Musculoskeletal Flashcards
What cell type are responsible for the inflammatory response in gout? And what drug targets this inflammatory response?
Neutrophils
Colchicine - interferes with microtubule formation necessary for neutrophil chemotaxis.
What are the 5 layers of the epidermis (from surface to base)?
“Californians Like Girls in String Bikinis”
- stratum Corneum
- stratum Lucidum
- stratum Granulosum
- stratum Spinosum
- stratus Basalis
Where in skin are blood vessels located?
in the dermis (below the epidermis)
Which layers of the epidermis are affected in psoriasis?
- stratum granulosum is decreased
- stratum spinosum is increased (get plaque formation in spinosum)
Eccrine glands
secrete sweat
Sebaceous glands
associated with hair follicles; holocrine secretions of sebum (holocrine secretions = plasma membrane ruptures, destroying cell, thereby secretion product into lumen)
Zona occudens
=tight junction
- ->between cells
- ->composed of claudins and occludins
Zona adherens
=intermediate junction
- ->between cells
- ->composed of Cadherins (Calcium-dependent Adhesion molecules) that connect to Actin
Macula adherens
=Desmosome
- ->between cells
- ->autoantibodies to desmosomes = pemphigus vulgaris
Gap junctions
between adjacent cells
–>cardiac cells, osteocytes, neurons (electrical coupling)
Integrin
connects basolateral surface of cell to basement membrane
Hemidesmosome
connects cell to underlying extracellular matrix (to basement membrane)
–>autoantibodies to hemidesmosomes = bullous pemphigoid
“Unhappy Triad” Knee injury:
- Force from Lateral side, causing damage to:
- MCL = Medial Collateral Ligament
- ACL = Anterior Cruciate Ligament
- Lateral (or Medial) Meniscus
Abnormal passive abduction of the knee?
indicates torn MCL (medial collateral ligament)
ACL and PCL attach to what bone?
Tibia
Level to do a lumbar puncture?
Level of Iliac crest (about L4)
Pudendal nerve block is done where?
Ischial spince
4 Rotator Cuff muscles:
SItS
- Supraspinatus
- Infraspinatus
- teres minor
- Subscapularis
Muscle that initiates abduction of the arm (first 10-15 degrees), before deltoid kicks in?
Supraspinatus
–>injury to supraspinatus is the most common rotator cuff injury
Common cause of long thoracic nerve injury (and thus winged scapula)?
–>Mastectomy (or any trauma/injury to axillary region)
Bones of the wrist (from thumb to pinky)
“Some Lovers Try Positions That They Can’t Handle”
- Scaphoid
- Lunate
- Triquetrum
- Pisiform
- Trapezium
- Trapezoid
- Capitate
- Hamate
Which nerve innervates the thumb + 2.5 fingers of the palm of the hand?
Median nerve
Which nerve innervates the thumb + half of the hand on the dorsum of the hand?
Radial nerve
Which nerve innervates the pinky + 1/2 ring finger on both the palm and dorsum of hand?
Ulnar nerve
What nerve is lesioned by a fracture of the surgical neck of the humerus or by dislocation of the humerus?
Axillary nerve
Nerve injured in a lesion to the shaft of humerus?
Radial nerve –> get “wrist drop”
Which nerve may be compressed by the use of crutches in the axilla or by “Saturday Night Palsy”?
Radial nerve compression –> get “wrist drop”
Lesioned nerve if fracture hook of hamate?
Ulnar nerve
Lesioned nerve if fracture medial epicondyle of humerus?
Ulnar nerve
Compressed nerve if fracture supracondylar area of humerus?
Median nerve
Part of brachial plexus that is compressed by a Pancoast tumor of the ung?
Lower trunk of brachial plexus –> get Kumpke’s palsy (total claw hand - loss of function of all lumbricals, get clawing of all the digits)
Which side of hand is the carpal tunnel?
–>flexor retinaculum, on palmar side of wrist
What muscle protects the brachial plexus from injury in a clavicle fracture?
Subclavius muscle
How to test for an axillary nerve injury?
Test sensation over deltoid
5 nerves that come off the brachial plexus? Which are extensors? Flexors?
“MARMU”
- Musculocutaneous
- Axilary
- Radial
- Median
- Ulnar
- Extensors = Axillary and Radial
- Flexors = Musculocutaneous, Median, Ulnar
Lesion to upper trunk of brachial plexus (C5, C6):
- what’s this called?
- symptoms?
- what may cause this?
Erb’s palsy = “waiter’s tip”
–> can’t abduct arm; arm is medially rotated; and hand is out behind back, like waiting for a tip
–>may be caused by trauma to shoulder (like in a car accident) or trauma during child delivery
Injury to Long Thoracic Nerve?
–>Winged Scapula
Injury to Lower trunk of Brachial Plexus (C8,T1):
- what’s this called?
- symptoms?
- what may cause this?
- ->”Klumpke’s palsy” = “Claw Hand” of ALL digits
- ->symptoms = all fingers form a claw (vs ulnar nerve injury claw hand–>only 4th and 5th digits can’t extend, form claw)
–>may occur d/t an embryologic or childbirth defect
Injury to Posterior Cord of Brachial Plexus?
Can’t extend hand, so get “wrist drop” (can’t extend, so hand just hangs flaccidly)
*makes sense, b/c posterior cord gives rise to the axillary and radial nerves, which are the extensors
Injury to axillary nerve:
- causes?
- symptoms?
- caused by fracture to surgical neck of humerus or dislocation of humerus
- symptoms:
- paralysis of deltoid, so can’t abduct arm at the shoulder (can still do initial abduction)
- decreased sensation over deltoid
Injury to Radial nerve:
- causes?
- symtpoms?
- causes:
- crutches compressing radial nerve at axilla or compression from saturday night palsy
- fracture of midshaft of humerus
- symptoms:
- wrist drop; can’t extend with brachioradialis, extensors of wrist and fingers, supinators, triceps… all extensors :(
- also: loss of sensation over posterior arm, dorsal hand (the part supplied by radial) and dorsal thumb
Injury to Musculocutaneous nerve:
-symptoms?
- decreased flexion of arm at the elbow (b/c musclocutaneous innervates the flexors: biceps, brachialis, coracobrachialis)
- decreased sensation at lateral forearm
Distal lesion to Median Nerve:
- cause?
- symptoms?
- Causes:
- carpal tunnel syndrome
- dislocated lunate
- Signs:
- “Pope’s blessing” –> can’t extend 2nd and 3rd digits, so they are both clawed
Proximal lesion to Median Nerve:
- cause?
- symptoms?
- Cause = fracture of supracondylar humerus
- symptoms:
- “Ape Hand” –> can’t oppose/abduct thumb d/t atrophy of thenar muscles (so thumb is basically glued to other fingers, laterally)
Distal lesion to Ulnar nerve:
- cause?
- symptoms?
- Cause = fractured hook of hamate (like if fall onto outstretched hand)
- Symptoms:
- Clumsiness of hands
- Ulnar “claw hand” –> can’t extend 4th and 5th digits, so they are both in a claw (pinky and ring finger)
Sensory defect over Lateral Forearm?
Injury to Musculocutaneous nerve
Sensory defect over Posterior arm?
Injury to Radial nerve
Proximal lesion to ulnar nerve:
- cause?
- symptoms?
- fracture at medial epicondyle (funny bone)
- problems with flexion; decreased sensation over the hypothenar eminence, medial 1.5 fingers.
Waiter’s tip position of hand: injury to?
Upper Trunk of brachial plexus (C5, C6)
Claw hand, involving all digits: injury to?
Inferior Trunk of Brachial Plexus (C8, T1)
Function of Lumbricals?
- Flex MCP joints
- Extend DIP and PIP joints
*so make an “L” with fingers/hand
Claw Hand, but of only the pinky and ring finger (4th and 5th digits): injury to?
Distal Ulnar Nerve injury: loss of medial lumbrical function
“Pope’s Blessing” - can’t extend the 2nd and 3rd digits: injury to?
median nerve injury–> loss of lateral lumbrical function
“Ape Hand” - can’t abduct the thumb: injury to?
Proximal median nerve injury (like if fracture the supracondylar humerus)
2 Complications of Mastectomy?
1) Winged Scapula (injury to Long thoracic nerve, and thus Serratus Anterior)
2) Lymphedema (which may lead to Lymphangiosarcoma)
Long Thoracic Nerve innervates what muscle?
Serratus Anterior
Muscles of the Thenar Eminence? Innervation?
Meat lOAF:
- Median Nerve
- Opponens pollicis
- Abductor pollicis brevis
- Flexor pollicis brevis
Muscles of the Hypothenar Eminence?
Innervation?
- Ulnar nerve
- Opponens digiti minimi
- Abductor digiti minimi
- Flexor digiti minimi
Functions of the Dorsal vs Palmar Interosseous Muscles:
“DAB PAD”
- Dorsal–> ABduction of fingers
- Palmar–> ADduction of fingers
Where should intramuscular injections into butt be done? Why?
- ->Inject into supero-lateral quadrant of but
- ->to avoid “gluteus medius gait”
- if inject into superomedial quadrant–>may injure gluteal nerves
- if inject into inferomedial quadrant–> may injure sciatic nerve
- if inject into inferolateral quadrant–> lots of muscles have tendinous insertions here
Positive Trendeleburg sign
- ->when standing on one leg, shift weight to opposite side of body than the standing leg
- ->d/t injury to the the superior gluteal nerve; so injury to gluteus medius and minimus muscles
Can’t evert or dorsiflex foot?
–>injury to common peroneal nerve; get “foot drop”
“PED” - “Peroneal Everts and Dorsiflexes; if injured, the foot is dropPED”
“Foot drop”
- d/t injury of common peroneal nerve
- can’t dorsiflex foot
Can’t invert or plantarflex foot?
Injury to Tibial Nerve
“TIP” - “Tibial nerve Inverts and Plantarflexes; if injured, can’t stand on TIP toes”
Sciatic Nerve
on posterior thigh; splits into common peroneal and tibial nerves
Deep Peroneal Nerve:
-innervates?
-innervates Anterior compartment of leg
Superficial Peroneal Nerve:
innervates?
innervates Lateral compartment of leg
Tibial Nerve:
- innervates?
- if injured?
Posterior compartment of leg
- if injured:
- can’t invert of plantarflex foot (inversion = moving sole foot towards medial plane; plantarflexion = standing on tiptoes; so, can’t do either of these things)
- decreased sensation at sole of foot
In skeletal muscle contraction, which parts of the sarcomere change length?
I-band and H-band both shorten in muscle contraction
- I-band = Thin filaments ONLY
- H-band = Thick filaments ONLY
- Z-lines will move closer together (b/c entire sarcomere contracts, gets shorter)
- **note: A-band is the entire length of the thick thilament, regardless of overlap by thin filament; so, it’s length does not change during contraction
Drugs that act at the Dihydropyridine receptor? What’s the effect?
Dihydropyridine Calcium-Channel Blockers (ie Nifedipine and Amlodipine
-by binding to the dihydropiridine receptor, can’t get conformational change, so don’t get Calcium release from sarcomplasmic reticulum (so, it blocks muscle contraction)
Dantrolene mechanism and use?
Dantrolene binds the Ryanodine receptor on the sarcoplasmic reticulum; so, prevents conformational change and release of Calcium from Sarcomplasmic Reticulum (so, blocks skeletal muscle contraction)
- Uses for dantrolene:
- Malignant hyperthermia (from inhalation anesthetics and succinylcholine)
- Neuroleptic malignant syndrome (toxicity of anti-psychotic drugs)
Dihydropyridine and Ryanodine receptors:
Dihydropyridine = voltage-dependent Calcium channels in T-tubules Ryanoide = Calcium release channels in sarcoplasmic reticulum
***in close proximity to each other…
Type 1 vs Type 2 muscles:
- Type 1:
- Red fibers (b/c lots of mitochondria and myoglobin; so increased oxidative phosphorylation)
- slow twitch
- for sustained conraction
- Type 2:
- white fibers (b/c fewer mitochondria and myogobin; more in anaerobic glycolysis)
- fast twitch
- get hypertrophy of fast-twitch, type 2 fibers in weight training
Which type of muscle fibers are hypertrophied in weight trainers?
Type 2 muscle fibers –> white, fast-twitch fibers; involved in anaerobic gycolysis
Effect of Nitric Oxide on Smooth Muscle Contraction (mechanism):
Nitric Oxide –> Guanylate Cyclase –> increased cGMP –> inhibits MLCK –> Smooth muscle Relaxation
MLCK (Myosin Light Chain Kinase) and MLCP (Myosin Light Chain Phosphatase)
*both are involved in mechanism of smooth muscle contraction/relaxation:
- MLCK–> phosphorylates myosin to myosin-P –> get smooth muscle contraction
- MLCK is activated by Calcium binding to Calmodulin
*MLCP –> dephosphorylates myosin-P to myosin –> get smooth muscle Relaxation (stimulated by Nitric Oxide, Sildenafil, etc… increased cGMP)
Calmodulin
Calcium-binding messenger protein
*in smooth muscle contraction: Calcium binds calmodulin –> activates MLCK –> phosphorylates myosin –> smooth muscle contraction
Endochondral ossification: what kind of bone growth?
- ->Longitudinal bone growth
- first have a cartaliginous bone model made by chondrocytes
- defect in endochondral ossification in achondroplasia; so short limbs
Membranous ossification: what kind of bones grow this way?
- ->flat bone growth (skull, face, axial skeleton)
- functional in achondroplasia; so, have large head…