AP 2 2.4: Spinal Nerves (part 2) Flashcards
Brachial Plexus
Nerves for the upper extremities branch off the brachial plexus (Figure 2.41) from combinations of the ventral rami of nerves C5-T1. The ventral rami of C5-T1 combine to form the roots of the brachial plexus.
roots then form three trunks
Brachial Plexus
The ventral rami of C5-T1 combine to form the roots of the brachial plexus. The roots then form three trunks: the superior, middle, and inferior.
divisions
Brachial Plexus
The roots then form three trunks: the superior, middle, and inferior. The trunks then form anterior or posterior divisions.
divisions branch into three cords
Brachial Plexus
The roots then form three trunks: the superior, middle, and inferior. The trunks then form anterior or posterior divisions. The divisions branch into three cords: lateral, posterior, and middle. The cords terminate in five major branches: the musculocutaneous nerve, axillary nerve, median nerve, radial nerve, and ulnar nerve. There are also several nerves that come off the brachial plexus at different locations that supply the entire upper extremity. The long thoracic nerve, suprascapular nerve, pectoral nerves, and the thoracodorsal nerves distribute sensory and motor information to locations in the upper extremity and shoulder.
axillary nerve
Brachial Plexus- cords terminate in five major branches
The five final branches form the five major nerves for the upper extremity. The axillary nerve (Figure 2.42) supplies three muscles: the deltoid (a muscle of the shoulder), teres minor (one of the rotator cuff muscles), and long head of the triceps brachii (an elbow extensor). The axillary nerve also carries sensory information from the shoulder joint.
radial nerve
Brachial Plexus- cords terminate in five major branches
The radial nerve (Figure 2.43, Figure 2.44) supplies the triceps brachii muscle of the arm, as well as twelve muscles in the forearm controlling wrist and finger extension. It carries sensory information from the associated joints and overlying skin. The radial nerve follows the posterior surface of the humerus (Figure 2.43) and then wraps around to the anterior surface close to the elbow joint. The radial nerve then follows the radial bone in the forearm.
median nerve
Brachial Plexus- cords terminate in five major branches
The median nerve (Figure 2.43) supplies flexor muscles of the forearm and the skin of the first three and a half fingers. The median nerve travels medially on the anterior surface of the elbow.
ulnar nerve
Brachial Plexus- cords terminate in five major branches
The ulnar nerve (Figure 2.43) supplies part of the flexor muscles of the forearm, wrist, and hand as well as the skin of half the ring finger and pinky finger. The ulnar nerve travels posteriorly behind the medial side of the elbow, then travels along the ulnar side of the forearm.
musculocutaneous
Brachial Plexus- cords terminate in five major branches
The musculocutaneous nerve (Figure 2.44) is responsible for the flexor muscles of the arm, including the biceps brachii and brachialis. The musculocutaneous nerve travels along the radial side of the forearm.
Lumbar plexus
The Lumbar plexus nerves arise from the ventral rami of T12-L4 (Figure 2.45). The lumbar plexus has an anterior division and a posterior division, which branch into the nerves to supply the pelvis and lower extremities
femoral nerve
Lumbar plexus branch into nerves supply pelvis and lower extremities
The femoral nerve (Figure 2.46) is the major nerve from the lumbar plexus. It supplies the hip flexors and knee extensors as well as sensation to the skin of the anterior thigh.
lateral femoral cutaneous nerve
Lumbar plexus branch into nerves supply pelvis and lower extremities
The lateral femoral cutaneous nerve supplies sensory information from the skin of the anterior, lateral, and posterior surfaces of the thigh
saphenous nerve
Lumbar plexus branch into nerves supply pelvis and lower extremities
The saphenous nerve receives sensation from the medial surface of the leg
tibial nerve
two main branches of the sciatic nerve in the lower leg
the tibial nerve, which travels along the posterior surface of the tibia
Sacral Plexus
Finally, the sacral plexus (Figure 2.47) nerves arise from the ventral rami of L4-S4.
