MSK Flashcards
Axillary nerve
Posterior cord
C5 + C6
Deltoid muscle
Injury: proximal humerus fracture dislocated shoulder
Radial nerve
Posterior cord
C5-T1
Extensor to arm, wrist, and fingers
Triceps (extension at elbow)
Sensory to back of hand/forearm
Injury: humeral midshaft fracture, crutches, Saturday night palsy
Musculocutaneous nerve
Lateral cord
C5-7
Biceps
Sensation to the lateral forearm
Upper trunk lesion (Erbs Palsy)
C5-C6
Caused by excessive angle at neck/shoulder (birth trauma)
Injures axillary nerve, musculocutaneous nerve, suprascapular nerve (arm straight at side and internally rotated)
Waiter’s tip
Lower trunk lesion (Klumpke Palsy)
C8-T1
Excessive abduction of arm (Catching tree while falling)
Injures ulnar and median nerves (intrinsic hand muscles)
Clawed hand
What supplies sensory to the hypogastric region?
Iliohypogastric nerve (T12-L1)
Commonly injured in abdominal/pelvic surgery
What nerve supplies the cremasteric muscle?
Genitofemoral nerve (L1-L2)
Also sensory to scrotum/labia + anterior thigh
Obturator nerve
L2-L4
Thigh adductors motor and sensory of medial thigh
Injured during pelvic surgery
What is the order of structures in the femoral triangle from lateral –> medial?
Nerve
Artery
Vein
Lymph
Femoral nerve
Flexion of thigh + extension of knee
Patellar reflex
Sensation to anterior thigh and medial leg
Sciatic nerve branches into what?
Common peroneal (common fibular) Evert and dorsiflex the foot (foot drop when injured) Sensory to dorsum of foot
Tibial
Plantar flexion and inversion (can’t stand on toes)
Sensory to sole of foot
What innervates the external anal sphincter?
Pudendal nerve (S2-S4)
Also supplies perineum, urethral sphincter, and levator ani and is sensory to these areas
Marker for a pudendal nerve block
Ischial spine of pelvis
What innervates the hamstrings?
Sciatic nerve (L4-S3)
Knee flexion, hip extension, and hip rotation
What can cause sciatic neuropathy?
Posterior hip dislocation and prolonged compression
Most common nerve roots compressed by IVD rupture?
L5 (lateral leg pain, cannot walk on heels)
S1 (back leg pain, no ankle reflex)
Rotator cuff
Supraspinatus - initial abduction (0-15)
Infraspinatus - external rotation
Subscapularis - internal rotation
Teres minor - external rotation
Shoulder abductors
0-15: supraspinatus
15-90: deltoid
90-180: trapezius
>180: serratus interior
Supracondylar fracture injures what
Median nerve (ulnar deviation and supination) Brachial artery
Dihydropyridine receptors
Proteins that span the ga between T-tubule and SR
L-type Ca+ channels that open ryanodine receptors to release Ca+ to initiate muscle contraction
Cause of malignant hyperthermia
Abnormal ryanodine receptors
Triggered by anesthetic use
Treat with dantrolene
