ch 4 - boney skeleton Flashcards
role bones play
• Provide a framework that supports the body (keep us upright, provides mobility)
• Provides sites for muscle attachment
• Protective covering for certain organs and regions of the body (ex. Skull protects the brain)
• Certain bones contain red bone marrow (flat) which produces new red blood cells (hemopoietic tissue)
– Bones that don’t have red bone marrow contain yellow bone marrow that contains fat and serves as an energy storage
• Bone acts as a storage medium and “buffer” for calcium in the blood. (Homeostasis)
– This helps to maintain a stable pH
types of bones
classified according to
- type of bone tissue
- general morphology of bone
types of bone tissue
Compact bone and rims of the bone – solid
This is the external part of the bone
Contain pillar like structures called osteon
Osteon has many rings
Spongy bone (trabecular = web-like)
Spongy on the inside
Internal web like
general morphology of bone
– Long bones (humus, femur, finger bones, ribs)
– Short bones (wrist bones, ankle bones)
– Flat bones (sternum, skull bones)
– Irregular bones they don’t fit into any categories
- Sesamoid bones: bones that are not attached to other bones but are embedded in a tendon
what makes bones strong
– The pillar like structures called Osteon and millions of these line up parallel to each other in the compact region
– Osteon is made up of collagen fibres which prevent cracks in bones as they are lined up in a parallel formation
– This organization makes bones very strong
– This pillars are organized to withstand the pressures and forces that they are exposed to
osteon
Central canal is the centre of the Osteon
– This is where vessels are situated
– The gaps are filled in the center with these vessels – in parallel to the osteon and these to add strength
Hollow rods are more lighter than solid rods and that is why bones are hollow
axial skeleton
• These are bones that are near proximity to the axis of symmetry
A. Skull
B. Vertebral column
C. Bony thorax (ex. sternum)
skull
• Made up mostly of flat bones
• Brain’s protective shell, but it is quite thin. This thinness doesn’t not limit its strength because the shape of the skull ensures its strength
– The curvature of the skull distributes and force applied to the skull
skull - sutures
• Joined by sutures
– Sutures have a jagged appeared where the bones meet and are very strong
– Not stitches but fibrous joints
– These are Synarthrodial joint (suture) which means they are not easily movable (vs. amphi and di-)
– Sutures leave small little holes known as foramen (these are bones that have joined together, but not fully as they leave gap)
skull - foramen
• Contain foramina for passage of nerves and vessels
– A true foramen: is where the hole is completely in cased by bone (not cartilages, not a ligament, etc)
bones of the skull
Can be categorized into 2 groups Cranium and facial bones
– Cranial bones: has some contribution to the cranial cavity (space where brain lies)
o Participates or forms some of the cranial
– Facial bones: all the other bones of the skull
cranial bones
Cranium has 8 large cranial bones (2 paired bones -> Parietal and Temporal) UNPAIRED -> SINGLE BONES
frontal, parietal (x2), temporal (x2), occipital, sphenoid, ethmoid
frontal bone
– Forms the forehead and the anterior portion of the cranial cavity
– The suture that joints the frontal bone to the parietal is known as the coronal suture
parietal
– Forms the roof of the cranial cavity
– The two parietal bones are jointed by the sagittital suture ( in the sagittal plane)
temporal
– There are 2 landmarks on the temporal bone
– Mastoid process is part of the temporal bone (means breast like shape) (many ligaments and muscles are attached to this)
– Styloid process (means column like) is part of the temporal bone located in front of the mastoid process (THIN AND LENGTHY; attachment for muscles and ligaments)
– Temporal -> time
– Grain of the hair over the temporal region to indicate age and wisdom?
occipital
– Located in the posterior skull
– Lying within or on-top are not the occipital lobes but the cerebellum
– The brain stem exists the cranial cravity through this side
sphenoid
– Forms a portion of the floor of the cranial cavity as it spans the width of the skull
– NOT a paired bone
ethmoid
- Forms the border between cranial and nasal cavity
other sutures
Lambdoid suture is between the parietal bone and the occipital bone (looks like a lambda symbol)
Occipital-temporal suture is between the occipital and the temporal bone
The squamous suture (means scale like) between the parietal and the temporal bone
pterion
(aka the boxer’s temple) it is a point of weakness and there is the medal (middle) meningeal artery (provides blood to brain (DURAL)) -> not all the bones but SEVERAL of them.
o blow to this region -> damage
o underneath the skull leads to confusion
facial and associated bones
There are 14 facial bones and they are much smaller than cranial
nasal (x2), maxillae (x2), zygomatic (x2), mandible, lacrimal (x2), palatines (x2), conchae (x2), vomer
nasal bones
– Paired bone
there are 2
– Mostly cartilage
maxillae
– Paired bone
– It extends into the mouth
– Fuses together right between the two front teeth
– Hard pallete -> 1/3 of the region is made of paired bone called pallentine
zygomatic
– Paired bones
– Form the cheek (holes)
mandible
– Jaw
– Holds the lower teeth
lacrimal
– Paired bone
– Located in the eye orbit (where the eye is)
– Has a small fossa that looks like a thumb print in the bone (called the lacrimal fossa) -> Fossa: places where structures attach
– Lacriminal fossa has a hole in it called the lacriminal foramen
– Lacriminal duct associated with lacrimincal gland that goes through lacriminal foramen
o The lacrimal gland sits on the lacrimal fossa which is a passage way for tears
o Duct bring it to nasal cavity as well -> sometimes u get a runny nose while crying
palatines
– Paired bones
– Forms part of the hard pallet (roof of the mouth)
– Portion of maxillae and palatine form hard roof
conchae
– Paired bones
– Bones by themselves that are in the nasal cavity
– Superior, inferior, middle concha
vomer
– In the nasal cavity that forms part of the septum
inside nasal cavity
- We moisten and warm air as well are remove foreign material in the atmosphere; this is done by a membrane
- The Concha, the perpendicular plate, and the vomer help create a larger surface area for the air to come in contact with the membrane
inside nasal cavity - the bones
The ethmoid bone (a cranial bone) protrude into the concha
– The superior concha of the ethmoid bone (not stand-alone bones; its ethmoid)
– The middle concha of the ethmoid bone
The Inferior concha should be known as just a concha bone
The perpendicular plate is also part of the ethmoid, so it is known as the perpendicular plate of the ethmoid bone
o Perpendicular plate of the ethmoid, along with the vomer forms the septum
not facial bones but close
Palatine bone is the roof of your mouth
A little lower than the skull is the hyoid bone
– It is an unpaired bone
– Located below the jaw
o When we swallow, we move the hyoid that moves the larynx
forgotten bones of the head
3 paired ossicles in middle ear (smallest bones in the body)
– Malleus = Hammer; Incus = Anvil; Stapes = Stirrup
– Eardrum -> tympanic membrane
– Vibrations from the tympanic membrane move the malleus which triggers vibrations of the incus and stapes
o Cranial nerve is responsible for sound reception
cranial fossa
Anterior fossa
– The frontal lobes
Middle fossa
– Temporal lobes are situated
Posterior fossa
– This is where the cerebellum is located
Cribriform plate
located on the top of the ethmoid bone
– The olfactory nerves run through these hole
– Crista galli is in the centre of the cribriform plate; they are the small holes in this plate which run all the way through the ethmoid bone and are entrances into the nasal bones
– Has a ligament called the faix cerebri
lesser wing
• The top of the anterior fossa is the lesser wing (of the sphenoid bone)
greater wing
• The greater wing (of the sphenoid bone) forms a portion of the middle fossa
optic foramen
• Optic foramen (optic canal) is near the lesser wing (x2)