5.4. SACRAL PLEXUS AND ITS IMPAIRMENT SYMPTOMS - Pain Clinic

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5.4. SACRAL PLEXUS AND ITS IMPAIRMENT SYMPTOMS

Colleagues > Handbooks > Neurological examination and topical diagnosis > Section I. Clinical examination and impairment symptoms of the nervous system function > Chapter 5. Peripheral nervous system: clinical examination and impairment symptoms

Sacral plexus is formed by the anterior branches of L5, S1-S4 spinal nerves. Plexus is located on the anterior surface of the sacrum near the sacroiliac joint, on the anterior surface of the piriformis muscle. Short branches of the sacral plexus go to the pelvic muscles, the gluteus muscles and the genitals. Long branches are the sciatic nerve and posterior cutaneous nerve of the thigh.

Motor fibers of the sacral plexus innervate the pelvic girdle muscles: piriformis, internal obturator, the superior and inferior gemellus, quadratus femoris, gluteus maximus, medius and minimus muscles, tensor fascia lata. These muscles abduct the lower limb and rotate it outwards; flex it in the hip joint; while in the standing position helps in flexing the torso allowing to bend in desired direction.

The clinical picture of the sacral plexus lesion is characterized by intense pain in the sacrum, buttocks, perineum, on the back of the thighs, legs, plantar surface of the feet. Also characterized by sensory disturbances in the innervation zone and paralysis of the pelvic girdle muscles, hamstrings, calves and feet; decreased or absent Achilles and plantar reflexes (Tab. 21).

Table 21

Nerves originating from sacral plexus

 

Peripheral nerves

Level of formation innervated muscles, possible sites of compression.

Impairment symptoms

Test for functional examination

Internal obturator nerve (n. obturatorius internus)

Motor fibers originate from L4 spinal root and innervate the internal obturator muscle.

The weakness in outward rotation of hip.

The patient is asked to rotate the thigh outward. The doctor resists this action.

Piriformis nerve (n.piriformis)

Consists of motor fibers from S1-S3 spinal roots and innervates the piriformis.

The weakness in outward rotation of hip.

The patient is asked to rotate the thigh outward. The doctor resists this action.

Qudratus femoris nerve (n. quadratus femoris)

Consists of motor fibers from L4-S1 spinal roots and innervates the quadratus femoris and the superior and inferior gemellus muscle.

The weakness in outward rotation of hip.

The patient lying on the spine, is asked to rotate the thigh outward. The doctor resists this action.

Superior gluteal nerve (n. gluteus superior)

Consists of motor fibers from L4-S5 spinal roots and supplies the gluteus medius and minimus muscles.

Weakness in abduction of the straightened limb.

Patient lying on the back with legs straight is asked to abduct them. The doctor should resist this action.

Inferior gluteal nerve (n.gluteus inferior)

Consists of motor fibers from L5-S1-S2 spinal roots and supplies the gluteus maximus muscles.

Weakness in extension of the hip joint.

Patient lying on his stomach is asked to raise straightened lower limb. The doctor resists this action.

Posterior cutaneous nerve of the thigh (n. cutaneus femoris posterior)

Consists of fibers from S1-S3 spinal roots and supplies the skin of the gluteal region, perineum and posterior surface of the thigh (hamstring).

Numbness and paresthesias in the gluteal region, the perineum and the posterior surface of the thigh.

Assessment of pain and temperature sensation in the area of ​​innervation.

ENMG.

Ischaidic/sciatic nerve (n.ischiadicus)

Consists of fibers from L4-S3 spinal roots innervating the biceps femoris, adductor magnus, semitendinosus and semimembranosus muscles. Above the popliteal fossa sciatic nerve divides into terminal branches - the tibial nerve and the common peroneal nerve.

Nerve can be damaged by injury, pelvic trauma, inflammatory processes in the pelvic floor and buttocks. Most commonly the nerve is affected in the tunnel syndrome of piriformis muscle/ Piriformis syndrome.

Weakness in the flexion of the knee joint and outwards and inwards rotation of the tibia.

Lower limb is straightened, impaired walking especially on stairs. Foot and toes moderately hanging, impaired postero-lateral sensitivity of the leg and foot, toes and soles. Possiblity of causalgia.

Patient lying on his stomach is asked to bend the lower limb at the knee, then rotate it inwards and then outwards.

The doctor resists these actions.

Tibial nerve (n.tibialis)

Originated from L4-S3 spinal roots. Innervates the triceps surae, flexor digitorum longus, plantaris, popliteal, posterior tibial, flexor policis longus muscles etc.

Cutaneous branches - medial cutaneous nerve of the leg and sural nerve - innervate postero-lateral surface on the lower third of the leg, ankle and tarsal joints, the heel area, the skin on the lateral foot and the fifth finger.

Medial plantar nerve supplies the skin on the medial plantar surface of the foot, 1st-3rd and half of the 4th toe, as well as flexor digitorum brevis. Lateral plantar nerve supplies the skin on the lateral surface of the foot, 5th and half of the 4th toe, as well as a quadrates plantae and lumbricales muscles.

Levels of compression :

1. At the level of the popliteal fossa

2. In the tarsal canal

a. At the level of the heel;

b. At bottom of the foot.

Inability to flex in the ankle joint and the toes. The foot is in plantar-flexion position (pes calcaneus). Difficulty in flexion and extension of the fingers (когтистая лапа)how is it possible clawed feet + paw in leg. Sensory impairment is localized in the leg and foot.

Damage of the nerve in tarsal canal affects the muscles of the foot, Sensory impairment localized only on the plantar surface. Possiblity of causalgia.

Patient lying on his back, is asked to flex the ankle joint and flex and spread the toes.

The doctor resists thes actions.

Common peroneal/ common fibular nerve (n. peroneus communis)

Consists of fibers from L4-L5, S1-S2 spinal nerves. At the level of fibular neck is divided into superficial, deep and recurrent branch. Superficial peroneal nerve supplies long and short peroneal muscles. Cutaneous branches supply the lower third of the leg and dorsal surface of the foot, the inner edge of the foot and dorsal surface of the toes. Deep branch innervates the extensor digitorum longus of the foot, the tibialis anterior muscle and extensor policis longus.

Levels of compression :

1. At the level of the neck of the fibula (upper peroneal tunnel syndrome).

2. On the dorsal surface of ankle joint, below extensor ligament of the foot (lower peroneal tunnel syndrome).

Inability in extendin the ankle joint and fingers, abduction and pronation of the foot.

Foot hangs and rotate inward when walking. Fingers bent in the proximal phalanges ("Foot drop", "clubbed foot", pes equinovarus). Characteristic steppage gait.

Patient lying on his back, is asked to extend the ankle, adduct and lift the inner edge of the foot. Ask to extend the proximal phalanges.

The doctor resists these actions.

Pudendal and coccygeal nerve (n. pudendus et n. coccigeus)

Consist of fibers from S3-S4 and S5-Co1- Co2 spinal roots and innervate the muscles of the perineum, the pelvic floor and skin in ano-genital region.

Impaired urinary, bowel and sexual function; anal reflex is lost and sensory disorders.

Assessment of pain and temperature sensation in the area of ​​innervation.

ENMG

 

 

Questions for self-control

 

1.       Name the structures related to the peripheral nervous system.

2.       What are the main nerves originating from the cervical plexus?

3.       Which segments of the spinal cord form the cervical plexus?

4.       Which segments of the spinal cord form the brachial plexus?

5.       What are the main nerves originating from the lumbar plexus?

6.       Which segments of the spinal cord form the lumbar plexus?

7.       Which segments of the spinal cord form the sacral plexus?

8.       Name the main "tunnels" of the upper limb.

9.       Name the main "tunnels" of the lower limb.

10.    Lesion in which nerve of the wrist forms the "monkey like hand".

11.    Lesion in which nerve causes the "foot drop".

12.    Describe meralgia paresthetic/ Bernhardt-Roth’s syndrome.

13.    What are the main clinical symptoms detected in lesions of genital and coccygeal nerves.

 

 

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