ANATOMY: The Forearm the Hand

8/8/2019 ANATOMY: The Forearm the Hand

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The ForearmThe Forearm

(Bones & Muscles)(Bones & Muscles)


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Bones of The ForearmBones of The Forearm

Radius Bone:

- Lateral bone of the forearm

- Articulations:Humerus & Ulna

Scaphoid & Lunate

- Shaft is convex lat. & widerbelow than above


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Right radiusRight radius

1. Head ofRadius

2. Neck ofRadius

3. Radial Tuberosity

4. Radius (Shaft)

5. Styloid Process

6. Ulnar Notch


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Bones of The ForearmBones of The Forearm

Ulna:Ulna:

- Medial bone of the forearm

- Articulations:Humerus & Radius

Radius

- Longer than Radius

Stabilizing bone of forearmStabilizing bone of forearm


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Right UlnaRight Ulna

1. Olecranon Process

2. Trochlear notch

3. Coronoid Process4. Tuberosity

5. Radial Notch

6.Ulna (Shaft)

7. Head of Ulna

8.Styloid Process


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Fractures of Distal End ofRadiusFractures of Distal End ofRadius

Colles Fracture:

Fracture of distal end of the radius,where the distal fragment movesposteriorly & superiorly

Most common fracture of the forearm

due to falls on open hands

dinner-fork deformity


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Elbow JointElbow Joint

Type:

Synovial hinge joint

Articular Surfaces:

Capitulum & Trochlea of humerus

Trochlear notch of ulna (med.)

Head of radius (lat.)

(continuous with proximal radio-ulnar joint)


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Supporting LigamentsSupporting Ligaments

Radial Collateral Ligament:

lateral thickening of the capsule

from: Lateral epicondyle of humerus

blends to:

Annular ligament of radius


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Ulnar Collateral Ligament:

medial thickening of fibrous capsule

medial epicondyle

coronoid & olecranon

3 bands:

Ant.: cordlike (strongest)

Post.: fanlike (weakest)

oblique: slender band

Movements:

Flexion & Extension


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Movements

Flexion:

brachialis > biceps brachii > brachioradialis

(chief flexors)

Extension:

triceps brachii (medial head) > anconeus

(chief extensors)


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Important relations to elbow joint

Anterior:

Median n. & Brachial a.

brachialis m. & biceps tendon

Posterior:

triceps muscle

Medial:

Ulnar n. posterior to medial

epicondyle

(subcutaneous:funny elbow)

Lateral:

Radial n. anterior to lateral

epicondyle


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Subluxation & Dislocation of radial head

Subluxation: ?

Due to sudden pull to Childs forearm

Especially when it is ??

Signs & Symptoms:

- The child refuse to use his limb & may cry out

- The child holds his limb with forearm flexed & pronated

Rx:

Subluxation: firm supination with forearm flexed (90o) & sling for 1 w

Dislocation: Refer to specialist


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Cubital FossaCubital Fossa


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Shallow triangular depression

on the anterior surface of the elbow

Superiorly: imaginary line connecting the epicondyles

Laterally: brachioradialis

Medially: pronator teres


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Floor:Floor:

Brachialis m. (med)

Supinator m. (lat)

Roof:Roof:

Skinreinforced by bicipital aponeurosis

median cubital vein)


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Contents of the cubital fossa

From medial to lateral:

Median n.

Brachial a.

Biceps tendon


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Skin

Superf. Fascia

(med. Cubital v.)

Deep fascia

Bicipitalaponeuro.

Median n.

Brachial a

Biceps t.

Brachialis

supinator


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Muscles of ForearmMuscles of Forearm


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Muscles of ForearmMuscles of Forearm

3 groups:

Anterior 8

(flexors & pronators)

Lateral 2

Posterior 10

(extensors & supinator)


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Naming The Forearm MusclesNaming The Forearm Muscles

Action:

Flexor or Extensor, Pronator or Supinator

Attachment:Carpi or Digitorum, or Pollicis

Length of the tendon:

Longus or Brevis


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Anterior Muscles of ForearmAnterior Muscles of Forearm

Include flexors of hand & pronators of hand & forearm

Originate from medial epicondyle of humerus by a common

tendon:Common Flexors Origin

Innervated by:

median & ulnar n.


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3 layers

Superficial: 4


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Intermediate: 1


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Deep: 3


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Lateral Muscles of ForearmLateral Muscles of Forearm

1. Brachioradialis m.:

Humerus (?) base of styloid process of radius

Flexes forearm at elbow

2. Extensor carpi radialis longus:

From Humerus (?) base of 2nd metacarpal bone

Innervation:

Radial nerve


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Posterior Muscles of ForearmPosterior Muscles of Forearm

Originate from lateral epicondyle of humerus:

Common Extensors Origin

All are innervated by Radial n.

Fxn. In extending the hand at wrist joint


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The Forearm 2The Forearm 2


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Nerves in The ForearmNerves in The Forearm

3 main nerves:

Median n.

Ulnar n.

Radial n.


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Median NerveMedian Nerve

Pass in the middle of forearm

anteriorly

Beneath FDS & ant. to FDP

At wrist:

beneath flexor retinaculum

(in carpal tunnel)

Innervates all ant. muscles

except:

FCU & medial ofFDP


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UlnarUlnar NerveNerve

Post. to medialepicondyle of humerus

Between: FCU & FDP

Medial to ulnar artery

At wrist:

Pass superficial to

flexor retinaculum

Innervate: FCU & medial

ofFDP


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Radial NerveRadial Nerve

Deep branch:Pierces supinator m.

Winds around radial neck (lat.)

& enters post. compartment of

forearm

To become:Post. interosseous Nerve

*innervates all post. muscles of

forearm

Superficial branch (sensory):

Pass beneath brachioradialis m.


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Arteries in ForearmArteries in Forearm

Radial ArteryRadial ArteryArises from brachial a.

Opposite to neck of radius (anteriorly)

Proximally:

Pass on lat. Aspect of forearm,Beneath brachioradialis m.

Distally: Pass lat. To tendon of FCR

(site for pulsation)

At wrist:

Wind backward to enter the

anatomical snuff box


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Anatomical Snuff Box Triangular depression on lat. Side

of the wrist

Boundaries

Medial: tendon of EPL

Lateral: tendons of EPB & AbPL

Floor: scaphoid & trapezium

ContentRadial artery


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Ulnar ArteryUlnar Artery

Larger than radial a.

Arises from brachial a.

Opposite to neck of radius

Proximally:

Pass between FDS & FDP

Distally:

Pass between FDS &

tendon of FCU


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The HandThe Hand


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The HandThe Hand

2 surfaces: Palm & Dorsum

3 Regions:

The Wrist

proximal part

carpal bones

The Hand Proper

main part

metacarpals (5)


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Bones of The HandBones of The Hand

Carpal bones (8):Carpal bones (8):

Proximal row (4) & distal row (4)

Metacarpals (5):Metacarpals (5):

Base, shaft & head

Phalanges:Phalanges:

Proximal, middle & distal

Thumb (Exception)


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Carpals of proximal row:Carpals of proximal row:

1.1. Scaphoid (Scaphoid (boatboat)) 2. Lunate (2. Lunate (moonmoon))

3. Triquetral (3. Triquetral (3 cornered3 cornered) 4. Pisiform () 4. Pisiform (peapea))


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Carpals of distal row:Carpals of distal row:

1. Trapezium (1. Trapezium (44--sidedsided)) 2. Trapezoid (2. Trapezoid (wedgewedge))

3. Capitate (3. Capitate (large, with rounded headlarge, with rounded head))

4. Hamate (4. Hamate (hummer, hook processhummer, hook process))


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Fracture of ScaphoidFracture of Scaphoid

Symptoms:Symptoms:

- Pain on lateral side of the wrist

- Deep tenderness in ????


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Wrist Joint (Radiocarpal Joint)Wrist Joint (Radiocarpal Joint)

Type: Condyloid(ellipsoid) synovialjoint

Articulations:

- Distal end of

radius (lat.) - Articular disc

(med.)


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Supporting LigamentsSupporting Ligaments

1. AnteriorRadiocarpal

ligament

(Palmar)

2. Posterior

Radiocarpalligament

(Dorsal)


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Flexor & Extensor RetinaculaFlexor & Extensor Retinacula

FlexorRetinaculum:

A band of deep fascia ant. to wrist joint

that holds the tendons of flexor

muscles.

ExtensorRetinaculum:

A band of deep fascia post. to wrist

joint that holds the tendons of extensor

muscles.


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Flexor RetinaculumFlexor Retinaculum


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ExtensorRetinaculumExtensorRetinaculum


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Deep Fascia of The PalmDeep Fascia of The Palm

At wrist:

flexor

Retinaculum

At hand proper:

Palmar

Aponeurosis

At fingers:

Fibrous Digital


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Flexor Retinaculum: A band of deep fascia ant. to wrist joint

that holds the tendons of flexor muscles.

Attachments ??

Proximal border:

distal transverse skin

crease of the wrist


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Carpal TunnelCarpal Tunnel

Passageway of flexor tendons betweenforearm & hand

Roof: ??

Floor: Carpal bones

Contents

Tendons of 4 muscles (??)

& 1 nerve (?)


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Carpal Tunnel SyndromeCarpal Tunnel Syndrome

Causes:

any lesion reduces the size of the

tunnel

(as inflammation of flexor tendons)

compression on median nerve.

Symptoms:

- Parasthesia over lateral fingers

- Difficulty of moving & opposing the

thumb


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PalmarAponeurosisPalmarAponeurosis

In central palm

Triangular in shape:

Apex (prox.) ?? &

??

Base (distal)

fibrous digital

sheaths


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Muscle Groups in The HandMuscle Groups in The Hand

5 Groups

Thenar group

3 m.,

related to thumb

Adductor pollicism.

adducts

thumb

Lumbricals

4 m.

Interossei:

4 palmar & 4 dorsal


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Thenar GroupThenar Group

3 thumb muscles:

Abductor pollicis

brevis

Flexor pollicis

brevis (cut)

Opponens pollicis


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Adductor PollicisAdductor Pollicis

NOT part ofthenar group

2 heads: Oblique: bases

of 2nd & 3rd

metacarpals

Transverse:

shaft of 3rd


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Hypothenar GroupHypothenar Group

3 muscles of littlefinger:

Abductor digitiminimi

Flexor digiti minimi

Opponens digiti

minimi

A t i l Bl d S l t ThA t i l Bl d S l t Th


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Arterial Blood Supply to TheArterial Blood Supply to The

HandHand

2 main arterial

arches

Superficial palmar

arch

Deep palmar arch


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Superficial PalmarArchSuperficial PalmarArch

Direct continuationof ??

Between: Palmar

aponeurosis

& Long flexor tendons

Anastomose lat.


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Deep PalmarArchDeep PalmarArch

Direct continuationof ??

Between: Long flexor tendons

&

Metacarpal bones

Anastomose med.

With ulnar a.


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Dorsal Venous Arch (or NetworkDorsal Venous Arch (or Network

Subcutaneous

Proximal to

metacarpophalang

eal joints

drains laterally

into cephalic vein

drains medially

Th S l f th H dTh S l f th H d


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The sensory Supplyof the HandThe sensory Supplyof the Hand

DORSUM:

Superficial branch of the radial nerve

supplies the lateral two thirds

Posterior cutaneous branch of the ulnar

nerve supplies the medial third of the dorsum

PALM:

Median nerve supply lateral two thirds

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ANATOMY: The Forearm the Hand