Forearm and Wrist Anatomy PDF

©  The Forearm and Wrist Dr. Sean McWatt, PhD [email protected] The Anatomy Lesson of Dr. Nicolaes Tulp – Rembrandt, 1632 Learning Outcomes By the end of this lesson, you will be able to… Identify and describe the...

©  The Forearm and Wrist Dr. Sean McWatt, PhD [email protected] The Anatomy Lesson of Dr. Nicolaes Tulp – Rembrandt, 1632 Learning Outcomes By the end of this lesson, you will be able to… Identify and describe the bones and joints related to the wrist and hand, and explain the basic movements that occur at the wrist Identify the muscles of the forearm, and describe their innervations and functions Predict functional implications of musculoskeletal injuries to the forearm and wrist regions Regions of the Upper Limb Deltoid region Shoulder Scapular region Arm Anterior and posterior compartments Axillary region Armpit Cubital fossa Elbow We will run through the anatomy of the upper limb according to these regions, Forearm from proximal to distal. Anterior and posterior compartments Carpal region Wrist Dorsal Palmar Back Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Posterior view © 2010, Icon Learning Systems, LLC. A subsidiary of MediMedia, USA, Inc. All right reserved Bones of the Upper Limb Clavicle Sternoclavicular joint Shoulder joint Scapula Humerus The carpal bones fill the space between the radius and ulna, proximally, and the Elbow joint metacarpals, distally, to form the wrist joint that distinguishes the forearm from the hand. Radius Ulna Wrist joint Carpal bones Bones of the hand and digits Anterior view Posterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Bones, Joints, and Ligaments  Ulna Osteology Radius ‘Dinner fork deformity’ Head of the ulna Distal radius Anterior view fracture At the distal end of the forearm, the head of the ulna articulates Styloid with the radius, enabling processes pronation and supination. Styloid process fractures are Posterior view common, especially of the radius. Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Radioulnar Joints Proximal radioulnar joint Annular ligament Superior view of radius Supination Pronation Interosseous membrane The anterior/palmar and Inferior view posterior/dorsal radioulnar ligaments Radioulnar hold the head of the ulna against the ligaments radius to support the distal radioulnar Distal radioulnar joint Anterior and posterior joint during pronation and supination. Anterior views Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Interosseus Membrane The interosseus membrane holds the radius and ulna together, Interosseous enabling them to serve as membrane a single unit: the forearm. …then from the Small amount It is vital for force of force ulna to the transfer from the hand to transmitted humerus, etc. from radius to be spread between the humerus Most of the force radius and ulna and into transmitted from the humerus. radius to the ulna Force via the interosseus transmitted membrane… from hand to radius Anterior views Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Bones of the Upper Limb Clavicle Sternoclavicular joint D D Shoulder joint M Scapula P P D Phalanges No middle Humerus P phalanx III Metacarpals Elbow joint Carpal bones Radius Ulna Anterior view Wrist joint Carpal bones The wrist consists of the carpal bones, whereas the hand is made up of the Bones of the metacarpals and phalanges. hand and digits Anterior view Posterior view Note, the thumb has no middle phalanx. Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Wrist and Hand Bones Articular disc Ulnocarpal disc Radiocarpal Radius joint D D Scaphoid fracture Phalanges M P P There are eight carpal Scaphoid So P D bones that articulate at Lunate Long III P No middle phalanx III intercarpal joints. Triquetrum To Pisiform Pinky Metacarpals These bones make up the Hamate Here Carpals wrist and carpal tunnel, Capitate Comes Articulating at through which structures Trapezoid The intercarpal joints cross into the hand. Trapezium Thumb Articular disc Ulnocarpal disc Anterior view Posterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Wrist Ligaments While the radioulnar ligaments stabilize the radioulnar joint, the carpal bones and wrist joint are stabilized by the radial and ulnar collateral ligaments of the wrist, the radiocarpal and ulnocarpal ligaments, and Intercarpal the intercarpal ligaments. ligaments Anterior and posterior Ulnar collateral Radioulnar Radiocarpal ligaments ligament …of the wrist ligaments Anterior and Anterior and posterior posterior Ulnocarpal ligament Radial collateral ligament Posterior view (right) Anterior view (right) …of the wrist Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Hand Joints Osteoarthritis (OA) usually I DIP, you PIP, we IP occurs here and here Distal interphalangeal joints (DIP) Proximal interphalangeal joints Rheumatoid (PIP) arthritis (RA) usually occurs here and here Metacarpophalangeal joints “Da’ Dip” by Freak Nasty (1996) (MCP) Carpometacarpal Since many muscles of the forearm joints act on the digits, we need to discuss (CM) these joints now; however, we will look at them and their ligaments more closely in the hand lecture. Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Muscles of the Forearm NOTE! I have given you very detailed information about the muscles’ attachments. These are there for your reference and explanation purposes, but you do not need memorize them. You will find a muscle chart at the end of the lecture with the detail that you are expected to know. Compartments of the Forearm Posterior compartment Muscles of the extensor/supinator compartment Fascia Interosseus that are innervated by the radial n. and its branches Containing forearm membrane muscles Anterior compartment Muscles of the flexor/pronator compartment that are innervated by the median n. and ulnar n. Anterior view Remember, the radial n. is derived from the posterior cord, whereas the median n. and ulnar n. are branches of cords derived from anterior Transverse view (inferior) divisions of the brachial plexus. Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Superficial Anterior Muscles Superficial Layer Pronator teres m. Common head of Medial Origin: epicondyle Medial epicondyle (CFO) wrist flexors Common origin: of the humerus Insertion: Medial epicondyle Shaft of radius (CFO) ‘CFO’ Common Innervation: flexor origin Median n. (C5–T1) Pronator teres acts on the radius to serve as the primary pronator of the forearm. It shares a common origin on the medial epicondyle of the humerus with the superficial and intermediate muscles of the anterior (flexor) compartment of the forearm. Anterior view Anterior view (pronated) Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins Superficial Anterior Muscles Do you have one? Palmaris longus m. Origin: Flexor carpi radialis m. Origin: Innervation: Flexor carpi Medial epicondyle (CFO) Flexor carpi radialis m. Median n. ulnaris m. Insertion: Medial epicondyle (CFO) Insertion: (C5–T1) Palmar aponeurosis 2 metacarpal nd Innervation: Median n. (C5–T1) Flexor carpi ulnaris m. Origin: Palmaris longus, Medial epicondyle (CFO) Innervation: Ulnar n. flexor carpi radials, and Insertion: 5 metacarpal th (C8–T1) flexor carpi ulnaris all contribute to flexion of the hand at the wrist. Flexor carpi radials also contributes to abduction, © Kate Murphy while flexor carpi ulnaris contributes to adduction of Palmaris longus m., the hand at the wrist. is absent in ~10% of individuals. Anterior view Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins Intermediate Anterior Muscle Flexor digitorum superficialis m. Flexor digitorum Origin: superficialis inserts onto the Medial epicondyle (CFO), radius middle phalanges. So, as its Insertion: name suggests, it Middle phalanges contributes to flexion of the Innervation: Median n. digits at each proximal joint (C5–T1) it crosses, as well as flexion of the hand at the wrist. Its tendons have a http://tiny.c c/et95dz characteristic ‘forked tongue’ split to allow deeper tendons to reach the distal phalanges. Anterior view Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins Deep Anterior Muscles Median n. https://tinyurl.com/y58y6 mz9 Flexor digitorum profundus m. The flexor digitorum Origin: Ulna, interosseus membrane profundus tendons insert Insertion: Distal phalanges onto the distal phalanges and, therefore, cause Innervation: Medial view Tendon of flexor flexion at every joint digitorum superficialis m. Ulnar n. (C8–T1) Median n. (C5–T1) proximal to the fingertips. Cut Its medial half is innervated by the ulnar n. and its Flexor pollicis longus m. Origin: lateral half is innervated Radius, interosseus membrane Ulnar n. Insertion: by the median n. Distal phalanx of thumb Innervation: Flexor pollicis longus is Anterior interosseous n. the equivalent of a flexor (Median n. – C5–T1) digitorum longus for the thumb. Anterior view Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins Deep Anterior Muscles Pronator quadratus m. Pronator Origin: Ulna teres m. Insertion: Radius Innervation: Anterior interosseous n. (Median n. – C5–T1) The bracelet-like pronator quadratus assists pronator teres in pronation of the forearm by acting on the distal end of the radius. Anterior views Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins Rotation of the Hand Shoulder joint? Medial/lateral rotation Where is the rotation occurring? Forearm? Pronation/supination Lateral rotation Have the patient lock their elbow to isolate rotation at the shoulder from Medial rotation pronation and supination of the forearm Anterior view Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Anterior Neurovasculature Brachial a. Ulnar n. Entering the cubital tunnel Ulnar a. Median n. Pierces pronator teres m. Posterior interosseous a. We’ll see this later… Radial a. Anterior interosseous n. Anterior view Median n. Ulnar a. The muscles of the Continued Continued anterior compartment of the forearm are Ulnar n. Palmar arches Flexor Continued innervated by the retinaculum https://tinyurl.com/y6au3f5x median and ulnar nn. Anterior views Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone The Carpal Tunnel Carpal tunnel release surgery http://tiny.cc/d7b9dz Ulnar n. and a. In the ulnar canal Flexor Carpal tunnel syndrome retinaculum Anterior view Median n. Tendons Together, the median n. For flexion of the digits and tendons of the Ulnar canal muscles that flex the Carpal tunnel digits pass through Synovial sheaths the carpal tunnel, which Ouch! is contained by the flexor retinaculum. Anterior view Gilroy, Anatomy: An Essential Textbook, Copyright © 2013 by Thieme Transverse views Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 by Lippincott Williams and Wilkins  Superficial Posterior Muscles Anconeus m. The muscles of the posterior compartment of the Origin: Lateral epicondyle forearm are innervated by the radial n. and its branches. (CEO) Insertion: Lateral Ulna The superficial muscles of the posterior epicondyle Innervation: of the humerus Radial n. (extensor) compartment of the forearm (C5–T1) ‘CEO’ (except for brachioradialis) all originate on Common the lateral epicondyle of the humerus. extensor origin Brachioradialis m. Extensor Origin: Common head of retinaculum Distal humerus Insertion: wrist extensors Styloid process of radius Origin: Lateral epicondyle Lateral view (left) (CEO) Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Innervation: Copyright © 2013 by Lippincott Williams and Wilkins Radial n. (C5–T1) Anconeus and brachioradialis are the only ones that don’t cross the wrist and, therefore, only contribute to extension and Anterior view flexion at the elbow, respectively. Posterior view Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Superficial Posterior Muscles Flexion Extensor carpi ulnaris m. Origin: Lateral epicondyle (CEO) Insertion: Extensor carpi Abduction Flexor carpi radialis longus m. Adduction 5 metacarpal th ulnaris m. Inferior view Origin: …of radius and ulna **Simplification** Innervation: Lateral epicondyle (CEO) Obviously Posterior Insertion: interosseus n. 2 metacarpal nd Flexor carpi (Radial n.; C5–T1) radialis m. Extension Extensor carpi radialis brevis m. The extensor carpi radialis longus, extensor carpi Origin: radialis brevis, and extensor carpi ulnaris all Lateral epicondyle (CEO) Insertion: contribute to extension of the hand at the wrist. 3rd metacarpal extensor carpi radialis longus and extensor Innervation: Radial n. carpi radialis brevis work with the flexor (C5–T1) carpi radialis to abduct the hand at the wrist. Conversely, extensor carpi ulnaris works with flexor carpi ulnaris to adduct the wrist. Posterior view Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Superficial Posterior Muscles Extensor digitorum, attaches on the extensor Extensor digitorum m. Origin: expansions of digits 2–5 and contributes to Lateral epicondyle (CEO) Extensor extension at all proximal joints. expansion Insertion: Digits 2–5 Aponeurosis Innervation: Posterior interosseus n. (Radial n. – C5–T1) Specialized extensors of the index and ‘pinky’ fingers allow for finer Posterior view Medial view movements (e.g., extensor digiti Extensor digiti minimi m. Origin: minimi extends Lateral epicondyle (CEO) the 5th digit Insertion: Digit 5 independently). Posterior view Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Copyright © 2013 Posterior view by Lippincott Williams and Wilkins Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Deep Posterior Muscles Biceps brachii m. Supinator m. Transverse view Origin: https://tinyurl.com/yxfllb5s Lateral epicondyle (CEO), ulna Insertion: Radius Innervation: Radial n. Supinator m. (C5–T1) The supinator m. works with the biceps brachii m. to rotate the radius and uncross it from the ulna (i.e., supination of the forearm). This brings the hand from a pronated position into a supinated position (like holding a bowl of soup). Posterior view Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Deep Posterior Muscles Extensor pollicis longus m. Origin: Extensor pollicis longus and extensor Ulna, interosseous membrane Insertion: pollicis brevis extend the thumb and Distal phalanx of thumb assist with extension of the hand at the wrist. Abductor pollicis longus will Extensor pollicis brevis m. Origin: abduct the thumb, as well as assist in Radius, interosseous membrane Insertion: abduction of the hand at the wrist. Proximal phalanx of thumb Dorsal tubercle Abductor pollicis longus m. of radius The Extensor pollicis longus and Origin: extensor pollicis brevis border the Ulna, radius, interosseous membrane Insertion: ‘anatomical snuff box’, which is a 1st metacarpal Anatomical ‘snuff box’ landmark for the radial a. and superficial branch of the radial n. Extensor indices m. Origin: Ulna, interosseous membrane Insertion: The extensor indices m. extends the Digit 2 2nd digit independently and assists Innervation: with extension of the hand at the wrist. Posterior interosseus n. (Radial n.; C5–T1) Posterior view Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Posterior Neurovasculature Radial n. Deep branch Posterior of radial n. interosseous a. and n. Piercing supinator m. How would you test paralysis of the radial n. versus paralysis of the posterior interosseus n.? Superficial branch of radial n. Running deep to Wrist drop brachioradialis m. Posterior view to eventually provide cutaneous innervation to the dorsum of The posterior compartment of the the hand forearm is entirely innervated by Anatomical the radial n. and its branches, the ‘snuff box’ Location for deep branch of the radial n. and radial a. pulse the posterior interosseus n. Lateral view Agur and Dalley, Grant’s Atlas of Anatomy, 13th Ed. Anterior view Copyright © 2013 by Lippincott Williams and Wilkins Drake, Gray’s Anatomy for Students, 2nd Ed., Copyright © 2009 by Churchill Livingstone Lecture 3: Simplified Muscle Chart Attachments Muscle Group Muscle Origin Insertion Main action(s) Innervation Pronator teres Medial epicondyle Pronators Radius Pronation Median n. Anterior compartment Pronator quadratus Ulna Flexor carpi radialis Lateral metacarpal Flexion, abduction (wrist) Median n. Wrist flexors Palmaris longus Medial epicondyle Palmar aponeurosis Flexion (wrist) Flexor carpi ulnaris Metacarpal Flexion, adduction (wrist) Ulnar n. Flexor digitorum superficialis Medial epicondyle Middle phalanges Median n Finger flexion Digit flexors Flexor digitorum profundus Ulna Distal phalanges ½ Median n., ½ ulnar n. Also act at wrist Flexor pollicis longus Radius Distal phalanx Thumb flexion Median n. Supinators Supinator Lateral epicondyle Radius Supination (w/biceps brachii) Radial n. Extensor carpi radialis longus Extension, abduction (wrist) Wrist extensors Extensor carpi radialis brevis Lateral epicondyle Metacarpals Radial n. Posterior compartment Extensor carpi ulnaris Extension, adduction (wrist) Extensor digitorum Digits 2–5 Finger extension Lateral epicondyle Extensor digiti minimi Digit 5 Extension (5th digit) Extensor pollicis longus Ulna Distal phalanx Digit extensors Thumb extension Radial n. Also act at wrist Extensor pollicis brevis Radius Proximal phalanx Abductor pollicis Ulna, radius Metacarpal Thumb abduction Extensor indices Ulna Digit 2 Extension (2nd digit) Anconeus Lateral epicondyle Ulna Extension (elbow) Other Radial n. Brachioradialis Humerus Distal radius Flexion (elbow) Learning Outcomes By now, you should better understand how to… Identify and describe the bones and joints related to the wrist and hand, and explain the basic movements that occur at the wrist Identify the muscles of the forearm, and describe their innervations and functions Predict functional implications of musculoskeletal injuries to the forearm and wrist regions  © [email protected]