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USMLE 1 > Musculoskeletal, Skin, and Connective Tissue- Anatomy and Physiology > Flashcards

Musculoskeletal, Skin, and Connective Tissue- Anatomy and Physiology Flashcards

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USMLE® Step 1 flashcards
1
Q

Arm abduction degree:

  • 0°–15°
  • 15°–100°
  • > 90°
  • > 100°
A

Supraspinatus (muscle) - Suprascapular (nerve)

Deltoid - Axillary

Trapezius - Accessory

Serratus Anterior - Long Thoracic (SALT)

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2
Q

Rotator cuff muscles

A

ƒƒ Supraspinatus (suprascapular nerve)
ƒƒ Infraspinatus (suprascapular nerve)
ƒƒ teres minor (axillary nerve)
ƒƒ Subscapularis (upper and lower subscapular nerves)

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3
Q

Overuse injuries of the elbow

  • Medial epicondylitis (golfer’s elbow)
  • Lateral epicondylitis (tennis elbow)
A

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

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

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4
Q

Wrist region

- Bones

A

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

*Scaphoid (palpable in anatomic snuff box) is the most commonly fractured carpal bone. Dislocation of lunate may cause acute carpal tunnel syndrome.

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5
Q

Metacarpal neck fracture (boxer’s fracture)

A

Common fracture caused by direct blow with a closed fist (eg, from punching a wall or individual). Most commonly seen in 4th and 5th metacarpals.

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6
Q

Carpal tunnel syndrome

  • Definition
  • Clinical manifestations
  • Diseases associated
A

Entrapment of median nerve in carpal tunnel

paresthesia, pain, and numbness in distribution of median nerve. Thenar eminence atrophies but sensation spared, because palmar cutaneous branch
enters hand external to carpal tunnel.

Associated with pregnancy (due to edema), rheumatoid arthritis, hypothyroidism, diabetes, acromegaly, dialysis-related amyloidosis.

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7
Q

Guyon canal syndrom

A

Compression of ulnar nerve at wrist. Classically

seen in cyclists due to pressure from handlebars.

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8
Q

Common pediatric fractures

- Greenstick fracture

A

Incomplete fracture extending partway through
width of bone following bending stress; bone fails on tension side; compression side intact (compare to torus fracture). Bone is bent like a green twig

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9
Q

Common pediatric fractures

- Torus (buckle) fracture

A

Axial force applied to immature bone Ž cortex buckles on compression side and fractures. Tension side (other side of cortex) remains intac

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10
Q

Hand muscles

- Thenar (median)

A

Oppose, Abduct, and Flex (OAF).

Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis, superficial head (deep head by ulnar nerve).

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11
Q

Hand muscles

- Hypothenar (Ulnar)

A

Oppose, Abduct, and Flex (OAF).

Opponens digiti minimi, Abductor digiti minimi, Flexor digiti minimi brevis.

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12
Q

Hand muscles

  • Dorsal interossei (ulnar)
  • Palmar interossei (ulnar)
  • Lumbricals (1st/2nd, median; 3rd/4th, ulnar)
A

abduct the fingers.

adduct the fingers.

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

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13
Q

Axillary (C5-C6)

  • Causes of injury
  • Presentation
A
  • Fractured surgical neck of humerus
  • Anterior dislocation of humerus
  • Flattened deltoid
  • Loss of arm abduction at shoulder (> 15°)
  • Loss of sensation over deltoid muscle and lateral arm
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14
Q

Musculocutaneous (C5-C7)

  • Causes of injury
  • Presentation
A

Upper trunk compression

  • Loss of forearm flexion and supination
  • Loss of sensation over lateral forearm
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15
Q

Radial (C5-T1)

  • Causes of injury
  • Presentation
A
  • Compression of axilla (“Saturday night palsy”)
  • Midshaft fracture of humerus
  • Repetitive pronation/supination of forearm
  • Wrist drop: loss of elbow, wrist, and finger extension
  • Loss of sensation over posterior arm/forearm and dorsal hand
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16
Q

Median (C5-T1)

  • Causes of injury
  • Presentation
A
  • Supracondylar fracture of humerus (proximal lesion)
  • Carpal tunnel syndrome and wrist laceration (distal lesion)
  • “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 31⁄2 fingers with proximal lesion.
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17
Q

Ulnar (C8-T1)

  • Causes of injury
  • Presentation
A
  • Fracture of medial epicondyle of humerus “funny bone” (proximal lesion)
  • Fractured hook of hamate (distal lesion) from fall on outstretched hand
  • “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 11/2 fingers
    including hypothenar eminence
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18
Q

Recurrent branch of median nerve (C5-T1)

  • Causes of injury
  • Presentation
A

Superficial laceration of palm

  • “Ape hand”
  • Loss of thenar muscle group: opposition, abduction, and flexion of thumb
  • No loss of sensation
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19
Q

Humerus fractures, proximally to distally, nerves affected

A

follow the ARM (Axillary Ž Radial Ž Median)

20
Q

Erb palsy (“waiter’s tip”)

  • Injury
  • Causes
  • Muscle deficit
A

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

Infants—latera ltraction on neck during delivery
Adults—trauma

Deltoid, supraspinatus, Infraspinatus, Biceps brachii

21
Q

Klumpke palsy

  • Injury
  • Causes
  • Muscle deficit
A

Traction or tear of lower trunk: C8-T1 root

Infants—upward force on arm during delivery
Adults—trauma (eg, grabbing a tree branch to break a fall)

Intrinsic hand muscles: lumbricals, interossei, thenar,
hypothenar

22
Q

Thoracic outlet syndrome

  • Injury
  • Causes
  • Presentation
A

Compression of lower trunk and subclavian vessels

Cervical rib, Pancoast tumor

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

23
Q

Winged scapula

  • Injury
  • Causes
  • Muscle deficit
A

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

Axillary node dissection after mastectomy, stab wound

Serratus anterior

24
Q

Distortions of the hand (nerve affected)

  • “Ulnar claw”
  • “Pope’s blessing”
  • “Median claw”
  • “OK gesture”
A

Distal ulnar nerve

Proximal median nerve

Distal median nerve

Proximal ulnar nerve

25
Q

Knee exam

A

LAMP:

Lateral femoral condyle to anterior tibia: ACL.
Medial femoral condyle to posterior tibia: PCL.

26
Q

Knee exam

  • Anterior drawer sign
  • Posterior drawer sign
A 
Bending knee at 90° angle, more anterior gliding
of tibia (relative to femur) due to ACL injury.

Bending knee at 90° angle, more posterior gliding of
tibia due to PCL injury.

*Lachman test also tests ACL, but is more sensitive

27
Q

Knee exam

  • Abnormal passive abduction
  • Abnormal passive adduction
A

Knee either extended or at ∼ 30° angle, lateral (valgus) force Ž medial space widening of tibia Ž MCL injury.

Knee either extended or at ~ 30° angle, medial (varus) force Ž lateral space widening of tibia Ž LCL injury

28
Q

Knee exam

- McMurray test

A

During flexion and extension of knee with rotation of tibia/foot:

  • Pain, “popping” on external rotation Ž medial meniscal tear (external rotation stresses medial meniscus)
  • Pain, “popping” on internal rotation Ž lateral meniscal tear (internal rotation stresses lateral meniscus)
29
Q

Common hip and knee conditions

- Trochanteric bursitis

A

Inflammation of the gluteal tendon and bursa lateral to greater trochanter of femur. Treat pain with NSAIDs, heat, stretching.

30
Q

Common hip and knee conditions

- “Unhappy triad”

A

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.

31
Q

Common hip and knee conditions

- Prepatellar bursitis

A

Can be caused by repeated trauma or pressure from excessive kneeling (also called “housemaid’s knee”).

32
Q

Common hip and knee conditions

- Baker cyst

A

Popliteal fluid collection in gastrocnemius semimembranosus bursa commonly communicating with synovial space and related to chronic joint disease (eg, osteoarthritis, rheumatoid arthritis).

33
Q

Ankle sprains

A

“Always Tears First.”
Anterior Talo Fibular ligament—most common ankle sprain overall, classified as a low ankle sprain. Due to overinversion/supination of foot.

Anterior inferior tibiofibular ligament—most common high ankle sprain

34
Q

Iliohypogastric (T12-L1)

  • Innervation
  • Injury Presentation
A

Sensory—suprapubic region
Motor—transversus abdominis and internal oblique

Burning or tingling pain in surgical incision site radiating to inguinal and suprapubic region

35
Q

Genitofemoral nerve (L1-L2

  • Innervation
  • Injury Presentation)
A

Sensory—scrotum/labia majora, medial thigh
Motor—cremaster

anterior thigh sensation beneath inguinal ligament; absent cremasteric reflex

36
Q

Lateral femoral cutaneous (L2-L3)

  • Innervation
  • Injury Presentation
A

Sensory—anterior and lateral thigh

thigh sensation (anterior and lateral)

37
Q

Obturator (L2-L4)

  • Innervation
  • Injury Presentation
A

Sensory—medial thigh
Motor—obturator externus, adductor longus, adductor
brevis, gracilis, pectineus, adductor magnus.

thigh sensation (medial) and adduction

38
Q

Femoral (L2-L4)

  • Innervation
  • Injury Presentation
A

Sensory—anterior thigh, medial leg
Motor—quadriceps, iliacus, pectineus, sartorius

thigh flexion and leg extension

39
Q

Sciatic (L4-S3)

  • Innervation
  • Branches
A

Motor—semitendinosus, semimembranosus, biceps femoris, adductor magnus

Splits into common peroneal and tibial nerves

40
Q 
Common peroneal (L4-S2)
- Innervation
A

Superficial peroneal nerve:
ƒƒ Sensory—dorsum of foot (except webspace between hallux and 2nd digit)
ƒƒMotor—peroneus longus and brevis

Deep peroneal nerve:
ƒƒ Sensory—webspace between hallux and 2nd digit
ƒƒMotor—tibialis anterior

41
Q 
Common peroneal (L4-S2)
- Injury Presentation
A

Loss of sensation on dorsum of foot

Foot drop—inverted and plantarflexed at rest, loss of
eversion and dorsiflexion; “steppage gait”

42
Q

Tibial (L4-S3)

  • Innervation
  • Injury Presentation
A

Sensory—sole of foot
Motor—biceps femoris (long head), triceps surae, plantaris, popliteus, flexor muscles of foot

Inability to curl toes and loss of sensation on sole; in proximal lesions, foot everted at rest with loss of inversion and plantarflexion

43
Q

Superior gluteal (L4‑S1)

  • Innervation
  • Injury Presentation
A

Motor—gluteus medius, gluteus minimus, tensor fascia latae

Trendelenburg sign/gait— pelvis tilts because weightbearing leg cannot maintain alignment of pelvis through hip abduction.

Lesion is contralateral to the side of the hip that drops,
ipsilateral to extremity on which the patient stands.

44
Q

Inferior gluteal (L5-S2)

A

Motor—gluteus maximus

Difficulty climbing stairs, rising from seated position; loss of hip extension

45
Q

Pudendal (S2-S4)

A

Sensory—perineum
Motor—external urethral and anal sphincters

sensation in perineum and genital area; can cause fecal
or urinary incontinence

46
Q

Actions of hip muscles

A

Pag. 443

47
Q

Signs of lumbosacral radiculopathy

  • L3–L4
  • L4–L5
  • L5-S1
A

Weakness of knee extension, decrease patellar reflex

Weakness of dorsiflexion, difficulty in heelwalking

Weakness of plantar flexion, difficulty in toewalking,
decrease Achilles reflex

USMLE 1 (73 decks)

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