Chapter 7 Flashcards
Skeletal System (Fun Facts)
Composition- bones, cartilages, joints, ligaments 20% of body mass Two major parts -Axial -Appendicular
Axial Skeleton
Consists of 80 bones Three major regions -Skull -Vertebral Column -Thoracic Cage
The Skull
Formed by 2 sets of bones
- Cranial Bones (Cranium)
- Facial Bones
Cranial Bones
Enclose the brain in the cranial cavity
-Cranial vault
-Cranial base: anterior, middle, and posterior fossae
Provide sites of attachment for head and neck muscles
Facial Bones
Framework of face
Cavities for special sense organs for sight, taste, and smell
Openings for air and food passage
Sites of attachment for teeth and muscles of facial expression
Skull Geography
Cranial cavity Middle and internal ear cavities Nasal cavity Orbits 85 named openings -Foramina, canals, fissures
Cranial Bones (Number)
8
Cranial Bones (Name)
Frontal Bone Parietal Bones (2) Occipital Bone Temporal Bones (2) Sphenoid Bone Ethmoid Bone
Frontal Bone
Location -Anterior portion of cranium -Most of anterior cranial fossa Superior walls of orbits Contains air-filled frontal sinus
Parietal Bones and Major Associated Sutures
Superior and lateral aspects of cranial vault
Four sutures mark articulations of parietal bones with frontal, occipital, and temporal bones
-Coronal suture
-Sagittal suture
-Lambdoid suture
-Squamous suture
Coronal Suture
Separates frontal and parietal
Sagittal Suture
Separates 2 parietals
Lambdoid Suture
Separates occipital and parietal
Squamous Suture
Separates temporal and parietal
Occipital Bone
Location
-Most of skull’s posterior wall and posterior cranial fossa
-Articulates with 1st vertebra
Sites of attachment for ligamentum nuchae and many neck and back muscles
Foramen magnum
Temporal Bones
Location
-Inferolateral aspects of skull and parts of cranial base
Sphenoid Bone
Complex, bat-shaped bone
Keystone bone
-Articulates with all other cranial bones
Ethmoid Bone
Deepest skull bone
Superior part of nasal septum, roof of nasal cavities
Contributes to medial wall of orbits
Sutural Bones
Tiny irregularly shaped bones that appear within sutures
Facial Bones (Number)
14
Facial Bones (Name)
Mandible Maxillary Bone -Maxillae (2) Zygomatic Bones (2) Nasal Bones (2) Lacrimal Bones (2) Palatine Bones (2) Vomer Inferior Nasal Conchae (2)
Mandible
Lower jaw
Largest, strongest bone of face
Temporomandibular Joint
-Only freely movable joint in skull
Maxillary Bones
Medially fused to form upper jaw and central portion of facial skeleton
Keystone Bones
-Articulate with all other facial bones except mandible
Top part of mouth where upper teeth attach
Zygomatic Bones
Cheekbones
Inferolateral margins of orbits
Nasal Bones
Form bridge of nose
Lacrimal Bones
In medial walls of orbits
Lacrimal fossa houses lacrimal sac
Palatine Bones
Posterior one-third of hard palate
Posterolateral walls of the nasal cavity
Small part of the orbits
Vomer
Plow shaped
Inferior part of nasal septum
Orbits
Cavities that encase eyes and lacrimal glands
Sites of attachment for eye muscles
Formed by parts of seven bones
Nasal Cavity
Roof, lateral walls, and floor Nasal septum of bone and hyaline cartilage -Perpendicular plate of ethmoid -Vomer -Anterior septal cartilage
Paranasal Sinuses
Mucosa-lined, air-filled spaces Lighten skull Enhance resonance of voice Warm and humidify air -Think of breathing in cold Found in frontal, sphenoid, ethmoid, and maxillary bones
Hyoid Bone
Not bone of skull
Does not articulate directly with another bone
Movable base for tongue
Site of attachment for muscles of swallowing and speech
Vertebral Column (Fun facts)
Transmits weight of trunk to lower limbs
Surrounds and protects spinal cord
Flexible curved structure containing 26 irregular bones (vertebrae) in 5 major regions
5 Regions of Vertebral Column (And Number)
Cervical Vertebrae -7 (neck) Thoracic Vertebrae -12 (ribs) Lumbar Vertebrae -5 (lower back) Sacrum Coccyx
Vertebral Column: Curvatures
Increase resilience and flexibility of spine
- Cervical and Lumbar curvatures
- -Concave posteriorly
- Thoracic curvatures
- -Concave anteriorly
Abnormal Spine Curvatures
Scoliosis- Frontal plane (S curve straight on)
Kyphosis- Sagittal plane (hunched over)
Lordosis- Sagittal plane (indentation in back)
Ligaments
Anterior and posterior longitudinal ligaments
-From neck to sacrum
Ligamentum Flavum
-Connects adjacent vertebrae
Short ligaments
-Connect each vertebra to those above and below
Intevertebral Discs
Cushion-like pad composed of two parts
Nucleus Pulposus
Anulus Fibrosus
Nucleus Pulposus
Inner gelatinous nucleus
Gives disc its elasticity and compressibility
Anulus Fibrosus
Outer collar composed of collagen and fibrocartilage
General Structure of Vertebrae
Body
Vertebral Arch
Vertebral Foramina
Intervertebral Formina
Body
Anterior weight-bearing region
Vertebral Arch
Composed of pedicles and laminae that, along with body, encloses vertebral foramen
Vertebral Foramina
Together make up vertebral canal for spinal cord
Intervertebral Formina
Lateral openings between adjacent vertebrae for spinal nerves
7 Processes per Vertebra
Spinous Process- projects posteriorly
Transverse Processes (2)- project laterally
Superior Articular Processes (2)- protrude superiorly
Inferior Articular Processes (2)- protrude inferiorly
Cervical Vertebrae
C1-C7: Smallest, lightest vertebrae C3-C7: Share following features -Oval body -Spinous processes are bifid (except C7) -Large, triangular vertebral foramen -Transverse foramen in each transverse process -C7 is vertebra prominens
Atlas
C1
- No body or spinous process
- Consists of anterior and posterior arches, and two lateral masses
- Superior surfaces of lateral masses articulate with occipital condyles
- Movement for “Yes”
Axis
C2
- Dens projects superiorly into anterior arch of atlas
- -Is “missing” body of atlas
- Dens is a pivot for rotation of atlas
- Movement of “no”
- Breaking your neck would be breaking dens
Thoracic Vertebrae
T1-T12
- All articulate with ribs at facets
- Long, spinous process that points inferiorly
- Circular vertebral foramen
- Location of articular facets allows rotation of this area of spine
Lumbar Vertebrae
L1-L5
- Receives most stress
- Short, thick pedicles and laminae
- Flat hatchet-shaped spinous processes point posteriorly
- Vertebral foramen triangular
- Orientation of articular facets locks lumbar vertebrae together to prevent rotation
Sacrum
- 5 fused vertebrae
- Forms posterior wall of pelvis
- Articulates with L5 superiorly, and with auricular surfaces of hip bones, forming sacroiliac joints
Coccyx
- Tailbone
- 3-5 fused vertebrae
- Articulates superiorly with sacrum
Thoracic Cage
Composed of -Posteriorly -Anteriorly -Laterally Functions -Protects vital organs -Supports shoulder girdles and upper limbs -Provides attachment sites for muscles of neck, back, chest, and shoulders
Sternum (Breastbone)
Three fused bones
- Manubrium (Superior portion)
- -Articulates with clavicles and ribs 1 and 1
- Body (Mid-portion)
- -Articulates with costal cartilages of ribs 2 and 7
- Xiphoid Process (Inferior Portion)
- Site of muscle attachment
Anatomical Landmarks of Sternum
Jugular Notch
Sternal Angle
Xiphisternal Joint
Jugular Notch
Central indentation in superior border of manubrium
Sternal Angle
Horizontal ridge across front sternum
Xiphisternal Joint
Point where sternal body and xiphiod process fuse
Ribs and Their Attachments
12 pairs total -All attach to thoracic vertebrae Pairs 1-7 -True (Vertebrosternal) Ribs -Attach directly to sternum by individual costal cartilages
Ribs and Their Attachments
Pairs 8-12 False Ribs -Pairs 8-10 --Attach indirectly to sternum by joining costal cartilage of rib above Pairs 11-12 also called floating ribs -no attachment to sternum
Bones of Limbs and Their Girdles
Pectoral Girdle
-Attaches upper limbs to body trunk
Pelvic Girdle
-Attaches lower limbs to body trunk
Pectoral Girdle
Clavicles and Scapulae
- Attach upper limbs to axial skeleton
- Provide attachment sites for muscles that move upper limbs
Clavicles (Collarbones)
- Cone-shaped sternal end articulates with sternum medially
- Flattened acromial end articulates laterally with scapula
- Anchor muscles
- Act as braces to hold the scapulae and arms out laterally
Scapulae (Shoulder Blades)
- On dorsal surface of rib cage
- Flat and triangular, with three borders and three angles
- Several large fossae named according to location
The Upper Limb
30 Bones form skeleton framework of each upper limb
- Arm- Humerus
- Forearm- Radius and Ulna
- Hand- Carpal, Metacarpal, Phalanges
Humerus
- Largest, longest bone of upper limb
- Articulates superiorly with glenoid cavity of scapula
- Articulates inferiorly with radius and ulna
Radius
- Lateral bone in forearm
- Head articulates with capitulum of humerus and radial notch of ulna
- Interosseous membrane connects radius and ulna along their entire length
Ulna
- Medial bone in forearm
- Forms major portion of elbow joint with humerus
Carpus
8 Bones of Wrist
Forms Wrist
Metacarpus
5 metacarpal bones
Forms Palm
Phalanges
Fingers
2 Bones in Thumb
3 Bones in Other 4 digits
Pelvic (Hip) Girdle
Two Hip bones and sacrum
-Attach lower limbs to axial skeleton with strong ligaments
-Transmit weight of upper body to lower limbs
-Support pelvic organs
Less mobility but more stable than shoulder joint
3 fused together
-Ilium, Ischium, and Pubis
Bony pelvis formed by coxal bones, sacrum, and coccyx
Female Pelvis
- Adapted for childbearing
- True pelvis (inferior to pelvic brim) defines birth canal
- Cavity of true pelvis is broad, shallow, and has greater capacity
Male Pelvis
- Adapted for support of male’s heavier build and stronger muscles
- Cavity of true pelvis is narrow and deep
Lower Limb
- Carries entire weight of erect body
- Subjected to exceptional forces if jump or run
- 3 segments
- -Thigh
- -Leg
- -Foot
Thigh Bones
Femur
Patella
Femur
- Largest and strongest bone in the body
- Length about 1/4 of person’s height
- Articulates proximally with aceabulum of hip and distally with tibia and patella
Patella
-Sesamoid bone in quadriceps tendon
Leg Bones
Tibia
Fibula
*Both connected by interosseous membrane
Tibia
- Medial leg bone
- Receives weight of body from femur; transmit to foot
Fibula
- Not weight bearing: no articulation with femur
- Several muscles originate from fibula
- Articulates proximally and distally with tibia
Tarus
- 7 Tarsal bones form posterior half of foot
- Body weight carried primarily by talus and calcaneus
Metatarsals
- 5 metatarsal bones
- Enlarges head of metatarsal forms “ball of foot”
Phalanges
14 bones of toes
- Great toe has 2
- Rest of digits have 3
Arches of Foot
- Maintained by interlocking foot bones, ligaments, and tendons
- Allows foot to bear weight
- 3 arches
- -Lateral Longitudinal
- -Medial Longitudinal
- -Transverse
Fetal Skull
Has more bones than adult
- mandible and frontal bones are unfused
- skull bones connect by fontanelles
Cleft Palate
No medial fusion of right and left halves of palate
Growth Rates
- At birth, cranium is huge relative to face
- At 9 months, cranium is 1/2 size adult size
- Mandible and maxilla are foreshortened but lengthen with age
- Arms and legs grow at faster rate than head and trunk, leading to adult proportions
Spinal Curvature
Primary thoracic and sacral curvatures obvious at birth
-Give spine a C shape
-Convex posteriorly
Secondary curvatures
-Cervical and lumbar - convex anteriorly
-Appear as child develops (lifts head, walk)
Old Age
Intervertebral discs
-several centimeter height loss common by 55
-Costal cartilage ossifies
All bones lose mass, so fracture risk increases
