Embryology
The dermatome of somites contributes to:
A. Vertebral bodies
B. Dermis of skin
C. Cranial nerves
D. Sclerotome cartilage
E. Limb rotation
Answer: B. Dermatome → dermis of dorsal skin.
Neural crest cells contribute to which skeletal structures?
A. Vertebrae
B. Ribs
C. Skull base
D. Craniofacial bones and cartilage
E. Pelvis
Answer: D. Neural crest forms craniofacial skeleton
A 21-year-old college wrestler sustains an anterior shoulder dislocation. On exam, he cannot abduct his arm and has numbness over the lateral shoulder (“sergeant’s patch” area).
Which nerve is most likely injured?
Answer: B – Axillary nerve
Associated Objective:
02-1627: Identify the skeletal components of the pectoral girdle and proximal humerus, including bony landmarks and surface anatomy.
• Shoulder dislocation → relationship between humeral head (surgical neck) and axillary nerve/posterior circumflex humeral artery.
During the depolarization phase of the action potential, the rapid influx of this ion through voltage-gated channels drives the membrane potential closer to +30 mV.
Answer: What is sodium (Na⁺)?
By the end of week 8, which feature is present?
A. Gastrulation complete but no neural folds
B. Craniofacial bones fully ossified
C. Recognizable limbs with digits and rotation
D. Secondary ossification in long bones
E. Mature vertebral column
Answer: C. By week 8 → limbs with digits, embryo recognizable.
The bilaminar embryonic disc (epiblast and hypoblast) forms during:
A. Week 1
B. Week 2
C. Week 3
D. Week 4
E. Week 5
Answer: B. Week 2 = bilaminar disc.
A 42-year-old woman presents with sharp, stabbing facial pain triggered by brushing her teeth. Neurologic exam suggests trigeminal neuralgia. The affected fibers are thinly myelinated, medium-diameter sensory nerves.
Which fiber type is involved?
A) Group I
B) Group II
C) Group III (Aδ)
D) Group IV (C)
Answer: C – Group III (Aδ fibers)
• Carry fast, sharp pain (myelinated, smaller than I/II).
• Group IV (C fibers) = dull, unmyelinated slow pain.
Objective:
05-1230 – Explain the role of diameter and myelination in determining conduction velocities of sensory nerves (Group I–IV).
These two factors primarily determine the conduction velocity of sensory nerve fibers such as Aα, Aβ, Aδ, and C fibers.
Answer: What are axon diameter and degree of myelination?
During week 3 of development, the trilaminar disc forms through:
A. Neurulation
B. Somitogenesis
C. Gastrulation
D. Limb bud formation
E. Primary ossification
Answer: C. Gastrulation produces ectoderm, mesoderm, endoderm.
Answer: C. Gastrulation produces ectoderm, mesoderm, endoderm.
Secondary ossification centers form in:
A. Diaphysis during embryonic life
B. Epiphyses after birth
C. Neural crest-derived cartilage
D. Paraxial mesoderm
E. Flat bones during week 8
Answer: B. Secondary centers appear postnatally in epiphyses.
A 37-year-old office worker presents with chronic low back tightness from prolonged sitting. You decide to use direct myofascial release (DMFR). Compared with indirect MFR, which of the following BEST describes the principle of DMFR?
A) Engages the restrictive barrier directly until release is palpated
B) Moves tissues away from the restrictive barrier into ease of motion
C) Uses only muscle energy to stretch tissues against patient resistance
D) Requires high-velocity, low-amplitude thrust through the barrier
E) Focuses solely on balancing autonomic tone without tissue contact
Answer: A – Engages the restrictive barrier directly until release is palpated
• DMFR = direct technique → engage the restrictive barrier, apply steady pressure/stretch, wait for creep and release.
• Indirect MFR = move tissues into ease of motion.
• HVLA = thrust, not myofascial.
• Muscle energy = patient actively contracts against resistance.
Associated Objective:
03-1217 (Soft Tissue / DMFR Lab): List the indications and absolute & relative contraindications for soft tissue/DMFR.
• Also: Differentiate direct vs. indirect myofascial release techniques.
This division of the autonomic nervous systemis primarily responsible for maintaining homeostasis at rest, regulating digestion, heart rate, and glandular secretion.
Answer: What is the parasympathetic nervous system?
Answer: What is the parasympathetic nervous system?
Polydactyly most commonly results from disruption in which signaling pathway?
A. BMP-mediated apoptosis
B. SHH signaling in ZPA
C. WNT7a signaling
D. FGF8 from AER
E. RUNX2 transcription factor
Answer: B. Excess/abnormal SHH from ZPA → polydactyly.
The upper limb rotates in which direction
A. Dorsally
B. Laterally
C. Medially
D. Anteriorly
E. Posteriorly
Answer: B. Upper limbs rotate laterally
A 26-year-old man falls while snowboarding and is unable to initiate abduction of the left arm. Once assisted, he can abduct fully. Which muscle and nerve are injured?
A) Deltoid – Axillary nerve
B) Supraspinatus – Suprascapular nerve
C) Infraspinatus – Suprascapular nerve
D) Teres minor – Axillary nerve
Answer: B – Supraspinatus – Suprascapular nerve
• Supraspinatus initiates abduction (0–15°).
• Deltoid takes over after 15°.
Objective:
05-1897 (Scapular Region Lab): Identify muscles of the scapular region, their attachments, innervation, and actions.
This hormone activates the enzyme responsible for converting norepinephrine to epinephrine in the adrenal medulla.
Answer: What is cortisol?
The somite compartment that forms skeletal muscle is the:
A. Sclerotome
B. Myotome
C. Dermatome
D. Notochord
E. Neural crest
Answer: B. Myotome → skeletal muscle
The notochord primarily functions to:
A. Form vertebral bodies directly
B. Induce neural plate development
C. Become the dorsal root ganglia
D. Provide vascular supply to embryo
E. Differentiate into the somites
Answer: B. Notochord → signaling center inducing neural plate.
A biopsy of nervous tissue shows cells with round central nuclei and abundant rough ER (Nissl substance). These cells are responsible for transmitting electrical signals.
Which cell type is described?
A) Astrocytes
B) Neurons
C) Oligodendrocytes
D) Schwann cells
E) Satellite cells
Answer: B – Neurons
• Large cell bodies with Nissl substance (RER).
• Astrocytes = support/immune roles, Schwann/oligodendrocytes = myelin.
Objective:
01-1424 (Nervous Tissue Pre-record / Lab): Recall main cell types of CNS and PNS, and describe their functions.
A 62-year-old patient presents with right-sided weakness, spasticity, hyperreflexia, and a positive Babinski sign following a stroke affecting the left internal capsule.
Answer: What is an upper motor neuron lesion?