Nerves of the Thoracic Limb Flashcards
Cranial Nerve XI (Accessory Nerve)
Cleidocephalicus m.
Omotransversarius m.
Sternocephalicus m.
Trapezius m.
Thoracic limb muscles innervated by the Brachial Plexus
Cutaneus trunci m.
Superficial pectoral m.
Deep pectoral m.
Latissimus dorsi m.
Serratus Ventralis Thoracis m.
All intrinsic muscles of the thoracic limb
Brachial Plexus origins and functions
Network of nerves formed by ventral branches of spinal nerves C6-8, T1-2 (sometimes C5)
Gives rise to series of nerves that innervate the thoracic limb
-Motor innervation to skeletal muscles
-Cutaneous sensory innervation from the skin
-Proprioception from muscles and tendons
Nerves from brachial plexus that innervate EXTRINSIC thoracic limb mm.
Cranial pectoral nn. - superficial pectoral m.
Thoracodorsal n. - latissimus dorsi m.
Caudal pectoral nn. - deep pectoral m.
Lateral thoracic n. - deep pectoral and cutaneous trunci mm.
Long thoracic n. - serratus ventralis thoracis m.
Nerves from brachial plexus that innervate INTRINSIC thoracic limb mm.
Suprascapular n. - supraspinatous, infraspinatous mm.
Subscapular n. - subscapularis m.
Musculocutaneous n. - biceps brachii, brachialis, coracobrachialis mm.
Axillary n. - deltoideus, teres minor, subscapularis, teres major mm.
Radial n. - triceps brachii, anconeus, tensor fasciae antebrachii mm., and all extensor mm. in the antebrachium
Median n. - all flexor mm. except flexor carpi ulnaris m.
Ulnar n. - flexor carpi ulnaris, deep digital flexor mm.
Suprascapular n.
Courses between subscapularis and supraspinatus mm. and across scapular notch
Motor to: supraspinatus and infraspinatus m.
Action:
No cutaneous innervation
Nerve dysfunction: Motor - reduced shoulder joint extension, supra/infraspinatus mm. atrophy with prominent spine of scapula, shortened stride, contracture of infraspinatus m. (lameness)
Subscapular n.
Motor to: subscapularis m.
Action
No cutaneous innervation
Nerve dysfunction: No marked change in gait
Musculocutaneous n.
Motor to: coracobrachialis, biceps brachii, brachialis mm.
Action:
Sensory from: medial aspect of antebrachium (AZ) (medial cutaneous antebrachial n.), palmar aspect of manus (communicating br.)
Nerve dysfunction: Motor - reduced flexion of elbow joint, loss of bicipital reflex; Sensory - loss of sensation over medial aspect of forearm
Axillary n.
Motor to: Caudal part of subscapularis, teres major, teres minor, deltoideus mm.
Action:
Sensory from: craniolateral shoulder area (AZ) (cranial lateral cutaneous brachial n.), cranial aspect of the antebrachium (cranial cutaneous antebrachial n.)
Nerve dysfunction: Motor - reduced shoulder joint flexion, atrophy of deltoideus m. with prominent acromion; Sensory - reduced sensation over lateral surface of shoulder
Radial n.
Motor to: Triceps brachii, anconeus, tensor fasciae antebrachii mm.
Action:
Divides into deep and superficial branches
Nerve dysfunction: degree of incapacitation depends on location of n. damage; high damage (reduced extension of elbow, carpus and digits, inability to support weight, dropped elbow, walking on dorsum of manus, loss of tricipital reflex, atrophy of triceps brachii m., reduced sensation of dorsal aspect of manus and craniolateral aspect of forearm), low damage (reduced sensation of dorsal aspect of manus and craniolateral aspect of forearm)
Deep radial br.
Motor to: all extensor mm.
Action:
Superficial radial br.
Medial br. - Sensory from: cranial aspect of antebrachium, medial aspect of manus (AZ)
Lateral br. - Sensory from: craniolateral aspect of antebrachium, dorsal aspect of manus (AZ)
Median n.
Motor to: all flexor mm. except flexor carpi ulnaris m.
Action:
Sensory from: palmar aspect of manus
Nerve dysfunction: Motor - reduced flexion of carpus and digits
Ulnar n.
Motor to: flexor carpi ulnaris (ulnar and humeral heads), deep digital flexor (ulnar and humeral heads) mm.
Divides into dorsal and palmar brr.
Nerve dysfunction: Motor - reduced flexion of carpus and digits; Sensory - reduced sensation over the caudal aspect of forearm and lateral aspect of manus
Dorsal br. of ulnar n.
Sensory to abaxial surface of digit 5 (lateral aspect of manus) (AZ)