Anterior compartment of the forearm and hand

Question 1

why is the anterior compartment of the forearm usually considered a flexor compartment

Answer 1

b/c the majority of its muscular components flex the wrist and fibers. a few muscles are pronators. extend the study to the hand to fowwlow tendon and neuromuscular structures to the fibers and study under the palm

Question 2

muscles: anterior compartment: three layers

Answer 2

superficial, intermediate, deep layer of muscles

Question 3

muscles: anterior compartment: superficial layer

Answer 3

all the muscles in this layer
origin: from the anterior surface of the medial epicondyle
innervation: branches of median nerve
arranged from lateral to medial are: pronator trees, flexor carpi radials, palmaris longus, flexor carpi ulnaris

Question 4

pronator teres

Answer 4

(most lateral) short, obliquely directed fibers from their medial origin to their fleshy insertion to the middle of the shaft of the radius. primarily a pronator, also helps in flexing the forearm

Question 5

flexor carpi radialis

Answer 5

from its medial origin, it veers towards a lateral position in the forearm; its tendon passes through the carpal tunnel to be inserted to the bases of the 2nd and 3rd metacarpal bones. although primarily a flexor of the wrist it helps in its abduction. demonstrate

Question 6

palmaris longus

Answer 6

occasionally absent, it is a thin, short strip of muscle fibers ending into a long tendon positioned at the middle of the forearm extending distally to the wrist where it passes over the flexor retinaculum to be attached to the proximal part of the deep fascia of the palm. aids in flexing the wrist and as synergist in flexing the metacarpopharalangeal joints b/c will pass over the carpal tunnel and continuos with the palmar aponeurosis

Question 7

flexor carpi ulnaris

Answer 7

most medial muscle.
origin - proximal end of ulna.
its almost vertical fibers becomes a tendon attached to the pisiform bone but extending to the base of the 5th metacarpal bone. it is the only muscle of the group INNERVATED by ulnar nerve. primarily a flexor of the wrist. it helps in adducting the hand (wrist)

Question 8

Intermediate layer

Answer 8

only one fleshy muscle

Question 9

flexor digitorum superficial

Answer 9

with origins from the medial epicondyle, coronoid process of the ulna and upper 2/3 of the anterior border of radius
innervation: median nerve
insertions of the tendons enable them to flex the first phalangeal and metacarpophalangeal joints of the corresponding fingers
fibers form 2 tendons, which pass through the carpal tunnel (covered by synovial sheathes), and into the palm where each tendon further subdivides into two, resulting into 4 tendons that split terminally to insert at the sides of the middle phalanx of each of the 4 medial digits. little finger not provided with a tendon from this muscle

Question 10

deep layer of muscles

Answer 10

all innervated by the deep or intercostal branch of the median nerve

Question 11

flexor digitorum profundus

Answer 11

a fleshy muscle from the anterior surface of the middle thirds of the ulna and the interosseous membrane
the muscle forms 4 tendons that pass through the carpal tunnel and are positioned deep to the tendons of the superficialis to pass through their split tendons to their insertions at the tips of the distal phalanges of the medial 4 fingers.
the tendons of both superficial and deep flexors are reinforced at their attachments by short and long fibrous extensions to the bones “vincula tendinae”
medial 2 fascicles of this muscle are innervated by ulnar nerve. inserted to the 4th and 5th fingers
these two floors can curl the fingers to grip an object held on the palm or to make a fist which involve flexing the interphalangeal and metacarpo-phalangeal joints

Question 12

flexor pollicis longus

Answer 12

attached to the anterior surface of the middle third of the radial shaft. the fibers form a single tendon which passes through the carpal tunnel, turning laterally to be inserted at the base of the distal phalanx of the thumb (pollex).
innervation deep branch of the median nerve, the muscle flexes the distal phalanx and helps in flexing the metacarpophalangeal joint to point thumb medially

Question 13

pronator quadratus

Answer 13

deepest muscle at the distal part of the forearm. it is a thin quadrilateral muscle with transverse fibers attached to the distal 4th of both the ulna and radius. also innervated by the velar interosseous nerve, the fibers pull on the lateral side of radius towards ulna to rotate the forearm and hand, putting them in the pronate (palm faces downwards) position

Question 14

median nerve: anterior compartment

Answer 14

leaves cubital fossa by penetrating deep to the pronator trees and the gap between the origins of the flexor digitorum superficalis. it courses down the middle of the forearm in the deep fascia covering the posterior surface of the flexor digit. superficial is. at the wrist, it assumes a more superficial position as it emerges between the tendons of the flexors, passing through the carpal tunnel to enter the palm. pressure on the nerve in the tunnel produces a “carpal tunnel syndrome”

Question 15

ulnar nerve

Answer 15

enters the anterior compartment between the origins of the flexor carpi ulnaris. it then proceeds distally deep to this muscle enveloped in a fashical sheath with the ulna vessels. at the wrist , the nerve and vessels surface close and lateral to the pisiform bone its terminal branches are distributed in the palm

Question 16

radial artery first part

Answer 16

from its commencement at the level of the neck of the radius, it courses almost vertically along the lateral side proximally covered by the brachioradialis muscle. it surfaces at the distal half of the forearm and at the wrist, it lies close to the lateral border of the tendon of the flexor carpi radials where its pulsations are easily and commonly palpated

Question 17

radial artery second part

Answer 17

from the tip of the styloid process of the radius, it turns around the trapezium and lies at the base of the thumb between the tendons of the deep muscles of the posterior compartment, where it passes in a shallow depression when the thumb is hyperextended backward- archaically called “anatomical snuff box” the radial pulse may also be felt here. the artery continues to curve around the base of the first metacarpal bone to penetrate between the fibers of the first dorsal interossesous and adductor pollicis muscles to enter the palm

Question 18

radial artery third part

Answer 18

from the point of entry into the palm, it curves laterally as the “deep palmar arch” joind by the deep branch of ulnar artery

Question 19

branches: radial recurrent artery

Answer 19

given off cubital fossa. it anastomoses with the anterior branch of the profunda brachia in front of lateral epicondyle

Question 20

superficial palmar branch

Answer 20

slender and inconstant, given off above the wrist. it passes through the thenar muscle to merge superficially in the palm and anastomose with the end of the ulnar artery thus completing the “superficial palmar arch”

Question 21

anterior and posterior carpal arteries

Answer 21

slender vessels which course superficially on the corresponding surfaces of the wrist, anastomosing with similar branches of the ulnar artery with which they form the carpal arches

Question 22

muscle and nutrient arteries

Answer 22

latter penetrating the radius

Question 23

princeps pollicis artery

Answer 23

given off as the radial artery and winds around the base of the thumb. it supplies the dorsum of the thumb

Question 24

dorsalis indicis

Answer 24

branch second part supplying the dorsum of index finger

Question 25

ulnar artery

Answer 25

runs obliquely medially from its cubital origin courses deep to the flexor digitorum superficial is and on the anterior surface of the flexor digitorum profundus, bound by a common fascial sheath with the accompanying vein and nerve

Question 26

ulnar recurrent arteries

Answer 26

which anastamose with the ulnar collateral branches of the brachial artery in front and behind the medial epicondyle

Question 27

ulnar recurrent arteries

Answer 27

which anastamose with the ulnar collateral branches of the brachial artery in front and behind the medial epicondyle

Question 28

common interosseous artery

Answer 28

short, small stem given off near the origin of the ulnar artery. its “anterior and posterior interosseous” branches course on the corresponding surfaces of the interosseous membrane

Question 29

carpal branches

Answer 29

forming with those branches from the deep palmar branch with radial artery

Question 30

course ulnar artery

Answer 30

ulnar artery then passes at the lateral side of the pisiform bone were it is protected by the velar carpal ligament with its accompanying vein and nerve. upon entering the palm beneath the palmar aponeurosis it gives off its deep branch which courses laterally to meet the end of the radial artery to form the deep velar arch while the parent trunk continues superficially to anastomose with the superficial palmar branch of the radial artery to form the superficial palmar arch

Question 31

palmar aponeuorisis

Answer 31

triangular shape
glistening appearance and tough
continuos proximally with flexor retinaculum
distally it divides into fibrous slips that join the tendon sheaths of the four medial fingers extending to the dorsal extensors
verify the insertion of palmaris longs and occasional presence of a small “palmaris brevis” over the hypothenar eminence, directed horizontally and medially

Question 32

cutaneous nerves and blood vessels palm of the hand

Answer 32

branches of the median nerve are distributed to the skin of the lateral 2/3 of the palm and the muscles of the thenar eminence. its terminal digital banshees corse the sides of the lateral 3 fingers and on the lateral side of the 4th finger, accompanied by the digital branches from the superficial and deep palmar arches and their vena comitantes
The ulnar nerve distributes branches to the ,uscles of the hypothenar eminence and digital branches to the medial side of the pal,; and both sides of the 5th finger and the medial side of the 4th finger with the corresponding vessels

Question 33

superficial palmar muscles?: those that form the thenar eminence at the lateral proximal part of the palm

Answer 33

abductor pollicis brevis, flexor pollicis brevis, opponens pollicis

Question 34

abductor pollicis brevis

Answer 34

most lateral superifical muscle of the thumb, attached to the scaphoid bone proximally and to the lateral side of the base of the first phalanx, distally

Question 35

flexor pollicis brevis

Answer 35

slightly deeper and medial to the abductor, arises superficially from the flexor retinaculum, scaphoid and trapezium. slender tendon is inserted to the lateral side of the base of the first phalanx

Question 36

opponens pollicis

Answer 36

lies deep to the above muscles, originating from scaphoid and trapezium and interested to anterolateral surface of the first metacarpal. medially rotates the bone

Question 37

superficial palmar muscles?: those that form the hypothenar eminence at the medial side of the palm

Answer 37

abductor digiti quinti minimi, flexor digiti qunti minimi, opponens digit quinti miinimi

Question 38

abductor digiti quinti minimi

Answer 38

lies superficially at the medial border of the palm. it arises from the pisiform bone and inserts at the base of the proximal phalanx of the little finger

Question 39

flexor digiti quinti minimi

Answer 39

lateral and deep to the abductor it arises from the hook of the ham mate and its small tendon inserts adjacent to that of the abductor

Question 40

opponens digiti quinti minimi

Answer 40

deepest arises also from the hook of the hammate and its small tendon inserts adjacent to that of the abuctor

Question 41

deep structures in the middle of the palm: tendons of the long flexors from the forearm

Answer 41

4 tendons of the flexor digitorum superficialis. follow the tendons of the 3rd and 4th fingers to their split insertions at the sides of the 2nd phalanx of each finger
4 tendons of the flexor digitorum profundues lie deep to the superficial is. observe their position between the split tendons of the superficial is to be inserted at the tip of the distal phalanx of each finger
verify presece of synovial sheaths for these tendons in the palm, and the vincula tendinae at their insertions

Question 42

lumbrical muscles

Answer 42

these are four thin short muscular slips rising form the tendons of the flexor digitorum profundus the slender tendons from each lumbrical twist around the proximal end of the corresponding phalanx to be inserted with the extensor tendons at the dorsal surfaces of the 4 medial phalanges. the two lateral lumbricals are innervated by the median nerve; while the two medial by the ulnar nerve. they assis in flexing and extending the metacarpophalangeal joints adjusting the position of the fingers to the desired degree

Question 43

adductor pollicis

Answer 43

short triangular muscle deep to the flexor tendons and lumbricals. its fibers are directed from their 2nd and 3rd metacarpal origins towards their insertion at the base of the proximal phalanx of the thumb
innervation - ulnar nerve

Question 44

interosseous muscles

Answer 44

deepest two sets - palmar and dorsal both located between the metacarpal bones
the 3 palmar interossei are found in each of the inter meta carpal spaces from the second to the 4th
4 dorsal better seen during dissection of the dorsum of the hand
their slender tendons join corresponding expansions of the extensor tendons at the dorsum of the bases of the proximal phalanges
innervation ulnar nerve, the planar interossei are adductors while the dorsal are abductors of the fingers which are movements towards or away from the 3rd finger respectively. they also help in flexion and extension movements. it is claimed that with the lumbricals, they prevent jerking motions of the fingers so that with proper training, controlled and correlated movements of the fingers are managed with developed skills ex typing

Question 45

muscles of the forearm flex the interphalangeal joints

Answer 45

?

Question 46

nerve affected if numbness is felt in the 5th finger

Answer 46

?

Question 47

nerve affected numbness if the 3 lateral fingers can’t be flexed

Answer 47

?

Question 48

demonstrate adduction and abduction of fingers and state muscles and nerve supply involved

Answer 48

?

Question 49

functional and clinical significance of carpal tunnel

Answer 49

?

Question 50

proximal row of carpal bones are arranged from medial to lateral as follows

Answer 50

?

Question 51

only muscle in the anterior compartment inserted to one o the carpal bones

Answer 51

?

Question 52

ulnar neve does not innervate one of these muscles

Answer 52

?

Question 53

which of these veins may not be radily accessible for intravenous injections

Answer 53

?

Question 54

muscles comprise the thenar eminence

Answer 54

?

Question 55

inability to extend fingers

Answer 55

?

Question 56

inability to flex the forearm

Answer 56

?

Question 57

numbness at the tips of the lateral fingers

Answer 57

?

Question 58

inability to adduct the thumb

Answer 58

?

Question 59

inability to pronate the forearm

Answer 59

?

Question 60

Posterior compartment of forarm

Answer 60

general extensor action of most of the muscles in the compartment which are arranged as two laters: superficial and deep - all of which are innovated by the deep branch of the radial nerve (or dorsal interosseous). three of the deep muscles have other particular actions aside from extension of the wrist and fingers

Question 61

superficial group of muscles?

Answer 61

brachioradialis, extensor carpi radialis, extensor digitorum communis, extensor carpi ulnaris
innervated by posterior interosseous or deep branch of radial nerve which enters the posterior compartment by piercing the supinator muscle.

Question 62

brachioradialis

Answer 62

fleshy, superficial muscle at the lateral border of the forearm. the tapering fibers incline anterior laterally; and halfway down the forearm they form a tendon which occupies a more anterior than lateral position. the tendon is inserted to the base of the styloid process of the radius although it is classified as a posterior compartment muscle innervated by the radial nerve the muscle acts as a strong flexor of the elbow especially when the forearm is semi flexed and semi prone. also aids in pronation and supination movements.

Question 63

extensor carpi radialis

Answer 63

longus and brevis.
these two muscles are partially covered at their organs by their brachioradialis; their tendons emerge halfway down the lateral border of the radius and their tendons are crossed over by the tendons of the deep muscles just above the wrist.
then tendon of the ext carpi radials longs is more superficial (ex. lateral); inserted at the base of the 2nd metacarpal, while that of the brevis is deeper and inserted to the 3rd metacarpal.
aside from being extensors of the wrist these 2 muscles abduct the wrist and may help in flexing the elbow if the forearm is halfway between supination and pronation

Question 64

extensor digitorum communis

Answer 64

positioned in the middle of the dorsum of the forearm it has a wide fleshy belly that constricts distally to form 4 tendons which cross over the back of the wrist and with their synovial sheaths are held in place by the dorsal carpal ligament.
at the back of the hand those tendons spread out to their insertions at the middle and distal phalanges of the 4 medial fingers
at the metacarpophalangeal level, they intertwine and are joined by the tendons of the lumbricals and interosseous muscles
most medial small slip of muscle and tendon may be differentiated as extensor digit minimi

Question 65

extensor carpi ulnaris

Answer 65

most medial muscle in this group. has an additional origin from the posterior border of the ulna adjacent to anconeus muscle. at the medial border of the forearm, it should be differentiated from the adjacent flexor carpi ulnaris. their tendons are close to each other at their insertions to the base of the 5th metacarpal
although their actions are primarily opposed, they are synergistic when adducting the hand

Question 66

deep group of muscle

Answer 66

may be exposed by separating the lateral carpal extensors from the extensor digitorum communes muscle. have obliquely disposed fibers arranged in descending order as follows:suppinator, abductor pollicis longs, extensor pollicis brevis, extensor pollicis longus, extensor indices proprius,

Question 67

supinator

Answer 67

highest placed of the deep group. its fivers originate below the radial notch of ulna. its inserted fibers wrap around the proximal third of the radius observe the deep radial nerve as it pierces this muscle to gain access to the posterior compartment of forearm

Question 68

abductor pollicis longus

Answer 68

slender muscle with a wide origin at about the middle of the dorsal surfaces of both the radius and ulna including the adjacent interosseous membrane. its tendon is closely bound by a fascial sheath with the smaller interior (distal) tendon of the extensor pollicis brevis; as both tendons cross over the tendons of the carpal extensors

Question 69

extensor pollicis brevis -

Answer 69

arises immediately distal to the radial origin of the abductor pollicis longus. the tendons of these two muscles are both inserted to the base of the first metacarpal

Question 70

extensor pollicis longus

Answer 70

distinct and separate from the brevis , originates from the middle of the shaft of the ulna immediately distal to the area occupied by the abductor pollicis longus: also with additional fibers from the interosseous membrane
its tendon occupies the groove lateral to the dorsal tubercle at the distal end radius before crossing the dorsal surface of the carpal bones and the tendons of the carpal extensors. it is inserted at the base of the distal phalanx of the thumb. constitutes the medial boundary of the anatomical snuff box

Question 71

extensor indicis proprius

Answer 71

the lowest, most distal muscle , originating form the distal end of the ulna adjacent to the origin of the long extensor of the thumb. it is short muscle with a long slender tendon lying along the medial side of the tendon of the common extensor tendon to the index finger with which it inserts to the dorsum of its distal phalanx

Question 72

blood supply deep muscles posterior compartment

Answer 72

single posterior interosseous branch of the common iterosseous trunk of the ulnar artery. small auxiliary arteries come from the radial and ulnar arteries

Question 73

deep branch of radial nerve

Answer 73

composed mainly motor fibers. sensory fibers included i the superficial branch given off at cubital region. distal fourth of forearm, superficial branch separates from the radial artery to cross over the lateral border of the wrist and distributes its branches at the dorsum of hand, extending to the back of the proximal phalanges of the lateral 4 fingers. radial nerve also gives off a posterior cutaneious nerve to the forearm before it enters the posterior compartment of the forearm.