Chapter 7 Flashcards
The appendicular skeleton
- Pectoral (shoulder) girdle
* clavicle
* scapula - Upper limb: arm, forearm & hand
- Pelvic (hip) girdle
* ilium
* ischium
* pubis
-Lower limb: thigh, leg, foot
Glenoid
shallow socket to allow mobility
The upper limb
- 30 bones form skeletal framework
- Arm
- Humerus (funny bone)
- Forearm
- Radius and ulna
- Hand
- 8 carpal bones in the wrist
- 5 metacarpal bones in the palm
- 14 phalanges in the fingers
Humerus
- Articulates superiorly with glenoid cavity of scapula
- Articulates inferiorly with radius and ulna
- have greater and lesser tubercle
Bones of the forearm
- Ulna:
- Medial bone in forearm
- forms major portion of elbow joint with the humerus
- so much bigger
- Radius:
- Lateral bone in forearm
- Forms major portion of wrist joint
- Head articulates with capitulum of humerus and radial notch of ulna
- Interosseous membrane connects radius and ulna along their entire length
- small but as you get lower down, radius gets larger
Hand: carpus, metacarpus, and phalanges
-Carpus (wrist)
*8 bones in 2 rows
*Proximal row-lateral to
medial
**scaphoid, lunate,
triquetrum, and
pisiform
* Distal row-lateral to medial
* trapezium, trapezoid, capitate, an dhamate
- metacarpus (palm)
- phalanges (fingers)
Pelvic (Hip) Girdle
- Two hip bones (coxal bones) and sacrum
- Attach lower limbs to axial skeleton
- Support pelvic organs
-Less mobility but more stable than shoulder joint
- Three fused bones form coxal bone:
- Ilium, ischium, and pubis
Bony pelvis formed by coxal bones, sacrum, and coccyx, pelvic ring
Comparison of Male and Female Pelves
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
- tilted less far forward
- higher up, right under ribs
- adapted for support of males heavier build and stronger muscles
- cavity of true pelvis is narrow and deep
The lower limb
Carries entire weight of erect body
Subjected to exceptional forces if jump or run
Three segments of lower limb
- Thigh
- Leg
- Foot
Bones of the thigh
Femur
- Largest and strongest bone in the body
- Length~ 1/4 of persons height
- articulates proximally with acetabulum of hip and distally with tibia and patella
- comparison to humerous
Patella
-Sesamoid bone in quadriceps tendon
Bones of the leg
Tibia
- medial leg bone
- receives weight of body from femur; transmits to foot
Fibula
- Not weight bearing; no articulation with femur
- Several muscles originate from fibula
- Articulates proximally and distally with tibia
-Tibia and fibula connected by interosseous membrane
Foot: Tarsus, metatarsus, phalanges
Tarsus
- Seven tarsal bones
- Body weight carried primarily by talus and calcaneus
- Other tarsal bones: cuboid, navicular, and medial, intermediate, and lateral cuneiform bones
- Several joints in ankle and foot to accommodate uneven ground surfaces
Metatarsals (foot)
*Metatarsal head
Phalanges (toes)
Arches of the foot
- Maintained by interlocking foot bones, ligaments, and tendons
- Allow foot to bear weight
- Three arches
- Lateral longitudinal
- Medial longitudinal
* Transverse
Developmental Aspects: Fetal Skull
- Infant skull has more bones than adult skull
- Skull bones such as mandible and frontal bones are unfused
=Unossified remnants of fibrous membranes
=Ease birth and allow brain growth
=Four fontanelles (soft spots)
-Anterior, posterior,
mastoid, and
sphenoidal
Development of Spinal curves
At birth, only thoracic & sacral (primary) curves are present (convex posteriorly)
Cervical & lumbar (secondary) curvatures develop in childhood (convex anteriorly)
- cervical curve: when baby starts lifting head
- lumbar curve: baby begins to walk (12th mo.)
Developmental Aspects: old age
Intervertebral discs thin, less hydrated, and less elastic
*Risk of disc herniation increases
Several centimeter height loss common by 55
Costal cartilages ossify
*Rigid thorax causes shallow breathing and less efficient gas exchange
All bones lose mass, so fracture risk increases, spontaneous fractures
Skeletal System
Composed of bones, cartilages, joints, ligaments
Two major parts:
1. Axial:
-Skull
*Cranium and facial
bones
-Vertebral column
*Cervical, thoracic,
lumbar, sacrum, coccyx
- Thoracic cage
2. Appendicular
8 cranial bones
P (arietal) 2
E (thmoid)
S (phenoid)
T (emporal) 2
O (ccipital)
F (rontal)
6
Frontal bone (forehead)
Anterior portion of cranium
Most of anterior cranial fossa
Superior wall of orbits
Contains air-filled frontal sinus
Articulates with parietal bones by coronal suture
Parietal bones and major associated sutures (walls)
Superior and lateral aspects of cranial vault
Four sutures mark articulations:
- Coronal suture—between parietal bones and frontal bone
- Sagittal suture—between right and left parietal bones
- Lambdoid suture—between parietal bones and occipital bone
- Squamous (squamosal) sutures—between parietal and temporal bones on each side of skull
Occipital Bone
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
Temporal bones
Inferolateral aspects of skull and parts of cranial floor (complicated shape)
Four major regions:
Squamous - zygomatic
Tympanic –outer ear
Mastoid – anchor for neck MM
Petrous – inner/middle ear
Sphenoid bone
Complex, bat-shaped bone
Embedded in skull
Keystone bone:
Articulates with all other cranial bones
Three pairs of processes:
- Greater wings
- Lesser wings
- Pterygoid processes
Ethmoid bone (delicate bone)
Deepest skull bone
Superior part of nasal septum, roof of nasal cavities
Contributes to medial wall of orbits
Crista galli for dural attachment, secures brain in cranial cavity
14 facial bones
- Mandible
- Maxillary bones (maxillae) (2)
- Zygomatic bones (2)
- Nasal bones (2)
- Lacrimal bones (2)
- Palatine bones (2)
- Vomer
- Inferior nasal conchae (2)
“Zoro Likes Punching My Very Nose In”
Mandible
- Lower jaw, U-shaped
- Largest, strongest bone of face
- Body and 2 Rami
Temporomandibular joint (TMJ):
*Only freely movable joint
in skull
Maxillary Bones
Keystone bones:
*Articulate with all other
facial bones except
mandible
Contain maxillary sinuses
*Largest of paranasal
sinuses
Zygomatic bones
- cheekbones
- inferolateral margins of orbits
Nasal bones and lacrimal bones
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:
- Frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal, and ethmoid
Nasal cavity
Roof, lateral walls, and floor formed by parts of four bones:
- Ethmoid – sup/middle conchae
- Palatine bones – perpendicular plates
- Maxillary bones
- Inferior nasal conchae
-Nasal septum of bone and hyaline cartilage
*Perpendicular plate of
ethmoid
*Vomer
*Anterior septal cartilage
Hyoid bone
Not bone of skull
Does not articulate directly with another bone, attached by ligaments to styloid
process
Movable base for tongue
Site of attachment for muscles of swallowing and speech
vertebral column
Transmits weight of trunk to lower limbs
Surrounds and protects spinal cord
Flexible curved structure containing 26 irregular bones (vertebrae) in five major regions:
*Cervical vertebrae (7)—vertebrae of neck
- Thoracic vertebrae (12)—vertebrae of thoracic cage
- Lumbar vertebrae (5)—vertebrae of lower back
- Sacrum—bone inferior to lumbar vertebrae
- Coccyx—terminus of vertebral column
Vertebral Column: curvatures
Increase resilience and flexibility of spine:
*Cervical and lumbar
curvatures
-Concave posteriorly
*Thoracic and sacral
curvatures
-Convex posteriorly
- Abnormal spine curvatures:
- Scoliosis - abnormal lateral curve
- Kyphosis (hunchback) – exaggerated thoracic curvature
- Lordosis (swayback) – accentuated lumbar curvature
Ligaments
- Anterior and posterior longitudinal ligaments (on body)
- From neck to sacrum
- Anterior – stronger prevents hyperextension
- Posterior – narrow and weak, prevents extreme forward flexion
-Ligamentum flavum
*Connects adjacent
vertebrae
-Short ligaments
*Connect each vertebra to
those above and below
Intervertebral discs
Cushionlike pad composed of two parts:
-Nucleus pulposus
*Inner gelatinous nucleus
*Gives disc its elasticity
and compressibility
-Anulus fibrosus
*Outer collar composed of collagen and fibrocartilage *Limits expansion of nucleus pulposus
General Structure of vertebrae
Body or centrum:
*Anterior weight-bearing
region
Vertebral arch
*Composed of pedicles
and laminae that, along
with centrum, enclose
vertebral foramen
Vertebral foramina
*Together make up
vertebral canal for spinal
cord
Intervertebral foramina
*Lateral openings
between adjacent
vertebrae for spinal
nerves
Vertebrae
Cervical (C1-C7)
- short spinous process (bifid)
- transverse foramen in transverse processes
- C1 (atlas), C2 (axis)
Thoracic (T1-T12)
- long, downward-pointing spinous processes
- articulate with ribs in posterior
Lumbar (L1-L5)
- short, hatchet-shaped spinous processes
- very large bodies
Cervical Vertebrae
-C1 (atlas) and C2 (axis) have unique features
Atlas (C1):
*No body or spinous
process
*Consists of anterior and
posterior arches,
*Articulate with occipital condyles * Movement for "Yes” * Carries the skull
Cervical Vertebrae
Axis (C2):
*Dens projects superiorly into anterior arch of atlas
*Is “missing” body of
atlas
- Dens is a pivot for rotation of atlas
- Movement for “No”
- No intervertebral disc between atlas and axis
Thoracic Vertebrae
- T1 to T12
- All articulate with ribs at facets and demifacets
- Long, spinous process that points inferiorly
- Circular vertebral foramen
- Location of articular facets allows rotation of this area of spine
Lumbar Vertebrae
- L1 to 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 (S1–S5)
- Forms posterior wall of pelvis, completes the ring
- Articulates with L5 superiorly, and with auricular surfaces of hip bones, forming sacroiliac joints
Coccyx
- Tailbone
- 3–5 fused vertebrae
- Articulates superiorly with sacrum
Ribs and their attachments
-All attach posteriorly to bodies and transverse processes of thoracic vertebrae
-Pairs 1 through 7
*True ribs – attach directly
to sternum via costal
cartilage
-Pairs 8 through 12 (false ribs)
*Pairs 8–10: Attach
indirectly by joining
cartilage of rib above
*Pairs 11–12 also called floating ribs. No attachment to sternum
