Introduction To Limb Musculoskeletal Anatomy Flashcards
What are the different parts of a long bone?
- Epiphysis: where articulations take place
- Metaphysis
- Diaphysis: anatomical shaft
What do lumps/bumps and grooves on bones represent?
Lumps/bumps = where muscles attach so bone reinforces itself at this point
Grooves = structure is running over the bone at this point e.g. vessel
What are the different types of bone?
- Long: upper/lower limbs
- Short: hands/feet
- Sesamoid: tendons e.g. patella
- Flat bones e.g. pelvic girdle/skull/scapula
What are the features of sesamoid bones?
Bone situated within a tendon (look like free bones in X-rays) to:
- Reduce the wear of the tendon preventing it rubbing against bone
- Improve muscle efficiency
What are the features of flat bones?
- Large SA for muscle attachment
- Weight/force transfer region
- Protection
What is Wolff’s law?
Bone is deposited and reabsorbed (remodels) in accordance with the stresses placed upon it where LESS STRESS = LESS BONE which over time, can cause osteopenia (precursor of osteoporosis) if a bone is not utilised so the body reabsorbs it
What are the 2 types of bone within a bone? Why do we have these?
- Cancellous/trabecular: low density allowing bone to be flexible under weight bearing (metaphysis region)
- Cortical: high density allowing bone to compression bear (edges of diaphysis region)
What makes up the axial skeleton?
More medial structures: Skull Ribs Sternum Vertebrae Sacrum Coccyx
What makes up the appendicular skeleton?
More lateral structures:
Hip bones of pelvic girdle
Pectoral girdle
Limbs (upper/lower)
How do the limbs develop?
- Grow out as buds from week 4/5 forming flippers at top and bottom of embryo
- Digits and overall limb shape present by week 8 but hands/feet webbed
- Digits form by apoptosis along gaps to separate out the digits
What are the different types of developmental limb defects?
- Amelia: no limb development
- Meromelia/phocomelia: part limb/seal-like limb
- Polydactyly: additional digits
- Syndactyly: webbed digits
What are the causes of developmental limb defects?
- Genetic
- Teratogenic e.g. Thalidomide (anti-nauseant, sleeping pill) + Retinoids (Vit A derivatives)
- Mechanical e.g. amniotic bands strangle tissue cutting of blood supply preventing it developing properly
What are the main functions of the upper limbs?
Range of MOVEMENT in preference to strength/stability:
- Carriage
- Fine manipulative tasks
- Feeding
- MINIMAL locomotion
What are the main functions of the lower limbs?
STRENGTH/STABILITY in preference to range of movement:
- Support body weight
- Maintain upright posture
- Locomotion (gait)
- Accommodate shock loading
What is the same basic layout that limbs share?
- Girdle: appendage/attachment point)
- Single long bone
- Paired long bones
- Short and long bones: carpals/tarsals, metacarpals/metatarsals + phalanges
Synovial joints predominate in limbs. What are the different types?
Ball + socket Hinge Pivot Ellipsoid Mixed types
What are the 2 types of bone-to-bone joints of the body?
- Fibrous (e.g. suture, gomphosis + syndesmosis): relatively stable with little movement
- Cartilaginous (e.g. IV discs, epiphysis, symphysis + synovial): relatively fixed and stable to highly mobile respectively
All joints balance stability with mobility. In order of least-most mobile and most-least stable, list them.
- Fibrous: very stable with no movement so do not dislocate/fracture
- 1o and 2o cartilaginous: quite stable and slightly mobile e.g. pubic symphysis softens and parts slightly to allow for childbirth
- Synovial: not very stable because it is highly mobile making them more prone to dislocation
What are the structural features of synovial joints from innermost to outermost?
Hyaline cartilage: smooth articular surface between bones
Joint/synovial cavity: surrounds cartilage and contains synovial fluid to lubricate joint
Synovium (serous membrane): sheet of fibrous connective tissue that secretes synovial fluid
Joint capsule: ligament that protects and supports all of this connecting bone-bone
For a joint to increase its constraining forces and become more stable, what must it do?
DECREASE JOINT MOBILITY - why the hip joint is more stable than the shoulder