Chapter 7 - The Skeletal System: The Axial Skeleton Flashcards
What does the Axial Skeleton do for Homeostasis?
Bones of Axial Skeleton protect body’s organs
Cranium surrounds Brain
Vertebrae surround Spinal Cord
Ribs surround Heart and Lungs
Bones also support storage and release of Calcium
What is the the 2 Types of Skeleton? And how many Bones are there in the body?
Axial Skeleton
Appendicular Skeleton
206 Bones in body
What is the Axial Skeleton?
80 Bones
Skull bones
Auditory Ossicles (SIM: Stapes, Incus, Malleus)
Hyoid bone
Ribs
Sternum
Vertebrae
Sacrum
What is the Appendicular Skeleton?
126 Bones
Bones of upper and lower extremities
Bones forming Girdles (Pelvic and Pectoral Girdles) that connect limbs to Axial Skeleton
What is the Pelvic Girdle?
Hip bone
Also called Coxal bone, or Pelvic bone
What is the Pectoral Girdle?
Clavicle and Scapula
What are the bones of the Axial Skeleton?
- Skull:
Cranium (8)
Face (14) - Hyoid Bone (1)
-Auditory Ossicles (sim):
Stapes (2)
Incus (2)
Malleus (2)
- Vertebral Column (26)
- Thorax:
Sternum (1)
Ribs (24)
Total = 80 bones
What are the bones of the Appendicular Skeleton?
- Pectoral Girdles:
Clavicle (2)
Scapula (2) - Upper Limbs:
Humerus (2)
Ulna (2)
Radius (2)
Carpals (16)
Metacarpals (10)
Phalanges (28) - Pelvic Girdle:
Hip or Pelvic or Coxal Bone (2) - Lower Limbs:
Femur (2)
Patella (2)
Fibula (2)
Tibia (2)
Tarsals (14)
Metatarsals (10)
Phalanges (28)
Total = 126 bones
What are the 5 Shapes of Bone?
1- Long:
Greater in length than width
2- Short:
Cube shaped
3- Flat:
Thin layers of parallel plates
4- Irregular:
Complex shapes
5- Sesamoid:
Shaped like a sesame seed (ex: Patella)
What are bone Sutures? What are Sutural Bones?
Sutures:
Jointed areas where flat bone come together
Sutural Bones:
Small, extra bone plates located within sutures of cranial bones
What are Bone Surface Markings?
Bones have characteristic surface markings
Structural features adapted for specific functions
2 Major types:
1- Depressions and Openings:
Allow passage of soft tissue
Form joints
2- Processes:
Projections or outgrowths that form joints
Serve as attachment points for ligaments and tendons
What are some Bone Surface Markings?
Fissure
Foramen
Fossa
Sulcus
Meatus
Condyle
Facet
Head
Crest
Epicondyle
Line
Spinous Process
Trochanter
Tubercle
Tuberosity
What is a Fissure?
Narrow slit between bones for passage of blood vessels or nerves
ex: Superior orbital fissure
What is a Foramen?
Hole for passage of blood vessels, nerves, or ligaments
ex: Foramen magnum
What is a Fossa?
Shallow depression
ex: Mandibular fossa
What is a Sulcus?
Furrow on a bone for passage of blood vessels, nerves, or tendons
ex: Intertubercular sulcus of humerus
What is a Meatus?
Tubelike opening
ex: External auditory meatus
What is a Condyle?
Rounded projection with a smooth articular surface
ex: Occipital condyle
What is a Facet?
Smooth, flat, slightly concave articular surface
(Area meant for articulation)
ex: Superior articular facet in vertebrae
What is a Head?
Usually rounded articular process supported on a neck
ex: Head of clavicle
What is a Crest?
Prominent ridge or elongated process
ex: Median sacral crest
What is an Epicondyle?
Usually roughened projection on a condyle
ex: Medial epicondyle of femur
What is a Line?
Long, narrow ridge or border (less prominent than a crest)
ex: Superior nuchal line
What is a Spinal Process?
Sharp, slender projection
ex: Spinous process on vertebrae
What is a Trochanter?
Very large projection found only on the femur
What is a Tubercle?
Variably sized rounded projection
ex: Tubercle of rib
What is a Tuberosity?
Variably sized projection with rough, bumpy surfaces
ex: Sacral tuberosity
What is the Skull made of?
Skull contains 22 bones
Not including the 3 middle ear bones in both ears (Stapes, Incus, Malleus)
Associated with these bones are a number of processes, ridges, lines, depressions, and foramina
What is the Mandible?
Lower Jawbone
Largest and strongest facial bone
Other than Auditory Ossicles, it’s the only moveable skull bone
What passes through Carotid Foramen?
Internal carotid artery
Sympathetic nerves for eyes
What passes through Hypoglossal Canal?
Hypoglossal (XII) nerve
Branch of ascending pharyngeal artery
What passes through Infraorbital Foramen?
Infraorbital nerve and blood vessels
Branch of maxillary division of Trigeminal (V) nerve
What passes through Jugular Foramen?
Internal jugular vein
Glossopharyngeal (IX) nerve
Vagus (X) nerve
Accessory (XI) nerve
What passes through Foramen Lacerum?
Branch of ascending pharyngeal artery
What passes through Foramen Magnum?
Medulla Oblongata and its membranes (meninges)
Accessory (XI) nerve
Vertebral and spinal arteries
What passes through Mandibular Foramen?
Inferior alveolar nerve and blood vessels
What passes through Mastoid Foramen?
Emissary vein to transverse sinus
Branch of occipital artery to Dura Mater
What passes through Mental Foramen?
Mental nerve and vessels
What passes through Olfactory Foramen?
Olfactory (I) nerve
What passes through Optic Foramen?
Optic (II) nerve
Ophthalmic artery
What passes through Foramen Ovale?
Mandibular branch of Trigeminal (V) nerve
What passes through Foramen Rotundum?
Maxillary branch of Trigeminal (V) nerve
What passes through Stylomastoid Foramen?
Facial (VII) nerve
Stylomastoid artery
What passes through Supraorbital Foramen?
Supraorbital nerve and artery
What are Sutures of the Skull?
A suture is an immoveable joint
Found in skull holding bones such as temporal and parietal bones together
Coronal Suture
Sagittal (Parietal) Suture
Lambdoid Suture
Squamous Suture
What are Paranasal Sinuses of the Skull?
Paranasal Sinuses: mucous membrane-lined cavities in the frontal, axillary, sphenoid, and ethmoid bones
Used as resonating chambers to enhance voice
Increase surface area of nasal mucosa and help moisten as well
What are Fontanels of the Skull?
Fontanels: Areas of a fetus/baby where unossified mesenchyme develops into dense connective tissue
They close up through intramembranous ossification by age 2
Anterior Fontanel: Future Coronal Suture
Posterior Fontanel: Future Lambdoid Suture
Anterolateral and Posterolateral Fontanels: Future Squamous Suture
What is the Hyoid Bone?
Does not articulate with any other bone
Supports tongue and provides attachment site for some muscles of neck and pharynx
What is the Vertebral Column?
Spinal Column, Backbone, Spine
Composed of 26 vertebrae divided into 5 regions
Protects Spinal Cord
Vertebrae from each region have unique structures that help identify which type they are
What are the 5 regions of the Vertebral Column?
Cervical Vertebrae - 7
Thoracic Vertebrae - 12
Lumbar Vertebrae - 5
Sacrum - 1 (5 joint together)
Coccyx - 1 (4-5 joint together)
What are the 4 Curves of the Vertebral Column?
2 Primary curves (Thoracic and Sacral curves)
2 Secondary curves (Cervical and Lumbar curves)
Cervical curve
Thoracic curve
Lumbar curve
Sacral curve
Fetus has C-shaped vertebral column
Adult has left-C, C, left-C, C
What are Intervertebral Discs?
Located between bodies of vertebrae from 2nd cervical to sacrum
Composed of:
Outer ring of Fibrocartilage (annulus fibrosus)
Inner, soft nucleus (nucleus pulposus)
Layer of Hyaline cartilage on top and bottom of each disc
Absorb shock and separate vertebrae from one another
What are Cervical Vertebrae?
C1 - Atlas
C2 - Axis
C3
C4
C5
C6
C7 - Vertebra Prominens
What are Thoracic Vertebrae?
Support ribs and have special structures for rib head and tubercle attachment
T1: Smallest
T2-T8: Medium
T9-T12: Largest
What are Lumbar Vertebrae?
Largest and strongest vertebrae
No special structures that are specifically associated with lumbar vertebrae
What are the Sizes, Foramina, and Spinous Processes for Cervical, Thoracic, and Lumbar Vertebrae?
1- Size:
Cervical: Small
Thoracic: Larger
Lumbar: Largest
2- Foramina:
Cervical: 1 vertebral foramen and 2 transverse foramina
Thoracic: 1 vertebral foramen
Lumbar: 1 vertebral foramen
3- Spinous Processes:
Cervical: Slender, often bifid from C2-C6
Thoracic: Long, thick, inferiorly
Lumbar: Short, blunt, posteriorly
What are the Sacrum and Coccyx?
Sacrum:
Triangular shaped part of pelvic girdle
Composed of 5 vertebrae that fuse
Coccyx:
Much smaller than Sacrum
Also triangular shaped
Composed of 4 vertebrae that fuse
What is the Thorax?
Thorax is entire chest region
Bones that compose thoracic cage are Sternum, Ribs, and Costal Cartilage
True Ribs: 1-7
False Ribs: 8-10
Floating Ribs: 11-12
What is the Sternum?
Composed of 3 segments:
1- Manubrium
2- Body
3- Xiphoid Process
Sternum articulates with clavicles and costal cartilage
What are Ribs?
12 pairs
Provide structural support to thoracic cavity
True Ribs: 1-7
Their cartilage directly connected to sternum
False Ribs: 8-10
Cartilage indirectly connected to sternum
Floating Ribs: 11-12
Not connected to sternum
What is a Herniated Disc?
May occur due to trauma or sometimes is simply associated with aging
What are Disorders to Curves of Spinal Column?
Scoliosis:
Increased lateral curvature
Kyphosis:
Increased thoracic curve - bent forward
Lordosis:
Increased lumbar curve - bent backwards
What is Spina Bifida?
Spina Bifida is a congenital defect of vertebral column
Laminae do not develop normally
Degree of deformity vary from:
Minor: Spina Bifida Occulta
Severe: Spina Bifida with Meningomyelocele
What is Bone Marrow?
Bone Marrow is a soft connective tissue of bone
2 Types:
Red Bone Marrow
Yellow Bone Marrow
What is Red Bone Marrow?
Hemopoietic:
Produce RBC
Reticular connective tissue
Immature blood cells
Fat
Children:
Located in spongy bone and medullary cavity of long bones
Adults:
Located only in certain bones of Axial Skeleton
Skull
Vertebrae
Ribs
Sternum
Ossa Coxae
Proximal Epiphysis of Humerus and Femur
What is Yellow Bone Marrow?
Product of Red Bone Marrow degeneration as children mature
Fatty substance
May convert back to Red Bone Marrow during:
Severe Anemia
Facilitates production of additional Erythrocytes
What is Hyaline Cartilage? What is its composition?
Embedded in gel-like substance
Includes Proteoglycans but no Calcium
Resilient and flexible
High water percentage
Highly compressible and shock absorber
Avascular, and no nerves
Composition:
Chondroblasts
Chondrocytes
Perichondrium
What is a Chondroblast?
Hyaline cartilage cell
Produce cartilage matrix
What is a Chondrocyte?
Hyaline cartilage cell
Chondroblast encased within matrix
Occupy Lacunae
Maintain matrix
What is the Perichondrium?
Dense irregular connective tissue
Covers cartilage
Helps maintain its shape
What is Cartilage Growth?
Begins during embryological development
2 Types:
1- Interstitial Growth:
Grows in length
Within internal regions of cartilage
Declines as cartilage matures
2- Appositional Growth:
Grows in width
Outside cartilage’s outside edge
Growth stops when cartilage fully mature, unless injury
What is Achondroplasia?
Abnormal conversion of hyaline cartilage to bone
Most common - Achondroplastic Dwarfism:
Long bones of limbs stop growing in childhood
Other bones continue normal growth
Short in stature but large head
Failure of chondrocytes in epiphyseal plate to grow and enlarge
Inadequate endochondral ossification
