3a Axial Skeleton System Flashcards
Axial Skeleton Components
Skull, facial bones, spinal cord
5 basic types of bones
- long
- short
- flat
- irregular
- sesamoid
Long
compact (humerus)
short
spongy except surface (wrist-trapezoid)
Flat
plates of compact enclosing spongy (sternum and scapula)
Irregular
variable (vertebra)
Sesamoid
develop in tendons or ligaments (patella-knee caps)
Sutural bones
in joints between skull bones
immovable joints that hold the skull bones together
Skull is composed of how many bones and where
22 cranial and facial bones
Skull forms?
large cranial cavity and smaller cavities (including nasal cavity and orbits)
Paranasal sinuses
-Cavities in bones of the skull that communicate with the nasal cavity
~Mucous-lined cavities in the skull (filter and purify air) ~make the skull lighter
~Resonating chambers for speech
Mandible
only voluntary bone that we can move in the skull (other than the ear ossicles within the temporal bone)
The skull has how many cranial bones?
8
the skull has how many facial bones?
14
8 cranial bones purpose?
- protect brain & house ear ossicles
- muscle attachments for jaw, neck & facial muscles
14 facial bones purpose?
- protect delicate sense organs - smell, taste, vision
- support entrances to digestive and respiratory systems
8 cranial bones?
- frontal
- parietal (2)
- temporal (2)
- occipital
- sphenoid
- ethmoid
How many bones are in the human body?
206
How many bones are in the axial skeleton
80
Axial Skeleton
- lie along longitudinal axis
- skull, hyoid, vertebrae, ribs, sternum, ear ossicles
Appendicular skeleton composed of
Upper & lower limbs and pelvic & pectoral girdles
Frontal bone
-forehead, roof of orbits (eye sockets), anterior cranial floor
-supraorbital margin and frontal sinus(right above eye)
~a “black eye” not a lot of muscle and facia right there
Parietal bone
sides and roof of cranial cavity
Temporal bone
- two temporal bones connected by the temporal squama Sutures
- zygomatic process forms part of arch (stereotypical cheek bone)
- external auditory meatus (opening to the outside sound comes through)
- mastoid process (behind ear flat)
- styloid process (right below mastoid process for muscular attachment)
- stylomastoid foramen (VII) sits between styloid and mastoid process
- Mandibular fossa (TMJ)
- Petrous portion (VIII)
- carotid foramen (carotid artery) supplies blood to the brain
- jugular foramen (jugular vein) passes back to the heart through this
Occipital bone
-foramen magnum (spinal cord passes through connecting to the brain)
-occipital condyles (skull is going to sit on spinal cord)
-external occipital protuberance (bump of knowledge)
attachment for ligament nuchae (allows skull movement and supports spinal cord)
-superior (higher than inferior) and inferior nuchal lines (important for muscular and facia attachments)
Sphenoid bone (butterfly bone)
-Base of skull
(articulates with a number of bones)
-Pterygoid (p is silent) processes are attachment sites for jaw muscles
-Pterygoid plates
Sella turcica
holds pituitary gland (superior portion of the sphenoid bone)
Ethmoid bone forms:
- part of the anterior portion of the cranial floor
- the medial wall of the orbits
- the superior portion of the nasal septum
- most of the superior side walls of the nasal cavity
- major superior supporting structure of the nasal cavity
Crista Galli (ethmoid bone) & perpendicular plate
attaches to the membrane that covers the brain
Lateral masses of the ethmoid bone contain what
ethmoid sinuses (for filtering air, warm air, making skull lighter)
14 facial bones
- Nasal (2)
- Mandible (1) only voluntary
- Inferior nasal conchae (2)
- Maxillae (2)
- Lacrimal (2)
- Zygomatic (2)
- Palatine (2)
- Vomer (1)
Maxillary Bones
- floor of orbit (eye socket), floor of nasal cavity or hard palate (hard portion of upper mouth)
- maxillary sinus (filtering air, making skull lighter)
- alveolar processes hold upper teeth
- cleft palate is lack of union of maxillary bone
Zygomatic bones
- Cheekbones
- form lateral wall of orbit along with sphenoid bones
- Part of zygomatic arch along with part of temporal
Lacrimal and Inferior Nasal Conchae
-Lacrimal bones
~part of medial wall of orbit
~lacrimal fossa houses lacrimal sac
-Inferior nasal concha or turbinate (not part of ethmoid)
Mandible bone landmarks
- Body (main portion), angle (“jaw bone”) & rami (portion sits just anterior and a little inferior to ears)
- Condylar & coronoid processes (help form TMJ with temporal bone)
- Alveolar processes for lower teeth
- Mandibular & mental foramen (nerves are going to pass through)
TMJ (temporomandibular joint)
-the mandible articulates with the temporal bone
-tmj syndrome is dysfunction of tmj
~causes appear to be numerous and the treatment is similarly variable
Palatine bone
- L-shaped bone: one end is back part of the hard palate, other end is part of orbit
Vomer Bone
-Posterior part of nasal septum
Nasal Septum bone
- Divides nasal cavity into left and right sides
- formed by over, perpendicular plate of ethmoid and septal cartilage
Deviated Septum
-Does not line the midline
~developmental abnormality or trauma
The orbits (eye sockets)
- contain the eyeballs and associated structures and are formed by 7 bones of the skull
- 5 important foramina are associated with each orbit
Bones of the orbit
Frontal Sphenoid Zygomatic Maxilla Lacrimal Ethmoid Palatine
Bones of the roof of orbit
Frontal and sphenoid bones
Bones of the lateral wall of orbit
zygomatic ad sphenoid
Bones of floor of orbit
maxilla, zygomatic, and sphenoid
Bones of the medial wall of orbit
maxilla, lacrimal, ethmoid and sphenoid
Orbital fissures and optic foramen
allow optic nerves to pass through as well as other nerves to innervate muscles of the face to allow for expression and to move the eye ball as well as provide sensation to the area
Foramina of the skull (5)
- Foramen magnum
- Optic foramen
- Mandibular foramen
- Carotid Foramen
- Stylomastoid foramen
Foramen Magnum
- Occipital bone
- Sits inferior part of the brain connects with spinal cord (CN (cranial nerve11) XI)
- Vertebral and spinal arteries pass through this opening (supply blood to crucial structures in the brain and spinal cord)
Optic foramen
- Sphenoid Bone
- Optic nerve (II) & ophthalmic artery (important for the health of the eye)
Mandibular foramen
-Mandible
Carotid foramen
- Temporal bone (between greater and lesser wings)
- Internal carotid artery (supplying blood to brain)
Stylomastoid foramen
- Temporal bone (between mastoid and styloid processes - behind ears)
- Cranial Nerve (CN) VII (7) (facial nerve - allows facial expression) and stylomastoid artery
Sutures include (4):
Coronal
Sagittal
Lambdoid
Squamous
Coronal Suture
unites the frontal and both parietal bones
Sagittal Suture
unites the two parietal bones
Lambdoid Suture
unites the two parietal bones to the occipital
Squamous Suture
unites the parietal and temporal bones
Which cranial bones contain the sinuses
Frontal
Sphenoid
Ethmoid
Maxillae
When does Sinusitis occur?
when membranes of the paranasal sinuses become inflamed due to infection or allergy (pressure in skull - sinus infection)
Fontanels
-Dense connective tissue membrane-filled spaces between the cranial bones of fetuses and infants
~remain unossified at birth but closes early in a Childs life
2 major functions of fontanels?
- ) enables the fetal skull to modify its size and shape as it passes through the birth canal
- ) permit rapid growth of the brain during infancy
Major fontanels?
Anterior, Posterior, Anterolaterals, and Posterolaterals
Anterior fontanel is located where?
between frontal and parietal (future coronal suture)
Posterior fontanel is located where?
between parietal and occipital bone
Posterolateral fontanel
between the temporal, parietal and occipital bones
Anterolateral fontanel
sits between a number of bones (future squamous suture)
Hyoid Bone
- U-shaped single bone
-Throat area - No bony articulations
~suspended by ligament and muscle from skull (unique)
-Supports the tongue & provides attachment for tongue, neck and pharyngeal muscles
(floating important for muscular attachments to assist with swallowing)