BIO 122 Spring, 2011

Laboratory 4

The Brachial Plexus, Arm and Elbow Joint

OBJECTIVES

At the end of this laboratory you should:

1. Be able to draw a diagram of the brachial plexus and name all of its parts. This diagram should show the segmental origins from the spinal cord and the basic components (roots, trunks, divisions, cords and branches).

2. Know the motor and sensory distribution of all branches of the brachial plexus that supply the shoulder and know the motor and sensory losses that would occur with lesions of each nerve.

3. Know the general distribution of the five main branches of the brachial plexus to other muscle groups of the upper limb, i.e.:

axillary - to deltoid and teres minor

radial - to extensor muscles of arm, forearm, and hand (wrist)

musculocutaneous - to muscles of the flexor compartment of arm

median - to most forearm muscles and those that position the thumb

ulnar - to the intrinsic muscles of the hand (except thumb positioners)

4. Know the position of the different parts of the brachial plexus relative to the scalene muscles of the neck, axillary sheath, the first rib, axillary artery, clavicle, coracoid process and pectoralis minor muscle.

5. Know the general areas of origin and insertion, action and innervation for the muscles of the arm.

6. Know the names and course of the major vessels of the shoulder and arm, and the large cutaneous veins.

7. Know the position and significance of the following on the distal end of the humerus: medial epicondyle, lateral epicondyle, trochlea, capitulum, olecranon fossa, groove for ulnar nerve. On the proximal end of the ulna and radius identify and know the significance of the olecranon, trochlear notch, radial notch, coronoid process, head of the radius and radial tuberosity.

8. Review the movements of the shoulder and understand and be able to demonstrate the movements that occur at the elbow.

PRELAB PREPARATION

1. Read the material in MD&A on the brachial plexus, blood supply to the shoulder and the anterior and posterior compartments of the arm (pp. 721-744). In general, review the structure of synovial joints. You should understand the significance of the cartilaginous articular surface, the synovial membrane, the articular capsule and the involvement of ligaments as a means of structural support. Read the material on the elbow joint (pp. 800-806).

2. Study the basic structure of a long bone, giving detailed consideration to the component parts associated with adult vs. embryonic (postnatal) structure.