The Brachial Plexus

List the fours plexuses that arise from the spinal cord?

Cervical plexus brachial plexus lumbar plexus sacral plexus

give the root values for each of these plexus

Cervical: C1-C4 Brachial: C5-T1 Lumbar plexus: T12/L1-L4 Sacral plexus: L5-S5.

How are the cords of teh plexus named?

For their relationship to the axillary artery.

How is each of the cords of the brachial plexus formed?

From the the posterior and anterior divisions fusing

How does each trunk terminate

Into divisions (anterior and posterior)

What three nerves form the M over the surface of the axillary artery?

Musculocutaneous, median and ulnar nn.

Idnetifiy the anatomical region where you would find the following portions of the brachial plexus: roots, trunks, dividions, and cords

Roots: prevertebral musculature Trunks: posterior triangle Divisions: behind clavicle Cords: in axilla.

What is the relationship of the axillary vein to the axillary artery

The axillary v. is superficial (inferiorly) to the axillary artery.

List the trhee trunks of the brachial plexus

superior middle inferior

Name the brances of this trunk and what they innervate

suprascapular n. (C5,6): supraspinatus and infraspinatus mm. subclavius (C5,6): subclavius m.

Name the brances of the posterior cord and indicate what they innervate?

upper and lower subscapular nn. (C5,C6): subscapularis and teres major mm. thoracodorsal n. (C6,7,8): latissimus dorsi m. axillary n. (C5,6): deltoid and teres minor mm. + lateral cutaneous innervation of arm. radial nerve (C5-8,T1): in axilla gives branches to the triceps brachii and anconeus, passes into forearm - it is the terminal branch of the posterior cord.

Which of the three trunks exhibit branches?

upper trunk

Which division of a spinal nerve forms the roots of the brachial plexus?

ventral rami

Which component of the spinal nerve is responsible for the formation of a plexus

ventral ramus

What is the relationship of the median nervew to the axillary artery?

The median nerve lies superficial (anteriorly) to the axillary artery.

What is the relationship of the radial nerve to the axillary artery?

The radial nerve lies posterior to the axillary artery.

How are the trunks of the brachiale plexus formed?

The roots fuse to form trunks.

HOw do these trunks get their anatomical names?

They are named for their anatomical relationship to one another.

List the branches off the roots of the brachial plexus and what each innervates

dorsal subscapular n. (C5): levator scapulae, rhomboideus major and minor; long thoracic n. (C5,6,7): serratus anterior.

Name the three banches from the lateral cord and indicate they they innervate

lateral pectoral n. (C5,6,7): pectoralis major musculocutaneous n. (C5,6,7): motor to the muscles of the flexor compartment of the arm (and sensory to lateral aspect of the forearm) lateral root of the medial nerve (C6,7): joins to form the median n.

Name the brances of the medical cord and indicate what they innervate

medial pectoral n. (C8,T1): pectoralis minor m. medial cutaneous n. of the arm and medial cutaneous n. of the forearm: sensory to these regions medial root of the median nerve (C8,T1): joined by lateral cord to form median which is motor to mm. of the forearm ulnar nerve (C8,T1): supplies mm. and skin of the forearm (terminal br. of the medial cord).

What happens to the dorsal rami of these spinal nerves?

passes segmentally to the back

List the various trunks and what forms each one?

roots of C5 and C6 unite to form the superior trunk root of C7 continues to become the middle trunk lower two roots (C8 and T1) unite to form the inferior trunk.