteriorly), to the posterior edge of the lesser wings in the sphenoid bone (posteriorly)
79
What is the middle cranial fossa?
- Inferior and posterior to the anterior cranial fossa
- Ranges from the posterior edge of the lesser wings of the sphenoid bone (anteriorly), to the anterior part of the petrous part of the temporal bone (posteriorly)
- Formed by the parietal, sphenoid and temporal bones
- Houses temporal lobes of the cerebral hemispheres and part of the brainstem
80
What is the posterior cranial fossa?
- The most inferior and posterior cranial fossa
- Extends from the posterior part of the petrous part of the temporal bones to the internal posterior surface of the skull
- Formed by occipital, temporal and parietal bones
- Houses the cerebellum and part of the brainstem
81
What is the vomer bone?
- Has a triangular shape, is curved, thin and has a horizontal projection ( called ala- which articulates superiorly with the sphenoid bone)
- Articulates along its midline with both the maxillae and the palatine bones
- Its vertical plate articulates with the perpendicular plate of the ethmoid bone
82
What is the mandibular foramen? (mandible bone)
- On the medial aspect of the ramus, a prominent foramen provides a passageway for blood vessels and nerves that innervate the inferior teeth
83
What is the condylar? (mandible bone)
- The posterior projection of each mandibular ramus
| - Terminates at the head of the mandible
84
What is the temporomandibular joint? (mandible bone)
- Each articulation of the head of the mandible with the mandibular fossa of the temporal bone is this mobile joint
- Allows us to move the lower jaw when we talk or chew
85
What is the nasal complex?
- Composed of bones and cartilage that enclose the nasal cavity and the paranasal sinuses
- Most of the anterior walls are formed by cartilage and soft tissues of the nose
- Bridge of the nose is supported by the maxillae and the nasal bones
86
What are paranasal sinuses?
- Ethmoidal, frontal, maxillary and sphenoidal air-filled chambers that open into the nasal cavities
- Have mucous lining that helps humidify and warm inhaled air
87
What is the orbital complex?
- Bony cavities called orbits enclose and protect the eyes and the muscles that move them
- This complex consists of multiple bones that form each orbit
88
What are the bones that are associated with the skull?
-The auditory ossicles and the hyoid bone
89
What are the auditory ossicles?
- 3 tiny ear bones that are housed within the petrous part of the temporal bones
- Malleus, incus and stapes
90
What is the hyoid bone?
- A slender, curved bone located inferior to the skull
- Between the mandible and the larynx (voice box)
- Doesn't articulate with any other bone in the skeleton
- Has a midline body and 2 horn-like processes called greater cornu and lesser cornu (serve as attachment sites for the tongue and anterior muscles/ligaments)
