52 Questions
Which nerve innervates all the posterior forearm muscles?
Radial nerve
Which muscle is not part of the superficial layer of the posterior forearm muscles?
Supinator
Which structure forms the dorsal digital expansion in the posterior forearm?
Tendons of extensor muscles
Which of these muscles attaches to proximal lateral surface of radius?
Supinator
Which condition is caused by forceful and repeated bending of the wrist and fingers?
Medial epicondylitis
Which nerve is related to the anatomic snuff box?
Radial nerve
Which muscle does the deep branch of radial nerve travel under?
Supinator
Which movement is affected by radial nerve injury?
Extension of the wrist
Which aspect of the shoulder experiences sensory deficits due to radial nerve injury?
Lateral
Which of these muscle is mostly responsible for locking the elbow?
Aconeus
Which nerve innervates the superficial layer muscles of the posterior forearm?
Radial nerve
Which condition is caused by overstrain, overuse, or direct impact on the common extensor tendon?
Lateral epicondylitis
Which nerve innervates the thenar muscles of the hand?
Median nerve
Which muscle is not part of the hypothenar muscles of the hand?
Abductor pollicis brevis
Where do the dorsal interosseous muscles insert?
Dorsal digital expansion of the fingers
Which nerve innervates the hypothenar muscles of the hand?
Ulnar nerve
Where do the palmar interosseous muscles originate?
Anterior side of the metacarpals
Which muscle originates from the tendons of the flexor digitorum profundus of each finger?
Lumbricals
Which muscle is not part of the central group of intrinsic hand muscles?
Palmaris longus
Which part of the hand is innervated by the ulnar nerve?
Fingers (digits)
How many tendons does the carpal tunnel house?
9
Which of these groups of muscles are capable of doing the "Ta-Ta" movement"? (flexion of MCP + extension of PIP & DIP)
All of the above
What is the direction of the carpal arch, forming the carpal tunnel?
Anterior
Extensor carpi radialis and Flexor carpi radialis are synergists for _______ of the wrist
Which of the following muscles originate from the lateral supracondylar ridge of humerus?
Brachioradialis
Extensor carpi radialis brevis (ECRB) attaches to base of 2nd metacarpal
False
Both brachioradialis and ECRL originate from the ______
Extensor digiti minimi attaches to....
A & B
Dorsal digital expansions pull PIPs and DIPs into complete ________ (hint: Ta-Ta position)
Extensor carpi ulnaris attaches to base of _____ metacarpal
Where does the Aconeus muscle insert?
Olecranon process
Supinator originates from lateral epicondyle and the ________ ________ of the ulna
Abductor policis longus can extend the thumb at the CMC joint
True
Extensor policis brevis provides one of the tendons that forms the ______ border of the anatomical snuff box (hint: medial or lateral)
Extensor policis longus inserts onto......
Distal phalanx of digit 1
Which of these actions are carried out by Extensor policis longus?
All of the above
Extensor indicis originates from...
Proximal 1/3 of ulna
Abductor pollicis brevis originates from ....
All of the above
Abductor policis brevis and flexor policis brevis both insert onto the lateral side of the base of ________
Oponens policis inserts onto the first metacarpal
True
Palmar interosseous 1 originates from metacarpal 1
False
Palmar interosseous 2 inserts onto finger #_____
Lumbricals, Dorsal Interosseous, and Palmar interosseous all insert onto the dorsal digital expansions
True
Dorsal interosseous #2 inserts onto...
Lateral side of 3rd finger
Which of these groups is innervated by both the ulnar nerve and the median nerve?
Lumbricals
Oblique head of Adductor policis originates from....
All of the above
Both heads of Adductor Policis insert onto the ______ of the thumb
Which of these muscles originates from hook of hamate?
Flexor digiti minimi brevis
Both Flexor digiti minimi brevis and Opponens digiti minimi have the same origins
True
All of the hypothenar muscles act on the pinky
True
Both Opponens Pollicis and Flexor Pollicis brevis originate from the ______ and the trapezium
Which of these muscles originates from the pisiform?
Abductor digiti minimi
Study Notes
Posterior Forearm Muscles and Clinical Correlations
- Posterior forearm muscles are all innervated by the radial nerve and originate from C5, C6, C7, C8, and T1 roots.
- The superficial layer muscles include Brachioradialis (BR), Extensor Carpi Radialis Brevis (ECRB), Extensor Digitorum (ED), Flexor Carpi Radialis Longus (ECRL), Extensor Digiti Minimi (EDM), Extensor Carpi Ulnaris, and Anconeus.
- The deep layer includes Supinator, Abductor Pollicis Longus (APL), Extensor Pollicis Brevis (EPB), Extensor Pollicis Longus (EPL), and Extensor Indicis (EI).
- The dorsal digital expansion (extensor hood) is formed by extensor tendons, allowing them to work together and individually.
- Supinator originates from the supinator crest of the ulna and has two heads with a relationship with the deep branch of the radial nerve.
- Anatomic snuff box contains tendons of APL, EPB, and EPL and is related to the radial artery.
- Medial epicondylitis (golf elbow) is caused by forceful and repeated bending of the wrist and fingers, leading to tiny ruptures of the common flexor tendon.
- Lateral epicondylitis (tennis elbow) is caused by overstrain, overuse, or direct impact on the common extensor tendon.
- Radial nerve injury leads to damage to the posterior cord of the brachial plexus, affecting muscles such as deltoid, teres minor, triceps, and forearm muscles, resulting in weakness and sensory deficits.
- The clinical correlation of radial nerve injury includes weakness in abduction and external rotation of the shoulder, loss of extension in the elbow, wrist, and fingers, and sensory deficits in the lateral aspect of the shoulder and posterior forearm.
- The text provides detailed information about the origin, insertion, function, and innervation of each muscle and their clinical implications.
- The text emphasizes the importance of understanding the innervation and function of the posterior forearm muscles in clinical practice and the potential impact of nerve injuries on muscle function and sensation.
Anatomy and Function of Intrinsic Muscles of the Hand
- The hand is divided into three parts: wrist (carpus), hand proper (metacarpus), and fingers (digits)
- The long axis of the thumb has a 90° medial rotation to the rest of the fingers, resulting in movements of the thumb being at right angles to the movements of other fingers
- The carpal arch is directed anteriorly, forming the carpal tunnel via attachment of the flexor retinaculum to its sides
- The carpal tunnel houses 9 tendons (4 FDS, 4 FDP, 1 FPL) and the median nerve, and an enlargement can lead to carpal tunnel syndrome
- The flexor carpi radialis tendon does not pass through the carpal tunnel, only the flexor retinaculum
- The intrinsic muscles of the hand consist of the thenar, hypothenar, and central muscles
- The thenar muscles, innervated by the median nerve, include the abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis
- The hypothenar muscles, innervated by the ulnar nerve, consist of the abductor digiti minimi, flexor digiti minimi brevis manus, and opponens digiti minimi
- The central group of intrinsic hand muscles includes the adductor pollicis, lumbricals, dorsal interosseous muscles, and palmar interosseous muscles
- The lumbricals originate from the tendons of the flexor digitorum profundus of each finger and insert into the dorsal digital expansion of the medial fingers
- The dorsal interosseous muscles originate from the metacarpals and insert into the base of the proximal phalanges and dorsal digital expansion of the fingers
- The palmar interosseous muscles originate from the anterior side of the metacarpals and insert into the base of the proximal phalanges and dorsal digital expansion of the fingers, facilitating flexion, extension, and adduction of the fingers
Test your knowledge of posterior forearm muscles and intrinsic hand muscles with this anatomy and clinical correlations quiz. Explore the innervation, function, and clinical implications of these important muscle groups.
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