Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Human Anatomy ppt lectures Topic 10 Extensor Forearm Bs Output Notes. - anatomy ppt free download human anatomy ppt lectures, medicine notes ppt, anatomy handwritten notes pdf, mbbs 1st year anatomy notes pdf download, best anatomy notes pdf, human anatomy notes pdf, anatomy easy notes pdf, anatomy notes online, anatomy short notes, Anatomy ppt, Powerpoint Presentations and lecture notes.
Learning objectives
? At end of this session, students should be able to:
? DESCRIBE
? Attachments, actions & innervations of ? groups of
muscles of posterior compartment of forearm
? Contents of post compartment of forearm , their
anatomical Relations and clinical importance
? Nerve of post compartment and applied anatomy.
Forearm
In general, muscles in the anterior
compartment of the forearm perform
flexion at the wrist and fingers, and
pronation of forearm.
?anterior compartment, muscles are split
into three categories ?
?superficial,
?intemediate &
?deep.
Forearm
?Muscles of the forearm are mainly extrinsic
muscles of hand
? are principle flexors and extensors of hand
? as well as pronators and supinators of
forearm.
?Forearm is divided into two muscular
compartments;
?Anterior or flexor/pronator &
?Posterior or extensor/supinator
compartments.
? A crross-section of the forearm to show the muscular
compartments
Forearm Extensors - 3 functional groups
Muscles - extend & abduct /adduct hand at wrist
extensor carpi radialis longus, extensor carpi radialis brevis
& extensor carpi ulnaris
Muscles- extend medial four digits ? Ext
digitorum, ext indices & extensor digiti minimi
Muscles - extend or abduct thumb
Abductor pollicis longus / brevis &
extensor pollicis longus/brevis
Anconeus Supinator & Brachioradialis
Posterior facial compartment
Superficial group
1. extensor carpi radialis brevis
2. extensor digitorum
Common Extensor
3. extensor digiti minimi
Tendon
4. extensor carpi ulnaris
5. anconeus
Deep group
Supinator,
Lateral facial
abductor pollicis longus
compartment
extensor pollicis brevis
Brachioradialis
extensor pollicis longus
Exten. Carpi radialis
extensor indices
longus
Posterior Compartment of Forearm
? commonly known as extensor & supinator group
of muscles.
? general action - is extension at wrist & fingers
? and supination of forearm.
? innervated by radial nerve.
?Anatomically, muscles can be divided into two
layers;
?deep and superficial.
?These two layers are separated by a layer of fascia.
Posterior compartment: 3 groups
Superficial group 5
?
Extensor carpi radialis brevis Origin: Common Extensor
?
Extensor digitorum
Origin , front of lateral
?
Extensor digiti minimi
epicondyle of Humerus.).
?
Extensor carpi ulnaris
? Anconeus (posterior of lateral
epicondyle).
Deep group 5 (3 to thumb+ 1
? Lateral group 2
to index + supinator).
? Brachioradialis
? Supinator.
? Extensor carpi radialis
? Abductor pollicis longus.
longus - (2 muscles
? Extensor pollicis brevis.
originate from lateral
? Extensor pollicis longus.
supracondylar ridge).
? Extensor indices.
?Superficial
The superficial muscles in the anterior compartment are
the flexor carpi ulnaris, palmaris longus, flexor carpi
radialis and pronator teres. They all originate from a
common tendon called the common flexor origin. This
arises from the medial epicondyle of the humerus.
?Intermediate
The flexor digitorum superficialis is the only muscle of
the intermediate compartment. It can sometimes be
classed as a superficial muscle, but in most cadavers it
lies between the deep and superficial muscle layers.
?Deep
There are three muscles in the deep anterior forearm;
flexor digitorum profundus, flexor pollicis longus, and
pronator quadratus.
Superficial layer:
?contains seven muscles.
?Four of these muscles ?
?extensor carpi radialis brevis ECRB,
?extensor digitorum ED,
?extensor carpi ulnaris ECU
?extensor digiti minimi EDM
? common tendinous origin fromlateral
epicondyle. common extensor origin
? Muscles of the
Posterior/extensor
Compartment of
the
forearm
Superficial group
Common
Anconeus
Extensor
Tendon
5
1
4
2
3
Superficial : 7 muscles
lateral to medial -
? Brachioradialis.
? Extensor carpi radialis
longus, (ECRL).
? Extensor carpi radialis
brevis, (ECRB).
? Extensor digitorum.
? Extensor digiti minimi .
? Extensor carpi ulnaris.
? Anconeus (An).
Superficial extensor
? Arises - common extensor
origin, front of lateral
epicondyle of humerus,
Except, 2 (BR & ECRL).
? All cross wrist Except, 1
brachioradialis.
? All supplied - deep branch
of radial nerve, Except ABE
? Anconeus
? Brachioradialis
? Extensor carpi radialis
longus
? These 3 by radial nerve .
? Brachioradialis
? Origin:
? Lateral supracondylar
ridge of humerus
? Insertion:
? Base of styloid process
of radius
? Action:
? Flexes forearm;
(elbow).
? Rotates forearm to
midprone position
? Extensor Carpi
radialis longus
? Origin: Lateral
supracondylar
ridge of humerus
? Insertion:
? Posterior surface
of base of
second
metacarpal bone
? Action:
?
Extends and
abducts hand at
wrist joint
Extensor carpi radialis
brevis: base of 3rd
metacarpal bone.
Extensor digitorum:
Extensor expansion of
medial 4 fingers.
Extensor digiti minimi:
Extensor expansion of
little finger.
Extensor carpi ulnaris:
Base of 5th metacarpal
bone.
?Brachioradialis is a paradoxical
muscle.
?Origin and innervation are
characteristic of a extensor muscle,
?But it is actually a flexor at elbow.
?Muscle is most visible when forearm
is half pronated, and flexing at the
elbow against resistance.
Deep Muscles ? five muscles
? supinator,
?abductor pollicis longus,
?extensor pollicis brevis,
?extensor pollicis longus
?extensor indicis.
?all these muscles act on thumb and the index
finger.
?exception of supinator.
II- Deep group: 5 muscles
? Abductor pollicis longus,
(APL).
? Extensor pollicis brevis,
(EPB).
? Extensor pollicis longus,
(EPL).
? Extensor indicis (EI).
? Supinator.
All back muscles of forearm
are supplied by posterior
interosseous nerve except ,
ABE by Radial nerve.
Dorsal Extensor Expansion
It is formed by union of tendons :
Extensor digitorum, Extensor indicis, Extensor
digiti minimi, palmar, dorsal interossei &
lumbricals muscles.
? All these tendons unite to form one
tendon which divides into 3 slips,
? median one attached to middle phalanges
&
? 2 lateral attached to terminal phalanges.
Dorsal Extensor Expansion
Deep group
extensor indices
Lateral Compartment
Arteries of Posterior Compartment
Nerves of Posterior
Compartment
Synovial tendon
sheath
5
2
6
4
3
1
Extensor retinaculum
Extensor retinaculum
Posterior interosseous nerve syndrome
weakness or paralysis of the wrist and digital extensors.
Pain may be present, but it usually is not a primary
symptom. Attempts at active wrist extension often result
in weak dorsoradial deviation as a consequence of
preservation of the radial wrist extensors but
involvement of the extensor carpi ulnaris and extensor
digitorum communis.
These patients do not have a sensory deficit.
Rarely, compression of the posterior interosseous nerve
may occur after bifurcation into medial and lateral
branches.
?Clinical correlates
1. Brachial Pulse and Blood Pressure: The brachial
pulse palpation and measuring blood pressure can be
done immediately medial to the biceps tendon in the
cubital fossa. The stethoscope must be placed there,
to hear the korotkoff sounds.
2. Venipuncture
The median cubital vein is located superficially within
the roof of the cubital fossa. It connects the basilic
and cephalic veins, and can be accessed easily ? this
makes it a common site for venipuncture.
This post was last modified on 05 April 2022