Lumbar Myotomes

Dorn Spinal Therapy

Spine Healing Therapy

Get Instant Access

The precise region of impaired sensation to light touch and noxious stimuli is an important clue for the clinical localization of spinal cord and peripheral nerve lesions. Reflex abnormalities and autonomic dysfunction are further ones, as discussed below (p. 40, p. 110).

Dermatomes (pp.34, 36)

A dermatome is defined as the cutaneous area whose sensory innervation is derived from a single spinal nerve (i.e., dorsal root). The division of the skin into dermatomes reflects the segmental organization of the spinal cord and its associated nerves. Pain dermatomes are narrower, and overlap with each other less, than touch dermatomes (p. 104); thus, the level of a spinal cord lesion causing sensory impairment is easier to determine by pinprick testing than by light touch. (The opposite is true of peripheral nerve lesions.) Radicular pain is pain in the distribution of a spinal nerve root, i.e., in a der-matome; pseudoradicular pain may occupy a bandlike area but cannot be assigned to any particular dermatome. Pseudoradicular pain can be caused by tendomyosis (pain in the muscles that move a particular joint), generalized tendomy-opathy or fibromyalgia, facet syndrome (inflammation of the intervertebral joints), myelogelo-sis (persistent muscle spasm resulting from overexertion), and other conditions. For mnemonic purposes, it is useful to know that the C2 dermatome begins in front of the ear and ends at the occipital hairline; the T1 dermatome comes to the midline of the forearm; the T4 der-matome is at the level of the nipples (which, however, belong to T5); the T10 dermatome includes the navel; the L1 dermatome is in the groin; and the S1 dermatome is at the outer edge of the foot and heel.

through the dorsal branches of the spinal nerves. Knowledge of the myotomes of each spinal nerve, and of the segment-indicating muscles (Table 2, p. 357) in particular, enables the clinical and electromyographic localization of radicular lesions causing motor dysfunction. The segment-indicating muscles are usually innervated by a single spinal nerve, or by two, though there is anatomic variation.

Plexuses (pp.34, 36) and Peripheral Nerves (pp.35, 37)

The ventral branches of spinal nerves supplying the limbs join together to form the cervical (C1-C4), brachial (C5-T1), lumbar (T12-L4), and sacral plexuses (L4-S4). The brachial plexus begins as three trunks, the upper (derived from the C5 and C6 roots), middle (C7), and lower (C8, T1). These trunks split into divisions, which recombine to form the lateral (C5-C7), posterior (C5-C8), and medial (C8 and T1) cords (named by their relation to the axillary artery). The cords of the brachial plexus branch into the nerves of the upper limb (p. 35). The nerves of the anterior portion of the lower limb are derived from the lumbar plexus, which lies behind and within the psoas major muscle (p. 37); those of the posterior portion of the lower limb from the sacral plexus. The coccygeal nerve (the last spinal nerve to emerge from the sacral hiatus) joins with the S3-S5 nerves to form the coccygeal plexus, which innervates the coccy-geus and the skin over the coccyx and anus (mediates the pain of coccygodynia).

Myotomes

A myotome is defined as the muscular distribution of a single spinal nerve (i.e., ventral root), and is thus the muscular analogue of a cutaneous dermatome. Many muscles are innervated by multiple spinal nerves; only in the par-avertebral musculature of the back (erector spinae muscle) is the myotomal pattern clearly segmental (p. 31); the nerve supply here is

Rhomboid mm. Supraspinatus m. Infraspinatus m. Triceps brachii m. Diaphragm Iliopsoas m

Pectoralis m. Deltoid m.

Biceps brachii m.

Brachio-adialis m.

Thenar muscles

Pectoralis m. Deltoid m.

Biceps brachii m.

Brachio-adialis m.

Thenar muscles

Biceps Longus Syndrom

Peroneus longus m.

- Extensor hallucis longus m.

Myotomes

(left, posterior view; right, anterior view)

Dermatomes (left, posterior view; right, anterior view)

Peroneus longus m.

- Extensor hallucis longus m.

Myotomes

(left, posterior view; right, anterior view)

Dermatomes (left, posterior view; right, anterior view)

Diaphragm

Diaphragm

Hypoglossal n. (XII) Great auricular n. -Lesser occipital n. Transversus colli n. Ansa cervicalis (from C1 to C3) Supraclavicular nn.

Middle trunk (C7)-

Upper trunk (C5/C6) Dorsal scapular n. (C3-C5) Suprascapular n. (C4-C6) Subclavian n. (C5/C6) —

Lower trunk (C8/T1)

Musculocutaneous n. (C5-C7)

Axillary a.

C 3/C 4 Radial n. (C5-T1) Ulnar n. (C7/8-T1) Medial cutaneous n. of forearm Medial cutaneous n. of arm Posterior cord (C5-C8)

Biceps brachii m

Lower trunk (C8/T1)

Musculocutaneous n. (C5-C7)

Axillary a.

Musculocutaneous

Cervícobrachíal plexus

(C = cervical vertebra; T = thoracic vertebra)

Medial pectoral n. (C8/T1)

Ribs 1 and 2

Long thoracic n. (C5-C7)

Cervícobrachíal plexus

(C = cervical vertebra; T = thoracic vertebra)

Flexor carpi ulnaris

Supra- and infraspinatus mm.

Brachioradialis

Biceps brachii m

Supra- and infraspinatus mm.

Brachioradialis

Ulnar Nerve Myotomes

Flexor carpi ulnaris

Was this article helpful?

0 0
Peripheral Neuropathy Natural Treatment Options

Peripheral Neuropathy Natural Treatment Options

This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.

Get My Free Ebook


Responses

Post a comment