When giving an epidural injection the order of structures the needle passes through goes as follows: skin, fascia and subcutaneous fat, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space 

When giving an lumbar puncture the order of structures the needle passes through goes as follows: skin, fascia and subcutaneous fat, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater, subarachnoid space. Note that the pia mater is not pierced during a lumbar puncture. 

"Saturday night" palsy is a nickname for radial nerve paralysis. Because the wrist extensors are innervated by the radial nerve, this type of paralysis would prevent a person from being able to perform wrist extension. While the supinator is innervated by the radial nerve, the biceps brachii is also a supinator, so although supination may be weaker with radial nerve paralysis, it would not be absent. 

The "soup" method involves collecting a tissue sample from the specific CNS are that one is interested in, isolating it and grinding it to form a homogenate which can be analyzed. This is useful for quantifying binding or molecule levels, through the application of radiolabels to specific neurotransmitters and receptors of interest. The radiolabels let you see how much those neurotransmitters and receptors interact, and what their relative levels are.

When performing a spinal tap the layers that the needle passes through (from superficial to deep)are as follows: epidermis, muscle, ligamentum flavum, epidural space, dura-mater, arachnoid mater, subarachnoid space. The CSF, which you collect in a spinal tap, is located in the subarachnoid space. 

When performing a spinal tap you enter the intervertebral space at the L3/L4 or L4/L5 level. This is because the spinal cord ends around L1/L2. Nerves continue past this point as part of the cauda equina, however they are not in danger of being pierced as they move out of the way of the needle. The needle will pass through various layers until the subarachnoid space where CSF is located.

In human adults the spinal cord (caudal tip) usually ends at the level of L1/L2. Thus lumbar punctures are performed between the L3 and L4 vertebrae or between L4 and L5, so there is no risk of damage to the spinal cord. 

Although electrodiagnostic testing would be needed to definitively diagnose a dorsal scapular nerve pathology, excess scapular upward rotation could suggest dysfunction of this nerve. Because the dorsal scapular nerve innervates the rhomboid major and minor, which are downward scapular rotators (as well as scapular elevators, and adductors) injury to this nerve would decrease eccentric control of upward rotation, causing excessive movement in that direction. Excess scapular internal rotation is associated with injury to the long thoracic nerve, not the dorsal scapular nerve.

The boy is suffering from Duchenne Muscular Dystrophy (DMD). This condition is a genetic disorder caused by a mutation resulting in absence of the dystrophin protein.

DMD is an X-linked recessive disease that caused muscle wasting and death. Mutations in the dystrophin gene on the X-chromosome cause absence of the protein dystrophin and instability in muscle cell membranes. Proximal muscles are affected first with noticeable atrophy of the legs and pelvis. This spreads to the arms, neck, and other parts of the body. Patients have pseudohypertrophy of the calves and deltoids and have poor endurance. Patients often show Gower’s sign, pushing on their thighs with their arms to help them stand up. A diagnosis is made with DNA testing or muscle biopsy showing absence of dystrophin. Becker’s muscular dystrophy is a less severe form of DMD in which mutated dystrophin is produced. Signs and symptoms are similar, but less severe.

Frataxin is a mitochondrial protein that is deficient in patients with Freidrich's ataxia, an autosomal recessive trinucleotide repeat disorder. It is the most common hereditary ataxia involving the posterior column, lateral corticospinal tracts, and spinocerebellar tracts of the spinal cord. This is a result of progressive atrophy and sclerosis of the dorsal root ganglia and dorsal roots. This condition is characterized by staggering gait, frequent falling, nystagmus, pes cavus, kyphoscoliosis, and hypertrophic cardiomyopathy.

Actin is a protein found in eukaryotes with multiple functions, including muscle contraction, vesicle and organelle transport, and cell signaling.

Troponin is a regulatory protein in muscle contraction. In skeletal muscle, troponin is bound to tropomyosin, a protein that covers actin binding sites, prohibiting muscle contraction. Binding of calcium to troponin causes a conformational change in troponin, which shifts tropomyosin to expose actin binding sites.

Huntingtin is a protein that, when mutated, causes Huntington's disease, a genetic disorder that progressively damages brain cells to result in chorea (jerky, uncontrollable movements) as well as changes in personality and dementia.

Golfer's elbow, or medial epicondylitis, is due to inflammation of the medial epicondyle of the elbow. The tendons of several muscles involved in flexing the forearm, wrist, and fingers originate at the medial epicondyle of the humerus at the elbow and this insertion point can become inflamed in response to injury.

Lateral epicondylitis is sometimes associated with tennis elbow.