What are dermatomes and myotomes. How do they differ. Where are dermatomes located on the body. What is the clinical significance of dermatomes. How are dermatomes used in medical diagnosis. What are the key dermatome maps used by clinicians. How do dermatomes develop embryologically.

Understanding Dermatomes: Definition and Embryonic Origins

A dermatome is defined as a strip of skin innervated by a single spinal nerve. These sensory areas play a crucial role in medical diagnosis, allowing clinicians to assess potential spinal cord damage and determine the extent of spinal injuries. But how do dermatomes develop, and what is their embryological basis?

The origins of dermatomes can be traced back to the third week of embryogenesis. Around day 20, the tri-laminar disc is established, and the middle layer (mesoderm) differentiates. The paraxial mesoderm, located adjacent to the neural tube, gives rise to somites – segmented blocks of tissue that form along the embryo’s length.

Initially, 44 pairs of somites develop, but 13 of these break down, leaving 31 somites. This number corresponds to the 31 sets of spinal nerves in the adult human body. Each somite consists of a ventral portion (sclerotome) and a dorsal portion (dermomyotome). The sclerotome develops into ribs and vertebrae, while the dermomyotome gives rise to dermis and muscle tissue.

As embryonic development progresses, the dermomyotome disperses to form the dermis. The growth of limbs causes the associated dermis to stretch and migrate, creating the segmental innervation pattern observed in modern dermatome maps.

Dermatome Maps: Keegan and Garrett vs. Foerster

Two primary dermatome maps are recognized in the medical community: the Keegan and Garrett map (1948) and the Foerster map (1933). Each offers a unique perspective on dermatome distribution:

• Keegan and Garrett Map (1948): This map illustrates dermatomes in a way that aligns with the segmental progression of limb development. It provides a comprehensive view of dermatome distribution across the entire body.
• Foerster Map (1933): This map is more commonly used in clinical settings and is featured in the ASIA (American Spinal Injury Association) scale for assessing spinal injuries. It depicts the medial part of the upper limb as being innervated by T1-T3, which corresponds to the distribution of pain from angina or myocardial infarction.

Both maps show dermatome progression around an axial line, with no overlap across this line but slight overlap between adjacent dermatomes. Understanding these maps is crucial for accurate clinical assessment and diagnosis.

Dermatomes vs. Myotomes: Key Differences and Similarities

While dermatomes and myotomes are closely related, they serve different functions in the body. Both originate from somites during embryonic development, but their end results differ significantly:

• Dermatome: A portion of skin supplied by a single spinal nerve, responsible for sensory information.
• Myotome: A group of muscles innervated by a single spinal nerve, responsible for motor function.

Understanding the distinction between dermatomes and myotomes is crucial for healthcare professionals, as it allows for more precise diagnosis and treatment of neurological conditions. How do clinicians use this knowledge in practice?

Clinical Applications of Dermatome Knowledge

Dermatome mapping plays a vital role in clinical assessment, particularly in cases of suspected spinal cord injury or nerve damage. Here’s how clinicians utilize dermatome knowledge:

1. Assessing Spinal Cord Lesions: Following a traumatic injury that may involve the spinal cord, clinicians test dermatomes to determine the presence and extent of a spinal cord lesion.
2. Sensory Testing: Using cotton wool, clinicians test for light touch sensation along the limbs and torso, touching areas corresponding to different dermatomes. Pain sensitivity is tested separately using a small pin.
3. Locating Nerve Damage: By noting regions of paresthesia (abnormal sensations) and comparing them to dermatome maps, clinicians can determine whether nerve involvement is at the spinal root or peripheral nerve level.
4. ASIA Scale: The American Spinal Injury Association (ASIA) scale, which incorporates dermatome mapping, is used to assess patients with potential spinal nerve lesions.

This systematic approach allows healthcare professionals to make accurate diagnoses and develop appropriate treatment plans for patients with neurological issues.

Dermatome Distribution in the Human Body

Dermatomes follow a specific pattern across the human body. Understanding this distribution is essential for accurate clinical assessment. Let’s explore the dermatome layout in different body regions:

Head and Neck

The head, particularly the face, is primarily innervated by branches of the trigeminal nerve:

• Ophthalmic branch: Supplies the lateral side of the forehead
• Maxillary branch: Innervates the cheek area
• Mandibular branch: Supplies the lower jaw, except for the angle of the mandible

Other areas of the head and neck are innervated by the C2 and C3 nerve roots. The area just behind the ear is supplied by C2, while C3 innervates the side and back of the neck.

Upper Limbs

The upper limbs have a complex dermatome distribution:

• C5: Outer arm from shoulder to elbow
• C6: Thumb side of the forearm and hand
• C7: Middle finger and back of the hand
• C8: Little finger side of the hand and forearm
• T1: Inner aspect of the forearm

Trunk

Dermatomes of the trunk follow a relatively straightforward pattern:

• T2-T12: Wrap around the chest and abdomen in horizontal bands
• L1: Covers the groin and upper thigh

Lower Limbs

The lower limbs have a more complex dermatome pattern:

• L2: Front and inner thigh
• L3: Knee and medial lower leg
• L4: Medial ankle and foot
• L5: Lateral lower leg and top of the foot
• S1: Outer foot and heel
• S2-S4: Posterior thigh and leg

This distribution allows clinicians to quickly identify potential areas of nerve damage or compression based on a patient’s reported symptoms.

Memorizing Dermatomes: Tips and Tricks

Memorizing dermatome patterns can be challenging, but several mnemonic devices and visual aids can help healthcare professionals and students remember key distributions:

1. “C5, T5, T10, L5”: This simple mnemonic helps recall the levels of major dermatomes. C5 is at the clavicle, T5 at the nipple, T10 at the umbilicus, and L5 at the knee.
2. “T4 Tits, T10 Tail”: A memorable phrase indicating that the T4 dermatome corresponds to the nipple level, while T10 aligns with the umbilicus or “tail” of the ribcage.
3. “Shoulders to Elbows, Wrists to Hips”: This phrase helps remember that C5 innervates from the shoulders to the elbows, while T1 covers from the wrists to the hips.
4. Visual Maps: Creating or studying visual dermatome maps can help reinforce the distribution patterns in your mind.
5. Practice with Case Studies: Reviewing clinical case studies that involve dermatome assessment can help solidify your understanding of their practical applications.

By employing these memorization techniques, healthcare professionals can more easily recall dermatome patterns during clinical assessments, leading to more accurate diagnoses and treatment plans.

Importance of Dermatomes in Pain Management

Dermatome knowledge is not only crucial for diagnosing spinal cord injuries but also plays a significant role in pain management. Understanding dermatome distribution helps clinicians in several ways:

• Localizing Pain Sources: By mapping a patient’s pain to specific dermatomes, clinicians can better identify the source of the pain, whether it’s from a herniated disc, nerve compression, or other spinal issues.
• Guiding Treatment: Knowing which dermatomes are affected can help guide treatment decisions, such as determining the appropriate level for epidural injections or other interventional pain procedures.
• Differential Diagnosis: Dermatome patterns can help differentiate between various conditions. For example, pain following a specific dermatome may indicate a radiculopathy, while pain that doesn’t follow dermatome patterns might suggest a different etiology.
• Monitoring Progress: By regularly assessing dermatome-related symptoms, clinicians can track a patient’s progress during treatment and adjust their approach as needed.

How does this knowledge translate into practical pain management strategies? Consider the following scenarios:

1. Cervical Radiculopathy: A patient complaining of pain and numbness along the outer arm and thumb may be experiencing C6 nerve root compression. This knowledge would guide the clinician to focus on that specific level of the cervical spine for further evaluation and treatment.
2. Lumbar Disc Herniation: A patient with pain radiating down the back of the thigh and calf, along with numbness in the outer foot, likely has an S1 radiculopathy. This information would help the clinician determine the appropriate level for potential interventions like epidural steroid injections.
3. Shingles (Herpes Zoster): Early recognition of shingles can be aided by observing that the characteristic rash typically follows a specific dermatome pattern, usually in the thoracic or lumbar regions.

By integrating dermatome knowledge into pain management strategies, clinicians can provide more targeted and effective treatments, ultimately improving patient outcomes and quality of life.

Limitations and Variations in Dermatome Mapping

While dermatome maps are invaluable tools in clinical practice, it’s important to recognize their limitations and potential variations. Understanding these factors can help healthcare professionals make more accurate assessments and avoid misdiagnosis:

• Individual Variations: Dermatome patterns can vary slightly from person to person. What’s considered “textbook” may not apply universally to all patients.
• Overlap Between Dermatomes: Adjacent dermatomes often have areas of overlap, which can make precise localization challenging in some cases.
• Sensory Innervation Complexity: Some areas of the body receive sensory innervation from multiple spinal levels, complicating the interpretation of dermatome-based assessments.
• Differences Between Maps: As noted earlier, different dermatome maps (like Keegan and Garrett vs. Foerster) may show slight variations in dermatome distribution.
• Dynamic Nature of Nervous System: The nervous system’s plasticity means that innervation patterns can change over time, particularly following injury or in response to chronic conditions.

How can clinicians account for these limitations in their practice? Consider the following approaches:

1. Use Multiple Assessment Methods: Combine dermatome testing with other neurological examinations for a more comprehensive evaluation.
2. Consider Patient History: A thorough patient history can provide context for interpreting dermatome-based findings.
3. Be Aware of Variations: Recognize that slight deviations from standard dermatome patterns don’t necessarily indicate pathology.
4. Utilize Imaging: When necessary, correlate clinical findings with imaging studies for more accurate diagnosis.
5. Continuous Learning: Stay updated on the latest research and understanding of neuroanatomy and dermatome mapping.

By acknowledging these limitations and adopting a holistic approach to assessment, clinicians can maximize the utility of dermatome knowledge while minimizing the risk of misinterpretation.

Future Directions in Dermatome Research and Clinical Applications

As our understanding of neuroanatomy and neurophysiology continues to evolve, so too does our approach to dermatome mapping and its clinical applications. What developments can we expect in the future of dermatome research and practice?

• Advanced Imaging Techniques: Emerging neuroimaging technologies may provide more detailed and personalized dermatome maps, allowing for more precise diagnoses and treatments.
• Artificial Intelligence Integration: AI algorithms could potentially analyze patient symptoms and clinical findings to generate more accurate dermatome-based diagnoses.
• Personalized Medicine: As we gain a better understanding of individual variations in neural innervation, treatments could be tailored more specifically to each patient’s unique dermatome patterns.
• Neuromodulation Advancements: Improved knowledge of dermatome distribution could lead to more targeted and effective neuromodulation therapies for pain management.
• Educational Tools: Virtual and augmented reality technologies may offer new ways to teach and visualize dermatome patterns, enhancing medical education.

These advancements have the potential to significantly improve patient care and outcomes. For example:

1. More Precise Diagnostics: Enhanced imaging and AI-assisted analysis could lead to earlier and more accurate diagnoses of conditions like radiculopathies or spinal cord injuries.
2. Tailored Pain Management: Personalized dermatome mapping could allow for more targeted interventions in pain management, potentially reducing the need for systemic medications.
3. Improved Surgical Planning: Detailed, patient-specific dermatome information could help neurosurgeons plan more precise and less invasive procedures.
4. Enhanced Rehabilitation Strategies: A deeper understanding of individual dermatome patterns could inform more effective rehabilitation protocols for patients recovering from spinal cord injuries or strokes.

As research in this field progresses, healthcare professionals should stay informed about these developments and consider how they might incorporate new findings and technologies into their clinical practice. The future of dermatome mapping holds exciting possibilities for improving patient care across various medical specialties.

Dermatomes – Development – Maps

A dermatome is defined as ‘a strip of skin that is innervated by a single spinal nerve‘. They are of great diagnostic importance, as they allow the clinician to determine whether there is damage to the spinal cord, and to estimate the extent of a spinal injury if there is one present.

In this article, we shall look at the embryonic origins of dermatomes, and explore their clinical uses.

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Origins of Dermatomes

Fig 1 – Somites adjacent to the neural tube.

We can trace back the origins of dermatomes to the 3^rd week of embryogenesis. At around day 20, the tri-laminar disc has been established and the middle layer (mesoderm) has differentiated into its different types. The portion that is directly adjacent to the neural tube is called paraxial mesoderm.

From day 20 onwards the paraxial mesoderm differentiates into segments called somites. 44 pairs of somites are formed, but 13 of these break down leaving 31 somites. This corresponds to the 31 sets of spinal nerves in the body.

The somites themselves are comprised of a ventral and a dorsal portion. The ventral portion consists of sclerotome, the precursor to the ribs and vertebral column.

The dorsal portion consists of dermomyotome. Over time, the myotome proliferates and the dermatome disperses to form dermis. As the limbs grow, the dermis associated with the precursor of the limbs is stretched and moved down the limb, creating the segmental innervation that is associated with the Keegan and Garrett dermatome map of 1948.

---

Dermatome Maps

There are two main maps that are accepted by the medical profession. The first is the Keegan and Garret map of 1948. This depicts dermatomes in a way that correlates with the segmental progression of limb development. The second is the Foerster map of 1933 which depicts the medial part of the upper limb as being innervated by T1-T3 which follows the distribution of pain from angina or an MI. This is the most commonly used map, and features in the ASIA scale of assessing spinal injury.

Both maps depict progression of limb growth around an axial line. Across this line there is no overlap between dermatomes, but often those adjacent each other have a slight overlap.

Fig 2 – The Keegan and Garrett dermatomal distribution.

[start-clinical]

Clinical Relevance: Assessing Spinal Cord Lesions

Following a traumatic injury that may involve the spinal cord, the clinician can test dermatomes to determine the presence and the extent of a spinal cord lesion.

Firstly, the clinician uses cotton wool to test for light touch sensation along the limbs and torso, touching areas which correspond to the different dermatomes. Secondly the clinician uses a small pin to test for responsiveness to pain. The patient is instructed to close their eyes and say when they feel contact with their skin (Light touch and pain are tested separately as their fibres travel in different parts of the spinal cord – see here).

By using their knowledge of dermatomal and peripheral cutaneous innervation, and noting any regions of paresthesia, the clinician is able to ascertain whether there is any nerve involvement. Also, they can determine whether this is at the spinal root or peripheral nerve level.

Fig 3 – The ASIA scale. It used to assess patients with a potential spinal nerve lesion.

[end-clinical]

 

 

 

Dermatomes and Myotomes

 

Today we are going to be going into the dermatomes and myotomes of the human body.  We will discuss what dermatomes and myotomes are, how to remember certain dermatomes and myotomes and show where they are laid out on the body!

 

Dermatome vs.

Myotome

 

So first let’s talk about dermatome vs. myotome.  Both myotomes and dermatomes come from somites, which are parts of the body of an embryo.  These somites come in pairs which run from head to toe on the body.

 

A dermatome is a portion of the skin that is supplied by an individual spinal nerve.  Whereas a myotome is a group of muscles that are innervated by a single spinal nerve.

 

 

 

Dermatomes

 

To understand dermatomes, we must appreciate the body as a “map”.  Each dermatome represents an area of skin that is supplied sensation by a certain nerve.  We will go through each region of the body next regarding how to remember myotomes and dermatomes.

 

 

Head

For the human head, particularly of the face, the dermatomes are innervated by the branches of the trigeminal nerve.  The ophthalmic branch of the trigeminal nerve supplies the dermatome on the lateral side of the forehead.   The maxillary branch supplies the cheek, and the mandibular branch supplies the lower jaw, except for the angle of the mandible.

Other areas of the head are innervated by the C2 and C3 nerve roots.  The 1-2 cm area lateral to the occipital protuberance is innervated by C2.  The supraclavicular fossa in the midclavicular line is innervated by the C3 nerve root.

 

Upper Extremities

As we progress down the spinal column, the next several levels innervate the upper extremities.  These include C4, C5, C6, C7, C8, and T1.

The area overlying the acromioclavicular joint is supplied by C4.  The area overlying the lateral portion of the lower edge of the deltoid is innervated by C5.  This area can also be known as the area of the regimental badge.

The palmar side of the thumb is innervated by C6, the middle finger by C7, and the little finger by C8.  Lastly, the medial portion of the antecubital fossa, proximal to the medial epicondyle of the humerus is innervated by T1.

 

Chest and Back

 

The next area to cover is the chest and back (torso).  The dermatomes of this area are innervated by T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12.

The apex of the axilla is innervated by the T2 nerve root.  The T3 nerve root will supply the area where the midclavicular line and third intercostal space intersect.  The area where the midclavicular line and the fourth intercostal space at the level of the nipple is supplied by T4.

The T5 nerve root supplies the area where the midclavicular line and the fifth intercostal space intersect and spans horizontally midway between the level of the nipple and xiphoid process.

The area where the midclavicular line and the horizontal level of the xiphoid process intersects is innervated by the T6 nerve root.

The T7 nerve root supplies the area where the midclavicular line and the level at ¼ the distance between the level of the xiphoid process and the umbilicus horizontally.

The area where the midclavicular line and the level at ½ the distance between the level of the xiphoid process and the umbilicus horizontally intersection is innervated by the T8 nerve.

The T9 nerve will supply the area the midclavicular line and the level at ¾ the distance between the level of the xiphoid process and the umbilicus horizontally, and T10 innervates the area of the midclavicular line at the level of the umbilicus horizontally.

The nerve root of T11 supplies the area of the midclavicular line and the level at the mid between the umbilicus and the inguinal ligament horizontally; whereas the T12 nerve supplies the intersection of the midclavicular line and the midpoint of the inguinal ligament.

https://dphhs.mt.gov/Portals/85/dsd/documents/DDP/MedicalDirector/Shingles.pdf

 

Lower Extremities

Next for the lower extremity dermatomes.  These are supplied by the following nerve roots: L1, L2, L3, L4, L5, S1, S2, S3, S4, and S5.

The area over the inguinal region and the most proximal portion of the medial thigh is innervated by L1 nerve root.   The middle and lateral portions of the anterior thigh are supplied by the L2 nerve.

The L3 nerve root innervates the medial epicondyle of the femur, the L4 root supplies the medial malleolus, and the L5 nerve root innervates the dorsum of the foot at the level of the third metatarsophalangeal joint.

The area of the lateral portion of the calcaneus is supplied by S1, the midpoint of the popliteal fossa by S2, the gluteal crease horizontally by S3, and the perineal area by S4 and S5 nerve roots.

https://www.stepwards.com/?page_id=10671

 

And lastly here on dermatomes to summarize is all in one picture, see the below dermatome chart!

https://www.ebmconsult.com/articles/dermatomes-full-body-anterior-posterior

 

Myotomes

 

Lastly here today let’s talk about myotomes.  As mentioned earlier a myotome is a group of muscles that are innervated by a single spinal nerve.

Some important myotomes and what actions that they produce to remember are the following:

• C4
• C5
  • Shoulder abduction, shoulder external rotation, and elbow flexion

• C6
• C7
  • Elbow and finger extension and wrist flexion

• C8
  • Thumb extension and finger flexion

• T1
• L1
• L2
  • Hip flexion and abduction

• L3
• L4
  • Ankle dorsiflexion and knee extension

• L5
  • Big toe extension and knee flexion

• S1
  • Ankle plantarflexion, knee flexion, big toe flexion

• S4
  • Bladder and rectal motor supply

 

 

Below see a nice summary chart of the high yield myotomes and what function they provide to the body!

https://befittrainingphysio. com/dermatomes-myotomes-and-reflexes-whats-it-all-about/

 

Resources

1. https://befittrainingphysio.com/dermatomes-myotomes-and-reflexes-whats-it-all-about/
2. https://www.ebmconsult.com/articles/dermatomes-full-body-anterior-posterior
3. https://www.stepwards.com/?page_id=10671
4. https://dphhs.mt.gov/Portals/85/dsd/documents/DDP/MedicalDirector/Shingles.pdf
5. https://geekymedics.com/dermatomes-and-myotomes/

 

This article or blog post should not be used in any legal capacity whatsoever, including but not limited to establishing standard of care in a legal sense or as a basis of expert witness testimony. No guarantee is given regarding the accuracy of any statements or opinions made on the podcast or blog.

Dermatomes – Neurology – Medbullets Step 1

Snapshot

A 40-year-old man presents to his primary care physician with bilateral upper extremity weakness and sensory changes. He describes the sensory changes as “numb to pain and heat.” Approximately 8 months ago, he had a multiple sclerosis exacerbation that required hospitalization with intravenous methylprednisolone for 5 days. On physical exam, there is sensory loss to pain and temperature in a “cape-like” distribution of the upper extremity, as well as 4/5 strength. The patient is scheduled for an MRI of the spine. (Post-inflammatory syringomyelia)

Introduction

Dermatomal maps reflect the sensory distribution for a specific level therefore, one can determine at which level (e.g., brainstem and spinal cord) the lesion is located recall that the primary sensory modalities tested on physical exam includes light touch pain temperature vibration proprioception The dorsal root ganglia contain cell bodies of spinal nerve sensory neurons

Head and Neck

Upper Extremity

Hand

Chest and Abdomen

Important Dermatomal Landmarks of The Chest and Abdomen Vertebral Level Sensory Area T4 Chest at level of nipple “T4 at teat pore” T7 Chest at level of xiphoid process “T7 at bottom of sternum” T10 Abdomen at level of umbilicus “T10 at belly button (butTEN)”

Lower Extremity

Sensation Testing – Peripheral Nerve Lesion — Rayner & Smale

Documentation

The final aspect of sensory testing that I wanted to cover with this blog is terminology (O’Sullivan et al. , 2013). Here are a few words…

Words relating to pain:

• Analgesia – the complete loss of pain sensitivity.
• Dysesthesia – touch sensation experienced as pain.
• Hyperalgesia – increased sensitivity to pain and hypalgesia – decreased sensitivity to pain.
• Allodynia – pain provoked by non-noxious stimulus.
• Causalgia – painful burning sensation (usually along the distribution of a nerve).

Words relating to sensation:

• Atopognosia – inability to localise a sensation.
• Hyperesthesia – increase sensitivity to a sensory stimuli and hypesthesia – decreased sensitivity to a sensory stimuli.
• Paraesthesia – abnormal sensation such as pins and needles, numbness, tingling.
• Thigmanesthesia – loss of light touch sensibility .

Words relating to temperature:

• Thermanalgesia – inability to perceive heat.
• Thermanesthesia – inability to perceive sensations of heat or cold.
• Thermhyperesthesia – increased sensitivity to temperature and thermhypesthesia – decreased temperature sensibility.

When I think back to my university days, I remember being quite overwhelmed with the number of sensory tests we learnt in neurology and musculoskeletal subjects. Always remember that when put in the context of a full neurological screen (deep tendon reflexes, strength and sensation) the clinical patterns are much easier to recognise. However, it is definitely important to know the purpose and method for these sensory assessments and the most common tests you will use such as light touch, sharp/blunt discrimination, and temperature. The focus initially is to rule out any sensory impairment during a neurological exam and once sensory impairment has been detected, you can then be more specific in your mapping of the distribution and description of the symptoms.  

Sian

References:

Adams RD, Victor M and Ropper MD (2001): Principles of Neurology (7th ed.) New York: McGraw Hill. (Chapter 3 & 9).

Fredericks C and Saladin L (1996): Pathophysiology of the Motor Systems: Principles and Clinical Presentations. Philadelphia: F.A Davis pp. 275 – 288.

Kingsley R.E (2000): Concise Text of Neuroscience. (2nd ed.) Philadelphia: Lippincott, Williams & Wilkins. (Chapter 6, Appendix 2).

Nolte J (1999): The Human Brain: An Introduction to its Functional Anatomy. (4th ed.) St Louis: Mosby Year Book. (Chapter 10).

Nolte J and Angevine JB (1995): The Human Brain in Photographs and Diagrams. (1st ed.) St Louis: Mosby Year Book Inc.

O’Sullivan, S. B., Schmitz, T. J., & Fulk, G. (2013). Physical rehabilitation. FA Davis.

 

 

The Organization of the Dermatome and Afferent Myotome on JSTOR

Abstract

Single fibres were dissected from the dorsal spinal roots of the nerves serving the brachial plexus in African green monkeys. The dermatomal organization of these spinal nerves was deduced from data concerning the receptive fields of 2834 single afferent fibres. These data were collected in an attempt to reconcile some of the discrepancies that exist in published descriptions of the dermatomes in primates; our results and the literature reviewed suggest that the cutaneous region served by one spinal nerve is actually much wider and much more variable in location than is generally recognized. This makes any summary diagram a misleading indicator of the true complexity of the spinal innervation of the upper limb. In spite of this variability among individuals, within any specific individual there is a regular and orderly progression of innervation which allows prediction of the region served by a particular spinal nerve when information concerning the site of innervation of adjacent nerves is available. The territory of each myotome tended to be larger than the dermatome of the same spinal nerve. Most muscles of the limb received afferent innervation from three to four different spinal nerves. Further, the territory of the myotome did not of necessity coincide with the dermatome of the same spinal nerve. Even those nerves innervating the hand still innervated axial muscles. These observations have important implications for the diagnosis of spinal nerve injuries.

Publisher Information

The Royal Society is a self-governing Fellowship of many of the world’s most distinguished scientists drawn from all areas of science, engineering and medicine, and is the oldest scientific academy in continuous existence. The Society’s fundamental purpose, reflected in its founding Charters of the 1660s, is to recognise, promote, and support excellence in science and to encourage the development and use of science for the benefit of humanity. The Society has played a part in some of the most fundamental, significant, and life-changing discoveries in scientific history and Royal Society scientists continue to make outstanding contributions to science in many research areas.

Assessing the spatial distribution of cervical spinal cord activity during tactile stimulation of the upper extremity in humans with functional magnetic resonance imaging

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3. Assessing the spatial distribution of cervical spinal cord activity during tactile stimulation of the upper extremity in humans with functional magnetic resonance imaging

Kenneth A Weber, Yufen Chen, Monica Paliwal, Christine S Law, Benjamin S Hopkins, Sean Mackey, Yasin Dhaher, Todd B Parrish, and Zachary A Smith. 2020. “Assessing the spatial distribution of cervical spinal cord activity during tactile stimulation of the upper extremity in humans with functional magnetic resonance imaging”. Neuroimage, 217, Pp. 116905.Copy at https://is.gd/kBJK7E

Dermatomal maps are a mainstay of clinical practice and provide information on the spatial distribution of the cutaneous innervation of spinal nerves. Dermatomal deficits can help isolate the level of spinal nerve root involvement in spinal conditions and guide clinicians in diagnosis and treatment. Dermatomal maps, however, have limitations, and the spatial distribution of spinal cord sensory activity in humans remains to be quantitatively assessed. Here we used spinal cord functional MRI to map and quantitatively compare the spatial distribution of sensory spinal cord activity during tactile stimulation of the left and right lateral shoulders (i.e. C5 dermatome) and dorsal third digits of the hands (i.e., C7 dermatome) in healthy humans (n ​= ​24, age ​= ​36.8 ​\$\pm\$ ​11.8 years). Based on the central sites for processing of innocuous tactile sensory information, we hypothesized that the activity would be localized more to the ipsilateral dorsal spinal cord with the lateral shoulder stimulation activity being localized more superiorly than the dorsal third digit. The findings demonstrate lateralization of the activity with the left- and right-sided stimuli having more activation in the ipsilateral hemicord. Contradictory to our hypotheses, the activity for both stimulation sites was spread across the dorsal and ventral hemicords and did not demonstrate a clear superior-inferior localization. Instead, the activity for both stimuli had a broader than expected distribution, extending across the C5, C6, and C7 spinal cord segments. We highlight the complexity of the human spinal cord neuroanatomy and several sources of variability that may explain the observed patterns of activity. While the findings were not completely consistent with our a priori hypotheses, this study provides a foundation for continued work and is an important step towards developing normative quantitative spinal cord measures of sensory function, which may become useful objective MRI-based biomarkers of neurological injury and improve the management of spinal disorders.

Last updated on 03/02/2021

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Dermatome wireless Humeca D42 St. Petersburg

General characteristics

The width of the transplanted tissue is 42 mm, which can be reduced to 36 and 30 mm by means of clamps (special clips). The cordless dermatome weighs only 985 grams, which is exceptional for cordless dermatomes.

The handle of the wireless dermatome contains a rechargeable 7.4 V Li-ion 1200 mAh battery, which gives the ability to work for 45 minutes continuously.Optionally, the wireless dermatome D42 can be equipped with a more powerful 2400 mAh Li-Ion battery.

Wireless dermatome D42 is ideal for working with the MEEK technique (brand method), because the flap width is 42 mm, which is fully compatible with the special substrates used by MEEK Humeca equipment (brand method).

The speed of the wireless dermatome is 7000 rpm. The thickness of the transplanted tissue varies from 0.0-1.2 mm in 0.1 mm increments and is adjusted using the handle located on the side of the dermatome, in mm.A latch on the handle prevents changes in the thickness of the flap during surgery. The battery and motor of the hand dermatome are not sterilized, in order to avoid accidental sterilization of the dermatome, together with the battery, a special sterilization box has been developed, into which a wireless dermatome can be placed only without a battery and a motor.

Before use, the non-sterile battery and motor are placed in the cordless dermatome using a special sterile funnel to prevent contamination.The batteries are fully charged in 2-3 hours.

Advantages of the cordless dermatome D 42

• The extremely small size of the D42 cordless dermatome allows precision, especially in problem areas and pediatric surgery
• Portable design for optimal mobility and lightness
• The exact thickness of the graft flap is from 0. 0 to 1.2 mm in 0.1 mm increments
• The width of the transplanted flap of 42 mm guarantees optimal performance in combination with the MEEK

technique

• The use of narrowing clamps on the top of the dermatome allows you to set the desired flap width.
• The battery and motor of the instrument are not sterilized, thus guaranteeing a long service life
• The thickness of the flap is securely fixed to prevent accidental changes in tissue thickness during the procedure
• Safe and quick blade replacement
• Powerful lithium-ion batteries without memory effect allow continuous operation for a long time without intermediate charging

Dermatom electric Humeca D80 St. Petersburg

General characteristics

The D80 electric dermatome has a speed of 7000 rpm.The thickness of the transplanted tissue varies from 0.0-1.2 mm in 0.1 mm increments and is adjusted using the handle located on the side of the dermatome, in mm. A latch on the handle prevents changes in the thickness of the flap during surgery. The battery and motor of the electric dermatome are not sterilizable. In order to avoid accidental sterilization of the dermatome, together with the battery, a special sterilization box has been developed, in which an electric dermatome can be placed only without a battery and a motor.

Before use, the non-sterile battery and motor are placed in the dermatome using a special sterile funnel to prevent contamination.The batteries are fully charged in 2-3 hours.

Advantages of the D80 electric dermatome

• The extremely small size of the D80 electric dermatome allows precision, especially in problem areas and pediatric surgery;
• Wearable design provides optimal mobility and lightness;
• The exact thickness of the transplanted flap is from 0.0 to 1.2 mm with a step of 0.1 mm;
• The width of the transplanted flap of 42 mm guarantees optimal performance in combination with the MEEK

technique

• The use of reducing the width of the clamps on the top of the electrical dermatome allows you to set the desired flap width.
• The battery and motor of the instrument are not sterilized, thus guaranteeing a long service life
• The thickness of the flap is securely fixed to prevent accidental changes in tissue thickness during the procedure
• Safe and quick blade replacement
• Powerful lithium-ion batteries without memory effect allow continuous operation for a long time without intermediate charging

Dermatome What is it, types and clinical significance / Anatomy and physiology | Thpanorama

dermatoma is an area of ​​skin that is innervated by one spinal nerve.In particular, they are controlled by sensory neurons that arise from the spinal nerve ganglion.

There are eight cervical nerves, twelve thoracic nerves, five lumbar nerves, and five sacral nerves. Each of these nerves allows us to feel temperature, touch, pressure, and even pain.

Information travels from a specific area of ​​the skin to the brain. Dermatomes are organized as a stack of discs in a portion of the chest and abdomen, with each disc equipped with a different spinal nerve….

The picture is different in the limbs. Thus, dermatomes run longitudinally along the arms and legs. Thus, each half of each limb has its own dermatome.

Although all people usually have the same overall picture of the organization of dermatomes, specific areas of innervation may differ from person to person, as if they were fingerprints.

The vertebral column has over 30 different vertebrae, which are divided according to their location, from the neck to the coccyx.They are classified as cervical, thoracic, lumbar, and sacral. Each vertebra contains a specific spinal nerve that will innervate specific areas of the skin.

All nerves, except for the first cervical nerve (C1), are connected to the dermatome. Dermatomes provide a map of the spinal cord, which is very useful for healthcare professionals and researchers. And also for the diagnosis and treatment of pathologies.

There are currently two main charts in the medical profession. The first is Keegan and Garrett’s 1948 map, and the second is Förster’s 1933 map, the latter being the most widely used….

What is a dermatome?

Have you ever wondered why back pain leads to tingling in the legs? Or why do neck cramps make you feel numb in your fingers?

Apparently, this is due to the fact that there is a connection between sensations and disorders on the surface of the skin with specific nerve roots that originate in the spine. Therefore, each region that is innervated by each of these nerve roots is called a dermat.

Dermatome is subdivided into dermat, which means skin, and oma, which means mass. We have 29 dermatomes in the human body. These nerves are connected to each other, as they arose from the same somite groups during embryonic development. Somites are structures formed on the sides of the neural tube during the fourth week of human development.

For example, nerve fibers on the surface of the skin that cover part of the legs and feet constitute a dermatome that originates from the nerve root of the lower back….

Dermatomes should not be confused with myotomes. On the other hand, myotomes are those that innervate the skeletal muscles of the same group of somites ..

type

Dermatomes, like the spine, are divided into four parts: cervical, thoracic, lumbar and sacral. Each dermatome is classified according to the spinal nerve that innervates it. That is, the seventh cervical nerve innervates the C7 dermatome.

This dermatome gives sensitivity to the skin of the shoulder, parts of the hand, and the index and ring fingers….

Cervical dermatomes

They nourish the skin of the neck, neck, back, arms and hands.

Thoracic dermatomes

These cover the skin of the inner arm, chest, abdomen and mid-back.

Lumbar dermatomes

Invert the skin that lies in the lower back, in the frontal area of ​​the legs, outer thighs and in the upper and lower legs.

Sacral Dermatomes

These cover the genital and anal areas, the back of the legs, the back of the thighs and the calf, in addition to the outer edge of the legs.

However, it is important to note that dermatomes have been discovered in recent years by clinical observation and are only a guideline. Each person can present small changes within the dermatomes.

Clinical Significance

It is important to know how dermatomes work in a clinical setting to localize nerve or spinal cord lesions.

If certain symptoms are located along the area associated with the dermatome (pain, skin irritation, rash…), it may have something to do with a nerve root. For example, a herniated disc that compresses the L5 nerve root results in pain and tingling in the lower leg and foot.

Dermatomes are useful for the diagnosis and treatment of various conditions. The main ones are viral diseases, radiculopathy and spinal cord injuries.

Viral diseases

There are certain viral diseases that are found in certain dermatomes, such as shingles.This virus is hidden in the spinal cord, and when it manifests, it travels through the spinal cord, causing a painful skin rash that is associated with this nerve.

Herpes zoster is usually limited to a specific dermatome, such as the chest, leg, or arm. Usually appears years or even decades after recovery from chickenpox.

radiculopathy

This condition consists of pain caused by damage to the root of any nerve. It can also lead to loss or decrease in sensory function.The most common regions of the lesion are L5 and S1, and less often C6 and C7 ..

The pain increases when we put ourselves in a position in which the nerve roots are stretched. It can be cervical or lumbar depending on where the pain is.

Spinal Cord Injuries

When there is a spinal cord injury, the healthcare professional will look for the affected dermatome. To do this, it will start with the part of the skin where the patient has noticed changes. It will travel with a pin or fork on either side of the body until you achieve normal sensation.

You can also check if it records vibration along the vertebrae. Typically, the sensory level is two to three levels below the injury.

References

1. Dermatomes. (N.D.). Retrieved April 16, 2017, from Teach Me Anatomy: teachmeanatomy.info.
2. Dermatome Map – Overview Chart, Anatomy and Clinical Significance. (N.D.). Retrieved April 16, 2017, from Pain care: paincare.org.
3. Dermatomas. (N.D.). Retrieved April 16, 2017.from Queen’s University, Kingston: meds.queensu.ca.
4. Dermatomas. (N.D.). Retrieved on April 16, 2017, from Boundless: boundless.com.
5. Kishner S. (s.f.). Dermatome anatomy. Retrieved on August 12, 2015 from MedScape: emedicine.medscape.com.
6. What is a dermatome? – Definition and distribution. (N.D.). Retrieved on April 16, 2017, from Study: study.com.

Clinical Study Cervicogenic Headache: Traction Mobilization, Non-Traction Mobilization – Clinical Trials Registry

Intervention	Intervention type: Other Intervention name: Mobilization of traction Description: After the therapist has assessed the subject and found the most comparable patient symptom, he will perform a high-velocity push at the end of the patient’s available range, as described in Maitland’s approach.The lunge will only be performed once. The therapist will perform either a localized rotation of the cervical spine, the main movement of which is rotation, or a longitudinal thrust in the head of the C1 and C2, aimed at the upper cervical spine. Arm Group label: Mobilization of the cervical push Intervention type: Other Intervention name: Mobilization without traction Description: Therapists will perform Grade I-IV unilateral posterior to anterior (UPA) or central posterior to anterior (CPA) mobilization as described above in the Maitland concept at C0-C3 levels that mimic the patient’s most comparable trait.Therapists will be instructed to perform 3 mobilization cycles of 30 seconds at this level. Arm Group label: Cervical mobilization without push	Eligibility	Criteria: Inclusion Criteria: 1. The patient must speak English and have appropriate medical literacy to participate. In Study 2. Physical examination should give reproducible familiar / matching neck, head, jaw. symptom or dysfunction 3. Pain reports of at least 2/10 for headache or neck pain intensity.4. Reports of neck disability with consequences of at least 20% or higher. 5. Patients who report having at least two headaches within one month. Exclusion criterion: 1. The presence of any known red flags (eg, tumor, metabolic disease, RA, osteoporosis, long history of steroid use, etc.) 2. Patients who show any danger symptoms: positive upper or lower motor neuron testing. Signs or symptoms of cervical myelopathy or radiculopathy with nerve root compression (muscle weakness affecting a large muscle group of the upper limb, decreased stretch reflex of the muscles of the upper limb, or decreased or no pinprick sensation in any dermatome of the upper limb 3.Patients who show any red signs of cervical instability tests or a positive VBI or CAD test showing 5 D signs (dizziness, drop attacks, dysarthria, dysphagia, diplopia) or patients with 3 H signs (nystagmus, nausea , other neurological symptoms). 4. Before surgery on the cervical spine or head (including cerebral shunts) 5. Women who are pregnant in the third trimester. Floor: Everything Minimum age: 18 years Maximum age: 65 years Healthy volunteers: Not

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90,000 Dermatome (anatomy) – Dermatome (anatomy)

Dermatome is an area of ​​skin that is mainly supplied by afferent nerve fibers from the dorsal root of any given spinal nerve.There are 8 cervical nerves (excluding C1 without a dermatome), 12 thoracic nerves, 5 lumbar nerves, and 5 sacral nerves. Each of these nerves transmits sensation (including pain) from a specific area of ​​the skin to the brain.

This term is also used to refer to the part of the somite in the embryo.

Along the chest and abdomen, dermatomes are like a stack of discs that form a person, each with its own spinal nerve. The picture is different along the arms and legs: dermatomes run longitudinally along the limbs.Although the overall picture is the same for all people, the exact areas of innervation are as unique to each person as fingerprints.

The area of ​​the skin innervated by one nerve is called the peripheral nerve field.

The word by dermatome is derived from the ancient Greek δέρμα (“skin, skin”) and τέμνω (“I cut”).

Clinical significance

Reported pain: Conscious perception of internal sensations refers to specific areas of the body that are not sources of sensation.Some of the reflected pains due to visceral sensations are related to dermatomes, which send fibers to the same level of the spinal cord.

A dermatome is an area of ​​skin that contains sensory neurons that arise from the spinal nerve ganglion. Symptoms that accompany the dermatome (such as pain or rash) may indicate a pathology affecting the corresponding nerve root. Examples include somatic spinal dysfunction or viral infection. Certain skin problems tend to orient lesions dermatomally.

In reflected pain, sensory nerve fibers, such as those from the dermatome, can come together in the same spinal cord level as common visceral afferent fibers, such as those from the heart. When the common visceral sensory fiber is modeled, the central nervous system cannot clearly determine whether the pain is coming from the body wall or from internal organs, so it perceives the pain as coming from somewhere on the body wall, such as the left arm / hand.pain, pain in the jaw. Thus, pain is “attributed” to related dermatomes of the same segment of the spine.

Viruses that are dormant in nerve ganglia (for example, varicella-zoster virus, which causes both chickenpox and herpes zoster, usually shingles), often cause pain, rash, or both, depending on the dermatome (shingles deprive). However, not all dermatomes may show symptoms.

Important dermatomes and anatomical landmarks

The following is a list of spinal nerves and points that characterize the dermatome of each nerve:

Dermatomas of the lower extremities (modified, from Fender, according to Foerster)

The following is a list of the cranial nerves responsible for facial sensation:

Additional images

• Scheme of segmental distribution of cutaneous nerves of the right upper limb.

• Lower limb.

See also

Recommendations

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7 Segmental structure of the body “StudIzba

Lower

neo-rectum muscles, transverse intestinal muscles

Segments		Kozha 9002	Kozha 9002
C1			Small muscles of the occiput	C3–4 lungs
C2–3		Occipital region trapezoidal
C4		Occipital region, lower part of the neck above the collarbones	Scalaceae, diaphragm, lifting the scapula, large and small 90-300 rhomboid and sub-9000 on the left 9143 9000 : ser dce, pancreas, spleen, stomach, duodenum C3-4 on the right: liver and gallbladder, intestines
C5		Occipital region, clavicle region, anterior surface of the shoulder girdle, flexor surface of the shoulder and shoulder flexor	Deltoid, biceps, humeral, brachioradial, instep support, large and small thoracic, supra- and infraspinatal
C6		The back of the head, and the outer surface of the upper arm thumb	The pectoralis major and minor, the broad muscle of the back, the large circular muscle, the subscapularis deltoid, dentate, pronator, triceps
C7		The posterior surface of the supraculum extensor surface II and III fingers	Extenders of the wrist and fingers, flexors of the wrist joint
C8		Above the scapula, medial surface of the shoulder and forearm, The long extensor and flexor of the fingers
D1		Posteriorly obliquely to the armpit, in front almost horizontally below the clavicle, flexor surface of the shoulder and forearm to the wrist	fingers Small D1-5 heart
D2-6		Along the back, starting at the skull, outward and downward, almost horizontally in front	D2-12, back muscles, intercostal muscles	D8-11 right: liver and gallbladder pb D5-11 left stomach D6-10 right duodenum
D7-9		Starting from VII-IX thoracic vertebrae obliquely downward and outward, in front of the VII rib and up to a place slightly higher navel	Muscles of the back, muscles of the abdominal wall
D10-12		Behind the X – XII thoracic vertebra obliquely downward and outward in front from the level of the navel to the place above the umbilical cord 902 902 9014	D3-5 lungs D7-9 on the left pancreas D8-10 on the left spleen
L1		From the I lumbar vertebra obliquely downward and outward, inguinal region, region of the urinary bladder	walls	D9-L2 intestine D10-L2 kidney D12-L3 ovaries
L2		From the II lumbar vertebra to the iliac crest.On the thigh from above outside downwards inward along the sartorius muscle	Iliopsoas, lifting the testicle, quadriceps femur
L3		From the third lumbar vertebrae through the superior port to the inner surface of the knee and the upper third of the inner surface of the lower leg	Iliolumbar, quadriceps femur, thigh adductors, muscle that rotates the thigh inward L2 and L3 – flexion, inward rotation and abduction of the thigh
9000 9000		From the IV lumbar vertebra to the apex of the greater trochanter posteriorly, the middle outer third of the thigh, the anterior surface of the knee joint, the middle inner third of the lower leg	Quadriceps femur, the extensor of the leg
L5 9000 214		From the V lumbar vertebra through the buttock, the posterior outer surface of the thigh to the outer surface of the knee joint, along the lower leg to the back of the foot with the capture of I – IV fingers.On the sole, only the inner edge with the grip of the I toe	Middle and small gluteal, semimembranous, semitendinosus, biceps femur, straining the broad fascia of the thigh, anterior tibial
		S132 cross buttocks, middle third of the thigh behind, patella, posterior outer half of the leg, sole, plantar surface of II – V fingers, dorsum of V toe, outer edge of the foot		Gluteus maximus, pear-shaped, square femoris muscle, leg extensors, anterior tibial, fibular , extensor longus of the thumb
S2	The middle part of the sacrum, buttock, the posterior inner surface of the thigh and lower leg to the inner condyle		Triceps muscle of the leg, extensor muscle and flexor lechebical, small muscles of the foot	Urinary bladder and rectum
S3	Inner surface of the buttock, perineum, scrotum, penis		9000 and genitals, sphincters
S4-5	Perineum, anus and its circumference		Voluntary urination and defecation	324 902 902	324 902 902 . Leave a Reply Cancel reply Your email address will not be published. Required fields are marked * Comment * Name * Email * Website