Upper Extremity - Anterior Compartment Forearm and Cubital Fossa Flashcards
the anterior compartment of the forearm can be divided into 3 different layers
superficial
middle
deep
name the muscles in the superficial layer of the anterior compartment of the forearm?
pronator teres (most lateral)
FCR
Palmaris Longus
FCU
name the muscle in the middle layer of the anterior compartment of the forearm
FDS
name the muscles in the deep layer of the anterior compartment of the forearm
FDP
FPL
Pronator Quadratus
what is the common origin for the muscles of the anterior compartment of the forearm?
medial epicondyle of humerus
the nerve supply to the anterior compartment of the forearm is?
the median N. (C6-C7)
with some exceptions
Pronator Teres
O: medial epicondyle
I: mid point of lateral surface of radius
N: median N (C6-C7)
A: pronates and flexes forearm at elbow
FCR
O: medial epicondyle
I: base of 2nd and 3rd metacarpal bones
N: median N (C6-C7)
A: flexion and radial deviation of wrist
Palmaris Longus
O: medial epicondyl
I: apex of palmar aponeurosis and distal 1/2 of flexor retinaculum
N: median N (C6-C7)
A: flexion of wrist
fun fact: some people are missing this muscle on one side ; covers median nerve right above level of wrist
FCU
O: medial epicondyle of humerus and olecranon
I: pisiform, hook of hamate, and 5th metacarpal bone
N: ulnar nerve (C7-C8)
A: flexion and ulnar deviation of wrist
FDS
Ori: medial epicondyle of humerus
I: four tendons divide (in front of proximal phalax) into two slips each. Slips insert into the sides of the middle phalanges of four medial finger
N: median nerve (C7-T1)
A: flexes PIPs, MCPs and wrist
FDP
O: ant and medial surfaces of ulna just below coronoid process
I: bases of distal phalanges of medial four fingers
N: medial 1/2 digits 4 and 5 (ulnar N); lateral 1/2 digits 2 and 4 (median N.) (C8-T1)
A: PRIME MOVER wrist flexion; flexion of DIPs, PIPs, MCPs
when assessing strength how do you differentiate between FDP and FDS?
Test strength of DIPs
FPL
O: medial epicondyle of humerus (origin sometimes absent); anterior surface of radius
I: base of distal phalanx of thumb
N: anterior interosseous N. (from median N.) (C8-T1)
A: PRIME MOVER thumb flexion; abducts wrist
Pronator Quadratus
attachments: distal 1/4 of ant surface of ulna and radius
N: anterior interosseous N from median N. (C8-T1)
A: PRIME MOVER arm pronation
under which muscle do the radial A. and the superficial branch of radial N. descend in the forearm?
brachioradialis
under which muscle do the ulnar A. and N descend in the anterior compartment of the forearm?
FCU
the radial N. and musculocutaneous N run the same course in the forearm. What is their location wrt the brachialis muscle?
Radial N. is deep to brachialis
Musculocutaneous N. runs on top of brachialis
what is the course of the median nerve?
passes between the two heads of pronator teres and then descends between FDS and FDP; distally in the forearm the median N is deep to palmaris longus tendon
what muscles create the borders of the cubital fossa?
Lat: brachioradialis Med: pronator teres sup: line joining humeral epicondyles floor: brachialis roof: bicipital aponeurosis
what are the contents of the cubital fossa?
A: brachial and its terminal branches (radial and ulnar), recurrent branches of radial and ulnar arteries
N: median and radial (superficial and deep branches)
biceps tendon
lymph nodes
name the muscles of the posterior compartment of the forearm?
brachioradialis ECRL ECRB Extensor Digitorum EDM ECU Supinator APL EPL EPB Extensor Indicis
brachioradialis
O: lateral supracondylar line
I: lat surface of radius just above styloid process
N: radial N (C5-C7)
A: flexion of elbow in mid position
ECRL
O: supracondylar ridge of humerus
I: dorsal surface of base of 2nd metacarpal
N: radial nerve (C6, C7)
A: extension and abduction of wrist
ECRB
O: lateral epicondyle of humerus
I: dorsal surface of base of 3rd metacarpal
N: deep branch of radial N (C7, C8)
A: extension and abd of wrist
Extensor Digitorum
O: lateral condyle of humerus
I: dorsal digital expansion (four medial fingers)
N: post interosseous N (C7, C8)
A: PRIME MOVER wrist extension; extension of MCPs, PIPs, DIPs of medial 4 fingers
EDM
O: lateral epicondyle of humerus
I: dorsal digital expansion of 5th finger
N: post interosseous N (C7, C8)
A: wrist extension, MCP and IPs of 5th finger
ECU
O: lateral epicondyle of humerus and post border of ulna
I: dorsal surface of base of 5th metacarpal
N: post interosseous N (C7, C8)
A: extension and ulnar deviation of wrist; elbow extension
Supinator
very important deep muscle O: lateral epicondyle of humerus I: post surface of proximal 1/3 of radius (oblique line) N: deep branch of radial N. (C7, C8) A: supination of forearm
EPB
O: post surface of distal 1/3 of radius
I: dorsal surface of proximal phalanx of thumb
N: post interosseous N (C7, C8)
A: extension of MCP of thumb
Extensor Indicis
O: post surface of distal 1/3 of ulna and interosseous mb
I: dorsal digital expansion of 2nd finger
N: post interosseous N (C7, C8)
A: extension of wrist, MCP, and IPs of 2nd finger
APL
O: post surface of proximal 1/2 of ulna, radius and interosseous mb
I: base of 1st metacarpal
N: post interosseous nerve (C7, C8)
A: PRIME MOVER thumb abduction, extension of thumb at MCP joint
what muscles aid in extension of thumb?
APL
EPL
EPB
EPL
O: post surface of middle 1/3 of ulna
I: dorsal surface of base of distal phalanx of thumb
N: post interosseous nerve (C7, C8)
A: PRIME MOVER thumb extension
what muscle does the post interosseous N pass through to enter the post compartment of the forearm?
supinator
what muscles are supplied directly by the Radial N motor branches?
brachioradialis
ECRL
what muscles are supplied by the deep branch of the Radial N.?
ECRB
Supinator
what muscles are supplied by post interosseous N.?
ECU Extensor Digitorum EDM EPB Extensor Indicis APL EPL
