OBSERVATION OF THE FOREARM,

WRIST AND HAND

Concepts and Clinical Problems:

The student should use the cadaver and related materials to develop concepts to answer the following questions. Can you:

1. Recognize the principal functional groups of muscles

and the joints driven by them.

2. Explain the organization of musculofascial compartments of the forearm and hand.

3. Describe the effects of nerve injuries/deficits on the sensory and motor pathways to the forearm and hand muscles.

4. Explain the anatomicofunctional bases of the vascularization of the forearm and hand.

 

Prior to Dissection:

Examine the bony distal humerus; ulna, radius, carpal bones

and hand bones (metacarpals and phalanges) and recognize

their constituent parts as indicated in Grant's Dissector

(pp. 203-204; 208). Note that the lateral and medial

epicondyles give rise to the common extensor and flexor

tendons, respectively; which muscles arise from these tendons?

What are the effects of distal humeral fracture? What is

Colle's fracture and what are its symptoms? What is the

scaphoid and what are the effects of its fracture? Where is

the pisiform located?

Surface Anatomy:

Palpate on the living person the lateral and medial

epicondyles. Locate the median cubital vein. (What is its

clinical significance?). Locate the radial artery at the

wrist (Between which muscle tendons is it located?). Can you

feel the radial pulse at the wrist? At the anatomical snuff

box? What are the boundaries of the snuff box? Locate the

cephalic and basilic veins and the dorsal venous arch.

Images:

Study the radiographs (X-rays) and identify the significant

parts of the humerus, ulna radius, carpals and hand. Study

the MRI of the carpal tunnel and names its constituents.

Study the angiographs and recognize the radial, ulnar arteries

and the palmar arches.

Dissection:

Dissect the forearm, wrist and hand following instructions in

Grant's Dissector pp. 200-216. Be sure to organize your

information around the following questions:

1. What are the constituent compartments of the forearm

and hand?

2. What are the contents of each compartment and how

are the layers organized?

3. Precisely where are important nerves and blood vessels

located? Where are the common vulnerable points?

What are the clinical effects of injury to these

structures?

A LIMB FOR ALL AGES

Dr. Robert J. Cowie

On a clear, cool dawn you awake from a strange dream (of the gross anatomy lab?) to the sounds and smells of a new day. An ancient day without worry of new anatomical terms or of fuzzy biochemical pathways, but also a day without breakfast if you don't get out of your bed-nest and get moving. You gather your flint knife and trusty leather sling, and as you stride out of camp swinging your arms confidently you are fully alert to any signs of breakfast.

Shortly, you descend to the edge of a broad, slow river. You sense that there is danger here, but you have not had any water since last night. Squatting, you dip your cupped hands into a pool and raise the refreshing liquid to your lips. All the while you scan the brush-choked shoreline for movement. Suddenly, from the corner of your eye, you see a large yellow blur pounding down on you! There is no escape up the bank. Reflexively you leap into a flat dive which takes you as far as possible from the water's edge. Breast-stroking underwater, you swim until your lungs nearly burst. Even as your head clears the surface, you swim with powerful crawl strokes to the distant shore, safe from the snarling and frustrated feline.

Several unrewarding miles later, you enter a forested area and notice overhanging vines loaded with grape-like clusters of fruit. Reaching high over head, you pick several bunches of these pleasing morsels. You delicately pop them one-by-one into your mouth with your thumb and forefinger, thankful for the brief respite from increasing hunger. Later, as you wearily near the forest edge, you grasp the lower branches of a tree and swing up to climb high for an unobstructed view of gently rolling grasslands and many species of animals. Your spirits soar as you spot some small antelope busily grazing not far upwind of your perch.

Descending, you stealthily enter the grassy plain using all your skills as a hunter (possibly gained near late-night "watering holes"?). After patiently crawling on hands and knees, hidden within the tall grass, you are as close as you dare approach to the skittish animal you have chosen. You carefully remove a stone from your pouch, place it in the pocket of your sling and gather yourself for the cast. As you rise, the sling is already finishing its first quick revolution about your up-thrust wrist. You release the thong at the precise moment needed to launch the projectile forcefully into the temporal region of the surprised ungulate.

Throughout the grueling afternoon tasks of dressing, carrying, cooking and eating your hard-won meal, you realize that most of the animal species in your environment are faster, stronger, or have more lethal physical adaptations than you. However, you gain an appreciation of the great flexibility, strength and precision which has been engineered into your arm and hand. Eons of evolutionary selection have enhanced your ability to function in a great variety of environments by combining an enlarged brain with an unencumbered, manipulator of objects. You are increasingly anxious to return to the present, with its deceptively easy means of food procurement, shelter, travel, and safety, which are based on the sacrifices and cultural diversity of many hundreds of generations of your forefathers.

*You should be able to list the names, actions and primary innervation of the muscles involved in each of the movements presented in bold letters.