SUMMARY The present investigation was carried out on three apparently healthy ostriches of both sexes (two females and one male) and their age was 3 and 3.5 years as well as twenty-seven heads connected with parts of the neck. The specimens were also of both sexes and their ages ranged between 12-24 months. The heads and the necks of the three birds were dissected till the sternum to study the extrinsic muscles of the hyobranchial apparatus then separated and used in completing the other morphological investigation. In order to clarify the morphology, blood and nerve supply of the muscles related to hyobranchial apparatus and lower jaw. The present study revealed that the muscles of the hyobranchial apparatus were segregated into Extrinsic and Intrinsic muscles. The extrinsic muscles which includes M.intermandibularis, M.basibranchialis mandbularis (Pars superficialis, Pars medialis and Pars lateralis); M.epibranchialis mandibularis, M. cricocerato branchialis ventralis, M.cricocerato branchialis dorsalis, M.tracheo basibranchialis, paraglosso mandibularis, M.crico basibranchialis and esophago basibranchialis.Meanwhile the intrinsic muscle represented by M. paraglosso ceratobranchialis On the other hand muscles of the lower jaw includes M.depressor mandibulae, M.adductor mandibulae, M.pseudo temporalis, M. pterygoideus medialis and M. pterygoideus lateralis. The current study revealed that the arterial blood supply was represented by sublingual artery which supplies M.intermandibularis, M.basibranchialis mandibularis Pars superficialis, Pars medialis, Pars lateralis, M.paraglosso ceratobranchialis, M.epibranchialis mandibularis and M.paraglosso mandibularis. The hyoidal artery supplies M.cricocerato branchialis ventralis, M.cricocerato branchialis dorsalis, M. crico basibranchialis M., tracheo basibranchialis, M. esophago basibranchialis. The facial artery which supplies M. adductor mandibulae and M. pterygoideus. The occipital artery which supplies M. depressor mandibulae. M. pseudo temporalis was supplied by temporal artery The present study revealed that the venous drainage of the present muscles was represented by lingual vein which drained M. basibranchialis mandibularis, M. cricocerato branchialis dorsalis, M. cricocerato branchialis ventralis, and M. paraglosso ceratobranchialis. and M. esophago basibranchialis. Internal mandibular vein drained M. intermandibularis, descending tracheal vein drained M. tracheo basibranchialis, superficial occipital vein drained M. depressor mandibulae. The facial vein drained M. adductor mandibulae was, temporal vein drained M.pseudo temporalis and pterygopharyngeal vein drained M. pterygoideus. This investigation revealed that the nerve supply of the present muscles was represented by Ramus hyomandibularis of facial nerve innervated M. basibranchialis mandibularis Pars superficialis.The lingual nerve of glossopharyngeal nerve which innervated M.epibranchialis mandibularis and M.basibranchialis mandibularis Pars lateralis. The laryngeal nerve of glossopharyngeal nerve which innervated M. basibranchialis mandibularis Pars medialis, M.cricocerato branchials ventralis, M. cricocerato branchialis dorsalis, M. paraglosso ceratobranchialis and M. esophago basibranchialis. The lingual nerve of hypoglossal nerve which innervated M. crico basibranchialis, M.paraglosso ceratobranchialis and M.paraglosso mandibularis. The tracheal branch of hypoglossal nerve which innervated M. tracheo basibranchialis. M. depressor mandibulae was innervated by N. depressor mandibulae of the facial nerve. The mandibular nerve innervated M. adductor mandibulae; M. pterygoideus and M.pseudo temporalis. The micromorphology revealed that the muscle spindles were present in M. depressor mandibulae, M. adductor mandibulae and M.pseudo temporalis.Each muscle spindle was surrounded by an outer connective tissue capsule and contained intrafusal muscle fibers which were thinner than the extrafusal muscle fibers. Some muscle spindles contained periaxial spaces. The muscle spindle did not record in the available literatures neither in the aforementioned muscles nor in the other muscles of the hyobranchial apparatus and the lower jaw of the ostrich. The obtained results were discussed with that represented in the previous articles concerned with this field of study.