d-etre.blogspot.com Organization of the Upper Limb Audrone Biknevicius, Ph.D. Dept. Biomedical Sciences, OU HCOM at Dublin Clinical Anatomy Immersion 2014 “Anatomical Tool-Kit” www2.warwick.ac.uk www.medicinenet.com www.telegraph.co.uk virtuallaboratory.colorado.edu www.cedars-sinai.edu 2 Week 5 Week 7 RULE #1 Limbs are outgrowths of the ventral body wall that undergo distal growth and and rotation differentiation… [More detailed limb embryology in MS course] 3 The upper limbs are innervated by : A. Dorsal rami of spinal nn. B. Ventral rami of spinal nn. 50% Dorsal rami of spinal nn. 50% Ventral rami of spinal nn. 4 DEVELOPMENTAL/EVOLUTIONARY BASIS Primitive Pectoral Limb Developmentally-ventral limb mm. Stern Essential of Gross Anatomy Developmentally-dorsal limb mm. DEVELOPMENTAL/EVOLUTIONARY BASIS Stern Essential of Gross Anatomy • 90◦ lateral rotation (forearm mm. undergo incomplete rotation) • Limb adduction 6 RULE #2A: Ventral vs. dorsal limb mm. Developmentally-dorsal muscles: • Lie posterior to the long bones in anatomical position (* exceptions) Stern Essential of Gross Anatomy * Developmentally-ventral muscles: • Lie anterior to the long bones in anatomical position 7 Anterior Upper Limb Muscle Compartments Humerus ARM Posterior Anterior Radius FOREARM Ulnar Stern Essential of Gross Anatomy Posterior Anterior HAND 5th metacarpal 8 Anterior Humerus ARM Posterior Some posterior compartment mm. are found on the anterolateral aspect of the forearm (*brachioradialis, supinator) * Radius Anterior FOREARM Ulnar Stern Essential of Gross Anatomy Posterior No posterior compartment in the hand Anterior HAND 5th metacarpal 9 RULE #2B: Innervation of anterior vs. posterior compartment mm. Spinal nerve Dorsal primary ramus Ventral primary ramus (C5-T1) Anterior division Posterior division Stern Essential of Gross Anatomy limb axis 10 “Roots of BP” (=ventral rami) C5 C6 Brachial Plexus (right side; simplified) “Randy Travis Drinks Cold Beer” Trunks Divisions M Cord Terminal Branches C7 U Lat L C8 T1 Post Stern Essential of Gross Anatomy Med Anterior (ventral) division Posterior (dorsal) division 11 “Roots of BP” (=ventral rami) C5 C6 Brachial Plexus (right side; simplified) Trunks Divisions M Cord Terminal Branches Musculocutaneous n. C7 U Lat L C8 T1 Post Stern Essential of Gross Anatomy Med Median n. Radial n. Ulnar n. Anterior (ventral) division Posterior (dorsal) division 12 Anterior MOTOR INNERVATION Muscle Compartments of the Upper Limb Musculocutaneous n. Humerus Radial n. Posterior Anterior Median n. & Ulnar n. Radius Ulna Stern Essential of Gross Anatomy Radial n. Posterior Anterior Ulnar n. & Median n. 5th metacarpal Posterior Musculocutaneous Nerve (arm) All mm. in anterior (flexor) compartment of arm MRI of arm 1.Biceps brachii m. 2.Brachialis m. 3.Brachial a. 4.Humerus. 5.Triceps brachii m. www.med.umich.edu 14 http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3 Radial Nerve (arm) Radial nerve All mm. in posterior (extensor) compartment of arm BB B TLat TMed TLong 15 http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3 The brachialis m. is innervated by which division of the brachial plexus: : A. Anterior division B. Posterior division 50% 50% www.aokainc.com Anterior division Posterior division 16 The brachialis m. is innervated by: A. B. C. D. Median n. Musculocutaneous n. Radial n. Ulnar n. 25% 25% 25% 25% www.aokainc.com Median n. Musculocutaneous n. Radial n. Ulnar n. 17 The triceps brachii m. is innervated by: A. Musculocutaneous n. B. Radial n. 50% 50% Musculocutaneous n. Radial n. Radial Nerve (forearm) All mm. in posterior (extensor) compartment of forearm Also * brachioradialis and supinator mm. * 19 http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3 Ulnar Nerve (forearm) Limited mm. in anterior (flexor) compartment of forearm: - Flexor carpi ulnaris - Flexor digitorum profundus (medial ½) Med 1/2 20 http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3 Median Nerve (forearm) All anterior (flexor) compartment mm. of forearm except: - Flexor carpi ulnaris m. - Flexor digitorum profundus m. (med ½) en.wikipedia.org 21 http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3 RULE #2C www.acacpt.com 22 The extensor digitorum m. lies in the posterior compartment, originates on the lateral epicondyle, and is innervated by: A. Median n. Lateral epicondyle B. Musculocutaneous n. C. Radial n. Extensor digitorum m. D. Ulnar n. 25% 25% 25% 25% Median n. Musculocutaneous n. Radial n. Ulnar n. “Be specific” thepainsource.com 24 The flexor carpi radialis m. is in the anterior compartment, attaches to the medial epicondyle, and is innervated by: A. Median n. B. Radial n. C. Ulnar n. 33% 33% www.rad.washington.edu 33% Median n. Radial n. Ulnar n. 25 The flexor digitorum profundus m. is the anterior compartment, attaches to the medial epicondyle, and is innervated by: A. Median n. B. Median n. & Ulnar n. C. Ulnar n. 33% healthfavo.com 33% 33% Median n. Median n. & Ulnar n. Ulnar n. 26 The brachioradialis and supinator mm. lie in the anterior aspect of the forearm but attach to the lateral epicondyle of the humerus. They are innervated by: A. Median n. B. Radial n. C. Ulnar n. 33% 33% 33% www.pelhamrehab.com Median n. Radial n. Ulnar n. 27 Median Nerve (hand) Limited hand mm.: - Thenar mm. - Lateral two lumbricals www.studyblue.com 28 http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3 Ulnar Nerve (hand) cnx.org All hand mm. not innervated by median n. 29 http://emedicine.medscape.com/article/1877731-overview#aw2aab6b3 What about the most proximal muscles of the upper limb? medicine.academic.ru 30 RULE #2D Developmentally-dorsal muscles: •Lie posterior to the long bones in anatomical position (* exception = brachioradialis, supinator) -or•Arise from: – scapular blade ossification – vertebral column 31 Stern Essential of Gross Anatomy * Developmentally-ventral muscles: •Lie anterior to the long bones in anatomical position -or•Arise from: – coracoid ossification – sternum and costal cartilages Given the attachments of the latissimus dorsi muscle, its innervation will be from which of division of the brachial plexus: A. Anterior division B. Posterior division 50% 50% Anterior division Posterior division blog.corewalking.com 32 Brachial Plexus (branches) C5 C6 supraspinatus & infraspinatus mm. suprascapular n. C7 * C8 T1 Stern Essential of Gross Anatomy ** axillary n. upper subscapular n. thoracodorsal n. lower subscapular n. deltoid & teres minor mm. subscapularis m. latissimus dorsi m. subscapularis & teres major mm. Given the attachments of the pectoralis muscles muscle, its innervation will be from which of division of the brachial plexus: A. Anterior division B. Posterior division 50% 50% www.bnchiro.com Anterior division Posterior division 34 Brachial Plexus rhomboid mm. (branches) dorsal scapular n. C5 C6 suprascapular n. C7 * pectoralis mm. C8 lateral pectoral n. T1 musculoskeletal n. serratus anterior m. medial n. medial pectoral n. pectoralis mm. ** axillary n. ulnar n. radial n. upper subscapular n. thoracodorsal n. lower subscapular n. 35 Stern Essential of Gross Anatomy long thoracic n. posterior anterior RULE #3 Proximal-toDistal Rule Upper “roots” of the brachial plexus (C5-6 ventral rami) innervate proximal muscles (shoulder, elbow) Somatic motor nerve (GSE, with GSA) Cutaneous nerves (GSA, GVE, GVA) Lower “roots” of the brachial plexus (C8-T1 ventral rami) innervate distal muscles (hand) MYOTOME - group of muscles innervated by a single spinal nerve root sciartmag.blogspot.com 37 38 Dorsal scapular n. Brachial Plexus (all branches) C5 C6 Suprascapular n. C7 * C8 Lateral pectoral n. T1 Musculoskeletal n. Stern Essential of Gross Anatomy Long thoracic n. Medial n. ** Medial pectoral n. Upper & lower subscapular nn. Thoracodorsal n. Axillary n. Ulnar n. * Nerve to subclavius Radial n. ** Medial brachial & antebrachial cutaneous nn. 39 posterior anterior RULE #3 “MIXED FUNCTIONAL MODALITIES” Most terminal branches of the brachial plexus are mixed fiber nerves: 1. Somatic motor and somatic sensory (prioprioception) to skeletal mm. Somatic motor nerve (GSE, with GSA) Cutaneous nerves (GSA, GVE, GVA) 2. Then, cutaneous innervation with somatic sensory and sympathetics to skin Musculocutaneous n. Tank et al. Lippincott Williams & Wilkins Atlas of Anatomy 41 Some purely cutaneous brs. of brachial plexus Tank et al. Lippincott Williams & Wilkins Atlas of Anatomy 42 RULE #5: Dermatome vs. Cutaneous Nerve Distribution Segmental innervation (C5-T1) Dermatomes Segmental (Dermatome) Innervation of Upper Limb Foerster (1933) – based on clinical findings (used by neurologists) 44 Moore et al. Essential Clinical Anatomy Keegan and Garrett (1948) – based on limb development Segmental (Dermatome) Innervation of Upper Limb Preaxial: C5-C7 Postaxial: C8-T1 Thumb: C6 5th Digit: C8 45 Moore et al. Essential Clinical Anatomy 3rd Digit: C7 Dermatomes vs. Cutaneous Nerve Distribution Segmental innervation (C5-T1) Dermatomes Terminal branches Cutaneous nn. Peripheral (Cutaneous ) Innervation of Upper Limb Anterior Posterior Moore et al. Essential Clinical Anatomy 47 Test for Peripheral Nerve Sensory Function: M U R Ulnar n. – Tip of 5th digit (little finger) Median n. – Tip of 2nd digit (index finger) Radial n. – Webbing b/w thumb & index finger (dorsum) C7 M C8 U C6 R 49 Stretch Reflex Reciprocal inhibition of antagonist muscles apbrwww5.apsu.edu/ academic.scranton.edu Stretch Reflex Bicipital reflex (C6 cord level) Triceps reflex (C7 cord level) UPPER LIMB RADICULAR SYNDROMES IVD C4-C5 Root C5 Sensory Loss Shoulder Motor Weakness Shoulder weakness Cranial Caudal Proximal C5-C6 C6 Anterior upper arm, Lateral forearm, thumb Forearm flexion Biceps reflex C6-C7 C7 3rd digits Forearm extension Triceps reflex Wrist extension Hand grip C7-C8 C8 5th digits Medial forearm Wrist flexion Intrinsic hand mm. Source: Devinsky et al. Neurologic Pearls Distal