Podcast
Questions and Answers
Which muscles are innervated by the axillary nerve?
Which muscles are innervated by the axillary nerve?
What is one action performed by the anterior fibers of the deltoid?
What is one action performed by the anterior fibers of the deltoid?
What causes sensory loss in the area innervated by the axillary nerve?
What causes sensory loss in the area innervated by the axillary nerve?
What is a characteristic deformity seen in cases of axillary nerve injury?
What is a characteristic deformity seen in cases of axillary nerve injury?
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Which nerve roots contribute to the radial nerve's formation?
Which nerve roots contribute to the radial nerve's formation?
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Where does the radial nerve exit the axilla?
Where does the radial nerve exit the axilla?
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What are the two branches into which the radial nerve divides at the elbow?
What are the two branches into which the radial nerve divides at the elbow?
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How does the radial nerve pass under the extensor carpi radialis brevis?
How does the radial nerve pass under the extensor carpi radialis brevis?
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What is the primary action of the Infraspinatus muscle?
What is the primary action of the Infraspinatus muscle?
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Which nerve is affected in carpal tunnel syndrome, leading to the ape hand deformity?
Which nerve is affected in carpal tunnel syndrome, leading to the ape hand deformity?
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What action does the Subscapularis muscle primarily perform?
What action does the Subscapularis muscle primarily perform?
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Which muscle is NOT supplied by the Femoral nerve?
Which muscle is NOT supplied by the Femoral nerve?
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What is the function of the Dorsal Scapular nerve?
What is the function of the Dorsal Scapular nerve?
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Which nerve is primarily responsible for actions such as shoulder extension, adduction, and medial rotation at the shoulder?
Which nerve is primarily responsible for actions such as shoulder extension, adduction, and medial rotation at the shoulder?
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What is the main function of the Superficial Peroneal nerve?
What is the main function of the Superficial Peroneal nerve?
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What action does the Gluteus Medius help primarily with?
What action does the Gluteus Medius help primarily with?
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Which muscle is primarily responsible for elbow extension?
Which muscle is primarily responsible for elbow extension?
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What action does the brachioradialis perform?
What action does the brachioradialis perform?
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Which muscle's action is most affected by injury to the Suprascapular nerve?
Which muscle's action is most affected by injury to the Suprascapular nerve?
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Which of the following actions does the Tensor Fascia Latae perform?
Which of the following actions does the Tensor Fascia Latae perform?
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Which nerve supplies sensation to the skin of the lateral half of the dorsum of the hand?
Which nerve supplies sensation to the skin of the lateral half of the dorsum of the hand?
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What condition can result from injury to the Long Thoracic nerve?
What condition can result from injury to the Long Thoracic nerve?
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What is a common symptom of radial nerve injury?
What is a common symptom of radial nerve injury?
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Which nerve is responsible for supplying the skin on the medial side of the lower two-thirds of the thigh?
Which nerve is responsible for supplying the skin on the medial side of the lower two-thirds of the thigh?
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Which of the following muscles is innervated by the ulnar nerve?
Which of the following muscles is innervated by the ulnar nerve?
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What is the primary function of the Adductor Magnus muscle?
What is the primary function of the Adductor Magnus muscle?
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What is the primary action of the extensor digiti minimi?
What is the primary action of the extensor digiti minimi?
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Which condition is caused by compression of the ulnar nerve at the cubital tunnel?
Which condition is caused by compression of the ulnar nerve at the cubital tunnel?
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Which nerve root primarily contributes to the ulnar nerve?
Which nerve root primarily contributes to the ulnar nerve?
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Which muscle is affected in posterior interosseous nerve syndrome?
Which muscle is affected in posterior interosseous nerve syndrome?
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What is the primary function of the flexor carpi ulnaris?
What is the primary function of the flexor carpi ulnaris?
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Which muscle facilitates thumb opposition?
Which muscle facilitates thumb opposition?
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Which nerve injury can result from hypertrophy of the pronator teres muscle?
Which nerve injury can result from hypertrophy of the pronator teres muscle?
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What is the role of the palmaris longus muscle?
What is the role of the palmaris longus muscle?
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What is the function of the dorsal interossei muscles?
What is the function of the dorsal interossei muscles?
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Study Notes
Upper Extremity & Lower Extremity Nerves
- These notes cover the nerves of the upper and lower extremities.
Axillary Nerve
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Branch: Posterior cord of brachial plexus
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Nerve Roots: C5-C6
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Motor Supply: Teres minor, deltoid (anterior, posterior, acromial fibers)
- Action: Shoulder abduction, horizontal abduction, extension, external rotation
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Sensory Supply: Upper lateral cutaneous nerve of arm, skin covering the lower half of deltoid and upper part of long head of triceps
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Causes of Injury: Dislocation of the shoulder, fracture of the surgical neck of humerus
- Effects: "Square shoulder" from deltoid muscle atrophy, sensory loss over lower half of deltoid
Radial Nerve
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Branch: Posterior cord of brachial plexus
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Nerve Roots: C5-8, T1
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Motor Supply: Extensor muscles of the forearm & wrist, supinator, triceps, brachioradialis
- Action: Wrist extension, radial deviation, elbow extension, supination
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Sensory Supply: Lower lateral cutaneous nerve of arm, posterior cutaneous nerve of the arm, posterior cutaneous nerve of forearm, superficial branch, skin of lateral half of dorsum of hand, lateral two and half digits including thumb.
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Radial Nerve Injury: Axilla, musculospiral groove, around radial neck
- Radial Tunnel Syndrome: Tenderness in the extensor muscle mass of the forearm (distal to lateral epicondyle), pain on long finger extension test
- Posterior interosseous nerve syndrome:
- Wrist drop: Loss of extension.
Ulnar Nerve
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Branch: Medial cord of brachial plexus
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Nerve Roots: C7-T1 (main contribution from 8-T1)
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Motor Supply: Dorsal and palmar interossei, adductor pollicis, flexor carpi ulnaris, flexor digitorum profundus (medial half)
- Action: Hand/finger adduction, thumb adduction, wrist flexion, flexion of DIP of medial digits
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Sensory Supply: Palmar cutaneous branch (medial ½ of palm), dorsal cutaneous branch (dorsal aspect of medial one and half fingers), superficial branch (½ of 4th & 5th digits)
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Ulnar Nerve Lesion
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Cubital Tunnel Syndrome: Compression in cubital tunnel at elbow
- Effects: Sensory loss, progressive weakness of innervated muscles distal
- Guyon's Canal Syndrome: Sensory changes, progressive weakness of distal muscles
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Cubital Tunnel Syndrome: Compression in cubital tunnel at elbow
Median Nerve
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Origin: Medial and lateral cord of the brachial plexus
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Nerve Roots: C5-8, T1
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Motor Supply: Flexor digitorum profundus (radial half), flexor pollicis longus, pronator quadratus, pronator teres, opponens pollicis, palmar interossei, lumbricals (1 & 2), flexor carpi radialis, flexor digitorum superficialis
- Action: Elbow flexion, wrist flexion, hand/finger flexion, thumb opposition
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Sensory Supply: Palmar cutaneous branch, palmar digital branches (dorsal aspects of 1st, 2nd & 3rd finger), palmar skin of lateral 3 and ½ fingers
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Median Nerve Injuries:
- Pronator syndrome: Compression by hypertrophy of pronator teres muscle
- Carpal Tunnel Syndrome: Compression of median nerve under flexor retinaculum at the wrist
Musculocutaneous Nerve
- Branch: Lateral cord of brachial plexus
- Nerve Roots: C5-C7
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Motor Supply: Biceps, coracobrachialis, brachialis
- Action: Elbow flexion, forearm supination, flexion of arm
- Sensory Supply: Lateral cutaneous nerve of forearm supplies skin on lateral side of forearm.
Suprascapular Nerve
- Origin: Upper trunk of brachial plexus
- Nerve Roots: C5-C6
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Motor Supply: Infraspinatus, supraspinatus
- Action: Lateral rotation and abduction of arm, Shoulder abduction up to 15 degrees
Subscapular Nerve (Upper & Lower)
- Branch: Posterior cord of brachial plexus
- Nerve Roots: C5-C6
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Motor Supply: Teres Major (lower subscapular nerve), subscapularis (both upper and lower subscapular nerve)
- Action: Shoulder medial rotation, extension, adduction, and when arm is by side, adduction
Lateral Pectoral Nerve
- Branch: Lateral cord of brachial plexus
- Nerve Roots: C5-C7
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Motor Supply: Pectoralis Major
- Action: Medial rotation, adduction, horizontal adduction, scapular protraction, depression, clavicular fibers- shoulder flexion, sternocostal fibers- shoulder extension
Medial Pectoral Nerve
- Branch: Medial cord of brachial plexus
- Nerve Roots: C8, T1
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Motor Supply: Pectoralis Minor
- Action: Downward rotation of scapula, scapular protraction, depression
Long Thoracic Nerve
- Origin: Roots of brachial plexus
- Nerve Roots: C5, C6, C7
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Motor Supply: Serratus anterior
- Action: Upward rotation of scapula, scapular protraction, depression
- Injury: Winged scapula
Thoracodorsal Nerve
- Branch: Posterior cord of brachial plexus
- Nerve Roots: C6-C8
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Motor Supply: Latissimus Dorsi
- Action: Shoulder extension, adduction, medial rotation, depression, protraction of scapula
Dorsal Scapular Nerve
- Origin: Brachial plexus
- Nerve Root: C5
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Motor Supply: Rhomboid minor, rhomboid major, levator scapulae
- Action: Scapular elevation, retraction, downward rotation
Nerve to Subclavius
- Origin: Upper trunk of brachial plexus
- Nerve Roots: C5-C6
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Motor Supply: Subclavius
- Action: Depress & stabilize clavicle
Scapular Movements & Muscles
- Elevation: Upper trapezius, levator scapulae, rhomboids
- Protraction: Serratus anterior, pectoralis minor, and major
- Depression: Serratus anterior, pectoralis minor, and major, lower trapezius, latissimus dorsi
- Retraction: Trapezius, rhomboids
- Downward Rotation: Levator scapula, rhomboids, pectoralis minor
- Upward Rotation: Serratus anterior, trapezius (upper & lower fibers)
Spinal Accessory Nerve (CN XI)
- Motor supply: Trapezius (upper fibers- scapula elevation, middle fibers-retraction, lower fibers-depression, upper and lower fibers-upward rotation), sternocleidomastoid (cervical lateral flexion and opposite side rotation)
Superior Gluteal Nerve
- Nerve Roots: L4-S1
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Motor Supply: Gluteus medius, gluteus minimus, tensor fascia latae
- Action: Abduction of hip, assists in medial and lateral rotation of hip, abduction of hip, flexion, abduction and medial rotation of hip.
Inferior Gluteal Nerve
- Nerve Roots: L5-S2
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Motor Supply: Gluteus maximus
- Action: Hip extension & external rotation, secondary action- hip abduction
Nerve to Piriformis (Ventral Rami of L5-S2)
- Nerve Roots: L5-S2
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Motor Supply: Piriformis
- Action: Abduction and lateral rotation of hip
Obturator Nerve
- Nerve Roots: L2-L4
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Motor Supply: Adductor longus, adductor brevis, gracilis, obturator externus, adductor magnus
- Action: Hip adduction, flexion, medial rotation (anterior division), hip lateral rotation, adduction, medial rotation (posterior division)
Nerve to Quadratus Femoris
- Nerve Roots: L4-S1
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Motor Supply: Gemellus inferior, quadratus femoris
- Action: Lateral rotation of hip and adduction of hip
Nerve to Obturator Internus
- Nerve Roots: L5-S2
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Motor Supply: Gemellus superior and Obturator internus
- Action: Lateral rotation of hip
Sciatic Nerve
- Largest Branch: Sacral plexus
- Nerve Roots: L4-S3
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Motor Supply: Biceps femoris, semitendinosus, semimembranosus, adductor magnus
- Action: knee flexion, hip extension, lateral rotation of flexed leg (non-weight bearing)
Sciatic Nerve
- Sciatica: Herniated disk or bone spur compressing the sciatic nerve, causing radiating pain
- Piriformis Syndrome: Piriformis spasm or tightness compressing the sciatic nerve
Femoral Nerve
- Nerve Root: L2-L4
- Pathway: Passes through the femoral triangle, along with the femoral artery
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Motor Supply: Iliacus, pectineus, sartorius, rectus femoris, vastus medialis/intermedius/lateralis
- Action: Hip flexion, knee extension, hip flexion, adduction, medial rotation, hip flexion, abduction, lateral rotation, knee flexion, hip flexion, knee extension and hip flexion respectively.
Femoral Nerve - Sensory Supply
- Medial Cutaneous Nerve of Thigh: Supplies medial side of lower two-thirds of thigh.
- Intermediate Cutaneous Nerve of Thigh: Supplies anterior thigh skin.
- Saphenous Nerve: Supplies the medial side of the leg.
Tibial Nerve
- Terminal Branch: Sciatic nerve
- Nerve Roots: L4-S3
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Motor Supply: Gastrocnemius, soleus, tibialis posterior, flexor hallucis longus, flexor digitorium longus, plantar interossei, and lumbrical 1.
- Actions: Plantarflexion, knee flexion, plantar flexion, slight knee flexion and plantar flexion.
Tarsal Tunnel Syndrome
- Posterior tibial nerve compression or irritation within the tarsal tunnel
Tibial Nerve Branch - Medial Plantar Nerve
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Motor Supply: Abductor hallucis, flexor hallucis brevis, flexor digitorium brevis, lumbrical 1.
- Actions: Great toe abduction, 1st toe flexion, 2-4th toe flexion, MTP flexion and IP extension
Tibial Nerve Branch - Lateral Plantar Nerve
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Motor Supply: Plantar interossei, dorsal interossei, Quadratus plantae, Abductor digiti minimi, lumbricals 2, 3 & 4, Adductor hallucis
- Actions: Adduction of toes, abduction of toes, 2-4th toe flexion, flexion of toes, 5th toe abduction & flexion, MTP flexion, IP extension, and great toe adduction respectively.
Tibial Nerve - Sensory Branches
- Medial Calcaneal Branches: Supplies skin over the heel.
- Medial Plantar Nerve: Supplies medial side of sole
- Lateral Plantar Nerve: Supplies lateral side of sole.
Common Peroneal Nerve
- Nerve Roots: L4-S2
- Origin: Sciatic nerve
- Bifurcation: Just below the fibular neck into superficial and deep peroneal nerves.
Deep Peroneal Nerve
- Nerve Roots: L4-S1
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Motor Supply: Tibialis anterior, extensor hallucis longus, extensor digitorum longus, extensor digitorum brevis, peroneus tertius.
- Actions: Dorsiflexion, inversion, 1st toe extension, ankle dorsiflexion, inversion, toe extension, ankle dorsiflexion and eversion.
Superficial Peroneal Nerve
- Nerve Roots: L4-S2
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Motor Supply: Peroneus longus, peroneus brevis
- Action: Plantarflexion and eversion.
Superficial & Deep Peroneal Nerves - Sensory Supply
- Deep Peroneal Nerve: Supplies webbing between 1st and 2nd toes on the dorsal surface.
- Superficial Peroneal Nerve: Supplies dorsum of foot (except webbing between 1st and 2nd toes) and anterolateral portion of lower leg.
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Description
Test your knowledge on the axillary and radial nerves. This quiz covers muscle innervation, actions performed by the deltoid, and neurological impacts of nerve injuries. Explore the anatomy and clinical significance of these important nerves.
