Musculoskeletal Flashcards
Fat redistribution (drug reaction)
Protease inhibitors
Glucocorticoids
Gingival hyperplasia (drug reaction)
Phenytoin
Ca channel blockers
Cyclosporine
Hyperuricemia (gout) - drug reaction
Pyrazinamide Thiazides Furosemide Niacin Cyclosporine
Myopathy (drug reaction)
Fibrates Niacin Colchicine Hydroxychloroquine Interferon alpha Penicillamine Statins Glucocorticoids
Osteoporosis (drug reaction)
Croticosteroids
Heparin
Photosensitivity (drug reaction)
Sulfonamides
Amiodarone
Tetracyclines
5-FU
Rash (SJS) - drug reaction
Anti-epileptic drugs (esp lamotrigine)
Allopurinol
Sulfa drugs
Penicillin
SLE-like syndrome (drug reaction)
Sulfa drugs Hydralazine Isoniazid Procainamide Phenytoin Etanercept
Teeth discoloration (drug reaction)
Tetracyclines
Tendonitis, tendon rupture, and cartilage damage (drug reaction)
Fluoroquinolones
Anterior drawer sign
With patient supine, bending knee at 90 degree angle, increased anterior gliding of tibia due to ACL injury
Posterior drawer sign
With patient supine, bending knee at 90 degree angle, increased posterior gliding of tibia due to PCL injury
Abnormal passive abduction
With patient supine and knee either extended or at about 30 degree angle, lateral (valgus) force leads to medial space widening of tibia - MCL injury
Abnormal passive adduction
With patient supine and knee either extended or at about 30 degree angle. medial (varus) force leads to lateral space widening of tibia - LCL injury
McMurray Test
With the patient supine and knee internally and externally rotated during rotated during range of motion:
Pain, “popping” on external rotation - medial meniscus tear
Pain, “popping” on internal rotation - lateral meniscus tear
Unhappy Triad
Common injury in contact sports due to lateral force applied to a planted leg
Classically, consists of damage to ACL, MCL and medial meniscus (attached to MCL); however, lateral meniscus injury is more common.
Presents with acute knee pain and signs of joint injury/instability
Prepatellar bursitis
“Housemaid’s knee”
Can be caused by repeated trauma or pressure from extensive kneeling
Baker Cyst
Popliteal fluid collection commonly related to chronic joint disease
Rotator Cuff muscles
Shoulder muscles that form the cuff:
Supraspinatus (suprascapular nerve) - abducts arm initially (before the action of the deltoid); most common rotator cuff injury, assessed by “empty/full can” test
Infraspinatus (suprascapular nerve too) - laterally rotates arm; pitching injury
Teres minor (axillary nerve) - adducts and laterally rotates arm
Subscapularis (upper and lower subscapular nerves) - medially rotates and adducts arm
Innervated by C5-C6
Medial epicondylitis
Golfer’s elbow
Repetitive flexion (forehand shots) or idiopathic leading to pain near medial epicondyle
Lateral epicondylitis
Tennis elbow
Repetitive extension (backhand shot) or idiopathic leading to pan near lateral epicondyle
Wrist bones
So Long To Pinky, Here Comes The Thumb
Scaphoid Lunate Triquetrum Pisiform Hamate Capitate Trapezoid Trapezium
Scaphoid (palpated in anatomic snuff box) is the most commonly fractured carpal bone and is prone to avascular necrosis owing to retrograde blood supply
Dislocation of lunate may cause acute carpal tunnel syndrome
A fall on an outstretched hand that damages the hook of the hamate can cause ulnar nerve injury
Carpal tunnel syndrome
Entrapment of median nerve in carpal tunnel; nerve compression leads to paresthesia, pain, and numbness in distribution of median nerve. Associated with pregnancy, RA, hypothyroidism; may be associated with repetitive use
Guyon canal syndrome
Compression of ulnar nerve at wrist or hand. Classically seen in cyclists due to pressure from handlebars
Axillary nerve
C5-C6
Injury causes: Fractured surgical neck of humerus; anterior dislocation of humerus
Presents:
Flattened deltoid
Loss of arm abduction at shoulder (more than 15 degrees)
Loss of sensation over deltoid muscle and lateral arm
Musculocutaneous nerve
C5-C7
Injury from: Upper trunk compression
Presents:
Loss of forearm flexion and supination
Loss of sensation over lateral forearm
Median nerve
C5-T1
Injury from: Supracondylar fracture of humerus (proximal lesion); carpal tunnel syndrome and wrist laceration (distal lesion)
Presents:
Ape Hand and Pope’s Blessing
Loss of wrist flexion, flexion of lateral fingers, thumb opposition, lumbricals of 2nd and 3rd digits
Loss of sensation over thenar eminence and dorsal and palmar aspects of lateral 3 1/2 fingers with proximal lesion
Tinel sign (tingling on percussion) in carpal tunnel syndrome
Radial nerve
C5-T1
Injury from: Midshaft fracture of humerus; compression of axilla (due to crutches or sleeping with arm over chair) - “Saturday night palsy”
Presents:
Wrist Drop: loss of elbow, wrist and finger extension
Lower grip strength (wrist extension necessary for maximal action of flexors)
Loss of sensation over posterior arm/forearm and dorsal hand
Ulnar nerve
C8-T1
Injury from: Fracture of medial epicondyle of humerus “funny bone” (proximal lesion); fractured hook of hamate (distal lesion)
Presents:
Ulnar claw on digit extension
Radial deviation of wrist upon flexion (proximal lesion)
Loss of wrist flexion, flexion of medial fingers, abduction and adduction of fingers (interossei), actions of medial 2 lumbrical muscles
Loss of sensation over medial 1 1/2 fingers including hypothenar eminence
Recurrent branch of median nerve
C5-T1
Injury from: Superficial laceration of palm
Presents:
Ape Hand
Loss of thenar muscle group: opposition, abduction, and flexion of thumb
No loss of sensation
Erb Palsy (Waiter’s Tip)
Injury = traction or tear of upper trunk: C5-C6 roots
Causes = Infants - lateral traction on neck during delivery. Adults - trauma
Muscle deficit =
1) Deltoid, supraspinatus - Abduction (arm hangs by side)
2) Infraspinatus - Lateral rotation (arm medially rotated)
3) Biceps brachii - Flexion, supination (arm extended and pronated)
Klumpke Palsy
Injury = Traction or tear of lower trunk: C8-T1 root
Causes = Infants - upward force on arm during delivery
Adults - trauma (grabbing a tree branch to break a fall)
Muscle deficit = Intrinsic hand muscles: Lumbricals, interossei, thenar, hypothenar - Total claw hand: Lumbricals normally flex MCP joints and extend DIP and PIP joints
Thoracic outlet syndrome
Injury = compression of lower trunk and subclavian vessels
Causes = Cervical rib, Pancoast tumor
Muscle deficit = same as Klumpke - Atrophy of intrinsic hand muscles; ischemia, pain, and edema due to vascular compression
Winged Scapula
Injury = Lesion of long thoracic nerve
Causes = axillary node dissection after mastectomy, stab wounds
Muscle deficit = Serratus anterior - inability to anchor scapula to thoracic cage leading to inability to abduct arm above horizontal position
Distortions of the hand
At rest, a balance exists between the extrinsic flexors and extensors of the hand, as well as the intrinsic muscles of the hand - particularly the lumbrical muscles (flexion of MCP, extension of DIP and PIP joints)
Clawing - seen best with distal lesions of median or ulnar nerves. Remaining extrinsic flexors of the digits exaggerate the loss of the lumbricals - fingers extend at MCP, flex at DIP and PIP
Deficits less pronounced in proximal lesions; deficits present during voluntary flexion of digits
Hand muscles
Thenar (median) - Opponens pollicis; Abductor pollicis brevis, Flexor pollicis brevis, superficial head (deep head by ulnar nerve)
Hypothenar (ulnar) - Opponens digiti minimi, Abductor digiti minimi, Flexor digiti minimi brevis
OAF for both (Oppose, Abduct, Flex)
Dorsal interossei - abduct the fingers (DAB)
Palmar interossei - adduct the finers (PAD)
Lumbricals - flex at the MCP joint, extend PIP and DIP joints
Obturator nerve
L2-L4
Damage: Pelvic surgery
Presents:
Lower thigh sensation (medial) and lower adduction
Femoral nerve
L2-L4
Damage: Pelvic fracture
Presents:
Low thigh flexion and leg extension
Common peroneal nerve
L4-S2
Damage: Trauma or compression of lateral aspect of leg, fibular neck fracture
Presents:
Foot drop - inverted and plantarflexed at rest, loss of eversion and dorsiflexion. “Steppage Gait” Loss of sensation on dorsum of foot
Tibial nerve
L4-S3
Damage: Knee trauma, Baker Cyst (proximal lesion)
Tarsal tunnel syndrome (distal lesion)
Presents:
Inability to curl toes and loss of sensation on sole of foot. In prox lesions, foot everted at rest with loss of inversion and plantarflexion
Superior gluteal nerve
L4-S1
Damage: Iatrogenic injury during intramuscular injection to upper medial gluteal region
Presents:
Trendelenburg sign/gait - pelvis tilts bc weight-bearing leg cannot maintain alignment of pelvis through hip abduction (superior nerve supplies medius and minimus)
lesion is contralateral to the side of the hip that drops, ipsilateral to extremity on which the patient stands
Inferior gluteal nerve
L5-S2
Damage: Posterior hip dislocation
Presents:
trouble climbing stairs, rising from seated position. Loss of hip extension (inferior nerve - maximum)
Sciatic and pudendal nerves
Sciatic nerve (L4-S3) innervates posterior thigh, splits into common peroneal and tibial nerves
Pudendal nerve (S2-S4) innervates perineum. Can be blocked with local anesthetic during childbirth using the ischial spine as a landmark for injection
Signs of lumbrosacral radiculopathy
Paresthesias and weakness in distribution of specific lumbar or sacral spinal nerves.
Often due to IVdisc herniation in which the nerve association with the inferior vertebral body is impinged (herniation of L3-L4 disc affects the L4 spinal nerve)
IV discs generally herniate posterolaterally, due to the thin posterior longitudinal ligament and thicker anterior longitudinal ligament along the midline of the vertebral bodies
L3-L4 disc level - weakness of knee extension, reduced patellar reflex
L4-L5 disc level - Weakness of dorsiflexion, difficulty in heel-walking
L5-S1 disc level - Weakness of plantarflexion, difficulty in toe-walking, reduced Achilles reflex
Neurovascular pairings
Nerves and arteries are frequently named together by the bones/regions with which they are associated. There are exceptions though:
1) Axilla/lateral thorax = Long thoracic N/ Lateral thoracic A
2) Surgical neck of humerus = Axillary N/ Posterior circumflex A
3) Midshaft of humerus = Radial N/ Deep brachial A
4) Distal humerus/cubital fossa = Median N/ Brachial A
5) Popliteal fossa = Tibial N/ Popliteal A
6) Posterior to medial malleolus = Tibial N/ Posterior Tibial A
Muscle conduction to contraction (7 steps)
1) Action potential depolarization opens presynaptic voltage-gated Ca channels, inducing nt release
2) Postsynaptic ligand binding leads to muscle cell depolarization in the motor end plate
3) Depolarization travels along muscle cell and down T-tubule
4) Depolarization of the voltage sensitive dihydropyridine receptor, mechanically couple to the ryanodine receptor on the sarcoplasmic reticulum, induces a conformational change, causing Ca release from SR
5) Released Ca binds to troponin C, causing a conformational change that moves tropomyosin out of the myosin-binding groove on actin filaments
6) Myosin releases bound ADP and inorganic PO4 leading to displacement of myosin on the actin filament (power stroke). Contraction results in shortening of H and I bands and between Z lines (HIZ shrinkage), but the A band remains the same length (A is Always the same)
7) Binding of a new ATP molecule causes detachment of myosin head from actin filament. Hydrolysis of bound ATP to ADP, myosin head adapts high-energy position (“cocked”) for the next contraction cycle
T tubules (extensions of plasma membrane juxtaposed with terminal cisternae) are part of the sarcoplasmic reticulum
Skeletal muscle, 1 T tubule + 2 terminal cisternae = triad
Cardiac muscle, 1 T tubule + 1 terminal cisternae = diad
Types of muscle fibers
Type 1 - slow twitch; red fibers resulting from increased mitochondria and myoglobin concentration (Increased oxidative phosphorylation) - sustained contraction
Type 2 - fast twitch; white fibers resulting from lower mitochondria and myoglobin concentrations (increased anaerobic glycolysis); weight training results in hypertrophy of fast-twitch muscle fibers
