extends_fibers_into nerve accessory XI nerve A cranial nerve that originates from neurons in the medulla and in the cervical spinal cord. A small motor nerve which emerges from the lateral wall of the medulla with the roots of the vagus nerve, and innervates a single pectoral suspensory muscle, the m.cucullaris. AAO:0010476 BAMS:11n BAMS:XIn CN-XI Cranial nerve that innervates the sternocleidomastoid and trapezius complex of muscles. [Bemis_WE, Functional_Anatomy_of_the_Vertebrates:_An_Evolutionary_Perspective, Glossary_G-1, Grande_L, Liem_KF, Third_Edition_(2001)_Orlando_Fla.:_Harcourt_College_Publishers, Walker_WF][VHOG] Cranial nerves XI and XII evolved in the common ancestor to amniotes (non-amphibian tetrapods) thus totalling twelve pairs.[well established][VHOG] EHDAA2:0000106 EHDAA:2855 EMAPA:17265 FMA has distinct cranial and spinal parts - WP says 'Traditional descriptions of the accessory nerve divide it into two parts: a spinal part and a cranial part.[1] However, because the cranial component rapidly joins the vagus nerve, becoming an integral part of said nerve, modern descriptions often consider the cranial component to be part of the vagus nerve and not part of the accessory nerve proper.[2] FMA:6720 FMA:80284 GAID:825 HBA:9340 In mice, the spinal branch of this motor nerve innervates the trapezius and the sternocleidomastoid muscles. The cranial branch joins the vagus nerve and innervates the same targets as the vagus nerve MA:0001088 MBA:717 MESH:D000055 NCIT:C32041 OpenCyc:Mx4rwTEwI5wpEbGdrcN5Y29ycA Small motor nerve which innervates a single pectoral suspensory muscle, the m. cucullaris.[AAO] UBERON:0002019 UMLS:C0000905 UMLS:C1305777 VHOG:0000699 Willis' nerve XAO:0004214 accessory XI accessory XI nerve accessory nerve accessory nerve [XI] accessory spinal nerve cervical accessory nerve cranial nerve XI eleventh cranial nerve nervus accessorius [XI] pars spinalis nervus accessorius radix spinalis nervus accessorius spinal accessory nerve spinal accessory nerve tree spinal part of accessory nerve uberon accessory XI nerve nucleus laryngeal nerve