msk Flashcards
Rotator cuff muscles
SItS (small t is for teres minor)
Supraspinatus (suprascapular nerve)- abducts arm initially (before the action of the deltoid) MOST COMMON SItS injury– trauma or degeneration and impingement –> tendinopathy or tear assessed by empty/full can test
Infraspinatus (suprascapular nerve)– externally rotates arm, pitching injury
tERES mINOR (axillary nerve) – adducts and externally rotates arms
Subscapularis (upper and lower subscapular nerves) - internally rotates and adducts arm
Innervated primarily by C5 C6
Arm abduction
0-15 Supraspinatus (suprascapular n.)
15-100 Deltoid (Axillary n.)
> 90 Trapezius (Accessory n)
100 Serratus Anterior (Long Thoracic- SALT – winged scapula)
Axillary (C5 C6)
Fractured surgical neck of humerus, Anterior dislocation of humerus
Flattened deltoid
Loss of arm Abduction at shoulder >15’
Loss of sensation over deltoid and lateral arm
Musculocutaneous (C5-C7)
Upper trunk compression
decreased biceps reflex, weakness of forearm flexion and supination
Loss of sensation over lateral forearm
Radial (C5 T1)
Compression of axilla, due to crutches or sleeping with arm over chair (Saturday night palsy)
Midshaft fracture of humerus
repetitive pronation/supination of forearm due to screwdriver use (finger drop)
Wrist drop- loss of elbow, wrist, and finger extension
decreased grip strength wrist extension necessary for max action of flexors
Loss of sensation over posterior arm and fore arm and dorsal hang
Median (C5 T1)
supracondylar fracture of humerus–> proximal lesion of the nerve
Carpal tunnel syndrome and wrist laceration
Distal lesion of the nerve
Ape hand and popes blessing, loss of wrist flexion, flexion of lateral fingers, thumb opposition, lumbricals of index and middle fingers
Loss of sensation over thenar eminence and dorsal and palmar aspect of lateral 3/1/1 prox lesion
Ulnar nerve
C8 T1, Fracture of medial epicondyle of humerus (funny bone- proximal lesion
Fractured hook of hamate (distal lesion) from fall on outside on outstretched hand)
ulnar claw, Radial deviation of wrist upon flexion
Loss of wrist flexion, flexion of medial fingers, abduction and adduction of fingers (action of medial 2 lumbricles)
Loss of sensation over medial 1 1/2 fingers including hypothenar eminence
Recurrent branch of median nerve (c5 T1)
Superficial laceration of palm
Ape hand
loss of thenar muscle group - opposition, abduction, and flexion of thumb
No loss of sensation
Humerus fractures proximally to distally
ARM
Axillay
Radial
Median
Brachial plexus lesions
Erbs palsy ( waiters tip) Upper trunk C5-C6
Klumpke palsy (claw hand) Lower trunk (C8-T1)
Thoracic outlet syndrome (Compression of lower trunk due to scalenes or excess rib
Winged scapula- C5-C7 Long throracic nerve serratus anterior
Wrist drop- posterior cord
Decreased thumb function- Popes blessing- Median nerve
Intrinsic claw hand
wrist issues
scaphoid- anatomical snuff box, most commonly fractured due to fall on out stretched hand, avascular necrosis
dislocation of lunate- acute carpal tunnel
hand muscles
Thenar (median) Opponencs pollicis Abductor pollicis brevis, Flexor pollicis brevis , superficial head (deep head by ulnar nerve
Hypothena (ulnar)- opponens digiti mininimi, Abductor digiti minimi brevis
Dorsal (interossei (ulnar) - abduct the finger
Palmar interossei ulnar
DAB- dorsals ABduct
PAD- Palmars ADduct
Actions of hip muscles Abductors Adductors Extensors Flexors Internal rotation External rotation
Abductors- gluteus medius, minimus
Adductors- Adductors magnus, longus, brevis
Extensors- Gluteus maximus, semitendinosus, semimembranous
Flexors- iliopsoas, rectus femorus, tensor fascia lata, pectineus, sartorius
Internal rotation- gluteus medius, minimus, tensor fascia latae
External rotation- iliopsoas, gluteus maximus, piriformus, obturator
iliohypogastric (T12-L1)
Sensory- suprapubic region
Motor- transversus abdominis and internal oblique
Abdominal surgery lacerates it
Burning or tingling pain in surgical site radiating to inguinal and suprapubic region
Genitofemoral nerve (L1-L2)
Sensory- scrotum/labia majora, medial thigh
Motor- cremaster
Laproscopic surgery
Decreased upper medial thigh sensation beneath the inguinal ligament (lateral part of the femoral triangle, absent cremasteric reflex
Lateral fermoral cutaneous (L2-L3)
Sensory, anterior and lateral thigh
tight clothing, obesity, pregnancy, pelvic procedures
decreased thigh sensation (anterior and lateral)
Obturator (l2-L4)
Sensory Medial thigh
Motor Obturator externus, adductor longus, adductor brevus, gracilis, pectineus, adductor magnus
Pelvic surgery
Decreased thigh sensation, medial, and adduction
Femoral (L2-L4)
Sensory - anterior thigh, medial leg
Motor- quadriceps, iliacus, Pectineus, sartorius
Pelvic fracture
decreased leg extension (decreased patellar reflex)
Sciatic L4-S3
Motor- Semitendinosis, semimembranous, biceps femoris, adductor magnus
Herniated disc, posterior hip dislocation
Splits into common peroneal and tibial nerves
Common (fibular) peroneal (L4-S2)
Superficial peroneal nerve- Sensory (dorsum of foot- except webspace between hallux and 2nd digin). Motor- perneus longus and brevis.
Deep peroneal nerve- Sensory (webspace between hallux and 2nd digit), Motor- tibialis anterior
Trauma or compression of lateral aspect of leg, fibular neck fracture
PED- Peroneal everts and dorsifexes, if injured, foot dropPED. Loss of sensation on dorsum of foot, Foot drop (inverted and plantarflexed at rest, loss of eversion and dorsiflexion. steppage gait
Tibial (L4-S3)
Sensory- sole of foot
Motor- biceps femoris (long head) triceps surae, plantaris, popliteus, flexor muscles of foot
Knee trauma, baker cyst (proximal lesion), tarsal tunnel syndrome (distal lesion)
TIP- Tibial inverts and plantarflexes, if injured cant stand on TIP toes
Inability to curl toes and loss of sensation on sole , in proximal lesions, foot everted at rest with loss of inversion and plantar flexion
Superior gluteal (L4-S1)
motor- gluteus medius, gluteus minimus, tensor fascia latae
Iatrogenic injury during IM to supermedial gluteal region
Prevent by superolateal quadrant, pregerably anterolatal gion
Trendelenbur sign/ gait pelvis tils bc no stabilixato
Lesion is contralateral to hip dip
Inferior gluteal (L5-S2)
Motor- gluteus maximus
Posterior hip dislocation
Difficuly climbing stairs, rising from seated position, loss of hip sensation
Pudendal (S2-S4)
Sensory- perineum
Motor- external urethral and anal sphicters
Stretch injury during delivery, prolonged cycling
Horseback riding
Decreased sensation in perineum and genital area, can cause fecal and/or urinary incontinence
Can be blocked with local anesthetic during childbirth using ischial spine as a landmark for injection
Knee exam
Lateral femoral to condyle to anterior tibia (ACL) LA
Medial femoral to condyle to posterior Tibia (PCL) MP
LAMP
Anterior drawer sign due to ACL injury, LAchman test also test ACL (more sensitive
Posterior drawer sign- PCL injury
Valgus vs Varus stress
Varus stress- < > (Medial force)
VaLgus stress- >< (lateral force)
Ankle sprains
Anterior TaloFibular ligament- most common ankle sprain overall, low ankle sprain. Due to overinversion/supination of foot,
Anterior inferior tibiofibular ligament- most common high ankle sprain,
Always Tears First
Signs of lumbosacral radiculopathy
Paresthesia and weakness related to specific lumbosacral spinal nerves, interventricular disc (nucleus pulposus) herniates posterolaterally through and thicker annulus fibrosus (outer ring) into central canal due to thin posterior longitudinal ligament and thicker anterior longitudinal ligament along midline of vertebral bodies, nerve affected is usually below the level of herniation
L4 (L3-L4) - weakness of knee extenstion decreased patellar reflex
L5 (L4-L5) - weakness of dorsiflexion (difficultu in heel walking)
S1- Weakness of plantar flexion difficulty in the walking decreased toe walking, decreased achilies reflex
Motorneuron action potential to muscle contraction
T tubules are extensions of plasma membranes in contact with the Sarcoplasmic Reticulum, allowing for coordinated contraction of striated muscles
AP opens Presynaptic voltage gated Ca channels, inducing Ach release
Post synaptic Ach binding lead to muscle cell depolarization at the motor end plate
Depolarization travels over the entire muscle cell and deep into the muscle via T tubules
Membrane depolarization Activates the DHPR to pull on Ryanodine Receptor -> releases Ca into the cell from sracoplasmic reticulum
Tropomyosin is blocking myosin binding sites on actin filament, released CA++ binds to troponin C, shifting tropomyosin to expose the myosin-binding sites
The myosin head binds strongly to actin, forming a crossbrige, Pi is then released initiating the power stroke
During powerstroke force is produced as myosin pulls on the thin filament, Muscle shortening occurs, shortening of H and I bands and between Z lines (HIZ shrinkage) ADP is released at the end of the power stroke
Binding of a ner ATP molecule causes detachement of myosin head from actin filament and Ca is resepuestered
ATP hydrolysis into ADP and P result sin myosin returning to high energy state (cocked, , myosin binds a new site on actin if CA is available
types of muscle fibers
Type 1 slow red fibers Oxidative phospohorylation –> sustained contraction
Increased mitochondria myoglobin, endurance training
Type 2- fast white, anaerobic glycolyisi, Decreased weight/resistance training sprinting
Muscle proprioceptors
Muscle spindle- Increased length and speed of stretch–> DRG–> activation of inhibitory interneuron and a motor neuron–> simultaneous inhibittion of antagonist muscle , prevents overstretching and activation of agonist
muscle type 1a and 2 sensory axons, increased muscle stretch
Golgi tendon organ–> increased tension –> DRG–> activation on inhibitory neuron–> inhibition of agonist muscle and tendon
Tendons /type 1b sensory axons, increased muscle force
Cell bio of bone
Osteoblast bultds bone by secreting collagen and catalyzing mineralization in alk environment vial ALP (bone ALP, osteocalcin and propeptides of type 1 porcollagen
Osteoclast Dissolves crushes bone by secreting Hand collagenase, differentiates from a fusion of monocytes and macrophages lineage precursors, RANK r on osteoclasts are activated by RANK L on osteoblasts, OPG (a RANKL decoy binds RANKL to prevent RANK-RANKL interaction–> decreased osteoclast activity)
PTH- at low anabolic on osteoblasts and osteoclasts inderect, chronically increased PTH levels (1’ hyperparathyroidism) cause oseitis fibrosa cystica)
Estrogen- inhibits apoptosis in bone formin osteoblasts and induces apoptosis in bone resorbing osteoclasts, cause closure of epiphyseal plate during puberty, menopause–> increased cycles of remodeling and bone resorption –> osteoporosis
