MSK, Skin, and Connective Tissue (415-446)

Question 1

With patient supine, bending knee at 90-degree
angle, inc. anterior gliding of tibia due to ACL
injury.

Answer 1

Anterior Drawer Sign

Question 2

With patient supine, bending knee at 90-degree
angle, inc. posterior gliding of tibia due to PCL
injury.

Answer 2

Posterior drawer sign

Question 3

With patient supine and knee either extended
or at ∼ 30-degree angle, lateral (valgus) force
-> medial space widening of tibia -> MCL
injury.

Answer 3

Abnormal passive

abduction

Question 4

With patient supine and knee either extended
or at ~ 30-degree angle, medial (varus) force
-> lateral space widening of tibia -> LCL
injury.

Answer 4

Abnormal passive

adduction

Question 5

With patient supine and knee internally and
externally rotated during range of motion:
- Pain, “popping” on external rotation -> medial meniscal tear
- Pain, “popping” on internal rotation -> lateral meniscal tear

Answer 5

McMurray test

Question 6

Common injury in contact sports due to lateral
force applied to a planted leg. Classically,
consists of damage to the 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.

Answer 6

“Unhappy triad”

Question 7

“Housemaid’s knee”. Can be caused by repeated trauma or pressure from extensive kneeling.

Answer 7

Prepatellar bursitis

Question 8

Popliteal fluid collection commonly related to chronic joint disease.

Answer 8

Baker cyst

Question 9

Rotator cuff muscles

Answer 9

Shoulder muscles that form the rotator 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)—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 primarily by C5-C6.

Question 10

Repetitive flexion (forehand shots) or idiopathic -> pain near medial epicondyle.

Answer 10

Medial epicondylitis

golfer’s elbow

Question 11

Repetitive extension (backhand shots) or idiopathic -> pain near lateral epicondyle.

Answer 11

Lateral epicondylitis

tennis elbow

Question 12

Wrist bones

Answer 12

Scaphoid, Lunate, Triquetrum, Pisiform, Hamate, Capitate, Trapezoid, Trapezium. (So Long To Pinky, Here Comes The Thumb).
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.

Question 13

Entrapment of median nerve in carpal tunnel; nerve compression -> paresthesia, pain, and numbness in distribution of median nerve. Associated with pregnancy, rheumatoid arthritis, hypothyroidism; may be associated with repetitive use.

Answer 13

Carpal tunnel

syndrome

Question 14

Compression of ulnar nerve at wrist or hand. Classically seen in cyclists due to pressure from handlebars.

Answer 14

Guyon canal

syndrome

Question 15

Fractured surgical neck of humerus; anterior

dislocation of humerus

Answer 15

Axillary (C5-C6)

Flattened deltoid
Loss of arm abduction at shoulder (> 15 degrees)
Loss of sensation over deltoid muscle and lateral
arm

Question 16

Loss of forearm flexion and supination

Loss of sensation over lateral forearm

Answer 16

Musculocutaneous
(C5-C7)

Upper trunk compression

Question 17

Midshaft fracture of humerus; compression of
axilla, e.g., due to crutches or sleeping with
arm over chair (“Saturday night palsy”)

Answer 17

Radial (C5-T1)

Wrist drop: loss of elbow, wrist, and finger
extension
Dec. grip strength (wrist extension necessary for
maximal action of flexors)
Loss of sensation over posterior arm/forearm and
dorsal hand

Question 18

“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

Answer 18

Median (C5-T1)

Supracondylar fracture of humerus (proximal
lesion); carpal tunnel syndrome and wrist
laceration (distal lesion)

Question 19

Fracture of medial epicondyle of humerus
“funny bone” (proximal lesion); fractured hook
of hamate (distal lesion)

Answer 19

Ulnar (C8-T1)

“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

Question 20

Superficial laceration of palm

Answer 20

Recurrent branch of
median nerve (C5-T1)

“Ape hand”
Loss of thenar muscle group: opposition,
abduction, and flexion of thumb
No loss of sensation

Question 21

Infants—lateral
traction on neck
during delivery
Adults—trauma

Answer 21

Erb palsy (“waiter’s tip”)

Traction or tear of upper
(“Erb-er”) trunk: C5-C6 roots

Deltoid, supraspinatus
Abduction (arm hangs by side)

Infraspinatus Lateral rotation (arm medially rotated)

Biceps brachii Flexion, supination (arm extended and pronated)

Question 22

Traction or tear
of lower trunk:
C8-T1 root

Answer 22

Klumpke palsy

Infants—upward
force on arm
during delivery
Adults—trauma
(e.g., grabbing
a tree branch to
break a fall)
Intrinsic hand
muscles:
lumbricals,
interossei,
thenar,
hypothenar

Total claw hand:
lumbricals normally
flex MCP joints and
extend DIP and PIP
joints

Question 23

Atrophy of intrinsic
hand muscles;
ischemia, pain,
and edema
due to vascular
compression

Answer 23

Thoracic outlet
syndrome

Compression of lower trunk
and subclavian vessels

Cervical rib,
Pancoast tumor

Intrinsic hand
muscles: lumbricals, interossei, thenar,
hypothenar

Question 24

Axillary node
dissection after
mastectomy,
stab wounds

Answer 24

Winged scapula

Lesion of long
thoracic nerve

Serratus anterior

Inability to anchor
scapula to thoracic
cage -> cannot
abduct arm above
horizontal position

Question 25

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 joints.

Answer 25

Clawing

Question 26

“Ulnar claw”

Answer 26

Extending fingers/at rest Distal ulnar nerve

Question 27

“Pope’s blessing”

Answer 27

Making a fist Proximal median nerve

Question 28

“Median claw”

Answer 28

Extending fingers/at rest Distal median nerve

Question 29

“OK gesture” (with digits 1–3 flexed)

Answer 29

Making a fist Proximal ulnar nerve

Question 30

Atrophy of the thenar eminence (unopposable thumb -> “ape hand” vs Atrophy of the hypothenar eminence

Answer 30

Thenar: Median nerve Hypothenar: Ulnar nerve

Question 31

Thenar (median)

Answer 31

Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis, superficial head (deep head by ulnar nerve). Oppose, Abduct, and Flex (OAF).

Question 32

Hypothenar (ulnar)

Answer 32

Opponens digiti minimi, Abductor digiti minimi, Flexor digiti minimi brevis. Oppose, Abduct, and Flex (OAF).

Question 33

Dorsal interossei

Answer 33

abduct the fingers ``` DAB = Dorsals ABduct. PAD = Palmars ADduct. ```

Question 34

Palmar interossei

Answer 34

adduct the fingers. ``` DAB = Dorsals ABduct. PAD = Palmars ADduct. ```

Question 35

Lumbricals

Answer 35

flex at the MCP joint, extend PIP and DIP joints.

Question 36

Pelvic surgery Dec. thigh sensation (medial) and dec. adduction.

Answer 36

Obturator (L2–L4)

Question 37

Pelvic fracture Dec. thigh flexion and leg extension.

Answer 37

Femoral (L2–L4)

Question 38

Trauma or compression of lateral aspect of leg, | fibular neck fracture

Answer 38

Common peroneal (L4–S2) Foot drop—inverted and plantarflexed at rest, loss of eversion and dorsiflexion. “Steppage gait.” Loss of sensation on dorsum of foot. PED = Peroneal Everts and Dorsiflexes; if injured, foot dropPED.

Question 39

``` Knee trauma, Baker cyst (proximal lesion); tarsal tunnel syndrome (distal lesion) ```

Answer 39

Tibial (L4–S3) Inability to curl toes and loss of sensation on sole of foot. In proximal lesions, foot everted at rest with loss of inversion and plantarflexion. TIP = Tibial Inverts and Plantarflexes; if injured, can’t stand on TIPtoes.

Question 40

Iatrogenic injury during intramuscular injection | to upper medial gluteal region

Answer 40

Superior gluteal (L4–S1) Trendelenburg sign/gait—pelvis tilts because weight-bearing leg cannot maintain alignment of pelvis through hip abduction (superior nerve -> medius and minimus). Lesion is contralateral to the side of the hip that drops, ipsilateral to extremity on which the patient stands.

Question 41

Posterior hip dislocation

Answer 41

Inferior gluteal (L5–S2) Difficulty climbing stairs, rising from seated position. Loss of hip extension (inferior nerve - > maximus).

Question 42

Superior gluteal nerve innervates -----. Inferior gluteal nerve innervates -----.

Answer 42

Superior gluteal nerve innervates gluteus medius and minimus. Inferior gluteal nerve innervates gluteus maximus.

Question 43

Sciatic nerve (L4–S3) innervates -----, splits into -----.

Answer 43

Sciatic nerve (L4–S3) innervates posterior thigh, splits into common peroneal and tibial nerves.

Question 44

``` Pudendal nerve (S2–S4) innervates -----. Can be blocked with local anesthetic during childbirth using the ----- as a landmark for injection. ```

Answer 44

``` Pudendal nerve (S2–S4) innervates perineum. Can be blocked with local anesthetic during childbirth using the ischial spine as a landmark for injection. ```

Question 45

Paresthesias and weakness in distribution of specific lumbar or sacral spinal nerves. Often due to ----- in which the nerve association with the ----- vertebral body is impinged

Answer 45

Paresthesias and weakness in distribution of specific lumbar or sacral spinal nerves. Often due to intervertebral disc herniation in which the nerve association with the inferior vertebral body is impinged (e.g., herniation of L3–L4 disc affects the L4 spinal nerve).

Question 46

Intervertebral discs generally herniate ----- due to the thin ----- and thicker ----- along the midline of the vertebral bodies.

Answer 46

Intervertebral discs generally herniate posterolaterally, due to the thin posterior longitudinal ligament and thicker anterior longitudinal ligament along the midline of the vertebral bodies.

Question 47

L3–L4 Weakness of?

Answer 47

Weakness of knee extension, Dec. patellar reflex

Question 48

L4–L5 Weakness of?

Answer 48

Weakness of dorsiflexion, difficulty in heelwalking

Question 49

L5–S1 Weakness of?

Answer 49

Weakness of plantarflexion, difficulty in toewalking, | Dec. Achilles reflex

Question 50

Neurovascular pairing

Answer 50

Nerves and arteries are frequently named together by the bones/regions with which they are associated. Some exceptions (see other card)

Question 51

Exceptions to the neurovascular pairing rule. Axilla/lateral thorax

Answer 51

Long thoracic n. | Lateral thoracic a.

Question 52

Exceptions to the neurovascular pairing rule. Surgical neck of humerus

Answer 52

Axillary n. | Posterior circumflex a.

Question 53

Exceptions to the neurovascular pairing rule. Midshaft of humerus

Answer 53

Radial n. | Deep brachial a.

Question 54

Exceptions to the neurovascular pairing rule. Distal humerus/ cubital fossa

Answer 54

Median n. | Brachial a.

Question 55

Exceptions to the neurovascular pairing rule. Popliteal fossa

Answer 55

Tibial n. | Popliteal a.

Question 56

Exceptions to the neurovascular pairing rule. Posterior to medial malleolus

Answer 56

Tibial n. | Posterior tibial a.

Question 57

Muscle Physiology 1. Action potential depolarization opens - ---- voltage-gated ----- channels, inducing neurotransmitter release. 2. Postsynaptic ligand binding leads to ----- in the ------.

Answer 57

1. Action potential depolarization opens presynaptic voltage-gated Ca2+ channels, inducing neurotransmitter release. 2. Postsynaptic ligand binding leads to muscle cell depolarization in the motor end plate.

Question 58

Muscle Physiology 3. Depolarization travels along muscle cell and down the -----. 4. Depolarization of the voltage-sensitive ----- receptor, mechanically coupled to the ----- receptor on the sarcoplasmic reticulum, induces a conformational change, causing ----- from sarcoplasmic reticulum.

Answer 58

3. Depolarization travels along muscle cell and down the T-tubule. 4. Depolarization of the voltage-sensitive dihydropyridine receptor, mechanically coupled to the ryanodine receptor on the sarcoplasmic reticulum, induces a conformational change, causing Ca2+ release from sarcoplasmic reticulum.

Question 59

Muscle Physiology 5. Released Ca2+ binds to -----, causing a conformational change that moves ----- out of the myosin-binding groove on -----. 6. Myosin releases bound ADP and inorganic PO43 –> displacement of ----- on the ----- (power stroke). Contraction results in shortening of ----- and ----- bands and between ----- lines (----- shrinkage), but the ----- band remains the same length.

Answer 59

5. Released Ca2+ 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 PO43 –> 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 band is Always the same length).

Question 60

Muscle Physiology 7. Binding of a new ATP molecule causes ----- of myosin head from actin filament. Hydrolysis of bound ATP -> ADP, ----- head adopts high-energy position (“cocked”) for the next contraction cycle.

Answer 60

7. Binding of a new ATP molecule causes detachment of myosin head from actin filament. Hydrolysis of bound ATP -> ADP, myosin head adopts high-energy position (“cocked”) for the next contraction cycle.

Question 61

Muscle Physiology T-tubules (extensions of ----- juxtaposed with -----) are part of the -----. In skeletal muscle, ----- T-tubule + ----- terminal cisternae = triad. In cardiac muscle, ----- T-tubule + ----- terminal cisternae = diad.

Answer 61

T-tubules (extensions of plasma membrane juxtaposed with terminal cisternae) are part of the sarcoplasmic reticulum. In skeletal muscle, 1 T-tubule + 2 terminal cisternae = triad. In cardiac muscle, 1 T-tubule + 1 terminal cisternae = diad.

Question 62

Muscle Physiology Z-line - ? I-band - ? only A-band - ? H-band - ? only M-line - ?

Answer 62

Z-line - sarcomere between z-lines, actin anchor I-band - Actin only A-band - Actin, Myosin H-band - Myosin only M-line - Myosin anchor

Question 63

Slow twitch; red fibers resulting from inc. mitochondria and myoglobin concentration (inc. oxidative phosphorylation) -> sustained contraction.

Answer 63

Type 1 muscle Think “1 slow red ox.”

Question 64

Type 2 muscle

Answer 64

Fast twitch; white fibers resulting from dec. mitochondria and myoglobin concentration (dec. anaerobic glycolysis); weight training results in hypertrophy of fast-twitch muscle fibers.

Question 65

Smooth Muscle Contraction 1. AP causes membrane depolarization 2. Activation of ----- 3. Release of ----- intracellularly 4. Increased formation of ----- 5. Increased ----- 6. Increased ----- 7. Contraction via Cross bridging

Answer 65

1. AP causes membrane depolarization 2. Activation of L-type voltage-gated Ca2+ channel 3. Release of calcium intracellularly 4. Increased formation of Ca2+-Calmodulin complexes 5. Increased Myosin-light-chain-kinase (MLCK) 6. Increased Myosin-P and Actin 7. Contraction via Cross bridging Increased Ca2+ = contraction

Question 66

Smooth Muscle Relaxation 1. ----- 2. Increased ----- 3. Increased conversion of ----- to ----- 4. ----- increases ----- 5. Increased ----- 6. Relaxation

Answer 66

1. Nitric Oxide 2. Increased Guanylate Cyclase 3. Increased conversion of GTP to cGMP 4. cGMP increases Myosin-light-chain-phosphatase (MLCP) 5. Increased Myosin + actin 6. Relaxation NO2 = Relaxation

Question 67

Bone formation Endochondral ossification

Answer 67

Bones of axial and appendicular skeleton and base of skull. Cartilaginous model of bone is first made by chondrocytes. Osteoclasts and osteoblasts later replace with woven bone and then remodel to lamellar bone. In adults, woven bone occurs after fractures and in Paget disease.

Question 68

Bone formation Bones of calvarium and facial bones. Woven bone formed directly without cartilage. Later remodeled to lamellar bone.

Answer 68

Membranous | ossification

Question 69

Cell biology of bone Build bone by secreting collagen and catalyzing mineralization. Differentiate from mesenchymal stem cells in periosteum.

Answer 69

Osteoblasts

Question 70

Cell biology of bone Osteoclasts

Answer 70

Multinucleated cells that dissolve bone by secreting acid and collagenases. Differentiate from monocytes, macrophages.

Question 71

Cell biology of bone Parathyroid hormone At low, intermittent levels, exerts ----- effects on osteoblasts and osteoclasts (indirect). Chronically inc. PTH levels (1° hyperparathyroidism) cause ----- effects (osteitis fibrosa cystica).

Answer 71

At low, intermittent levels, exerts anabolic effects (building bone) on osteoblasts and osteoclasts (indirect). Chronically inc. PTH levels (1° hyperparathyroidism) cause catabolic effects (osteitis fibrosa cystica).

Question 72

Cell biology of bone Estrogen Estrogen inhibits ----- in ----- and induces ----- in -----. ``` Estrogen deficiency (surgical or postmenopausal), excess cycles of remodeling, and bone resorption lead to -----. ```

Answer 72

Estrogen inhibits apoptosis in bone-forming osteoblasts and induces apoptosis in bone-resorbing osteoclasts. ``` Estrogen deficiency (surgical or postmenopausal), excess cycles of remodeling, and bone resorption lead to osteoporosis. ```