This packet applies the full six-rubric system to the nervous-system unit of an undergraduate A&P lab. The dissection rubric is most concrete here — sheep brain dissection has a longer list of observable technique criteria than most A&P specimens.
By the end of the nervous-system unit, a student should be able to:
Brain regions, cranial nerves, spinal cord (Pages 2–4)
Same items as R1, paired with function (Page 5)
Multipolar neurons, astrocytes, oligodendrocytes, myelin (Page 6)
Sheep brain dissection — observed live (Page 7)
Weekly checklist applied across the 3-week unit (Page 8)
Nervous-system stations on the term-end practical (Page 9)
Sheep brain is the specimen most easily destroyed by a single bad cut — the corpus callosum, the ventricles, and the diencephalic structures all sit in the path of an over-eager midsagittal section. The R4 rubric is therefore stricter on tool discipline and orientation than the cardiovascular packet's. Students who pass R4 here can generally pass it in any other A&P unit.
Identification of brain regions on a midsagittal model or a midsagittally-sectioned sheep brain. Pre-approved synonyms pass; the spelling column shows the discriminator on common confusions.
| Canonical answer | Accepted synonyms | Spelling rule / common confusion |
|---|---|---|
| Cerebrum & cerebral structures | ||
| Frontal lobe | (none) | Lobe required; "frontal" alone → not yet |
| Parietal lobe | (none) | "Parital" passes (phonetic) |
| Temporal lobe | (none) | Confusion with the temporal bone → not yet on this slide |
| Occipital lobe | (none) | "Occipital" must include "lobe" |
| Insula | Insular cortex, island of Reil | — |
| Central sulcus | Central fissure, fissure of Rolando | Distinguish from longitudinal fissure → not yet (different feature) |
| Precentral gyrus | Primary motor cortex | Functional name accepted as synonym |
| Postcentral gyrus | Primary somatosensory cortex | Functional name accepted as synonym |
| Corpus callosum | (none) | "Corpus calossum" passes (phonetic) |
| Longitudinal fissure | Interhemispheric fissure | Distinguish from central sulcus → not yet |
| Diencephalon | ||
| Thalamus | (none) | Distinguish from hypothalamus → not yet (different region) |
| Hypothalamus | (none) | Same rule |
| Pineal gland | Pineal body, epiphysis cerebri | "Pinneal" passes (phonetic); confusion with pituitary → not yet |
| Pituitary gland | Hypophysis | If the gland is detached on the specimen, "stalk" is acceptable as "infundibulum" |
| Optic chiasm | Optic chiasma, optic decussation | "Optic chasm" → not yet (different word) |
| Brainstem & cerebellum | ||
| Midbrain | Mesencephalon | — |
| Pons | (none) | "Ponz" passes (phonetic) |
| Medulla oblongata | Medulla | "Medula" passes (phonetic) |
| Cerebellum | "Little brain" (informal but recognized) | "Cerebrum" → not yet (different structure) |
| Vermis (cerebellar) | Cerebellar vermis | — |
| Arbor vitae | Tree of life (informal) | — |
| Ventricles & CSF spaces | ||
| Lateral ventricle | First/second ventricle | Side optional unless pin specifies |
| Third ventricle | (none) | — |
| Cerebral aqueduct | Aqueduct of Sylvius, mesencephalic aqueduct | — |
| Fourth ventricle | (none) | — |
| Choroid plexus | (none) | "Coroid plexus" passes (phonetic) |
Each cranial nerve is graded on three judgments: Roman numeral, name, and primary function. A pin can be set to require any one, two, or all three; the score sheet specifies. The full table is the canonical reference TAs grade against.
| # | Name | Primary function (any one acceptable) | Spelling / sensory–motor–both |
|---|---|---|---|
| I | Olfactory | Smell · olfaction | Sensory · "Olfactary" passes |
| II | Optic | Vision · sight | Sensory · — |
| III | Oculomotor | Most extraocular eye movements · pupil constriction · lens accommodation | Motor · "Occulomotor" passes |
| IV | Trochlear | Superior oblique muscle (eye) · downward and lateral eye movement | Motor · "Trochelar" passes |
| V | Trigeminal | Facial sensation (V1, V2, V3 divisions) · mastication (V3 motor) | Both · "Trigeminus" passes |
| VI | Abducens | Lateral rectus (eye) · lateral eye movement | Motor · "Abducents" passes |
| VII | Facial | Facial expression · taste (anterior 2/3 of tongue) · lacrimation · salivation | Both · — |
| VIII | Vestibulocochlear | Hearing · balance / equilibrium | Sensory · "Vestibulocochlear" or "auditory" or "vestibular nerve" all accepted |
| IX | Glossopharyngeal | Taste (posterior 1/3 of tongue) · swallowing · salivation (parotid) · BP/CO2 sensing (carotid body/sinus) | Both · "Glosso-pharyngeal" with hyphen passes |
| X | Vagus | Parasympathetic innervation of thoracic and abdominal viscera · heart rate · digestion · vocalization | Both · — |
| XI | Accessory | Sternocleidomastoid · trapezius · head and shoulder movement | Motor · "Spinal accessory" accepted |
| XII | Hypoglossal | Tongue movement · speech and swallowing | Motor · "Hypogloseal" passes |
If a student writes a mnemonic ("On Old Olympus' Towering Tops...") instead of the answer, that is not yet. The mnemonic is a study aid; the rubric is for the named answer.
| Canonical answer | Accepted synonyms | Spelling rule / common confusion |
|---|---|---|
| Spinal cord cross-section | ||
| Gray matter | Grey matter | Confusion with white matter → not yet (location: gray inner H, white outer) |
| White matter | (none) | Same rule |
| Dorsal (posterior) horn | Posterior horn | Distinguish from ventral horn → not yet |
| Ventral (anterior) horn | Anterior horn | Same rule |
| Lateral horn | (none) | Only present in thoracolumbar segments — verify level |
| Central canal | (none) | — |
| Dorsal root | Posterior root | Sensory afferents |
| Ventral root | Anterior root | Motor efferents |
| Dorsal root ganglion | Posterior root ganglion, spinal ganglion, DRG | — |
| Meninges | ||
| Dura mater | Dura | Outermost; "tough mother" translation acceptable as recognition |
| Arachnoid mater | Arachnoid | "Arachnoid membrane" accepted |
| Pia mater | Pia | Innermost, adheres to cord surface |
For the monosynaptic reflex arc (e.g. patellar reflex):
Many students insert "the brain" into the monosynaptic reflex arc. The brain is not part of the arc — that's the entire point of the reflex (faster than conscious thought). If the student writes the arc with a brain step, that's not yet, and the coaching note on the score sheet should be: "the reflex bypasses the brain — what makes it fast?"
| Structure | Acceptable function statements (any one is sufficient) | What does NOT pass |
|---|---|---|
| Frontal lobe | Higher-order executive function · voluntary motor control (precentral gyrus) · personality and decision-making · Broca's area (speech production, dominant hemisphere) | "Thinking" alone (too vague) |
| Occipital lobe | Primary visual processing · interpretation of visual input from the optic radiations | "Sees" alone (must indicate processing/interpretation) |
| Cerebellum | Coordination of voluntary movement · balance · motor learning · timing of movement | "Movement" alone (must indicate coordination, not initiation) |
| Thalamus | Relay station for sensory input (except smell) to the cerebral cortex · gating and modulating sensory information | "Relay" alone (must indicate sensory and direction) |
| Hypothalamus | Homeostasis: temperature, hunger, thirst, autonomic regulation · endocrine control via the pituitary · circadian rhythm | "Hormones" alone (too vague) |
| Pituitary gland | Master endocrine gland; releases hormones controlling other endocrine glands · anterior secretes its own hormones, posterior releases hypothalamic hormones | "Makes hormones" alone (must indicate master role or hypothalamic relationship) |
| Pineal gland | Secretes melatonin · regulates circadian rhythm and sleep–wake cycle | "Sleep" alone (must indicate melatonin or circadian) |
| Medulla oblongata | Cardiovascular center, respiratory center, vomiting reflex · regulation of involuntary visceral functions | "Breathing" alone (acceptable shorthand only — escalate) |
| Pons | Bridge between cerebral cortex and cerebellum · respiratory rhythm modulation · sleep regulation | "Bridge" alone (must indicate what is bridged or function) |
| Corpus callosum | Connects the two cerebral hemispheres · allows interhemispheric communication and coordination | "Connects the brain" alone (must indicate hemispheres) |
| Choroid plexus | Produces cerebrospinal fluid (CSF) within the ventricles | "In the brain" alone → not yet |
| Dorsal root ganglion | Contains cell bodies of sensory (afferent) neurons entering the spinal cord | "Nerve cells" alone (must indicate sensory) |
| Ventral horn (gray matter) | Contains cell bodies of motor (efferent) neurons exiting the spinal cord | Confusion with dorsal horn → not yet |
| Vagus nerve (CN X) | Parasympathetic innervation of thoracic and abdominal viscera; slows heart rate; promotes digestion | "Vagus" alone (must indicate parasympathetic or specific organ) |
| Trigeminal nerve (CN V) | Sensation from the face (three divisions: V1 ophthalmic, V2 maxillary, V3 mandibular); motor to muscles of mastication | "Face" alone (must indicate sensation) |
| Slide | Canonical identification | Two features required (any two from list) |
|---|---|---|
| Multipolar neuron (smear, e.g. spinal cord ventral horn) | Multipolar neuron / motor neuron | Large cell body (soma) · Single axon · Multiple dendrites radiating from the soma · Prominent nucleus with conspicuous nucleolus · Nissl bodies visible in the cytoplasm |
| Astrocytes (e.g. silver-stained brain section) | Astrocyte | Star-shaped morphology · Multiple radiating processes · Foot processes contacting capillaries (if visible) · Located in CNS (gray or white matter context) |
| Myelinated nerve fiber (cross-section, peripheral nerve) | Myelinated peripheral nerve fiber / cross-section of peripheral nerve | Round axons surrounded by clear (washed-out) myelin sheath · Schwann cell nuclei at the periphery of myelin · Bundles (fascicles) of axons surrounded by perineurium · Endoneurium between individual fibers |
| Cerebellar cortex | Cerebellar cortex | Three distinct layers: molecular (outer), Purkinje cell (middle, single row of large cells), granular (inner, densely packed small cells) · Purkinje cells with elaborate dendritic arbors extending into molecular layer · Folia (folds) of cortex visible at low magnification |
Process is observed live during the lab session. The TA circulates with this clipboard; the student is not interrupted. The decision is made at the end of the dissection.
Sheep brains are an annual order. A student who routinely destroys structures during dissection isn't just failing R4 — they are depleting the cohort's shared resource. The repeat-on-second-specimen rule is one per student per term for that reason. A student who cannot pass on the second attempt is referred to a one-on-one coaching session before any further attempt is granted.
Applied each week of the unit. The notebook is reviewed at the bench at the end of the lab session; no take-home grading. The same six-item rubric is used across all units; what changes is the content the notebook documents.
The nervous-system unit is the one where most students will encounter the cranial-nerve and reflex examinations as the closest analog they have yet seen to a clinical workup. The notebook should include the student's own results and their partner's, recorded contemporaneously, with a brief comparison. This creates the small dataset the capstone (R6) integration question can draw on.
The nervous-system unit contributes 4 stations to the term-end capstone. Each station is 90 seconds and tests four judgments: identification, function, clinical context, and cross-system integration. The station passes at 3 of 4; excellence is 4 of 4.
Identification (per R1). Function (per R2). Clinical: name one pathology associated with the structure (e.g. "thalamic stroke," "cerebellar ataxia," "pituitary adenoma"). Integration: relate to another organ system (e.g. "hypothalamus controls anterior pituitary which controls thyroid").
Identification: Roman numeral + name from a labeled diagram or model. Function: primary function (per R2). Clinical: state one bedside test used to assess the nerve (e.g. "shrug shoulders for CN XI," "stick out tongue for CN XII"). Integration: relate to a system the nerve influences (e.g. CN X to cardiovascular, CN VII to musculoskeletal of the face).
Identification: indicated structure. Function: role in afferent or efferent pathway. Clinical: state one consequence of injury at the location (e.g. "ventral horn lesion → flaccid paralysis"). Integration: relate to muscular or sensory system as appropriate.
Performance station. Identification: name the reflex or nerve being tested. Function: explain what intact response demonstrates. Clinical: one normal/abnormal interpretation (e.g. "patellar reflex absent in L3 nerve root injury"). Integration: the same response under conditions that alter autonomic state (recent caffeine, recent exercise).
| Outcome per station | Counted as |
|---|---|
| 4 / 4 | Excellence (counts toward A bundle) |
| 3 / 4 | Pass (counts toward B and C bundles) |
| ≤ 2 / 4 | Not yet (counts toward D bundle if attempted; no F-bundle credit) |
| No attempt | Not counted toward any bundle |
Student: ______________________________________ Section: _______________ Date: _______________ TA: _______________
| # | Item | ID (R1) | Function (R2) | Notes |
|---|---|---|---|---|
| 1 | Brain region (cerebral) | P / NY | P / NY / — | |
| 2 | Brain region (diencephalic) | P / NY | P / NY / — | |
| 3 | Brainstem region | P / NY | P / NY / — | |
| 4 | Cerebellar feature | P / NY | P / NY / — | |
| 5 | Ventricle / CSF feature | P / NY | P / NY / — | |
| 6 | Cranial nerve (Roman + name + function) | P / NY | — | 3 sub-judgments combine to one decision |
| 7 | Cranial nerve (Roman + name + function) | P / NY | — | |
| 8 | Spinal cord cross-section structure | P / NY | P / NY / — | |
| 9 | Reflex arc sequencing | P / NY | — |
| # | Slide | ID | ≥2 features | Notes |
|---|---|---|---|---|
| 10 | Multipolar neuron | P / NY | P / NY | |
| 11 | Cerebellar cortex or peripheral nerve | P / NY | P / NY |
| Item | Criterion | Met |
|---|---|---|
| D1 | Pre-dissection inspection completed | P / NY |
| D2 | Tools used appropriately (probe + scalpel only) | P / NY |
| D3 | Midsagittal cut in the longitudinal fissure | P / NY |
| D4 | Internal structures preserved and identifiable | P / NY |
| D5 | Cleanup and storage per protocol | P / NY |
| R4 | Overall (5 of 5 = pass) | P / NY |
☐ No ☐ Yes — for item: __________ Tokens remaining: ☐ 3 ☐ 2 ☐ 1 ☐ 0
P = Pass · NY = Not yet · — = Not assessed · Edge cases: circle, do not check, bring to coordinator at end of session.