Pelvis, Sacrum, and Femur Flashcards
Synarthrosis
- No movement
Amphiarthrosis
- Slightly moveable
Diathrosis
- Freely moveable
Functional classification
- Amount of movement allowed
Structural classification
- Type of connective tissue that connects bone
Fibrous
- United by fibrous connective tissue
Cartilaginous
- United by cartilage
Synovial
- Multiple characteristics
Fibrous joints
- No joint cavity
- Bones united by fibrous CT
- Length of fibers determines movement allowed
Syndesmosis
- Fibrous, amphiarthrosis
- Ex: tibiofibular syndesmosis
Cartilaginous joints
- Lacks joint cavity
- Bones united by cartilage
Synchondroses
- United by hyaline cartilage (primary cartilaginous joint)
- Usually temporary, synarthrosis
- Examples: growth plates
Symphysis
- United by fibrocartilage (secondary cartilaginous joint)
- IVD and pubic symphysis, amphiarthrosis
Synovial joints include
- All are diarthrosis joints
- Articular capsule (2 layers)
- Synovial cavity
- Articular discs
- Bursa
Two layers of articular capsule (synovial joints)
- Outer fibrous capsule
- Inner synovial membrane (secretes fluid)
Articular cartilage (hyaline)
- Covers ends of bones in synovial joints
Accessory ligaments of synovial joints
- Capsular
- Intracapsular
- Extracapsular
- (some classify capsular and extracapsular into the same group)
Bursa
- Fluid filled sac (small amounts of fluid)
- Decreases friction between structures
Synovial joints are classified according to
- Shape of articular surfaces
Types of bone (osteology)
- Compact (cortical)
- Cancellous (trabecular, spongy)
Compact (cortical) bone
- Dense and solid
- White on x-ray
Cancellous (trabecular, spongy)
- Lattice-shaped plates of bone
- Highly vascular
- Develop along stress lines
More stress on cancellous bone leads to
- More dense trabeculae to resist force and direction of loading
Wolff’s Law (applies to both cortical and cancellous bone)
- Bone will develop/remodel based on forces it experiences
Forces applied to bone
- Muscle contraction
- Gravity
- Impact loading
Bone shapes
- Short
- Irregular
- Flat
- Long
- Sesamoid
- Accessory bones (ossicles)
Short bones
- Cubed shape
- Carpals and tarsals
- Trabecular bone covered by cortical
Irregular bones
- Shapes are more complex
- Vertebrae
Flat bones
- Plates of cortical bone with cancellous bone in between
- Ribs, cranial bones
Long bones
- Limbs of the extremities
- Length > width
- Curved
- Hollow medullary shaft, fat marrow in the adult, cancellous bone at the ends
Sesamoid bones
- Round (oval)
- Usually embedded in tendons
- Patella
- 1st metatarsophalangeal join
Sesamoid bones function
- Protect tendon
- Create mechanical advantage (alter angle of muscle pull)
Accessory bones (ossicles)
- Extra bone or non-fused part of existing bone
- Normal variants (not fractures)
- Smooth, regular edges
- Can become symptomatic
- Example: Os trigonum
Lower extremity bone ossification
- Ossify from cartilage to bone
- Endochondral ossification
- All lower extremity except tuft of distal phalanx (ungual tuberosity)
Long bones
- Primary ossification center
- Secondary ossification center
- Epiphyseal plate
Primary ossification center
- Around mid-shaft
- Contributes to formation of diaphysis
- Present at birth in all lower extremity long bones
Secondary ossification centers
- Ends of the long bones
- All not present at birth
- A long bone can have multiple
- Epiphysis
- Apophysis
Epiphysis
- Secondary ossification center that contributes to a joint
Apophysis
- Secondary ossification center for ligament/muscle attachment
Epiphyseal plate (Physis)
- Cartilage plate between diaphysis and epiphysis
- Allows for bone lengthening
- Forms metaphysis and diaphysis
Short bones
- Ossification center is at the bone center
- Not all are present at birth
- Most have 1 (not all)
- Can use for radiographical age determination
Pelvic girdle
- Coxal bones
- Ilium, Ishium, Pubis
- Often includes coccyx
Pelvic girdle articulation
- Articulates posteriorly with the sacrum
- Forms the pelvic skeleton or pelvic ring
Pelvic girdle function
- Strong and rigid
- Connects vertebral column to lower extremity
- Weight/force transfer
- Muscle attachment
- Protect and support pelvic/abdominal viscera
Sacrum
- Wedge shaped bone
- Formed by 5 fused vertebrae
- Forms a primary curviture
Male vs. female sacrum
- Male: longer/narrower
- Female: shorter wider
- Rudimentary disc can persist
Characteristics of sacrum
- Base is superior: articulates with L5 (weight-bearing)
- Apex is inferior: articulates with coccyx
Sacral promontory
- Anterior edge of S1
- Included in base of sacrum
4 anterior and 4 posterior sacral foramina
- Ventral and dorsal rami pass through
Superior articular process (of sacrum)
- Articular facet faces posteriorly
Auricular surface (of sacrum)
- Lateral aspect that articulates with auricular surface of ilium
- Has ridges and depressions
Auricular surface (of sacrum) forms
- Synovial joint
- Part of sacroiliac joint
Sacral tuberosity
- Posterior aspect of lateral surface
Sacral tuberosity forms
- Syndesmosis with ilium
- Ligament attachment
Bony landmarks of sacrum are remnants of
- Vertebral components
Transverse lines (ridges)
- Fused bodies
Sacral crests
- Located posteriorly
Median sacral crest
- Fused spinous processes
Intermediate sacral crest
- Medial side of posterior foramina
- Fused superior/inferior articular processes
Lateral sacral crest
- Lateral to posterior sacral foramina
- Fused transverse processes
Sacral alae
- Lateral projections
- Remnant of S1 TPs
Sacral groove
- Between median and intermediate crest
- Fused laminae