Musculoskeletal Flashcards
What are the thenar (median) muscles of the hand and what are their functions?
Opponens pollicus
Abductor pollicis brevis
Flexor pollicis brevis
Superficial head (deep head by ulnar nerve)
Oppose, Abduct, Flex
What are the hypothenar (ulnar) muscles of the hand and what are their functions?
Opponens digiti minimi
Abductor digiti minimi
Flexor digiti minimi brevis
Oppose, Abduct, Flex
What is the function of the dorsal and palmar interossei?
Dorsal - abduct (DAB)
Palmar - adduct (PAD)
What is the function of the lumbricals?
Flex at the MCP joint, extend PIP and DIP joints
Hip abductors?
Gluteus medium, gluteus minimus
Hip adductors?
Adductor magnus, adductor longus, adductor brevis
Hip extensors?
Gluteus maximus, semitendinosus, semimembranosus
Hip flexors?
Iliopsoas, rectus femoris, tensor fascia lata, pectineus
Hip internal rotators?
Gluteus medius, gluteus minimus, tensor fascia latae
Hip external rotation?
Iliopsoas, gluteus maximus, piriformis, obturator
Nerves and arteries are frequently named together by the bones/regions with which they are associated. The following are exceptions. Name the nerve and artery associated with:
- Axilla/lateral thorax
- Surgical neck of humerus
- Midshaft of humerus
- Distal humerus/cubital fossa
- Popliteal fossa
- Posterior to medial malleolus
- Long thoracic nerve, lateral thoracic artery
- Axillary nerve, posterior circumflex artery
- Radial nerve, deep brachial artery
- Median nerve, brachial artery
- Tibila nerve, popliteal artery
- Tibial nerve, posterior tibial artery
2 common pediatric fractures?
- Greenstick fracture
2. Torus fracture
Compare the morphology and cause of a Greenstick vs. Torus fracutre.
Greenstick - binding stress causes incomplete fracture extending partway through the width of the bone
Torus - axial force leads to a simple buckle fracture of the cortex (subtle
Define the unhappy triad.
Classically - damage to the ACL, MCL, medial meniscus (note - lateral meniscus injury is more common)
Common cause of the unhappy triad?
Lateral force to a planted leg in contact sports
What is the “housemaid’s knee” and what causes it?
Prepatellar bursitis due to repeated trauma or pressure from excessive kneeling
What is a Baker cyst?
Popliteal fluid collection in the gastrocnemius-seminmembranosus bursa (communicates with synovial space, related to chronic joint disease)
BACK OF THE LEG
Compare medial and lateral epicondylitis (etiology and presentation).
Medial epicondylitis (golfer’s elbow) - repetitive wrist flexion with pain near the medial
Lateral epicondylitis (tennis elbow) - repetitive wrist extension
What is commonly fractured due to a fall on an outstretched hand and why?
Scaphoid bone fracture; direct axial compression or wrist hyperextension
How does a scaphoid bone fracture present?
Persistent wrist pain and TENDERNESS IN THE ANATOMIC SNUFFBOX - scaphoid and trapezius form the floor of the snuffbox
What is a potential complication of a scaphoid bone fracture?
Avascular necrosis
Compare the nerves affected in carpal tunnel vs. Guyon canal syndrome.
Carpal - median nerve
Guyon - ulnar nerve
What other bone may be injured following a fall on an outstretched hand? What disease may this cause?
Lunate; carpal tunnel syndrome (acute)
What are some important associations with carpal tunnel syndrome?
Hypothyroidism Acromegaly Rheumatoid arthritis, repetitive use Diabetes, dialysis-related amyloidosis, dislocation of lunate Pregnancy (edema)
HARDP
How does carpal tunnel syndrome present?
Paresthesia, pain, numbness in the distribution of the median nerve (palmar surface, fingers 1-4 + dorsal surface, upper 1/3 of fingers 2-part of 4) WITH SPARING OF THENAR SENSATION - palmar cutaneous branch enters the hand external to the carpal tunnel; thenar eminence atrophies
What are two clinical tests used to test for carpal tunnel syndrome?
Tinel sign (percussion of wrist causes tingling)
Phalen maneuver (90 degree flexion of wrist causes tingling)
List the important nerves of the arm and their nerve roots.
- Axillary (C5-6)
- Musculocutaneous (C5-7)
- Radial (C5-T1)
- Median (C5-T1)
- Ulnar (C8-61)
Name the nerve injury associated with the following presentation:
Flattened deltoid
Loss of arm abduction >15 degrees
Loss of sensation of deltoid muscle and lateral arm
Axillary nerve (C5-C6)
3 possible causes of axillary nerve (C5-C6) injury
- Fracture surgical neck of the humerus
- Anterior dislocation of the humerus
- Brachial plexus injury
Name the nerve injury associated with the following presentation:
Loss of forearm flexion and supination
Loss of sensation over the lateral forearm
Musculocutaneous nerve (C5-C7)
1 possible cause of musculocutaneous (C5-C7) injury
- Brachial plexus injury (upper trunk compression)
Name the nerve injury associated with the following presentation:
Wrist drop
Decreased grip strength
Loss of sensation over the posterior arm/forearm and dorsal hand
Radial (C5-T1) injury
3 possible causes of radial (C5-T1) nerve injury
- Midshaft fracture of the humerus
- Compression of the axilla (crutches)
- Brachial plexus lesion - posterior cord or at the radial nerve branch) - sleeping with arm over chair
Compare the presentation of a brachial plexus injury of the radial nerve at the posterior cord vs. at the radial nerve branch.
Posterior cord - wrist drop + Saturday night palsy
Branch - Saturday night palsy
Name the nerve injury associated with the following presentation:
“Ape hand”
“Pope’s blessing”
Loss of wrist flexion, flexion of the lateral fingers, thumb opposition, the lumbricals of 2 and 3
Loss of sensation over the thenar eminence and dorsal and palmar aspects of the lateral 3..5 fingers
Median (C5-T1) nerve
4 possible causes of median (C5-T1) nerve injury; specifiy if proximal or distal
- Supracondylar fracture of the humerus - proximal
- Carpal tunnel syndrome - distal
- Wrist laceration - distal
- Brachial plexus lesion
Cause of the “Pope’s blessing” presentation?
Median nerve injury (brachial plexus lesion)
Cause of Saturday night palsy presentation?
Radial nerve injury (brachial plexus lesion)
Cause of Ape hand presentation?
Median nerve injury or recurrent branch of the median nerve injury
Name the nerve injury associated with the following presentation:
Radial deviation of wrist upon flexion (proximal)
Loss of wrist flexion/adduction, flexion of the medial fingers, abduction and adduction of the fingers (interossei), actions of medial 2 lumbricals
Loss of sensation over the medial 1.5 fingers including the hypothenar eminence
Ulnar (C8-T1) nerve (also ulnar claw on digital extension)
3 possible causes of ulnar nerve injury; specify if proximal or distal
- Fracture of the medial epicondyle (proximal)
- Fractured hook of hamate (distal) - fall on an outstretched hand
- Brachial plexus injury of the ulnar nerve branch
(Elbow injury more common)
How does an injury of the recurrent branch of the median nerve present differently than a median nerve injury?
Both have ape hand
Recurrent has no loss of sensation
Recurrent has loss of entire thenar muscle group (OAF - thumb)
What is a common cause of injury to the recurrent branch of the median nerve?
Superficial laceration of the palm
Describe the features of Erb’s palsy, aka “waiter’s tip.”
The arm is at the patient’s side, medially rotated, extended, and pronated.
What muscle function is impaired in Erb’s palsy?
Deltoid and supraspinatus dysfunction (impaired abduction) Infraspinatus dysfunction (impaired lateral rotation) Biceps brachii dysfunction (impaired flexion and supination)
What nerve injury causes Erb’s palsy? Give examples of situations in which this might occur.
Traction/tear of the upper trunk (C5-C6) roots; trauma in adults, lateral traction during delivery in infants
Describe the features of Klumpke’s palsy?
Total claw hand
What muscle function is impaired in Klumpke’s palsy?
Dysfunction of lumbricals, interossei, thenar, and hypothanar muscles (impaired flexion of MCP and extension of DIP/PIP)
What nerve injury causes Klumbke’s palsy? Give examples of situations in which this might occur.
Traction or tear of the lower trunk of the brachial plexus (C8-T1); sudden upward jerking of the arm (grabbing a tree branch to break a fall); upward force on arm during delivery (infants)
How does thoracic outlet syndrome present?
Atrophy of intrinsic hand muscles + ischemia, pain, and edema (vascular compression)
What causes thoracic outlet syndrome and what nerve is injured?
Compression of the lower trunk of the brachial plexus (C8-T1) + compression of the subclavian vessels; can be due to a cervical rib or a pancoast tumor
What muscle is impaired in a winged scapula? What movements are impaired?
Serratus anterior; cannot abduct arm above horizontal
What nerve injury causes a winged scapula? Give examples of situations in which this might occur.
Lesion of the long thoracic nerve; axillary lymph node dissection after a mastectomy or a stab wound
List the six classic distortions of the hand.
- Ulnar claw
- Pope’s blessing
- Median claw
- OK gesture
- Ape hand (atrophy of thenar eminence)
- Atrophy of the hypothenar eminence
Which classic hand distortion is caused by a distal ulnar nerve lesion?
Ulnar claw
Which classic hand distortion is caused by a proximal median nerve lesion?
Pope’s blessing
Which classic hand distortion is caused by a distal median nerve lesion?
Median claw
Which classic hand distortion is caused by a proximal ulnar nerve lesion?
OK gesture
Which classic hand distortion is caused by ulnar nerve lesions?
Proximal - OK gesture
Distal - ulnar claw
Atrophy of hypothenar eminence
Which classic hand distortion is caused by median nerve lesions?
Proximal - Pope’s blessing
Distal - median claw
Ape hand (atrophy of the thenar eminence)
Which classic hand distortion is seen when making a fist?
Pope’s blessing (proximal median nerve)
OK gesture (proximal ulnar nerve)
Pair the classic hand distortions (which present identically)?
Ulnar claw + Pope’s blessing
Median claw + OK gesture
List the 11 important nerves of the legs and their nerve roots.
- Iliohypogastric (T12-L1)
- Genitofemoral (L1-L2)
- Lateral femoral cutaneous (L2-L3)
- Obturator (L2-L4)
- Femoral (L2-L4)
- Sciatic (L4-S3)
- Common perineal (L4-S2)
- Tibial (L4-S3)
- Superior gluteal (L4-S1)
- Inferior gluteal (L5-S2)
- Pudendal (S2-S4)
Name the nerve injury associated with the following presentation:
Loss of sensory innervation to the suprapubic region
Loss of transversus abdominis and internal oblique function
Iliohypogastric (T12-L1) injury; may also present with burning or tingling at the incision site (may be due to abdominal surgery) radiating to the inguinal and suprapubic region
Loss of sensory innervation to the scrotum/labia major, medial thigh (behind inguinal ligament)
Absent cremasteric reflex
Genitofemoral (L1-L2) injury; may be due to laparoscopic surgery
Name the nerve injury associated with the following presentation:
Decreased thigh sensation (anterior and lateral)
Lateral femoral cutaneous (L2-L3) injury; may be due to tight clothing, obesity, or pregnancy
Name the nerve injury associated with the following presentation:
Decreased thigh sensation (medial) and adduction
Obturator (L2-L4) injury; innervates the obturator externus, adductor longus/brevis/magnus, gracilis, pectineus; may be due to pelvic surgery
Name the nerve injury associated with the following presentation:
Decreased thigh flexion and leg extension
Decreased sensation of the anterior thigh and medial leg
Femoral (L2-L4) injury; innervates the quadriceps, iliopsoas, pectineus, sartorius; may be due to a plevic fracture
Name the nerve injury associated with the following presentation:
Decreased posterior thigh sensation
Decreased motor function of semitendinosis/semimembranosus, biceps femoris, adductor magnus
Sciatic (L4-S3) nerve injury; often due to a herniated disc (most often compressed at L5 or S1)
Name the nerve injury associated with the following presentation:
Loss of sensation on the dorsum of the foot Foot drop (inverted and plantarflexed at rest, loss of eversion and dorsiflexion - biceps femoris, tibialis anterior, extensor muscles of the foot) Steppage gate
Common peroneal (L4-S2) nerve injury; often due to trauma/compression of the lateral aspect of the leg, fibular neck fracture
Name the nerve injury associated with the following presentation:
Inability to curl toes, loss of sensation on sole
+/- foot eversion at rest with loss of inversion and plantarflexion
Tibial (L4-S3) nerve injury
+/- = proximal lesion
May be due to knee trauma, Baker cyst (proximal lesion), tarsal tunnel syndrome (distal)
Name the nerve injury associated with the following presentation:
Trendelenburg sign/gait
Superior gluteal (L4-S1) nerve injury; lesion is contralateral to the side of the hip that drops, ipsilateral to the extremity on which the patient stands; may be due to iatrogenic injury during injection to upper medial gluteal region
Name the nerve injury associated with the following presentation:
Difficulty climbing stairs, rising from seated position
Inferior gluteal (L5-S2) injury; may be due to a posterior hip dislocation
Loss of innervation to gluteus maximus
Name the nerve injury associated with the following presentation:
Decreased sensation to the perineum and genital area
+/- fecal or urinary incontinence
Pudendal (S2-S4) nerve injury; may be injured during childbirth
(motor innervation to external urethral and anal sphincters)
Where does the intervertebral disc herniate and which nerve does it affect?
Central canal; inferior nerve
Presenting symptoms of lumbosacral radiculopathy?
Paresthesia and weakness related to specific lumbosacral spinal nerves
L3-L4 - weak knee extension, decreased patellar reflex
L4-L5 - weak dorsiflexion, difficulty heel-walking
S1-S2 - weak plantar flexion, difficulty toe walking, decreased Achilles reflex
Etiology of achondroplasia?
Autosomal dominant or sporadic gain of function mutation on chromosome 4 -> constitutive activation of FGFR3 (fibroblast growth factor - inhibition of chondrocyte proliferation)
Pathogenesis of achondroplasia?
Inhibition of chondrocyte proliferation leads to failure of endochondral ossification (long bone growth)
Presentation of achondroplasia?
Dwarfism (short limbs, large head relative to limbs)
DDx - osteonecrosis
Corticosteroids Alcoholism Sickle cell disease Trauma The Bends (caisson/decompression disease) Legg-Calve-Perthes disease (idiopathic) Gaucher disease Slipped capital femoral epiphysis
“CAST Bent LEGS”
Etiology - osteogenesis imperfecta?
Autosomal dominant mutations of collagen type I
Pathogenesis - osteogenesis imperfecta?
Defective type 1 collagen due to IMPAIRED FORMATION OF THE TRIPLE HELIX DURING GLYCOSYLATION
Presentation - osteogenesis imperfecta?
Multiple fractures with minimal trauma
Blue sclerae
Tooth abnormalities (opalescent teeth)
Hearing loss (abnormal ossicles)
Osteoarthritis vs. RA - etiology?
OA - mechanical wear and tear
RA - autoimmune
What are the stages of Paget disease of bone?
- Lytic (osteoclasts, excessive resorption)
- Mixed
- Sclerotic (osteoblasts, excess formation)
- Quiescent (minimal activity)
Key gross morphology of Paget disease of bone?
Abnormal mosaic pattern of woven and lamellar bone
Large osteoclasts with up to 100 nuclei?
Paget disease of bone
Presentation of Paget disease of bone?
Bone pain, long bone deformity and chalk-stick fractures Increased hat size (skull thickening) Hearing loss (auditory foramen narrowing)
What is a significant complication of Paget disease of bone and why does it happen?
High-output heart failure; increased AV shunts -> increased blood flow
Osteoarthritis vs. RA - risk factors?
OA - age, obesity, joint trauma
RA - HLA-DR4, smoking, silica exposure
Both - female
Osteoarthritis vs. RA - joint findings?
OA - osteophytes (spurs), subchondral sclerosis
RA: erosions, juxta-articular osteopenia, soft tissue swelling
Both: Joint space narrowing, subchondral cysts
Osteoarthritis vs. RA - involved joints?
OA - DIP, PIP, and first CMC; NOT the MCP
Osteoarthritis vs. RA - synovial fluid?
OA - non-inflammatory
RA - inflammatory
Osteoarthritis vs. RA - pannus formation (proliferative granulation tissue)?
RA only
Osteoarthritis vs. RA - presentation?
OA - pain in weight-bearing joints after use (end of day), improves with rest; asymmetric joint involvement; no systemic symptoms
RA - pain, swelling, and morning stiffness lasting >1 hour improves with use; symmetric joint involvement; systemic symptoms; extra-articular manifestations common
What is Caplan syndrome?
Extra-articular manifestation of RA - rheumatoid nodules in the lung with pneumoconiosis
What are the key autoantibodies of RA?
- Rheumatoid factor (IgM Ab against IgG Fc region)
2. Anti-CCP (more specific)
Compare the presentation of gout vs. calcium pyrophosphate deposition disease.
G - asymmetric joint swelling, redness, pain, podagra (painful MTP joint of big toe), tophus formation
Pain and swelling with acute inflammation (pseudogout) and/or chronic degeneration (pseudo-osteoarthritis), most commonly in the knee
Compare the crystals deposited in joints in gout vs. calcium pyrophosphate deposition disease.
G - monosodium urate crystals
C - calcium pyrophosphate crystals
Compare the appearance of the crystals causing gout vs. calcium pyrophosphate deposition disease
G - needle shaped, negative birefringent under polarized light (yellow under parallel, blue under perpendicular)
C - rhomboid, weakly positive birefringent under polarized light (blue under parallel)
What is the pathogenesis of Sjogren syndrome?
Destruction of exocrine glands (especially lacrimal and salivary) by lymphocytic infiltrates
Key presentation of Sjogren syndrome?
BILATERAL PAROTID ENLARGEMENT, inflammatory joint pain, keratoconjunctivitis sicca (decreased tear production -> corneal damage), xerostomia (decreased saliva production)
What are two important complications of Sjogren syndrome?
Dental caries, MALT lymphoma
