Muscles Of The Anterior Forearm

Forearm And Hand

Branches Of Radial Artery In Forearm

Branches in

1. Forearm

1. Radial recurrent artery
2. Muscular branches

2. Hand

Branches of the deep palmar arch

1. Branch to superficial palmar branch,
2. Princeps pollicis artery, and
3. Radialis indices artery.
4. Palmar metacarpal branch

Dorsum of hand: Dorsal carpal branch

Anterior Forearm Muscles

Read And Learn More: Anatomy Notes And Important Question And Answers

 

Question-2: Name The Boundaries And Contents Of Anatomical Snuffbox

Answer:

Boundaries and contents:

Boundaries, floor, and contents are formed by “3” structures each.

1. 3 structures form boundaries, 3 structures form the floor and 3 structures form the contents.

2. Laterally: Tendon of

1. Abductor pollicis longus, and
2. Extensor pollicis brevis.

Medially: Extensor pollicis longus.

2. Floor: From proximal to distal 3 bones

1. Scaphoid,
2. Trapezium, and
3. The base of 1st metacarpal bone.

3. Contents are 3:

From superficial to deep

1. Cephalic vein (over the roof),
2. The superficial branch of the radial nerve, and
3. Radial artery.

Anterior Forearm Superficial Muscles

Anatomical Snuffbox

Anatomical Snuffbox Introduction:

It is a depressed lar area present on the lateral side of the wrist and becomes prominent when the thumb is fully extended.

1. Boundaries and contents:

Boundaries, floor, and contents are formed by “3” structures each.

3 structures form boundaries, 3 structures form the floor and 3 structures form the contents. (“3”)

Laterally: Tendon of abductor pollicis longus and tendon of extensor pollicis brevis.
Medially: Extensor pollicis longus.

2. Anatomical Snuffbox Floor:

From proximal to distal 3 bones

1. Scaphoid,
2. Trapezium, and
3. The base of 1st metacarpal bone.

3. Anatomical Snuffbox Contents:

From superficial to deep

1. Cephalic vein (over the roof),
2. The superficial branch of the radial nerve, and
3. Radial artery.

4. Anatomical Snuffbox Applied anatomy:

A person having a fracture of the scaphoid complains of pain in the wrist. There is no impairment in function

Anterior Forearm Superficial Muscles

Question-3: What Are The Attachments Of The Flexor Retinaculum?

Answer:

1. Attachments Of The Flexor Retinaculum Proximally and

1. Laterally to the tubercle of the scaphoid, and
2. Medially to hook the pisiform.

2. Attachments Of The Flexor Retinaculum Distally and

1. Laterally to the crest of the trapezium, and
2. Medially to hook the hamate.

3. Attachments Of The Flexor Retinaculum On either side, the retinaculum has a slip:

A lateral deep slip is attached to the medial lip of the groove on the trapezium.

The medial superficial slip (volar carpal ligament) is attached to the pisiform bone.

Flexor Retinaculum

Flexor Retinaculum Introduction:

It is a strong fibrous band of deep fascia connecting proximal and distal carpal bones of the medial and lateral sides.

1. Flexor Retinaculum Gross anatomy:

Attachments of the flexor retinaculum

 

 

2. Flexor Retinaculum Relations:

Relations of the flexor retinaculum

 

 

3. Flexor Retinaculum Importance:

1. It gives origin to the thenar and hypothenar muscles.
2. The tendon of the palmaris longus is fused in the midline.
3. It keeps all the flexor tendons in position.
4. It converts the bony gutter into a tunnel.
5. It prevents bowstringing of muscles during, flexion thereby leading to effective contraction.

Anterior Forearm Superficial Muscles

Extensor Retinaculum

1. Extensor Retinaculum Definition:

The deep fascia on the back of the wrist is thickened to form the extensor retinaculum. It holds the extensor tendons in place. It is an oblique band, directed downwards and medially. It is about 2 cm broad vertically.

2. Extensor Retinaculum Attachments:

1. Laterally: Lower part of the anterior border of the radius.

2. Medially

1. Styloid process of the ulna,
2. Triquetral, and
3. Pisiform.

Anterior Forearm Superficial Muscles

3. Extensor Retinaculum Compartments:

The retinaculum sends septa and makes various compartments. They are attached to the longitudinal ridges on the posterior surface of the lower end of the radius.

In this way, 6 osseofascial compartments are formed on the back of the wrist. The structures passing through each compartment, from the lateral to the medial side, are

1. 1st Compartment

1. Abductor pollicis longus
2. Extensor pollicis brevis

2. 2nd compartment

1. Extensor carpi radialis longus
2. Extensor carpi radialis brevis,

3. 3rd compartment: Extensor pollicis longus,

4. 4th compartment

1. Extensor digitorum,
2. Extensor indices,
3. Posterior interosseous nerve,
4. Anterior interosseous artery,

5. 5th compartment: Extensor digit minimi, and

6. 6th compartment: Extensor carpi ulnaris.

Anterior Forearm Superficial Muscles

Question-4: Name The Muscles Supplied By Median Nerve In Hand

Answer:

(LOAF)

1st and 2nd Lumbricals,
Opponents pollicis,
Abductor pollicis brevis, and
Flexor pollicis brevis-superficial head.

 

Question-6: Name The Superficial Flexors Of The Forearm And Their Nerve Supply.

Answer:

Superficial flexors of the forearm

1. Pronator teres,
2. Flexor carpi radialis,
3. Palmaris longus,
4. Flexor digitorum superficialis, and
5. Flexor carpi ulnaris.
6. Nerve supply: All superficial flexors are supplied by the median nerve except flexor carpi ulnaris which is supplied by the ulnar nerve.

Branches Of Ulnar Nerve In Forearm

1. Articular,
2. Muscular, and
3. Cutaneous.

1. Articular branch to the elbow joint. It is given as the nerve lies on the medial collateral ligament.

2. Muscular branches to

1. Medial half of flexor digitorum profundus, and
2. Flexor carpi ulnaris.

3. Cutaneous branches are palmar cutaneous and dorsal cutaneous.

1. Palmar cutaneous branch.

1. It pierces the deep fascia above the flexor retinaculum.
2. It supplies the skin over the hypothenar muscles.

2. Dorsal cutaneous branch:

1. It winds around the lower end of the ulna.

2. It is distributed to the skin of the dorsal surface of 1 1/2 fingers except for the skin over the

1. The distal phalanx of the little finger, and the
2. Middle and distal phalanges of the ring finger.
3. It is important to note that the pulp of the little finger is an autonomous area for the ulnar nerve.

An autonomous sensory area is that part of a dermatome that has no overlap from adjacent nerves.

Question-7: Name The Muscles Inserted In The Extensor Expansion Of The Index Finger

Answer:

Muscles inserted in the extensor expansion of the index finger

Enumerate The Muscles That Pass Through The Carpal Tunnel

Muscles passing from superficial to deep are

1. Four tendons of flexor digitorum superficialis,
2. Flexor carpi radialis,
3. Four tendons of flexor digitorum profundus, and
4. Flexor pollicis longus.

Carpal Tunnel

Carpal Tunnel Introduction:

It is a fibro-osseous tunnel formed by concave palmar surfaces of carpal bones. It is situated in the lower part of the anterior surface of the forearm.

1. Carpal Tunnel Location:

It is located near the wrist joint.

2. Carpal Tunnel Formation:

Pillars

Bones forming the pillars of carpal tunnel

Anterior: Flexor retinaculum.

Posterior: Palmar surfaces of carpal bones.

3. Relations:

1. Anteriorly

1. Skin,
2. Palmaris longus tendon,
3. Palmar cutaneous branch of ulnar nerve,
4. Palmar cutaneous branch of the median nerve,
5. Superficial palmar branch of the radial artery, and
6. Ulnar nerve,
7. Ulnar vessels.

2. Posteriorly palmar surfaces of carpal bone

4. Carpal Tunnel Contents (From superficial to deep):

1. Flexor digitorum superficialis,
2. Flexor carpi radialis,
3. Flexor digitorum profundus,
4. Flexor pollicis longus,
5. Median nerve, and
6. Radial and ulnar bursa.

5. Carpal Tunnel Applied anatomy:

Carpal Tunnel Syndrome: Compression of the median nerve in the carpal tunnel gives rise to loss of sensations and weakness of the muscles of the thenar eminence, which constitute carpal tunnel syndrome.

Carpal Tunnel Syndrome Etiology: The following are the causes of carpal tunnel syndrome.

Carpal Tunnel Syndrome Median Trap

Myxedema
Edema premenstrual
Diabetes mellitus
Acromegaly
Neoplasia
Trauma
Rheumatoid arthritis
Amyloidosis
Pregnancy

Carpal Tunnel Syndrome Gender variation: Carpal tunnel syndrome is common in females.

Carpal Tunnel Syndrome Age group: Occurs between 40 and 70 years.

1. Carpal Tunnel Syndrome Clinical features: It presents as
·
Intermittent attacks of pain, which are more in the night. It is referred to as the proximal part of the forearm. It may be relieved by dorsiflexion.

Wasting of thenar muscles, namely

1. Flexor pollicis brevis,
2. Opponens pollicis, and
3. Abductor pollicis brevis.

2. Carpal Tunnel Syndrome Treatment

1. Pain is relieved by splinting of the wrist in slight dorsiflexion.
2. The division of flexor retinaculum is required in severe cases.

Cutaneous Supply Of Palm Of Hand

Palmar surface

1. Lateral 3½ fingers-median nerve.
2. Medial 1½ fingers-ulnar nerve.

Cutaneous Supply Of Dorsum Of Hand

Dorsal surface

1. Lateral 2 ½ fingers-median nerve.
2. Medial 2 ½ fingers-radial nerve.

Palmar Aponeurosis

It is a flattened tendon of palmaris longus present in the hand.

1. Palmar Aponeurosis Features:

1. Shape: lar
2. Apex: Blends with the flexor retinaculum.
3. Base: It is directed distally and divides into 4 slips opposite the head of the metacarpals of the medial four fingers. Each slip divides into two parts which provide the passage for digital vessels, nerves, and tendons of lubricants. The palm is divided into compartments by the slips arising from the lateral and medial margins of the palmar aponeurosis.

2. Palmar Aponeurosis Morphology:

Phylogenetically it represents degenerated tendon of palmaris longus. It is homologous to plantar aponeurosis.

3. Palmar Aponeurosis Functions:

1. It improves the grip of the hand by fixing the skin.
2. It protects the vessels and nerves of the palmar surface of the hand.

4. Palmar Aponeurosis Applied anatomy:

Dupuytren’s contracture: It is an inflammation of the ulnar side of the palmar aponeurosis. There is thickening and contracture of the palmar aponeurosis.

Dupuytren’s Contracture

Dupuytren’s Contracture Introduction:

It is an inflammation of the ulnar side of the palmar aponeurosis. There is thickening and contracture of the palmar aponeurosis.

1. Dupuytren’s Contracture Cause:

It is due to fibrosis and shortening of the palmar aponeurosis

2. Dupuytren’s Contracture Features:

1. Usually, the left hand is involved.
2. It is more severe towards the ulnar side.
3. There is progressive flexion of the 4th and 5th digits.
4. There is an involvement of the proximal and middle phalanx because of the insertion of the palmar aponeurosis.
5. A high correlation exists between Dupuytren’s contracture and coronary artery disease.

It is possibly due to the result of vasospasm of the arteries innervated by 1st thoracic spinal nerve.

Dorsal Digital Expansion

Dorsal Digital Expansion Introduction:

It is a small aponeurosis formed by each extensor tendon that covers the dorsum of the proximal phalanx and the sides of its base.

1. Dorsal Digital Expansion Shape:

It is lar, base directs proximally and apex directs distally.

2. Formation:

It is mainly formed by the extensor digitorum tendon and it is contributed by interossei and lumbrical muscles. In addition to the above tendon

1. In the little finger, it is formed by the extensor digit minimi, and
2. In the index finger, by extensor indices.

3. Dorsal Digital Expansion Features:

1. Base of dorsal digital expansion

1. It covers the dorsal and collateral aspects of the metacarpophalangeal joint.
2. It gives attachment to the extensor tendon at the center of the base of digital expansion.
3. It forms a hood over the head of the metacarpal.
4. It is movable distally and proximally with flexion and extension at the metacarpophalangeal joint.
5. Each basal angle is attached to the deep transverse metacarpal ligament.

2. Margins

The lateral margin is thickened by the insertion of the tendon of lumbrical and interossei muscles. The medial margin is thickened by the attachments of interossei only.

3. Wing tendons are of two types

1. Proximal wings: Formed by dorsal and palmar interossei.
2. Distal wings: Formed by lubricants.

4. Apex of expansion: At the distal end of the proximal phalanx, the apex of the expansion is divided into three bands. They are:

1. One central, and
2. Two collaterals.

The central band is inserted into the base of the middle phalanx. The two collateral bands unite and finally are inserted into the dorsal aspect of the base of the distal phalanx.

4. Dorsal Digital Expansion Actions:

1. It keeps the extensor tendons in the midline.
2. It is the only extensor of metacarpophalangeal joints (besides the extensor indices and the extensor digit minimi) for the medial 4 fingers.
3. The collateral bands extend the proximal and distal interphalangeal joint through the dorsal digital expansion.

 

Enumerate The Muscles Inserted In The Extensor Expansion Of The Middle Finger

Muscles inserted in the extensor expansion of the middle finger

 

 

 

Question-10: Describe The Deep Palmar Arch Under The Following Heads

1. Deep Palmar Arch Formation,
2. Deep Palmar Arch Location,
3. Deep Palmar Arch Arch,
4. Deep Palmar Arch Relations,
5. Deep Palmar Arch Branches, and
6. Deep Palmar Arch Applied Anatomy.

Answer:

Deep Palmar Arch Introduction:

It is an arterial arch present deep in the flexor tendons of digits.

1. Deep Palmar Arch Formation:

It is mainly formed by the radial artery and completed on the medial side by a deep palmar branch of the ulnar artery.

2. Deep Palmar Arch Location:

It is present at the proximal palmar crease.

3. Deep Palmar Arch Arch:

It may be complete.

4. Deep Palmar Arch Relations:

1. Anterior

1. Oblique head of adductor pollicis,
2. Flexor tendons of fingers, and
3. Lumbricals.

2. Posterior: Shaft of metacarpal and interossei.

5. Deep Palmar Arch Branches:

1. From the convexity of the arch, 3 palmar metacarpal arteries run distally in the 2nd, 3rd, and 4th spaces. They supply medial 4 metacarpals; terminate in the finger cleft by joining with a common digital branch of the superficial palmar arch.

2. From the dorsal side, 3 perforating arteries pass through medial 3 interosseous spaces to anastomose with dorsal metacarpal arteries.

3. From the convexity of the arch, a recurrent branch arises to supply carpal bones and ends in a palmar carpal arch.

6. Deep Palmar Arch Applied Anatomy:

It is one of the important anastomotic channels for the efficient blood supply of the palm. It is important in case of blockage of the radial or ulnar artery.

Question-11: Name The Muscles Supplied By Ulnar Nerve In the Hand

Answer:

1. Palmaris brevis,

2. Abductor digit minimi,

3. Flexor digit minimi,

4. Opponens digit minimi,

5. Adductor pollicis,

6. Flexor pollicis brevis (deep head),

7. Interossei,

1. 4 palmar, and
2. 4 dorsal.

8. Lumbricals: 2 medial.