Download the muscles of the anterior compartment of forearm and flexor

THE MUSCLES OF THE ANTERIOR
COMPARTMENT OF FOREARM AND
FLEXOR RETINACULUM
LEARNING OBJECTIVES
At the end of the lecture, the student should be able to:
 Describe the muscles of forearm.
 Tell the nerve supply of these muscles.
 Explain actions of the muscles of anterior compartment of
forearm.
MUSCLES OF THE ANTERIOR
COMPARTMENT OF FOREARM
Arranged in two Groups.

Superficial Group of Muscles.

Deep Group of Muscles.
A. SUPERFICIAL MUSCLES ARE,
•
•
•
•
•
Pronator teres.
Flexor carpi radialis.
Flexor digitorium superficials.
Palmaris longus.
Flexor carpi ulnaris.
B. DEEP MUSCLES ARE,
• Flexor digitorium profundus.
• Pronator quaradatus.
• Flexor pollicis longus.
SUPERFICIAL MUSCLES
• Arise from a common origin from a smooth area on the anterior
surface of the medial epicondyl.
• Three of them have additional origin also i.e. Pronator teres,
flexor carpi radials, flexor digitorium superficials.
Pronator teres
Arises from:
A. LARGE SUPERFICIAL HEAD:
1. Common origin.
2. Supra condylar ridge.
B. SMALL DEEP HEAD:
From medial border of the coronoid process of ulna just distal to the tubercle on it.
Inserted by:
Flat tendon into the middle of lateral surface of shaft of radius at
its most prominent part of its outward convexity.
NERVE SUPPLY:
Muscular branches of median nerve.
ACTION:
 Pronates the forearm.
 Weak flexor of elbow .
Flexor carpi radialis
Arise from:
•
common origin.
• Fleshy turn in to long tendon.
• Grooves trapezium.
Inserted on:
• the bases of 2nd and 3rd metacarpals.
•
• Radial artery lies lateral to the tendon.
• Median nerve lies medial to it.
Nerve supply:
• median nerve.
Actions:
• Flexor and radial abductor of the wrist.
• It is stabilizer of the wrist
Flexor digitorium superficialis
• Arises from
1 Common origin
2. Medial ligament of the elbow.
3. Tubercle of the coronoid process of ulna (sublime
tubercle).
4. Fibrous arch continues the origin across the radius from
whole length of anterior oblique line.
• Passes beneath the superficial retinaculum.
• Tendons of middle and ring fingers are superficial to the
index and little fingers.
Insertion:
• Enters the fibrous flexor sheath, divides in two halves and is attached to the margins of
the front of the middle phalanges.
• Nerve supply: Median nerve(7,8).
Action:
• flexor of proximal interphalangeal joints,
metacarpophalangeal joints, wrist joint and
assists in flexion of elbow.
Palmaris longus
Arises from

common origin.
• Broadens as it passes flexor retinaculum to which it
is partially adherent.
• It is slits to form longitudinally directed fibers.
Action:
• weak flexor of wrist.
• Anchors the skin and fascia of hand.
Flexor carpi radialis
Aries from :
• common origin and wide apponeurosis from the medial border of olecronon process
and subcutaneous border of ulna.
• Ulnar nerve lies between humeral and ulnar head.
•
Insertion:
is on the pisiform and end by the pisohamate and
pisometacarpal ligament into the
hamate and 5th metacarpal.
Nerve supply:
• Ulnar nerve (C7,8).
Action:
• It is flexor and ulnar adductor of wrist.
Deep muscles
Flexor digitorium profundus
• Most powerful and the bulkiest muscle of the forearm.
• ORIGION:
• Medial surface of the olecronon.
• Upper three quarters of anterior and medial
surface of ulna (including its subcutaneous
border and interosseus membrane).
• Tendon of the index finger separates in the
forearm.
INSERTION:
• At the base of terminal phalanges of fingers.
NERVE SUPPLY:
• Anterior interosseus branch of median nerve
and ulnar nerve
(C 8,T1 little finger side).
ACTION:
• Flexes terminal interphalangeal joint.
• Great gripping muscle.
Flexor polices longus
• Origin:
• Anterior surface of the of the radius below the oblique
line and above the insertion of Pronator quaradatus and
from interosseus membrane.
• Tendon forms on ulnar side.
• Passes underneath the flexor retinaculum.
Insertion:
•
at the base of first distal phalanx.
Nerve supply:
• Anterior interosseus branch of median nerve (C6,7).
FLEXION OF THE
METACARPOPHALANGEAL JOINT
Action:
• Flexor of interphalangeal joint of thumb.
• Also flexes metacarpophalangeal joint and carpometacarpophalangeal joints of thumb
and wrist joint.
Pronator quaradatus
ORIGIN:
• From a ridge on anterioromedial aspect of ulna.
INSERTION:
• Anterior surface of lower fourth of radius and triangular
area above ulnar notch.
NERVE SUPPLY:
• Anterior interosseus branch of median nerve.
ACTION:
• Pronates the forearm and help to hold lower end of radius
and ulna together.
Flexor retinaculum
• Strong fibrous band.
• Lies across the carpus bones at proximal part of hand.
• Attached to the,
• 1. Hook of hamate and pisiform medially.
• 2. Tubercle of the scaphoid and ridge of trapezium
laterally.
• As carpal bones are concave so flexor retinaculum forms
carpal tunnel.
• Median nerve and long flexor tendons pass through the capal tunnel.
• Superficialis tendon pass through in two separate rows, middle and ring
fingers in front of the index and little fingers tendons.
• Tendons of flexor digitorium
profundus pass deeply in separate
compartment.
• Flexor pollicis longus lies in its own
sheath as it passes through osseous
tunnel.
• Median nerve pass deep between flexor digitorium
superficialis flexor carpi radialis when it is liable to
compression causing carpal tunnel syndrome.
Thanks to following great authors of Books of
Anatomy:
The reading material is taken from ,
Last’s Anatomy,
Gray’s anatomy,
Keith L Moore’s Anatomy,
Clinical Anatomy by Richard S Snell and
Atlas of human anatomy by Frank H Netter
with thanks.
The end