Brachial Plexuses

The anterior branches of the lower four cervical nerves and the first thoracic nerve give rise to brachial plexuses. These networks of nerve fibers are located deep within the shoulders between the neck and the axillae (armpits). The major branches emerging from the brachial plexuses include the following (fig. 11.34):

1. Musculocutaneous nerves supply muscles of the arms on the anterior sides and the skin of the forearms.

2. Ulnar nerves supply muscles of the forearms and hands and the skin of the hands.

3. Median nerves supply muscles of the forearms and muscles and skin of the hands.

Blood Vessle

Figure

(a) Dermatomes on the anterior body surface and (b) on the posterior surface. Note that spinal nerve C1 does not supply any skin area.

Figure

(a) Dermatomes on the anterior body surface and (b) on the posterior surface. Note that spinal nerve C1 does not supply any skin area.

4. Radial nerves supply muscles of the arms on the posterior sides and the skin of the forearms and hands.

5. Axillary nerves supply muscles and skin of the superior, lateral, and posterior regions of the arm.

Other nerves associated with the brachial plexus that innervate various skeletal muscles include the following:

1. The lateral and medial pectoral nerves supply the pectoralis major and pectoralis minor muscles.

2. The dorsal scapular nerve supplies the rhomboideus major and levator scapulae muscles.

3. The lower subscapular nerve supplies the subscapularis and teres major muscles.

4. The thoracodorsal nerve supplies the latissimus dorsi muscle.

5. The suprascapular nerve supplies the supraspinatus and infraspinatus muscles.

Dorsal root

Posterior median sulcus

Dorsal root Dorsal root ganlion

Posterior median sulcus

Dorsal root Dorsal root ganlion

Location Dorsal Root Ganglion

Paravertebral ganglion

Anterior branch of spinal nerve

Posterior branch of spinal nerve

Lateral horn Anterior horn

Central canal

Figure 11.32

(a) Each spinal nerve has a posterior and an anterior branch. (b) The thoracic and lumbar spinal nerves also have a visceral branch.

Ventral root

Lateral horn Anterior horn

Central canal

Paravertebral ganglion

Anterior branch of spinal nerve

Posterior branch of spinal nerve

Visceral branch of spinal nerve Paravertebral ganglion

Dorsal root

Ventral root

Central And Anterior Supraspinatus

Posteror branch of spinal nerve

Anterior branch of spinal nerve

Visceral branch of spinal nerve

Posteror branch of spinal nerve

Anterior branch of spinal nerve

Visceral branch of spinal nerve

Figure 11.32

(a) Each spinal nerve has a posterior and an anterior branch. (b) The thoracic and lumbar spinal nerves also have a visceral branch.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Post a comment