BACK
- Fracture of the densof the axis with posterior dislocation may crush the
spinal cord at the level of the first cervical vertebra with terminal paral-
ysis of respiratory musculature.
- The cruciform ligamentis the principal structure preventing subluxa-
tion at the atlantoaxial joint because the articular surfaces between the
axis and atlas are nearly horizontal and there is no intervertebral disk.
- Herniationusually occurs in the L4/L5 or L5/S1 intervertebral disks
because of the pronounced lumbar curvature and the considerable body
mass superior to this region.
High-Yield Facts 45
Long thoracic Serratus anterior Wing scapula
Suprascapular Supraspinatus, Difficulty initiating arm
infraspinatus abduction
Axillary Deltoid Inability to fully abduct arm
Radial Extensors of Triceps and Loss of arm extension;
forearm, wrist, wrist extension loss of forearm extension,
proximal reflexes supination, abduction;
phalanges, loss of wrist extension
and thumb (wrist-drop); loss of
proximal phalangeal
extension and thumb
extension
Musculocutaneous Flexors of arm, Biceps reflex Weak arm flexion, weak
forearm forearm flexion, weak
forearm supination
Median Wrist and hand Wrist flexion Paralysis of flexor, pronator,
flexors reflex and thenar muscles;
inability to fully flex the
index and middle fingers
(sign of benediction)
Ulnar Wrist and hand Inability to flex the
flexors, 4th and 5th fingers-
phalangeal (clawhand); loss
extensors of thumb adduction
NERVE FUNCTION,TESTS,AND DYSFUNCTION
Sign or Functional
Nerve Muscle Group Reflex Test Deficit
