Lab Manual - Superficial Limbs

Lab Manual - Superficial Limbs

Assignments:

Before lab:

Complete the learning module entitled Movements of the Upper Limb.
Review the Prelab Learning Module and the Prelab Images.
Review the Steps of Dissection and Dissection Videos.
Print out and answer the questions for the Prelab homework and bring your completed homework to lab.

During lab:

Follow the steps of the dissection procedure in the Lab Manual (this page).
Be certain to identify all of the Review Items.

After lab:

Read the Dissector Answers to cover the Learning Objectives for this lab.
Read the Clinical Case for this lab.
Review the Practice Questions for this lab.

Edutainment (optional activities):

Try out the Crossword Puzzle.
Review the Surgical Videos for this lab.
Check out these Links to Other Sites.

Learning Objectives:

Upon completion of this session, the student will be able to:

Identify and demonstrate the areas of distribution of the major cutaneous nerves of the upper limb.
Identify and demonstrate the major superficial veins of the upper limb.
Describe the subcutaneous venous drainage of the lower limb, its relation to the deep veins and the significance of perforating veins.
Describe the lymphatic drainage of the lower limb and areas draining into the superficial and deep inguinal lymph nodes.
Identify the major cutaneous nerves of the lower limb, their source and the areas they innervate.
Define the regional deep fascias of the lower limb and their regional specialization such as iliotibial tract, etc.

Procedure:

1. Review the bony landmarks of the upper and lower limbs. (Play movie; View images: N 419, 420, 421, 439, TG 2-03A, 2-03B, 2-04)

On a skeleton, review the following bony features of the upper limb: on the humerus, the head and anatomical and surgical necks, greater and lesser tubercles and their crests, the intertubercular or bicipital groove, deltoid tuberosity, and medial and lateral epicondyles; the styloid processes of the radius and ulna; on the scapula, the supraspinous and infraspinous fossae, scapular notch, and acromion process; and the clavicle.

Review the following bony features of the lower limb: on the ilium, identify the iliac crest and iliac tubercle, and the anterior superior iliac spine. On the femur, identify the medial and lateral epicondyles. On the tibia, find the medial malleolus; and on the fibula, the lateral malleolus.

2. Skin the upper limb (except the palm of the hand). (Play movie; View images: N 428, TG 2-02, 2-12)

With the body on its back, skin the upper limb except the palm of the hand. Leave the superficial fascia intact.

3. Find the superficial veins and cutaneous nerves of the upper limb. (Play movie; View images: N 189, 418, 429, 430, 431, 432, 474, 476, 477, 478, 479, 480, 481, 482, 483, TG 2-02, 2-15, 2-17, 2-18, 2-20, 2-39, 2-47, 2-50, 2-51A, 2-51B, 2-52A, 2-52B, 2-53, 4-07)

Superficial veins. To demonstrate the veins, begin on the posterior side of the wrist and hand where the subcutaneous tissue is the thinnest and pick up any cutaneous vein, trace it toward the digits. Note that all veins are interconnecting, forming plexiform networks. Identify dorsal digital veins, intercapitular veins (what do these do? ), dorsal metacarpal veins. The dorsal venous network of the hand provides communication between adjacent dorsal metacarpal veins. The patterns of this plexus vary. Note this arrangement on the dorsum of your own and your partners' hands. Trace the ulnar continuation of this plexus as the basilic vein (or plexus of veins) along the ulnar border of the forearm. It continues to the arm and normally perforates the deep (brachial) fascia about 5 cm above the medial epicondyle of the humerus. Do not trace beyond this point. Does the vein perforate here in your cadaver? As you traced the basilic vein did you find accompanying nerves? What are these? Trace the radial continuation of the dorsal venous network as the cephalic vein along the radial border of the forearm and arm. Where does it terminate (perforate the deep fascia)? Does the vein extend into the arm? If not, where and how does it continue? Identify the nerve or nerves accompanying the cephalic vein. Note the anastomosis in the cubital fossa, the median cubital vein. What is its course and direction? Look at other arms to determine pattern. What are other variations? Note the perforating veins which communicate through the antebrachial fascia with deep veins especially one anchoring the median cubital vein.

Venogram of the cutaneous veins

The cutaneous nerves of the forearm and hand are more easily found than those of the back. Each perforates the deep (investing) fascia and enters the subcutaneous tissue at an identifiable location, where it is readily found. They may accompany specific veins or other identifiable structures. The cutaneous nerves of the arm and chest are branches of ventral primary rami of the spinal nerves, as are all subsequent nerves of the upper limb.

Locate, trace and determine area of cutaneous distribution of the following nerves. The lateral antebrachial cutaneous nerve perforates the deep fascia lateral to the tendon of the biceps and accompanies the cephalic plexus of veins. The medial antebrachial cutaneous nerve perforates the deep fascia medial to the tendon of the biceps and accompanies the basilic plexus of veins. The posterior antebrachial cutaneous nerve perforates the deep fascia 5 cm above the lateral epicondyle of humerus. The superficial branch of the radial nerve perforates the deep fascia along the radial border of forearm at approximately the junction of the middle and distal thirds of the forearm and accompanies parts of the cephalic venous plexus. Trace into the hand and identify its dorsal digital branches and their area of distribution. Do any branches communicate with branches of the ulnar nerve?

Locate the dorsal cutaneous branch of the ulnar nerve as it enters the subcutaneous tissue just distal to the ulnar styloid process. Trace distribution of its dorsal digital branches. Compare with other hands for variations in patterns.

4. Skin the anterior surface of the lower limb, preserving the cutaneous vessels and nerves. (Play movie; View images: N 491, 544, TG 3-02, 3-16)

Skin the anterior surface of the lower limb. Remove the skin of the lower abdominal wall, 5cm superior to the groin crease and the iliac crest. The groin crease lies parallel to the inguinal ligament (which lies along a line projected from the anterior superior iliac spine to the pubic tubercle). Identify the inguinal ligament, but do not dissect through the superficial fascia superior to it. At the ankle and on the dorsum of the foot, the subcutaneous tissue is thin. Use great care here and watch for cutaneous nerves and veins.

5. Trace the greater saphenous vein from the foot upward to its termination. (Play movie; View images: N 262, 265, 266, 408, 545, 546, TG 3-02, 3-03, 3-16, 3-70, 5-34, 5-37, 6-33)

Locate the dorsal venous arch in the foot and trace it to the greater saphenous vein. Note specifically its relationships to the medial malleolus and the medial epicondyle. In the thigh its continuation may be found in several layers of the subcutaneous tissue. Note its plexiform arrangement. Do you see accessory tributaries or varicosities? Trace it to the saphenous opening in the thigh and identify the superficial epigastric, superficial circumflex iliac and superficial external pudendal veins as they join the greater saphenous vein. To what vein does the greater saphenous drain?

Open the greater saphenous vein at major junctions and examine the arrangement of the valves.

In the subcutaneous tissue of the inguinal area, define the superficial inguinal lymph nodes. From what regions do they receive lymph? Where do they drain? Where would you find the deep inguinal nodes?

6. Clean the subcutaneous tissue from the anterior surface of the lower limb and identify the cutaneous nerves and specializations of the fascia. (Play movie; View images: N 493, 496, 497, 499, 500, 506, 540, 542, 544, 546, TG 3-02, 3-14, 3-24, 3-25A, 3-25B, 3-26, 3-29, 3-63, 3-65, 3-68, 5-38)

Trace the following nerves within the subcutaneous tissue of the anterior thigh: lateral femoral cutaneous, anterior femoral cutaneous; what is the distribution of the femoral branch of genitofemoral nerve? From what are these derived?
On the anterior surface of the leg locate and trace the saphenous nerve and its infrapatellar branches (accompanies the greater saphenous vein). Source of nerve? Identify the superficial fibular (peroneal) nerve; trace it, consider its source and outline its distribution to the foot. The terminal end of the deep fibular (peroneal) nerve is found between the great and second toe. Map out areas of distribution for each nerve identified.

Now clear the remainder of the superficial fascia from the anterior surface of the lower limb and dorsum of the foot. Examine the deep fascia and define the fascia lata and the iliotibial tract. Carefully examine the arrangement of fascia lata in the formation of the saphenous opening.

Define the crural fascia and the dorsal fascia of the foot.

7. Turn the body over, and skin the posterior surface of the lower limb, preserving the cutaneous vessels and nerves. (Play movie; View images: N 547, TG 3-03)

Turn the body over (prone position). Skin the posterior surface of the lower limb. Watch for cutaneous nerves and veins.

8. Clean the subcutaneous tissue from the posterior surface of the lower limb, trace the lesser saphenous vein, and identify the cutaneous nerves. (Play movie; View images: N 496, 499, 501, 502, 541, 542, 545, 547, TG 3-03, 3-25A, 3-25B, 3-26, 3-28, 3-29, 3-31, 3-39, 3-65)

Beginning on the lateral side of the foot, trace the lesser saphenous vein behind the lateral malleolus and along the posterior side of the leg. Look for small branches of the lesser saphenous vein perforating the crural fascia to join the deep veins. What nerves accompany the lesser saphenous vein? Where does the vein disappear and where does it terminate?

In the calf, locate the lateral sural cutaneous nerve, medial sural cutaneous nerve (with lesser saphenous vein), and sural nerve (how formed? where does it distribute and by what name? ).

The posterior femoral cutaneous nerve runs down the midline of the back of the thigh deep to the fascia lata. Cut vertically through the fascia lata on either side of the midline on the posterior side of the thigh, locate the nerve (which usually clings to the underside of the fascia), and then trace it toward the buttock. Identify its inferior cluneal and perineal branches.