Brachial Plexus

_____ (C5-6) and _____ (C5-C8) nerves derive from the posterior cord. _____ nerve is the largest of the five terminal branches because it is responsible for innervating all of muscles of the posterior arm and forearm (the extensor compartments)

Axillary radial Radial

The ventral rami that form the 'Roots' of the brachial plexus derive from spinal nerves _______. These are ventral rami of spinal nerves so they carry both _________ and ________ fibers. The ventral rami (roots) of the plexus emerge in the neck, 'sandwiched' between the anterior and middle _____ mm

C5-T1 somatomotor somatosensory scalene

Now focus in on the Roots of the plexus and realize the roots of the plexus give off the following nerves (their spinal cord contributions are given in parentheses): • ______ _______ nerve (C5), which supplies the rhomboids and levator scapulae muscles • ______ ______ nerve (C5 - C7), which supplies serratus anterior

Dorsal scapular Long thoracic

The Anterior and Posterior Divisions form the Cords of the brachial plexus. There are 3 cords: • ______ cord: Formed by the Anterior Divisions of the Upper and Middle Trunks • _______ cord: Formed by the Anterior Division of the Lower Trunk •_____ Cord: Formed by all three Posterior Divisions.

Lateral Medial Posterior

There are five terminal nerves (or branches) of the brachial plexus: _________, _______, _______, ______ and _______ nn.. These terminal nerves provide the innervation to the remainder of the upper limb (arm, forearm, hand).

Musculocutaneous Median Ulnar Radial Axillary

Realize that the ____ of the plexus are the ventral rami of the spinal nerves that form the plexus (don't confuse the roots of the plexus with ventral or dorsal roots of spinal nerves).

Roots

There are 5 major components to the plexus:

Roots, Trunks, Divisions, Cords, and Terminal Nerves (or Terminal Branches)

The roots of the plexus unite to form three Trunks: the ______ (superior), ______, and ______ (inferior) Trunks. The Trunks are situated proximal to the ______. The Upper Trunk is formed by the union of ventral rami _______. The Lower Trunk is formed by the union of ventral rami _______. The Middle Trunk is formed simply by the ventral ramus of _____.

Upper Middle Lower clavicle C5 -C6 C8 - T1 C7

Only one Trunk - the ______ Trunk - gives rise to any nerve branches: • __________ nerve (C5 -6), which you already know supplies the supraspinatus and infraspinatus mm (two rotator cuff mm.). • Nerve to ________ (a small muscle situated between the inferior clavicle and 1st rib).

Upper Suprascapular subclavius (C5-6)

Musculocutaneous nerve derives from the _______ cord and receives contributions from spinal cord levels _______. Ulnar nerve derives from the ______ cord and receives contributions from ______. Median nerve is formed by contributions from both the lateral and medial cords_______.

lateral C5 - C7 medial C8 -T1 (C6 - T1)

The Posterior Cord gives rise to three nerves (in that order, from proximal to distal).: i) _______ ______ n. ii) _________ n. iii) _____ _____ n.

upper subscapular thoracodorsal lower subscapular

The __________ is responsible for innervating nearly all of the musculature of the upper limb. The ______ is a network of somatic nerves formed by the union of ventral rami ______, with variable contributions from ___ and ___. Note that all somatic plexuses are formed by ventral rami of spinal nerves.

brachial plexus brachial plexus C5 -T1 C4 T2

The brachial plexus originates in the _______ region. As the ______ rami forming the plexus join and separate, the plexus runs distal -_______, ________ to the clavicle, to enter the axilla. Branches of the plexus innervate the superficial back (excluding the trapezius m.) and extrinsic shoulder regions, the scapular, deltoid and pectoral regions as well as the arm, forearm and hand.

cervical ventral laterally, inferior

Each of the three trunks splits into an Anterior Division and a Posterior Division. The Divisions may be positioned proximal to the ________, or between the _______ and 1st rib; this is variable.

clavicle clavicle

The three Cords - Lateral, Medial, and Posterior - are so named according to their position relative to the Axillary artery. The cords generally run deep to the ________ and then deep to the tendon of insertion of the ____ ______.

clavicle pectoralis minor

The Lateral Cord gives rise to one nerve, the ______ ______ nerve (which typically serves both pectoralis major and minor).

lateral pectoral

The Medial Cord gives rise to three nerves: i) _____ _____ nerve (which typically serves pectoralis major and minor) ii) two nerves that are strictly cutaneous nerves: the ____ ____ _____ and _____ ____ ______ nerves (which distribute to the skin of the medial arm and medial forearm, respectively).

medial pectoral medial brachial cutaneous medial antebrachial cutaneous