Skeletal System Flashcards
Skeletal System
Job: structure and support
Organs: bones, cartilage, ligaments
Hematopoiesis
MARROW
Production of RBCs = red bone marrow
Fat storage/long-term energy storage = yellow BM
Where is red marrow located when bones are fully formed
Femur, hip bones, some skull bones, and some in sternum
Top end of bone
Epiphysis
Bone shaft
Diaphysis
Bone type composition
25% spongy bone - marrow located here
75% compact bone - no marrow
Where does blood run through an osteon?
Central canal (Haversian’s canal)
What are the rings of an osteon called?
Lamella
Osteoblast’s job
Lays down rings (lamella) and sets up ground substance (osteoid)
How do nutrients from the blood reach the outermost lamella and osteocytes?
Canaliculi
Osteocyte’s job
Takes care of maintenance inside the osteon
Osteoclast’s job
Breaks down bone; macrophage-like cells
Osteogenic cell’s job
Bone stem cells
Long bones
Any bones where they are longer than they are wide
Short bones
About the same long as they are wide
Example: carpals and tarsals
Flat bones
**intramembranous ossification
Example: sternum, skull, scapula
Irregular bones
Example: hip bones, vertebra
Sesamoid bones
Small, seed-shaped bone embedded in a tendon; strengthens the tendon and can withstand heavy pressure
Example: patella, “thumb kneecaps”
Functions of the skeletal system
- Structure and support - blob of goo without it
- Protection - rib cage and sternum protect the heart and lungs
- Storage - fat, minerals (PO4, Ca++, Mg), hematopoiesis (marrow)
Intramembranous ossification
For flat bones
Lay down membrane model and ossify on either side of it
Endochondral ossification (inside cartilage)
For long and short bones
1. Starts as a cartilage model
2. Chondrocytes die and for the medullary cavity (bone marrow here)
3. Osteoblasts invade and starts laying down osteoid and becomes vascularized
Which bone development process is involved in growth?
Endochondral ossification - bone chasing cartilage
What does the axial skeleton consist of?
Skull, vertebral column, thoracic cage
What are the skull bone categories?
Neurocranium - case around the brain; helmet
Facial bones - passageway for air and food
What are the three depressions inside the neurocranium and what part of the brain sits there?
Anterior cranial fossa - frontal lobe
Middle cranial fossa - temporal lobe
Posterior cranial fossa - cerebellum and medulla
Frontal bone
Forms forehead to top of head - anterior superior portion
Features: glabella, supraorbital foramen,
Glabella
Soft spot between eyebrows
Muscles attach here
Supraorbital foramen
Passageway for cranial nerves to innervate the faces
Little holes above orbit on brow ridge
Suture
Articulation
Knit bones together w/ small fibers
Parietal bones (2 of them)
Superior to posterior portion of the neurocranium
Features: temporal lines
Knit together via the sagittal suture
Temporal lines
Muscle attachment points on each parietal bone
Occipital bone
Posterior, inferior portion of the skull
Features: hypoglossal canal, foramen magnum, jugular foramen, external occipital protuberance, occipital condyles
Knit to the parietal bones via the lambdoid suture
Hypoglossal canal
Passageway for hypoglossal nerve (innervate under the tongue) for speech and eating
(Superior view with horizontal plane)
Foramen magnum
Large hole on inferior of skull; point that CNS tissue exits the skull and is then considered spinal cord
(Inferior view)
Jugular foramen
At junction of occipital bone and temporal bone on the inferior portion of the skull (on both sides); jugular vein/artery/nerve passageway
External occipital protuberance
Points of attachment for muscles at the posterior and inferior portion of the occipital bone (large bump)
Temporal bones (2 of them)
On either side of the head near the ears
Features: zygomatic process, external/internal acoustic meatus, mastoid process, styloid process, mandibular fossa
Zygomatic process
Near the cheek; muscle attachment for zygomaticus (smile muscle)
External acoustic meatus
External opening to the ear canal
Mastoid process
Behind the ear, protrusion of bone for muscle attachment of sternocleidomastoid muscle
Styloid process
Stylus-looking; muscle attachment point inferior to mastoid process for jaw muscles
Mandibular fossa
Small depression that the mandibular condyle sits in
Internal acoustic meatus
Internal ear canal
(Superior view with horizontal plane)
Ethmoid bone
In the anterior cranial fossa; projects downward vertically and sits behind the nasal bone
Features: cribiform foramina, crista galli, ethmoid air cells, perpendicular plate, superior nasal conchae
Cribiform foramina
Tiny holes that olfactory nerve endings pass through to the superior portion of the nasal cavity
Crista galli
Attach and anchor the meninges that the brain is inside (dura mater)
Meninges = fibrous membrane that protects brain
Looks like a ridge
Ethmoid air cells
Honeycomb-looking; known as sinuses
Cleans air as it comes in
Lightens the skull via air pockets
Perpendicular plate
Superior portion of the nasal septum
Superior nasal conchae
Lateral to the perpendicular plate and a little posterior
Hooks of bone that warm, moisten, and clean air before it enters the lungs
Sphenoid bone
Butterfly!
On the interior of the skull and projects horizontally; forms the floor of the neurocranium
Features: greater/lesser wing, sella turcica, hypophyseal fossa, optic foramen
Sella turcica
Looks like a saddle you’d put on a horse with ridges around it
Pituitary gland sits here in hypophyseal fossa
In the middle of the lesser and greater wings
Hypophyseal fossa
Deepest part of the sella turcica depression
Where the pituitary gland resides
Optic foramen
Optic nerve passageway
Superior to the sella turcica (2 little holes)
Facial bones
14 bones
Provide structure for the face
Establishes airway and food passageways
Mandible
Large facial bone; only moveable facial bone
Features: mandibular condyles, mandibular fossa, mental foramen, mental protuberance
Condyle
Extension of bone covered with hyaline cartilage
Less friction during movement
Symphysis
Joint; where 2 bones fused together
Mandibular condyles
Extension of mandible that allows for the jaw to move like a hinge joint
Mandibular fossa
Where jaw connects to the temporal bone
Mental foramen
Passageway for cranial nerves on mandible
Mental protuberance
Chin; sticks out a bit
Maxilla(e) - 2
Bones that make up just above the teeth to just under the orbits
Features: infraorbital foramen
Infraorbital foramen
Passageways for vasculature & cranial nerves
Nasal bones - 2
Superior portion of the nose
Lacrimal bones - 2
Lateral and posterior to nasal bones
Part of the orbit
Zygomatic bones - 2
Continuous with the zygomatic process of temporal bones to form the cheek bones
Orbit bones
Zygomatic, maxillae, frontal, lacrimal, ethmoid, sphenoid
Features: orbital fissure, floor of orbit
Location in orbit: zygomatic
Inferior to lateral
Location in orbit: maxillae
Anterior, medial
Location in orbit: frontal
Superior, anterior
Location in orbit: lacrimal
Inner; medial wall
Location in orbit: ethmoid
Inner; medial, posterior
Location in orbit: sphenoid
Inner; most posterior aspect
Floor of orbit
Made up by: part of palatine bone, maxillae, zygomatic
Palatine bones - 2
INFERIOR VIEW
Posterior portion of the hard palate
Vomer bone - 1
Inferior portion of the nasal septum
Plow shape
Inferior nasal conchae - 2
Lateral to nasal septum
Conch shell swirl looking - cause air pattern to swirl so the air comes into contact with more mucosa before going to the lungs
Sinuses - 4 sets
Concentrated around the nasal bone
Sphenoid, ethmoid, maxillary, frontal
Purpose: lightens the skull, warms and moistens air, create a resonance chamber for voice, crumple feature - punch face, sinus observes blow before the rest of skull
Hyoid bone
Doesn’t articulate with any other bone; held by stylohyoid muscles
Aids in the swallowing function
Vertebral column - backbone
Protect spinal cord
26 vertebra
How many cervical vertebra are there?
7
Breakfast
How many thoracic vertebra are there?
12
Lunch
How many lumbar vertebra are there?
5
Dinner
Cervical vertebra
Thin and stacked tightly together
C1
Atlas
Articulates with the occipital bone
Allows head to nod up and down
C2
Axis
Dens - thought to maybe be a part of atlas and evolved to protrude vertically off of axis
Allows head to turn side to side
C3-C6
Stereotypical cervical vertebra
Body, transverse processes, bifid spinous processes, transverse foramen (passageways for the nerves)
C7
Vertebra prominens - larger than usual spinous process
Thoracic vertebra
Transverse facets - smooth section with hyaline cartilage where the ribs articulate with thoracic vertebra
(Superior and inferior)
NO bifid spinous process
Lumbar vertebra
Noticeably larger and heavier - look at the thickness of the body
Sacrum
Stronger than lumbar vertebra to get most strength and support weight (5 fused vertebra)
Features: ala, auricular surface, foramina
Ala
Wing; anterior side of sacrum
Auricular surface
Looks like ears; posterior side of sacrum
Sacral foramina
Little foramen; spinal nerves pass through and serve the legs, buttock, and pelvic region
Coccyx
Between 3 and 5 fused vertebra
Point of fracture and hurts a lot
Finish fusing by the time you are 20
What does the thoracic cage consist of?
Sternum and ribs
Sternum
Flat bone that acts as a shield
3 bones fused together = manubrium, body, xiphoid process
Manubrium - sternum
Triangle shaped
Suprasternal (jugular) notch = v-shaped superior section of manubrium
Clavicular notch (both sides) = articulation between manubrium and clavicle
Body - sternum
Shield-like, flat bone
Articulate with ribs 3-12
Xiphoid process
Most inferior portion of the sternum
Looks like a little knob
How many pairs of ribs are there and what are the three kinds of ribs?
12 pairs of ribs
True ribs (1-7) - direct articulations with sternum
False ribs (8-12) - don’t articulate with sternum
**8, 9, 10 articulate with the rib above them
Floating ribs - only articulate with vertebral column
