Chapter 7 Skeletal System Flashcards
Skeletal System
Groups of bone that work together
Parts of skeleton include
–Axial skeleton
–Appendicular skeleton
Axial Skeleton
body’s longitudinal axis; encases body cavities (protect underlying organs)
-Skull
-Vertebral column
-Thoracic cage
Skull
22 bones (8 cranial and 14 facial bones)
-encases brain and form face
Vertebral column
33 bones
-24 individual vertebrae protect spinal cord
-remaining vertebrae fuse, forming sacrum and coccyx
Thoracic cage (rib cage)
12 pairs of ribs, sternum, and part of vertebral column
-encases and protects lungs, heart, and other delicate contents of thoracic cavity
Appendicular skeleton
Bones of pectoral girdle, upper limb, pelvic girdle, and lower limb
-primarily suited for movement, support, and muscle attachment
-Pectoral girdle
- Upper limb
- Pelvic girdle
- Lower limb
Pectoral Girdle
Clavicle and scapula
- anchors upper limb to trunk
Upper Limb
Three parts:
-arm (humerus)
-forearm (radius and ulna)
-wrist and hand (carpals, metacarpals, and phalanges)
Pelvic Girdle
Two pelvic bones and sacrum, (collectively called pelvis)
-anchors lower limb to trunk
Lower Limp
Three parts:
-thigh (femur)
-leg (tibia and fibula)
-ankle and foot (tarsals, metatarsals, and phalanges)
Surface features
-Depressions
-Openings
-Projections
Depressions
Pathways for blood vessels and nerves, or sites for articulations or joints between bones
ex:
-Facet
-Fossa
-Fovea
-Groove
Openings
Enclose delicate structures; allow them to travel through bone
ex:
-Canal
-Fissure
-Foramen
Projections
Sites where bones articulate or where ligaments and tendons attach
ex:
-Condyle
-Crest
-Head
-Tubercle and tuberosity
-Epicondyle
-Process
-Spine
-Protuberance
-Trochanter
-Line
Facet
Shallow convex or concave surface where two bones articulate
ex: Rib
Fossa (fossae)
Indentation in a bone into which another structure fits
ex:Humerus
Fovea
Shallow pit
ex:Femur
Groove (sulcus)
Long indentation along which a narrow structure travels
ex: Rib
Canal (meatus)
Tunnel through a bone
ex: Temporal bone
Fissure
Narrow slit in a bone or between adjacent parts of bones
ex: Sphenoid bone
Foramen
Hole in a bone
Condyle
Rounded end of a bone that articulates with another bone
Crest
Ridge or projection
Head
Round projection from a bones epiphysis
Tubercle and tuberosity
Small, rounded bony projection
Tuberosity- is a large tubercle
Epicondyle
Small projection usually proximal to a condyle
Process
Prominent bony projection
Spine
Sharp process
Protuberance
Outgrowth from a bone
Trochanter
Large projection found only on the femur
Line
Long, narrow ridge
Skull Structure
Skull- 22 bones organized in 2 groups:
- cranial bones
- Facial bones
Cranial bones
(cranium) eight bones:
▪Four single bones: frontal, occipital, ethmoid, and sphenoid bones
▪Two paired bones: temporal and parietal bones
Facial bones
(14 ) form framework of face:
▪Six paired bones: maxillary, zygomatic, nasal, lacrimal, palatine, and inferior nasal conchal bones
▪Two single bones: mandible and vomer
Sutures
Immovable joints that fuse all bones of the skull to one another , except the mandible
Sinuses
Air filled, membrane-lined spaces in skull bones
Paranasal sinuses
large sinuses, found in four bones surrounding nasal cavity
Cranial vault (calvarium)
Superior portion of cranial cavity
Cranial base
Inferior portion in which brain fits; divided into three indentations:
1. anterior
2. middle
3. posterior cranial fossae
Cranial Cavity
Formed by cranial bones, surrounds brain; houses special sense organs in small cavities
- orbits
- nasal cavity
- oral cavity
- other small cavities contain organs for hearing and balance
Orbits
Contain eyeballs:
- complex anatomical structure of seven fused bones; forms walls that encase eyeball, lacrimal gland, and associated blood vessels, muscles, and nerves
–Frontal bone – superior and posterosuperior orbital wall
–Maxilla – posteroinferior wall with small contribution from palatine bone
–Zygomatic bone- anterolateral wall
–Sphenoid bone – posterior wall
–Ethmoid, lacrimal, and palatine bones – medial wall
Nasal Cavity
Houses sensory receptors for smell
–Posterior wall – sphenoid body and pterygoid processes
–Lateral wall – ethmoid and perpendicular plate of palatine, inferior nasal conchae, and maxilla
–Roof – cribriform plate of ethmoid
–Floor or hard palate – palatine and palatine processes of maxillae
–Cartilage and connective tissue of nose are attached to margins of nasal bones and maxillae; form anterior wall
–Nasal septum – posterior to perpendicular plate of ethmoid bone and vomer; anterior to hyaline cartilage; divides nasal cavity into two nasal fossae
Oral Cavity
Surrounds teeth and tongue (taste receptors), first part of digestive tract:
–Roof of cavity is inferior surface of bones that form floor of nasal cavity (hard palate)
–Anterior and lateral walls of cavity are maxillae and mandible
–Posterior wall and bony floor are absent; replaced by soft tissues (muscles and connective tissue)
Paranasal sinuses
Within frontal, sphenoid, ethmoid, and maxillary bones:
–Communicate with adjacent nasal cavity through small bony openings; allow air to flow in and out of sinuses
–Mucous membranes lining sinuses filter, warm, and humidify inspired air
–Cavities also reduce weight of skull; enhance voice resonance
The Fetal Skull
Bones are not fused to one another like bones of adult skull
- Fontanels- present until full development of cranial bones (18-24 months)
-Fontanels and unfused sutures allow for flexibility
Fontanels
- Anterior fontanel
- Posterior fontanel
- Two Sphenoid fontanel
- Two Mastoid fontanel
Anterior fontanel
Between developing frontal and parietal bones where coronal and sagittal sutures meet; metopic suture divides frontal bone (fuses at birth to form single bone)
Posterior Fontanel
Between developing parietal and occipital bones at apex of lambdoid suture
Two Sphenoid Fontanels
On left and right sides of temple where sphenoid bone meets with other cranial bones
Two Mastoid Fontanels
At junction where lambdoid and squamous sutures of developing parietal, temporal, and occipital bones meet
Hyoid Bone
–C-shaped bone in superior neck; suspended by ligaments that attach it to styloid processes of temporal bone and larynx (voice box)
–Provides numerous attachment points for muscles involved in swallowing and speech
- Doesn’t articulate with any skull bones or any other bones
Gender differences of Skull anatomy
1.Forehead of male skull is sloped and female’s is straight
2.Male’s supraorbital ridge is more prominent 3.Mandibular angle of male skull is closer to 90 degrees and that of female skull is generally greater than 90 degrees
4.Mastoid process of male skull is larger and more prominent
Vertebral Column (spine)
Average of 33 bones (vertebrae)
–Vertebrae – classified by structure and location; each individual vertebra is given a letter (signifies region) and number (indicates position)
–Spaces between moveable vertebrae (intervertebral foramen) visible from lateral view of vertebral column; spinal nerve roots pass through foramina
Vertebral classification
–7 cervical – in neck; fourth cervical vertebra is abbreviated C4
–12 thoracic – articulate with ribs; eleventh thoracic vertebra is abbreviated T11
–5 lumbar – in lower back; third lumbar vertebra is abbreviated L3
–5 fused sacral (sacrum) – articulate with pelvic bones
–3–5 fused coccygeal (coccyx)– at most inferior end of vertebral column
Spinal Curvatures
C-shaped vertebral column of newborn develops into series of vaguely S-shaped secondary curvatures as infant grow:
- Primary curvatures
- Secondary curvatures
Primary Curvatures
(thoracic and sacral) – present during fetal period of development
Secondary Curvatures
(cervical and lumbar) – develop after fetal period. Critical for ability to walk upright
▪Cervical curvature allows us to hold our heads up. lumbar curvature shifts weight of body onto sacrum
▪Lends balance and support needed to walk on two leg
Abnormal spinal curavtures
- Scoliosis
- Lordosis
- Kyphosis
Scoliosis
Abnormal lateral curvatures in vertebral column
Lordosis (swayback)
Exaggerated cervical and lumbar curvatures
Kyphosis
Exaggeration of thoracic curvature resulting in hunch back appearance
Structure of Vertebrae
Protection and support of head and neck
Body or Centrum
Primary weight-bearing surface; most anterior aspect of vertebra
-intervertebral discs are between adjacent bodies- absorb shock of running and jumping
Vertebral Foramen
Just posterior to body; large opening through which spinal cord and associated tissues travel; all foraminae together form vertebral canal
Vertebral arch
Made up of two Pedicles that border vertebral foramen laterally and project posteriorly from body that merge with two laminae that border vertebral foramen posteriorly
Intervertebral Foramina
Made up of deep inferior vertebral notch on inferior side of each pedicle and superior vertebral notch on superior side
Superior and Inferior articular processes
At junction of each pedicle and lamina; facets on processes form joints between successive vertebrae
Transverse processes
Project from lateral sides of vertebral arch; attachment sites for muscles
Spinous processes
Projects from most posterior aspect of vertebral arch; attachment sites for muscles
Cervical (7)
Smallest vertebrae
–Easily identified by transverse foramina in their transverse processes; allows passage of vertebral arteries and veins, forked shape spinous processes
–C1 and C2 – notably different from other cervical vertebra
C1 (atlas)
▪Large, teardrop-shaped vertebral foramen; lacks vertebral body
▪Two anterior and posterior arches, no spinous process; form lateral masses; contain superior and inferior articular facets; articulate with occipital bone and C2 respectively, allows you to nod “yes”
C2 (axis)
▪Dens – prominent superior tooth-shaped projection (odontoid process) protrudes from body; articulates with atlas at atlantoaxial joint
▪Allows for rotational movement of head at neck; structure of dens in atlas allows joint to function (shaking head to indicate “no”), held in place with the transverse ligament
Thoracic vertebrae (12)
Larger than cervical vertebrae; heart-shaped bodies, circular vertebral foramina, and long spinous processes point inferiorly
–Superior costal facets and inferior costal facets, on lateral sides of vertebral body; provide points of articulation for ribs
–Two transverse costal facets on transverse processes; articulate with another portion of ribs
Lumbar Vertebrae (5)
Largest and heaviest of all vertebrae; well suited for bearing weight of torso
–Large, kidney-shaped bodies and thick spinous processes; point posteriorly
–Vertebral foramina have a flattened triangle shape
–Lumbar pedicles and laminae are thicker and shorter than those in other regions of column
Vertebral Compression fracture
Common fracture of vertebral body; reduces height of vertebra by more than 20%; most often result from trauma or diseases that destroy bone (osteoporosis and bone tumors):
- Wedge fractures
- Burst fractures
Wedge Fractures
Involve only anterior portion of vertebra; most common in elderly women with kyphosis or osteoporosis; can be induced by very minor trauma (sneezing or rolling over in bed); symptoms vary; ordinarily involve pain that may radiate to other location
Burst Fractures
Involve entire vertebral body, generally due to severe trauma; symptoms are usually more severe; bone fragments can damage spinal cord and nerves
Sacrum
5 fused sacral vertebrae form curved triangular-shaped posterior boundary of pelvic cavity
Sacrum Base
The superior surface articulates with 5th lumbar vertebra at facets of superior articular process
Sacral Promontory
Bony projection at anterior margin of base
Alae
Two smooth regions lateral to sacral promontory
Apex
Inferior surface that articulates with coccyx
Sacral Canal
Opening continuous with vertebral canal; on posterior surface; allows for passage of nerve roots and connective tissue
Median Sacral Crest
Ridge of bone formed by fused sacral spinous processes at posterior boundary of sacral canal
Sacral Foramina
Four pairs of holes on either side of median sacral crest; allows for passage of nerves exiting sacral canal
Lateral Sacral Crests
Lateral to sacral foramina; remnants of sacral transverse processes
Sacral Hiatus
Near apex; end of sacral canal
Coccyx
Formed by 4 fussed vertebrae (between 3 and 5 vertebrae)
Transverse Ridges
Remnants of transverse processes; on posterior surface
Coccygeal Cornu
Hornlike projections on each side of superior aspect of coccyx
Intervertebral Disc
(23 in total) – fibrocartilage pad between bodies of adjacent vertebrae; absorbs shock and binds vertebral column together; each disc has following components:
-Nucleus pulposus
-Anulus fibrosus
Nucleus pulposus
Soft, inner jelly-like substance; resilient shock absorber
Anulus fibrosus
Outer ring of fibrocartilage; contains nucleus pulposus; joins adjacent vertebrae
Herniated Disc (slipped disc)
Tear in anulus fibrosus can allow nucleus pulposus to protrude
- generally results from trauma, injuries secondary to improper lifting, or longer-term damage due to repeated motions (lifting and squatting)
Thoracic Cage
Sternum, 12 pairs of ribs, and thoracic vertebrae
-Protective peripheral boundary of thoracic cavity
Sternum or Breastbone
Anterior median section of thoracic cage:
- Manubrium
- Body
- Xiphoid process
Sternum Manubrium
Superior most segment
-suprasternal notch with clavicular notch on either side, articulates with clavicles of pectoral girdle
-first rib cartilages attach just below clavicular notches
Sternum Body
Large middle segment; features sternal angle where manubrium and body meet and second rib cartilage attaches
-lateral edge of remaining body has notches for third through seventh rib cartilage
Xiphoid Process of Sternum
Inferior segment; protrusion provides attachment site for certain abdominal muscle
Rib Cage
12 pairs of ribs and costal cartilages; curved into C-shape
▪Each rib attaches to thoracic vertebra posteriorly
▪Grouped into two classes (true and false), based on anterior attachments
Intercostal spaces
Gaps between successive ribs; allows for flexibility required during movement and breathing
Ribs 1-7
(true or vertebrosternal ribs) – attach to sternum via costal cartilages
Ribs 8-12
(false ribs) – not directly attached to sternum
–Vertebrochondral ribs 8–10 – attached to cartilage of seventh rib; costal margin formed by costal cartilage of ribs 7–10
–Ribs 11 and 12 – floating or vertebral, not attached to sternum
Cardiopulmonary resuscitation (CPR)
Lifesaving technique administered when individual’s heart and/or breathing has stopped; may restore circulation by application of repeated compressions to chest over sternum
Pectoral Girdle
Clavicle and scapula; supports 30 bones that make up upper limb; all are components of appendicular skeleton
Clavicle (collarbone)
Appears straight when viewed anteriorly; S-shaped when viewed superiorly or inferiorly
–Only bone of pectoral girdle that directly articulates with axial skeleton
–Sits between shoulder and thoracic cage; braces and supports upper limb
–Structure enables it to function like brace in building that supports two opposing beams
Clavicle ends
Distinct and palpable through skin:
- Sternal end
- Acromial end
Sternal End
Articulates medially with manubrium at sternoclavicular joint
Acromial End
Articulates laterally with acromion process of scapula at acromioclavicular joint; conoid tubercle provides site for attachment of ligaments near end
Scapula
Sits on posterosuperior rib cage between second and seventh ribs; body is largest section; has three borders: medial, lateral, and superior
- Coracoid process
- Subscapularis muscle
- Glenoid cavity
- Spine
- Supraspinous fossa
Coracoid process (scapula)
Hook-shaped projection on anterior surface
Subscapular fossa (scapula)
Inferior to coracoid process; provides attachment site for subscapularis muscle
Glenoid Cavity (scapula)
Shallow indentation on lateral surface; articulates with humerus in shoulder joint
Spine (scapula)
Posterior ridge of bone; crosses from medial to lateral along superior scapula; terminates as acromion at acromioclavicular joint (AC)
Supraspinous fossa (scapula)
superior to spine; infraspinous fossa is inferior
Humerus
Largest and strongest bone of upper limb; only bone in arm (brachium); consists of two epiphyses; articulate with other bones and long diaphysis
Proximal epiphysis (humerus)
Has medially oriented, ball-shaped humeral head; articulates with glenoid cavity at shoulder joint; anatomical neck is groove surrounding head
Greater tubercle (humerus)
Projection of bone lateral to anatomical neck; separated from smaller medial lesser tubercle by groove (intertubercular sulcus or bicipital groove); tendon of biceps brachii passes through groove
Surgical neck (humerus)
Where proximal epiphysis and diaphysis meet
Deltoid tubercle (humerus)
Main feature of diaphysis; site of attachment for deltoid muscle
Radial groove (humerus)
On posterior aspect of diaphysis; passageway for radial nerve
Distal epiphysis (humerus)
features medial and lateral epicondyle; attachment sites for muscles
Forearm (antebrachium)
*Lateral radius and medial ulna; held to one another by fibrous interosseous membrane
*Both articulate with humerus proximally and with carpal bones distally; articulate with one another both at proximal and distal radioulnar joint
Radius
narrow proximally; progressively enlarges distally:
- radial head
- radial neck
- ulnar notch
- radial styloid process
Radial head
Round and flattened structure; articulates with capitulum of humerus at elbow joint and ulna at proximal radioulnar joint
Radial neck
Distal to head, ends at radial tuberosity; on medial aspect of radius; attachment site for biceps brachii muscle
Ulnar notch
at medial aspect of widened distal epiphysis; location of distal radioulnar joint
Radial styloid process
at lateral tip of radius; forms lateral boundary of wrist; provides joint stabilization
Ulna
Widest at proximal epiphysis; progressively narrows as it travels distally
Trochlear notch (ulna)
U-shaped notch; articulates with trochlea of humerus
Olecranon
Palpable protrusion on posterior aspect of trochlear notch
Anterior lip of trochlear notch
Coronoid process; projection fits into coronoid fossa of humerus
Radial notch of ulna
lateral to coronoid process; smooth area; articulates with radial head
Distal epiphysis
Ulnar head whose medial side contains small styloid process
Wrist (carpus)
eight short bones (carpals) arranged in two rows containing four bones each
Four proximal carpal bones
(from lateral to medial):
–Scaphoid – boat-shaped; articulates with radius
–Lunate – slightly moon-shaped; articulates primarily with radius and lesser degree with ulna
–Triquetrum – triangular; articulates with ulna
–Pisiform – pea-shaped; articulates with anterior surface of triquetrum
Four distal carpal bones
(from lateral to medial):
–Trapezium – articulates proximally with scaphoid
–Trapezoid – articulates primarily with scaphoid
–Capitate – rounded; articulates proximally with scaphoid and lunate
–Hamate – hook like projection; articulates proximally with triquetrum
Hand (manus)
Five long bones (metacarpals)
*Numbered I–V from lateral to medial; articulate with distal carpal bones and bones of fingers
*Each metacarpal consists of three parts:
-proximal epiphysis (base)
-diaphysis (body)
-distal epiphysis (head)
Phalanges
Bones of fingers consist of 14 phalanges, each with base, body, and head
–Each finger consists of three bones: proximal, middle, and distal phalanx
–Thumb (pollex) consists of only proximal and distal phalanx
Pelvis (pelvic girdle) & Lower limbs
Complete appendicular skeleton
*Hipbones or coxal bones (also known as oscoxae) make up pelvic girdle
*Articulates with sacrum (component of axial skeleton)
Pelvis
Bowl-shaped; sacrum and two coxal bones; creates boundary for pelvic cavity:
–Pelvic inlet – oval opening formed by sacrum and pelvic girdle
–Pelvic brim – bony ridge surrounding inlet; defines boundaries between greater and lesser pelvis
–Greater (false pelvis) – area superior to pelvic brim
–Lesser (true pelvis) – inferior to brim
–Pelvic outlet – opening at inferior boundary of lesser pelvis
Fused bones of pelvic bone
- ilium
- ischium
- pubis
Ilium
Forms superior portion of pelvic bone
Ischium
Ischial body and ramus; forms C-shaped posteroinferior portion of pelvic bone
Pubis
Smallest pelvic bone; three parts that approximate C-shape
Femur
Largest and strongest bone in body and only bone in thigh
–Proximal epiphysis features prominent spherical head; articulates with acetabulum at hip joint
–Fovea capitis – small pit in center of head where small ligament attaches to stabilize joint
–Neck – just distal to head
–Greater trochanter – large protuberance lateral to neck
-Lesser trochanter – medial and distal to greater trochanter; trochanters connected by bony ridge on anterior side (intertrochanteric line); continues posteriorly to become intertrochanteric crest
Patella (kneecap)
Articulates with patellar surface on femur
Tibia and Fibula
Bones of leg; connected by interosseous membrane; articulate with one another at proximal and distal tibiofibular joints
Tibia
Larger medial bone of leg; bear weight of body
Fibula
Smaller lateral bone of leg, bears only one-sixth weight of tibia
Tarsals
Seven short bones make up ankle region; connects leg to foot
–Proximal tarsals: talus, calcaneus, and navicular
–Distal tarsals from medial to lateral: medial cuneiform, intermediate cuneiform, lateral cuneiform, and cuboid
Metatarsals
Numbered I–V from medial to lateral, have proximal base, middle shaft, and distal head
Phalanges
(14)
-Toes II–V have proximal, middle, and distal phalanges; great toe or hallux has only proximal and distal phalanx
Three arches of foot
–Medial longitudinal arch – most prominent arch; runs along medial side of foot from calcaneus to metatarsals I–III
–Lateral longitudinal arch – runs from lateral calcaneus to metatarsals IV–V
–Transverse arch – runs along middle of foot; involves distal tarsals and all five metatarsals
