• Source: Myotome

A myotome is the group of muscles that a single spinal nerve innervates. Similarly a dermatome is an area of skin that a single nerve innervates with sensory fibers. Myotomes are separated by myosepta (singular: myoseptum). In vertebrate embryonic development, a myotome is the part of a somite that develops into muscle.




Structure


The anatomical term myotome which describes the muscles served by a spinal nerve root, is also used in embryology to describe that part of the somite which develops into the muscles. In anatomy the myotome is the motor equivalent of a dermatome.




Function


Each muscle in the body is supplied by one or more levels or segments of the spinal cord and by their corresponding spinal nerves. A group of muscles innervated by the motor fibres of a single nerve root is known as a myotome.




= List of myotomes

=
Myotome distributions of the upper and lower extremity are as follows;

C1/C2: neck flexion/extension
C3: Lateral Neck Flexion
C4: shoulder elevation
C5: Shoulder abduction
C6: Elbow flexion/Wrist Extension
C7: Elbow extension/Wrist flexion
C8: Thumb extension
T1: Finger Abduction & Adduction
L1/L2: Hip Flexion
L3: Knee extension
L4: Ankle dorsi-flexion
L5: Great toe extension
S1: Hip extension/Ankle plantar-flexion/ankle eversion
S2: Knee flexion
S3–S4: anal wink




Clinical significance


In humans myotome testing can be an integral part of neurological examination as each nerve root coming from the spinal cord supplies a specific group of muscles. Testing of myotomes, in the form of isometric resisted muscle testing, provides the clinician with information about the level in the spine where a lesion may be present. During myotome testing, the clinician is looking for muscle weakness of a particular group of muscles. Results may indicate lesion to the spinal cord nerve root, or intervertebral disc herniation pressing on the spinal nerve roots.




References






Further reading


Neurology Textbook, edited by Professor L. Sokolva, M.D., D.Sc. 2012, ISBN 9789663824260




External links


Embryology at UNSW Notes/skmus7
Embryology at UNSW Notes/week3_6
mslimb-009—Embryo Images at University of North Carolina

Kata Kunci Pencarian:

• Myotome
• Somite
• Myotome (disambiguation)
• Mesoderm
• Omphalocele
• Muscle
• Adductor longus muscle
• Myalgia
• Somitomere
• Somitogenesis