Dorn Spinal Therapy
Axons of cranial nerve motor neurons originate from brain stem nuclei of three types corresponding to the embryological origin of the muscle groups:
1 Somatic nuclei: These are close to the midline, equivalent to spinal cord ventral horn cells. Somatic nuclei are oculomotor, trochlear, abducens and hypoglossal nuclei.
2 Branchiomotor nuclei: These develop lateral to somatic nuclei, between them and parasympathetic nuclei. Branchiomotor nuclei are trigeminal motor, facial motor and the nucleus ambiguus (and probably its cervical extension for the spinal accessory nerve, see Section 16.3).
3 Parasympathetic nuclei: These are the most laterally placed of the brain stem motor nuclei, equivalent to lateral horn cells of the spinal cord. They include Edinger-Westphal, superior and inferior salivatory, and the dorsal motor nucleus of the vagus.
Brain stem motor nuclei thus make up three interrupted columns: somatic motor, branchiomotor (special visceral motor) and parasym-pathetic (general visceral motor). This pattern is a useful basis for further study.
Table 2.2. Cranial nerve motor nuclei.
Nucleus
Position
Cranial nerve
Function
Somatic motor
Oculomotor
Trochlear
Abducens
Hypoglossal
- voluntary
Upper midbrain Lower midbrain Pons Medulla
Branchiomotor (special visceral motor) -Trigeminal Pons
Facial Pons
Nucleus ambiguus Medulla
Oculomotor III Trochlear IV Abducens VI Hypoglossal XII
voluntary*
Mandibular Vc (first) Facial VII (second)
Glossopharyngeal IX (third) ^ Vagus X, various branches (fourth)
Vagus (X), recurrent laryngeal (sixth)
Eyeball movements: extrinsic ocular muscles
Tongue muscles and movements
Chewing, tensor tympani Facial expression, buccinator, stapedius
Muscles of swallowing and phonation
Nucleus |
Position |
Cranial nerve |
Function |
Cervical accessory |
Upper cervical |
Spinal accessory XI |
Sternocleidomastoid, trapezius |
nucleus |
spinal cord |
(see Section 16.3) | |
Parasympathetic (general visceral motor) - |
- involuntary** | ||
Edinger-Westphal |
Midbrain |
Oculomotor III |
Ciliary muscle: lens |
accommodation, etc.; iris | |||
muscle: pupilloconstriction | |||
Salivatory: superior |
Pons |
Facial VII |
Secretomotor: lacrimal, nasal, |
palate, submandibular, sublingual | |||
glands | |||
Salivatory: inferior |
Upper medulla |
Glossopharyngeal IX |
Secretomotor: parotid gland |
Dorsal motor of |
Medulla |
Vagus X |
Heart, foregut and midgut |
vagus |
derivatives |
* Cranial nerve with branchial arch.
** Cranial nerve conveying fibres from brain stem.
Oc Tr
TM F
SSN ISN
DMNX
Hyp NA
Fig. 2.1 Cranial nerve motor nuclei.
Oc: oculomotor nucleus;
Tr: trochlear nucleus;
Ab: abducens nucleus;
F: facial motor nucleus;
SSN: superior salivatory nucleus;
ISN: inferior salivatory nucleus;
DMNX: dorsal motor nucleus of X;
NA: nucleus ambiguus;
Hyp: hypoglossal nucleus;
Acc: lateral horn cells in cervical cord giving spinal roots of XI.
Oc Tr
TM F
SSN ISN
Fig. 2.1 Cranial nerve motor nuclei.
EW: Edinger-Westphal nucleus;
Oc: oculomotor nucleus;
Tr: trochlear nucleus;
TM: trigeminal motor nucleus;
Ab: abducens nucleus;
F: facial motor nucleus;
SSN: superior salivatory nucleus;
ISN: inferior salivatory nucleus;
DMNX: dorsal motor nucleus of X;
NA: nucleus ambiguus;
Hyp: hypoglossal nucleus;
Acc: lateral horn cells in cervical cord giving spinal roots of XI.
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