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RADIOLOGY

Glenoid Clavicle Coracoid fossa

Surgical neck of humerus (axillary nerve and posterior circumflex humeral artery)

Mid-shaft of humerus­ radial groove (radial nerve and profunda brachii artery)

Figure 111-4-6. Upper Extremities: Anteroposterior

View of Shoulder (External Rotation)

Location of median nerve

Lateral epicondyle (location of radial nerve)

Coronoid process of ulna

Ulna

From the IMC, DxR Development

Group, Inc. All rights reserved.

Figure 111-4-7. Upper Extremities: Anteroposterior View of Elbow

Chapter If • Upper Limb

Clinical Correlate

Humeral Surgical Neck Fracture

The axillary nerve accompanies the posterior humeral circumflex artery as it passes around the surgical neck of the humerus.

A fracture in this area could lacerate both the artery and nerve.

Mid-Shaft (Radial Groove) Humeral

Fracture

The radial nerve accompanies the profunda brachii artery.

Both could be damaged as a result of a mid-shaft humeral fracture.

What deficits would result from laceration of the radial nerve?

MEDICAL 297

Lower Limb 5

LUMBOSACRAL PLEXUS

The lumbosacral plexus provides the motor and sensory innervation to the lower limb and is formed by ventral rami of the L2 through S3 spinal nerves.

• The major nerves of the plexus are the:

-

Femoral nerve

 

posteriordivisions of L2 through L4

-

 

v

 

 

t

ant rior divisions of L2 through L4

Obturator

 

-

 

 

 

nerve

 

 

 

Tibialner e

an-erioredivisions of L4 through S3

 

Common

fibular nerve-posterior divisions of L4 through S2

 

 

 

-

 

 

 

-

Superior gluteal nerve posterior divisions of L4 through S 1

Inferiorgluteal nerve -posterior divisions of LS through S2

 

 

 

 

 

 

 

-

• The tibial nerve and common fibular nerve travel together through the gluteal region and thigh in a common connective tissue sheath and together are called the sciatic nerve.

• The common fibular nerve divides in the proximal leg into the superfi­ cial and deep fibularnerves.

Sciatic nerve

Figure 111-5-1 . Lumbosacral Plexus

MEDICAL 301

Section Ill • Gross Anatomy

Terminal Nerves of Lumbosacral Plexus

The terminal nerves ofthe lumbosacral plexus are described in Table IIl-5- 1 .

Table 111-5-1. Terminal Nerves of Lumbosacral Plexus

Terminal Nerve

Origin

Muscles Innervated

Femoral nerve

L2 through L4

Anterior compartment of

 

posterior divisions

thigh (quadriceps femoris,

 

 

sartorius, pectineus)

Obturator nerve

L2 through L4

Medial com partment of

 

anterior divisions

thigh (gracilis, adductor

 

 

longus, adductor brevis,

 

 

anterior portion of adductor

 

 

magnus)

Primary Actions

Extend knee

Flex hip

Adduct thigh

Medially rotate thigh

Tibial nerve

L4 through 53

Posterior compartment of

 

anterior divisions

thigh (semimembranosus,

 

 

semitendinosus, long head

 

 

of biceps femoris, posterior

 

 

portion of adductor magnus)

 

 

Posterior compartment of

 

 

leg (gastrocnemius, soleus,

 

 

flexor digitorum longus,

 

 

flexor hallucis longus,

 

 

tibialis posterior)

 

 

Plantar muscles of foot

Common fibular nerve

L4 through 52

Short head of biceps femoris

 

posterior divisions

 

Superficial fibular nerve

 

Lateral compartment of leg

 

 

(fibularis longus, fibularis

 

 

brevis)

Flex knee

Extend thigh

Plantar flex foot (51-2)

Flex digits

Inversion

Flex knee

Eversion

Deep fibular nerve

Anterior compartment of leg

 

(tibialis anterior, extensor

 

hallucis, extensor digitorum,

 

fibularis tertius)

Dorsiflexfoot (L4-5)

Extend digits

Inversion

302 MEDICAL

Section Ill • Gross Anatomy

Clinical Correlate

The common fibular nerve crosses the lateral aspect of the knee at the neck ofthe fibula, where it is the most frequently damaged nerve ofthe lower limb. Patients will present with loss of dorsiflexion at the ankle (foot drop), loss of eversion, and sensory loss on the lateral surface ofthe leg and the dorsum ofthe foot.

Clinical Correlate

The common fibular nerve may be compressed by the piriformis muscle when the nerve passes through the piriformis instead of inferior to the muscle with the tibial nerve. Piriformis syndrome results in motor and sensory loss to the lateral and anterior compartments ofthe leg.

Clinical Correlate

The sciatic nerve is often damaged following posterior hip dislocation. A complete sciatic nerve lesion results in sensory and motor deficits in the posterior compartment ofthe thigh and all functions below the knee.

304 MEDICAL

NERVE INJURIES AND ABNORMALITIES OF GAIT

Superior Gluteal Nerve

•Weakness in abduction ofthe hip

•Impairment ofgait; patient cannot keep pelvis level when standing on one leg.

•Sign is "Trendelenburg gait."

Inferior Gluteal Nerve

•Weakened hip extension

•Difficulty rising from a sitting position or climbing stairs

Femoral Nerve

•Weakened hip flexion

•Weakened extension ofthe knee

•Sensory loss on the anterior thigh, medial leg, and foot

Obturator Nerve

• Loss ofadduction ofthe thigh as well as sensoryloss on medial thigh

Sciatic Nerve

•Weakened extension ofthe thigh

•Loss of flexion ofthe knee

•Loss ofallfunctions below the knee

•Sensory loss on the posterior thigh, leg (except medial side), and foot

Tibial nerve only

•Weakness in flexion ofthe knee

•Weakness in plantar flexion

•Weakened inversion

•Sensory loss on the leg (except medial) and plantar foot

Commonfibularnerve (neckoffibula)

Produces a combination of deficits oflesions of the deep and superficial fibular nerves

Deepfibularnerve

•Weakened inversion

•Loss ofextension ofthe digits

•Loss of dorsiflexion ("foot drop")

•Sensory loss limited to skin ofthe first web space between the great and second toes

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