Musculoskeletal/Skin/CT Flashcards
Normal Anatomy of the Knee
The ACL extends from ____ to _____
lateral femoral condyle to anterior tibia
Where does the PCL extend from and to?
From the medial femoral condyle to the posterior tibia
Valgus force on the knee cause the joint to expand medially suggest what?
MCL injury
What is an unhappy triad?
injury cuased by lateral forced being applied to a planted leg.
Consists:
- ACL damage
- MCL damage
- medial meniscus damage
What muscle is responsible for initial abduction of the arm?
Supraspinatus (suprascapular nerve)
Assessed by empty can test
What are the other rotator cuff muscles? Motions? Innervation?
- Infraspinatus (suprascapular nerve)-laterally rotates arm (pitching injury)
- teres minor (axillary nerve)- adducts and laterally rotates arm
- Subscapularis (upper and lower subscapular nerves)-medially roattes and adducts arm
What wrist bone is most susceptible to avascular necrosis?
the scaphoid due to retrograde blood supply
(radial) So Long to Pink (ulnar)
(radial, 2nd line) Here Comes the Thumb (ulnar)
volar surface
A fall on an outstretched hand that damages the hook of hamaet is most likely to cause ____ nerve injury.
Ulnar
Dislocation of which wrist bone may cause acute carpal tunnel syndorme?
Lunate
Why is sensation to the thenar eminence spared in carpal tunnel syndrome?
the palmar cutaneous branch enter the hand external to the tunnel (will still see some atrophy of this region)
What are some conditions associated with carpal tunnel?
- pregnancy
- Rheumatoid arthritis
- diabetes
- hypothyroidism
- B2M amyloidosis
What is Guyon canal syndrome?
compression of the ulnar nerve at wrist or hand. Classically seen in cyclists
Normal Humerus Anatomy
What are common causes of axillary (C5-C6) damage?
- fractured surgical neck of the humerus
- anterior dislocation of the humerus
How does axillary nerve (C5-C6) damage present?
- atrophied deltoid
- loss of arm abduction at should (greater than 15 degrees)
- loss of senseation over deltoid muscle and lateral arm
How does musculocutaneous (C5-C7) nerve damage present?
- loss of forearm flexion and supination
- loss of sensation over lateral forearm
What are some common causes of Median (C5-T1) nerve damage?
- supracondylar fratcure of humerus (proximal lesion)
- carpal tunnel syndrome
- wrist laceration
Distal Humerus Anatomy
Distal supracondylar humerus fracture- median nerve damage likely
Common Hand deformities
How does damage to the median nerve affect the hand?
- Ape Hand or Pope’s Blessing
- loss of wrist flexion, flexion of lateral fingersm thumb opposition
Brachial Plexus
Disease? Cause?
Erb’s Palsy caused by lateral traction during delivery (infants) or tear (adults) of upper (Erb-er) TRUNK (after C5 and C6 roots have combined)
What muscles are impaired in Erb’s Palsy?
- deltoid and supraspinatus (thus, no abduction)
- Infraspinatus (thus, arm becomes MEDIALLY rotated)
- Biceps brachii (=no flexion or supination)
Disease? Cause?
Klumpke Palsy-caused by pulling upward force on arm during delivery or falling and grabbing a tree in adults
results in tear of LOWER trunk (C8-T1)
What muscles are damaged in Klumpke palsy?
the intrinsic msucles of the hand
How does Klumpke Palsy present?
Total claw hand (the lumbricals usually flex the MCP joints and extend DIP and PIP joints)
Deformity? Cause?
Winged scapula caused by lesion of the long thoracic nerve
think stab wounds and axillary node dissection after mastectomy
Wrist drop (saturday night palsy) is casued by damage to which nerve?
Median nerve (coming off the posterior cord)
Role of the dorsal interossei? Palmar onterossei? Lumbricals?
Dorsal= abduct the fingers (DAB)
Palmar= adduct (PAD)
Lumbricals= flex the MCP; extend the PIP and DIP
What type of muscle increases after endurance training?
type 1 muscle (slow twitch red fibers that use oxidative phosphorylation)
1 slow red ox
What type of muscle increases after weight/resistance training?
Fast twitch, white fibers resulting from decreased mitcohondria and myoglobin concentration
How does endochondral ossification occur?
cartilaginous model of bone is first made by chondrocytes and osteoclasts/blasts later replace with woven bone and then remodel to lamellar bone
In membraneous ossification, woven bone forms directly without cartilage and is later remodeled to lamellar bone
What environment do osteoblasts need to function?
alkaline (via ALP activity) to catalyze mineralization of osteoid
What do osteoblasts differentiate from?
mesenchymal stem cells in periosteum
How do osteoclasts resorb bone? What do they differentiate from?
they secrete H+ and collagenases
from a fusion of monocyte/macrophage lineage precursors
How does estrogen affect bone?
inhibits apoptosis in bone-forming osteoblasts and induces apoptosis osteoclasts
What happens in achondroplasia?
failure of longitudinal bone growth (endochondral ossification) leads to short limbs due to FGFR3 activating mutation limiting chondrocyte proliferation
AD= homozygous is lethal
NOTE: Membranous ossification is not affected (calvarium and facial bones) so head is big
