Musculoskeletal, Skin, and Connective Tissue Flashcards by Emily Acton

Which bones are formed by endochondral ossification and which are formed by membranous ossification?

Endochondral Ossification:
- Bones of axial skeleton, appendicular skeleton, and base of skull

Membranous Ossification:
- Bones of calvarium, facial bones, and clavicle

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In endochondral ossification, ——— model of bone is first made by ———; ——— later replace with ——— and then remodel to ———

- cartilaginous

- chondrocytes

- osteoclasts and osteoblasts

- woven bone

- lamellar bone

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In normal adults, woven bone occurs:

after fractures

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In adults, woven bone can occurs with what disease?

Paget disease

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Endochondral ossification is defective with which disease?

achondroplasia

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In membranous ossification, ———formed directly without ———; Later remodeled to ———

- woven bone

- cartilage

- lamellar bone

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Osteoblasts function to ——— by secreting ——— and catalyzing ——— in ——— environment via ———

- build bone

- collagen

- mineralization

- alkaline

- ALP (alkaline phosphatase)

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Osteoblasts differentiate from ———in ———

- mesenchymal stem cells

- periosteum

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Osteoblastic activity is measured by which 3 factors:

- bone ALP (alkaline phosphatase)

- osteocalcin

- propeptides of type I procollagen

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Osteoclasts function to ——— by secreting ——— and ———

- dissolves (“crushes”) bone

- H+

- collagenases

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Osteoclasts differentiate from:

a fusion of monocyte/macrophage lineage precursors

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——— receptors on osteoclasts are stimulated by ——— (expressed on ———)

- RANK

- RANKL (RANK ligand)

- osteoblasts

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Osteoclast activity is decreased by ——— (which is a ———) binds ——— to prevent ———

- OPG (osteoprotegerin)

- RANKL decoy receptor

- RANKL

- RANK-RANKL interaction

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At low, intermittent levels, PTH exerts ——— effects (results in ———) on osteoblasts and osteoclasts (—direct or indirect effect?—)

- anabolic

- building bone

- indirect

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Chronically elevated PTH levels (name disease state ———) cause ——— effects on bone (name associated condition ———)

- 1° hyperparathyroidism

- catabolic

- osteitis fibrosa cystica

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Estrogen inhibits apoptosis in ———and induces apoptosis in ———

- bone-forming osteoblasts

- bone-resorbing osteoclasts

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Estrogen causes what bone related action during puberty?

closure of epiphyseal plate

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Estrogen deficiency (surgical or postmenopausal) has what effect on bone and is associated with what condition?

- causes cycles of remodeling and bone resorption

- increases the risk of osteoporosis

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Greenstick fracture are ——— fracture extending —— following ——— stress; bone fails on ——— side; ——— side intact

- incomplete

- partway through width of bone

- bending

- tension

- compression

(Bone is bent like a green twig)

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Torus (buckle) fracture is caused by a ——— force applied to ——— bone resulting in ——— on ——— side and fractures; ——— side remains solid (intact)

- axial

- immature

- cortex buckling

- compression (concave)

- tension (convex)

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Achondroplasia is a failure of ———, resulting in phenotype of ———

- longitudinal bone growth (endochondral ossification)

- short limbs

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In Achondroplasia, ——— is not affected, resulting in phenotype of ———

- membranous ossification

- large head relative to limbs

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In Achondroplasia, constitutive activation of ——— results in inhibition of ———

- fibroblast growth factor receptor (FGFR3)

- chondrocyte proliferation

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The mode of inheritance for Achondroplasia is ——— with ——— penetrance (homozygosity is ———) (> 85% of mutations occur ———)

- autosomal dominant

- full

- lethal

- sporadically

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Achondroplasia is associated with what relative to parents?

Associated with increased paternal age

What is the most common cause of short-limbed dwarfism?

Achondroplasia

With Osteoporosis, ——— lose mass despite normal ——— and ——— (I.e., ———)

- trabecular (spongy) and cortical bone - bone mineralization and lab values - serum Ca2+ and PO4 3−

Osteoporosis is most commonly due to ——— (due to ———) related to . ———, ———, and ———

- bone resorption - increased osteoclast number and activity - decreased estrogen levels, old age, and cigarette smoking

Give 5 examples of drugs and 5 examples of other conditions that Osteoporosis can be 2° to:

- drugs (eg, steroids, alcohol, anticonvulsants, anticoagulants, thyroid replacement therapy) - other conditions (eg, hyperparathyroidism, hyperthyroidism, multiple myeloma, malabsorption syndromes, anorexia)

Osteoporosis is diagnosed by measurement of ——— by ——— test looking at the ———, with a T-score of ≤ ——— or by a ——— (eg, ———) at ———

- bone mineral density - DEXA (dual-energy x-ray absorptiometry) - lumbar spine, total hip, and femoral neck - −2.5 - fragility fracture - fall from standing height, minimal trauma - hip or vertebra

One-time Osteoporosis screening recommended in ———

females ≥ 65 years old

List 2 approaches to prophylaxis against Osteoporosis:

- regular weight-bearing exercise - adequate Ca2+ and vitamin D intake throughout adulthood

List 4 treatments for Osteoporosis:

- bisphosphonates - teriparatide - SERMs (selective estrogen receptor modulators) -denosumab (monoclonal antibody against RANKL)

List 5 key symptoms of Osteoporosis:

- vertebral compression fractures - acute back pain - loss of height - kyphosis - fractures of femoral neck or distal radius (Colles fracture)

Osteopetrosis is a failure of ——— due to ———, resulting in ——— bones that are prone to ———

- normal bone resorption - defective osteoclasts - thickened, dense - fracture

In Osteopetrosis, mutations (eg, ———) impair ———

- carbonic anhydrase II - ability of osteoclast to generate acidic environment necessary for bone resorption

In Osteopetrosis, overgrowth of ——— fills ——— leading to ———

- cortical bone - marrow space - pancytopenia, extramedullary hematopoiesis

Osteopetrosis can result in ——— and ——— due to narrowed foramina

cranial nerve impingement and palsies

Osteopetrosis on x-rays shows:

diffuse symmetric sclerosis (bone-in-bone, “stone bone”)

For Osteopetrosis, ——— is potentially curative as ———

- bone marrow transplant -osteoclasts are derived from monocytes

Osteomalacia occurs due to defective ——— and rickets occurs due to defective ——— (occurs only in ———)

- mineralization of osteoid (unmineralized bone tissue) - mineralization of cartilaginous growth plates - children

Osteomalacia and rickets are most commonly due to:

vitamin D deficiency

In osteomalacia, X-rays in show what two findings:

osteopenia and pseudofractures (insufficiency fractures; also called Looser zones, cortical infractions, or Milkman line)

In rickets, X-rays in show what two findings:

epiphyseal widening and metaphyseal cupping/fraying

List 3 key findings in children with rickets:

- pathologic bow legs (genu varum) - beadlike costochondral junctions (rachitic rosary) craniotabes (soft skull)

Relative to osteomalacia/rickets, decreased vitamin D —> ———serum Ca2+ —> ——— PTH secretion —> ——— serum PO4 3−

- decreased - increased - decreased

Relative to osteomalacia/rickets, hyperactivity of osteoblasts —> ——— ALP

Increased

Osteitis deformans (also called ———) is a common, localized disorder of ——— caused by ——— activity followed by ——— activity that forms ——— bone

- Paget disease of bone - bone remodeling - increased osteoclastic activity - increased osteoblastic activity - poor-quality

In osteitis deformans, how are serum Ca2+, phosphorus, PTH, and ALP levels?

- Normal Serum Ca2+, phosphorus, and PTH levels - Elevated ALP

List the divisions of the brachial plexus:

Roots Trunk Divisions Cords Branches (Remember To Drink Cold Beer)

Relative to locations, ——— of brachial plexus and the ——— artery pass between ——— and ——— muscles (——— vein passes anteromedial to the ———)

- Trunks - subclavian - anterior scalene - middle scalene - subclavian - scalene triangle

The brachial plexus is composed of which nerve roots?

four cervical nerve roots (C5-C8) and first thoracic nerve root (T1)

Brachial plexus roots combine to form ——— trunks : ——— forms the upper trunk, ——— forms the middle trunk and ——— forms the lower trunk

- three - C5-C6 - C7 - C8-T1

What injury causes Erb palsy (“waiter’s tip”) ?

Traction or tear of upper trunk: C5-C6 roots

In infants, what tends to cause Erb palsy (“waiter’s tip”)?

lateral traction on neck during delivery

In adults, what tends to cause Erb palsy (“waiter’s tip”)?

trauma leading to neck traction (eg, falling on head and shoulder in motorcycle accident)

List the involved muscles and associated deficits in Erb palsy (“waiter’s tip”):

Deltoid, supraspinatus - Abduction (arm hangs by side) Infraspinatus, supraspinatus - Lateral rotation (arm medially rotated) Biceps brachii - Flexion, supination (arm extended and pronated) (ERB gets DIBS on TIPS )

Define abduction vs adduction:

Abduction refers to moving a limb away from the midline of body Adduction refers to moving a limb toward the midline of your body

Define supination vs pronation of the forearm:

Supination is a movement that turns the palm to face anteriorly or palm facing up Pronation is a movement that turns the palm to face posteriorly or palm facing down

What injury causes Klumpke palsy?

Traction or tear of lower trunk: C8-T1 roots

In infants, what tends to cause Klumpke palsy?

Upward force on arm during delivery

In adults, what tends to cause Klumpke palsy?

trauma (eg, grabbing a tree branch to break a fall)

List the involved muscles and associated deficits in Klumpke palsy:

Intrinsic hand muscles: lumbricals, interossei, thenar, hypothenar Claw hand: lumbricals normally flex MCP joints and extend DIP and PIP joints

What injury causes thoracic outlet syndrome?

Compression of lower trunk and subclavian vessels, most commonly within the scalene triangle

What tends to cause thoracic outlet syndrome?

Cervical/anomalous first ribs (arrows), Pancoast tumor

List the involved muscles and associated deficits in thoracic outlet syndrome:

Intrinsic hand muscles: lumbricals, interossei, thenar, hypothenar (Same as Klumpke palsy) Atrophy of intrinsic hand muscles; ischemia, pain, and edema due to vascular compression

What injury causes winged scapula?

Lesion of long thoracic nerve, roots C5-C7 (“wings of heaven”)

What are causes of a winged scapula?

Axillary node dissection after mastectomy, stab wounds

List the involved muscles and associated deficits in a winged scapula:

Serratus anterior Inability to anchor scapula to thoracic cage, thus cannot abduct arm above horizontal position