Dissection of the Anterior Compartment of the Forearm

Place the cadaver in the supine position. Make a vertical skin incision down the center of the anterior surface of the forearm from the cubital fossa to the distal transverse crease of the wrist. Incise the skin transversely across the front of the wrist. Reflect the skin flaps medially and laterally. Identify the cephalic and basilic veins and the lateral and medial cutaneous nerves of the forearm. Remove the superficial fascia along the lines of the skin incision.

Cut the bicipital aponeurosis and remove the deep fascia of the anterior compartment of the forearm along the lines of the skin incisions. Do not damage the underlying structures.

Identify again the brachiordialis muscle and confirm that it arises from the upper two-thirds of the lateral supracondylar ridge of the humerus. This muscle is situated in the lateral fascial compartment of the forearm and will be considered later.

Superficial Flexor muscles

Identify the following superficial group of muscles in the anterior fascial compartment and note that they possess a common tendon of origin which is attached to the medial epicondyle of the humerus. The muscles are named as follows, from lateral to medial:

1. Pronator teres, with its humeral and ulnar heads. 2. Flexor carpi radialis. 3. Palmaris longus (not always present). 4. Flexor carpi ulnaris.

Now transect the humeral head of the pronator teres as it crosses the underlying median nerve. At the same level, transect the bellies of the flexor carpi radialis and the palmaris longus muscles. The flexor digitorum superficialis muscle is now exposed.

Note that the pronator teres is supplied by a branch of the median nerve that arises in the cubital fossa. The flexor carpi radialis and the palmaris longus are supplied by branches of the median nerve deep to the pronator teres. The flexor carpi ulnaris is supplied by branches of the ulnar nerve as it enters the forearm by passing behind the medial epicondyly of the humerus.

Intermediate Flexor Muscle. Study now the flexor digitorum superficialis muscle. Note that the humeroulnar head arises from the common tendon attached to the medial epicondyle of the humerus and the medial margin of the coronoid process of the ulna; it is also attached to the medial ligament of the elbow joint. A radial head arises from the oblique line on the anterior surface of the shaft of the radius. Observe that the two heads are connected by a fibrous arch beneath which pass the median nerve and the ulnar artery.

Deep Flexor Muscles. Transect the distal portion of the belly of the flexor digitorum superficialis just proximal to the tendons. Avoid cutting the median nerve, which is bound to the deep surface of the muscle with fascia. Reflect the muscle and thus expose the deep muscles in this compartment, namely, the flexor pollicis longus, flexor digitorum profundus, and pronator quadratus muscles.

Now expose and clean the main arteries in the anterior compartment.

The radial artery, one of the terminal branches of the brachial artery, arises in the cubial fossa and passes downward and laterally overlapped by the brachioradialis muscle. Observe that in the lower half of the forearm the radial artery emerges on the medial side of the brachioradialis tendon and then lies on the lateral side of the tendon of the flexor carpi radialis.

Here, the radial artery is covered only by skin and fascia, and it rests posteriorly on the anterior surface of the distal part of the radius. Note that in the middle third of its course the superficial branch of the radial nerve lies lateral to it. The radial artery leaves the forearm by winding around the lateral aspect of the wrist to reach the posterior surface of the hand.

Identify the following branches of the radial artery:

1.Muscular branches to neighnoring muscles. 2. Recurrent branch, which joins the arterial anastomosis around the elbow joint. 3. Superficial palmar branch, which arises above the wrist and enters the palm of the hand.

The ulnar artery, one of the terminal branches of the brachial artery, arises in the cubital fossa and passes downward, deep to the superficial flexor muscles and the flexor digitorum superficialis.

At the wrist it emerges between the tendon of the flexor carpi ulnaris and the tendon of the flexor digitorum superficialis muscle. Note that in the lower two-thirds of its course the ulnar nerve lies on the medial side of the flexor digitorum superficialis muscle. The ulnar artery enters the palm on the lateral side of the pisiform bone.

Identify the following branches of the ulnar artery:

1.Muscilar branches to neighboring muscles. 2. Recurrent branches that join the arterial anastomosis around the elbow joint. 3. Anastomotic branches that take part in the arterial anastomosis around the wrist joint.

4. The common interosseous artery, which arises from the upper part of the ulnar artery and quickly divides into the anterior and posterior interosseous arteries. The anterior interosseous artery is small in size and should be followed down the anterior surface of the interosseous membrane between the flexor pollicis longus and the flexor digitorum profundus.

Nerves of the Anterior Compartment

Median nerve. Now trace the course of the median nerve in the forearm. The median nerve leaves the cubital fossa by passing between the two heads of pronator teres. It continues downward adherent to the posterior surface of the flexor digitorum superficialis. At the wrist it emerges between the lateral margin of the tendons of flexor digitorum superficialis and the tendon of flexor carpi radialis. Here it lies posterior to the palmaris longus tendon. The median nerve enters the palm by passing posterior to the flexor retinaculum.

Identify the following branches of the median nerve.

1. Muscular branches in the cubital fossa to the pronator teres, the flexor carpi radialis, the palmaris longus, and the flexor digitorum superficialis.

2. Articular branches to the elbow joint.

3. Anterior interosseous nerve, which arises from the median nerve as it emerges from between the two heads of the pronator teres muscle. It runs down on the anterior surface of the interosseous membrane. Trace branches from it to the flexor pollicis longus, the lateral half of flexor digitorum profundus, and the pronator quadratus.

4. Palmar cutaneous branch, Which passes to the skin over the lateral part of the palm.

Ulnar nerve. The ulnar nerve enters the forearm from behin the medial epicondyle of the humerus. Note that it crosses the medial ligament of the elbow joint and passes between the two heads of the flexor carpi ulnaris. Trace the nerve downward between the flexor carpi ulnaris and the flexor digitorum profundus muscles. At the wrist observe that the nerve lies between the tendons of the flexor carpi ulnar and the flexor digitorum superficialis muscles. The ulnar nerve enters the palm lateral to the pisiform bone, anterior to the flexor retinaculum.

Identify the following branches of the ulnar nerve:

1. Muscular branches to the flexor carpi ulnaris and to the medial half of the flexor digitorum profundus.

2. Articular branches to the elbow joint.

3. Palmar cutaneous branch, which arises in the middle of the forearm and supplies the skin over the hypothenar eminence.

4. Dorsal branch, or posterior cutaneous branch, which is large and passes medially between the tendon of flexor carpi ulnaris and the ulna and is distributed on the posterior surface of the hand and fingers.

Dissection of the Posterior Compartment of the Forearm

Clean the brachioradialis muscle and verify that it arises from the upper two-thirds of the lateral supracondylar ridge of the humerus and from the adjoining lateral intermuscular septum. Note that its tendon is inserted into the base of the styloid process of the radius.

Identify and clean the extensor carpi radialis longus muscle and note that it arises from the lower third of the lateral supracondylar ridge of the humerus and from the adjoining laterl intermuscular septum. Its tendon of insertion will be examined later.

Radial Nerve. Review the course of the radial nerve from the point where it pierces the lateral intermuscular septum and passes forward into the cubital fossa. Note that at the level of the lateral epicondyle the radial nerve divides into superficial and deep branches.

Identify and clean the

following branches of the

radial nerve:

1. Muscular branches to the brachioradialis, to the extensor carpi radialis longus, and to the lateral part of the brachialis muscle.

2. Articular branches to the elbow joint.

3. Deep branches of the radial nerve. The deep branch passes between the superficial and deep layers of the supinator muscle and enters the forearm by winding round the neck of the radius.

4. Superficial branch of the radial nerve, which runs down the forearm beneath the brachioradialis muscle. In the lower part of the forearm, trace the nerve backward under the tendon of the brachioradialis. It supplies the skin on the dorsum of the hand and dorsum of the lateral two and one-half fingers.

Dissection of the hand(the wrist, palm and dorsuum of hand, and fingers)

Section 5 the hand

Bones of the HandBones of the Hand1. Carpal Bones

scaphoid bone 、 lunate bone 、 triquetral bone 、 pisiform bone

trapezium bone 、 trapezoid bone 、 capitate bone 、 hamate bone

2. Metacarpal Bones (1st to 5th) base 、 shaft 、 head

3. Phalanges (1st to 5th) 1) proximal phalanx

2) middle phalanx

3) distal phalanx

The joints between radius and ulna

1. Proximal radioulnar joint

2. Interosseous membrane of forearm

3. Distal radioulnar joint

. Distal radioulnar joint

• Intercarpal joints• Carpometacarpal joints:★ Carpometacarpal joint of thumb

Bones: trapezium and base of first metacarpal– Movement: flexion, extension, adduction, abd

uction, – and opposition

• Intermetacarpal joints• Metacarpophalangeal joints• Interphalangeal joints

Pic.

The joints of hand

1. Wrist (radiocarpal) joint 2. Intercarpal joints 3. Carpometacarpal joints 4. Intermetacarpal joints5. Metacarpophalangeal joints6. Interphalangeal joints

The muscles of the hand

I) The lateral group Abductor pollicis brevis Flexor pollicis brevis Opponens pollicis Adductor pollicis

The intrinsic muscles of the hand are divided into three groups

Abductor pollicis brevis

Flexor pollicis brevis

Opponens pollicis

Adductor pollicis

Ⅱ) The medial group Abductor digiti minimi Flexor digiti minimi brevisOpponens digiti minimi

Abductor digiti minimi

Flexor digiti minimi brevis

Opponens digiti minimi

Ⅲ ) The intermediate group Lumbricales The interossei muscles Palmar interossei Dosal interossei Lumbricales

Palmar interossei Dosal interossei

Intermediate group 8) lumbricales ( 蚓状肌 ): 4 9) palmar interossei ( 骨间掌侧肌 ): 3 10) dorsal interossei ( 骨间背侧肌 ): 4

Muscles of the HandMuscles of the Hand

Muscles that move the wrist, hand, and fingers

Flexor carpi radialis Flexes and abducts wrist.Palmaris longus Flexes wrist.Flexor carpi ulnaris Flexes and adducts wrist.Flexor digitorum superficialis Flexes middle phalanges of each finger.Flexor digitorum profundus Flexes distal phalanges of each finger.Flexor pollicis longus Flexes thumb.Extensor carpi radialis longus Extends and abducts wrist.Extensor carpi radialis brevis Extends and abducts wrist.Extensor digitorum Extends phalanges.Extensor digiti minimi Extends little finger.Extensor carpi ulnaris Extends and adducts wrist.Abductor pollicis longus Extends thumb & abducts wrist.Extensor pollicis brevis Extends thumb & abducts wrist.Extensor indicis Extends index finger.

Abductor pollicis brevis Abducts thumb. Flexor pollicis brevis Flexes and adducts thumb. Opponens pollicis Draws thumb across palm to meet little finger (opposition). Adductor pollicis Adducts thumb. Abductor digiti minimi Abducts little finger. Flexor digiti minimi Flexes little finger. Opponens digiti minimi Draws little finger across palm to meet thumb. Lumbricals Extends interphalangeal joints and flexes metacarpophalangeal joints. Dorsal interossei Abducts fingers from middle finger; flexes metacarpophalangeal joints; and extends interphalangeal joints. Palmar interossei Adducts fingers toward middle finger; flexes metacarpophalangeal joints; and extends interphalangeal joints.

Muscles that move the fingers

Muscles that move the forearm (radius and ulna)Biceps brachii Flexes and supinates forearm;

flexes arm.Brachialis Flexes forearm.Brachioradialis Flexes forearm; semisupinates

and semipronates forearm.Triceps brachii Extends forearm; extends arm.Anconeus Extends forearm.Pronator teres Pronates forearm and hand and

flexes forearm.Pronator quadratus Pronates forearm and hand.Supinator Supinates forearm and hand.

1.Dissection of the the wrist, 1)anterior region of wrist 2)posterior region of wrist

Section 5 the hand

a. Superficia structures Skin Superficia fasia

1)anterior region of wrist

. Volar carpal lig.

. Flexor retinaculum(transverse carpal lig.).ulnar carpal canal. Carpal canal ( 腕管 ).radial carpal canal. palmaris longus muscles Palmar aponeurosis[carpal tunnel syndrome 腕管综合征 ]

b. Deep structures

2)posterior region of wrist

Anatomical snuffbox

a. Superficia structures Skin Superficia fasia

2)posterior region of wrist

b. Deep structures Extensor retinaculum ( 伸肌支持带 )

1.Abductor pollicis longus 1.Extensor pollicis brevis 2.Extensor carpi radialis longus2.Extensor carpi radialis brevis 3.Extensor pollicis longus4. Extensor indicis4.Extensor digitorum5.Extensor digiti minimi6.Extensor carpi ulnaris

Dissection of the palm and dorsuum of hand.

1. palm of hand.

2. dorsuum of hand.

1. palm of hand.

Muscles of the HandMuscles of the Hand1. Lateral group (thenar mus

cles 鱼际肌 ) 1) abductor pollicis brevis ( 拇短展肌 ) 2) flexor pollicis brevis ( 拇短屈肌 )

3) ★ opponens pollicis ( 拇对掌肌 ) [monkey paw 猿形手 ]4) adductor pollicis ( 拇收肌 )

Muscles of the HandMuscles of the Hand2. Medial group (hypoth

enar muscles 小鱼际肌 ) 5) abductor digiti minimi

( 小指展肌 ) 6) flexor digiti minimi br

evis ( 小指短屈肌 )7) opponens digiti minimi (小指对掌肌 )

Intermediate group 8) lumbricales ( 蚓状肌 ): 4 9) palmar interossei ( 骨间掌侧肌 ): 3 10) dorsal interossei ( 骨间背侧肌 ): 4

Muscles of the HandMuscles of the Hand

The superficial palmar arch

Ulnar artery

Ulnar nerve

Deep palmar branch

Superficial palmar arch

Proper palmar digital artery

Common palmardigital artery

Superficial palmar branchRadial artery

Median nerve

(6) The deep palmar arch

Radial artery

Principal artery of thumb

Ulnar artery

Deep palmar branch

Deep palmar arch

Palmar metacarpal artery

Common palmar digital arteries

Proper palmar digital arteries

（二）手掌的深层结构1. 深筋膜（ 1 ）腕部深筋膜：分两层

浅层——腕掌侧韧带深层——屈肌支持带

1 ）屈肌支持带（腕横韧带）尺侧端附于豌豆骨和钩骨钩，与腕掌侧韧带共同构成—— 腕尺侧管( 有尺神经和尺动、静脉通过 )

桡侧端分两层附于手舟骨和大多角骨结节——腕桡侧管（包绕桡侧腕屈肌腱）

2) 、腕管由屈肌支持带和腕骨沟共同构成。管内有指浅、深屈肌腱和拇长屈肌腱及其腱鞘以及正中神经通过。在管内，各指浅、深屈肌腱被一屈肌总腱鞘（尺侧囊）包裹；拇长屈肌腱被拇长屈肌腱腱鞘（桡侧囊）包绕。

两腱鞘均超过屈肌支持带近侧和远侧各 2.5cm ；屈肌总腱鞘常与小指指滑膜鞘相通；拇长屈肌腱腱鞘与拇指滑膜鞘相通。

正中神经在腕管内变扁平，近贴屈肌支持带桡侧的深面，腕骨骨折时可压迫正中神经，腕管引起综合征。

（ 2 ）掌部深筋膜 ：分浅、深两层1 ）浅层：分三部分 鱼际筋膜：被覆于鱼际肌表面 小鱼际筋膜：被覆于小鱼际肌表面 掌腱膜：掌心部致密的腱性纤维膜，覆盖于指浅屈肌腱的表面，厚而坚韧，略呈三角形，尖指向近侧，在屈肌支持带桡侧的浅面与掌长肌相连，并与屈肌支持带愈着；两侧部连于鱼际筋膜和小鱼际筋膜；远侧部分成 4 条纵行纤维，延伸至 2~5 指，附着于指纤维鞘和掌指关节的侧副韧带上。

2 ）深层：骨间掌侧筋膜和拇收肌筋膜，分别覆盖于掌骨及骨间肌的前方和拇收肌的表面。

（ 3 ）骨筋膜鞘及其内容从掌腱膜外侧发出掌外侧肌间隔，经拇收肌、示指屈肌腱与鱼际肌之间，止于第 1 掌骨。从掌腱膜内侧发出掌内侧肌间隔，经小鱼际和小指屈肌腱之间，附于第 5 掌骨。

手掌深筋膜的浅、深两层与掌外、外侧肌间隔，围成 3 个骨筋膜鞘：外侧鞘、中间鞘、内侧鞘1 ）外侧鞘（鱼际鞘）由鱼际筋膜、掌外侧肌间隔和第 1 掌骨围成。内含拇短展肌、拇短屈肌、拇对掌肌腱及其腱鞘，以及拇指的血管和神经

2 ）中间鞘由掌腱膜、掌内外侧肌间隔、骨间掌侧筋膜和拇收肌筋膜围成。内有指浅、深屈肌腱及屈肌总腱鞘、蚓状肌以及掌浅弓、指血管和神经

3 ）外侧鞘（小鱼际鞘）由小鱼际筋膜、掌内侧肌间隔和第 5 掌骨围成。内有小指展肌、小指短屈肌、小指对掌肌和小指的血管和神经

2. 手掌的血管（ 1 ）掌浅弓及指掌侧血管在掌腱膜和指屈肌腱及屈肌总腱鞘、蚓状机之间存在掌浅弓及同名静脉。由尺动脉末端和桡动脉掌浅支吻合而成。自掌浅弓发出 1 条小指尺掌侧动脉和 3 条指掌侧总动脉。

（ 2 ）掌深弓由桡动脉末端和尺动脉的掌深支吻合而成。有同名静脉和尺神经伴行，位于骨间掌侧肌与骨间掌侧筋膜之间。发出 3 条掌心动脉至指掌侧总动脉。

3. 手掌的神经1 ）尺神经浅支 小指指掌侧固有神经

指掌侧总神经掌短肌2 ）尺神经深支 支配小鱼际肌、第 3 、 4 蚓状机、

拇收肌和骨间肌3 ）正中神经 屈肌支持带深面 掌浅弓指掌侧 总神经与 指浅屈肌腱之间

返支指掌侧固有神经

4. 筋膜间隙 位于掌中间鞘深部，由掌腱膜桡侧发出一掌中隔，包绕示指屈肌腱和第 1 蚓状肌后，附于第 3 掌骨。掌中隔将手掌筋膜间隙分为掌中间隙和鱼际间隙

1 ）掌中间隙—— 位于掌中间鞘尺侧半的深面，在第 3~5 指屈肌腱、第 2~4 蚓状肌与骨间掌侧筋膜之间， 内侧为掌内侧肌间隔，外侧为掌中隔。 间隙近端位于屈肌总腱鞘深面，经腕管与前臂屈肌后间隙相通。 远侧端经第 2~4 蚓状肌达指蹼间隙，通手背。

2 ）鱼际间隙——位于掌中间鞘桡侧半的深面，在掌中隔、外侧肌间隔和拇收肌筋膜之间。 近端为盲端， 远侧经第 1 蚓状肌鞘通示指指背。

掌心区的层次1. 皮肤2. 浅筋膜3. 掌腱膜4. 掌浅弓、正中神经5. 指屈肌腱及屈肌总腱鞘6. 掌中间隙7. 骨间掌侧筋膜8. 掌深弓，尺神经深支9. 骨间掌侧肌10. 掌骨

二、手背（腕背和掌背）（一）浅层结构1. 皮肤2. 浅筋膜1 ）手背静脉网2 ）桡神经浅支3 ）尺神经手背支

（二）深层结构1. 伸肌支持带（腕背侧韧带）由腕背深筋膜增厚形成。内侧附于尺骨茎突和三角骨，外侧附于桡骨远侧外缘。此韧带向深面发出 5 个纤维隔，附着于桡、尺骨的背面，形成 6 个骨纤维管道，有 9 条前臂伸肌肌腱及其腱鞘通过。

各管道内从桡侧向尺侧依次通过：(1) 拇长展肌和拇短伸肌腱及其腱鞘；(2) 桡侧腕长伸肌、短伸肌腱及其腱鞘；(3) 拇长伸肌腱及其腱鞘；(4) 指伸肌和示指伸肌腱及其腱鞘；(5) 小指伸肌腱及其腱鞘；(6) 尺侧腕伸肌腱及其腱鞘。

2. 手背深筋膜分两层浅层为手背腱膜，是伸肌支持带（腕背侧韧带）的直接延续。深层为骨间背侧筋膜，覆盖 2~5 掌骨及 2~4 骨间背侧肌。

手背浅筋膜手背腱膜骨间背侧筋膜

手背皮下间隙手背腱膜下间隙

三、手指（一）浅层结构1. 皮肤：手指掌侧皮肤厚于背侧。指掌侧有三条横纹。指腹处神经末梢和血管特别丰富，感觉灵敏，手术时注意保护。2. 浅筋膜：手指掌侧浅筋膜内疏松结缔组织积聚成小球状，有纤维隔介于其间，将皮肤连于指屈肌腱鞘。

3. 指髓间隙（指髓）：位于各指远节指骨远侧 4/5 段掌侧的骨膜与皮肤之间。间隙两侧、掌面和各指末端都是致密的皮肤；近侧有纤维连于指远纹皮下和指深屈肌腱的末端，将指髓封闭成一个密闭的间隙。其内有许多纤维隔连于远节指骨骨膜和指腹皮肤之间，将间隙内脂肪分成许多小叶，并有许多血管和神经穿行其中。

4. 血管和神经：每指均有两条指掌侧固有动脉和两条指背动脉，分别与同名神经伴行。

（二）深层结构1. 指浅、深屈肌腱2. 指腱鞘（ 1 ）腱纤维鞘（ 2 ）腱滑膜鞘：——包绕各指屈肌腱的双层滑膜所形成的管状鞘，分脏、壁两层。从骨面移行到肌腱外面的两层滑膜部分，称腱系膜或腱纽。

Back

E. Fasciae of the Upper Limb

1. Flexor retinaculum ( 屈肌支持带 )2 .Extensor retinaculu

m ( 伸肌支持带 )3. Palmar aponeurosis

( 掌腱膜 )

5. Regional Anatomy of 5. Regional Anatomy of the Handthe Hand

Carpal canal ( 腕管 ) [carpal tunnel syndrome 腕管综合征 ]