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==Accessory nerve (XI)==

==Accessory nerve (XI)==

The accessory nerve is part of the group of cranial nerves responsible for innervation of structures derived from the branchial arches. It is also part of a group, together with the glossopharyngeal and vagus, nerves that passes through the '''jugular foramen''' which is termed the '''vagus group'''. The accessory nerve supplies structures related to the fourth branchial arch. The accessory nerve has cell bodies that are referred to as '''nucleus ambiguus''' and originate in the '''medulla oblongata'''. The cranial root of the accessory nerve actually contributes to the vagus nerve and to the striated muscles of the pharynx, larynx, palate and oesophagus.

The accessory nerve is part of the group of cranial nerves responsible for innervation of structures derived from the branchial arches. It is also part of a group, together with the glossopharyngeal and vagus, nerves that passes through the '''jugular foramen''' which is termed the '''vagus group'''. The accessory nerve supplies structures related to the fourth branchial arch. The accessory nerve has cell bodies that are referred to as '''nucleus ambiguus''' and originate in the '''medulla oblongata'''. The cranial root of the accessory nerve actually contributes to the vagus nerve and to the striated muscles of the pharynx, [[Equine Upper Respiratory Tract - Horse Anatomy#Larynx|larynx]], [[Alimentary System - Horse Anatomy#Palate|palate]] and [[Alimentary System - Horse Anatomy#Oesophagus|oesophagus]].

   

   

However, the accessory nerve also contributes to the cervical spinal cord and spinal root through the '''foramen magnum'''; providing innervation to muscles of the neck. The spinal root of the accessory nerve branches into the '''dorsal branch''' and the '''ventral branch'''. The dorsal branch innervates the ''brachiocephalicus'', ''trapezius'' and ''omotransversarius'' muscles of the dorsal neck. The ventral branch innervates the ''sternocephalicus'' muscle.

However, the accessory nerve also contributes to the cervical [[Equine Spinal Cord - Horse Anatomy|spinal cord]] and spinal root through the '''foramen magnum'''; providing innervation to muscles of the neck. The spinal root of the accessory nerve branches into the '''dorsal branch''' and the '''ventral branch'''. The dorsal branch innervates the ''brachiocephalicus'', ''trapezius'' and ''omotransversarius'' muscles of the dorsal neck. The ventral branch innervates the ''sternocephalicus'' muscle.

During clinical examination any difficulties in turning the neck or muscle atrophy around the dorsal and ventral neck may indicate a problem with the accessory nerve.

During clinical examination any difficulties in turning the neck or muscle atrophy around the dorsal and ventral neck may indicate a problem with the accessory nerve.

==Hypoglossal nerve (XII)==

==Hypoglossal nerve (XII)==

The hypoglossal nerve is part of the group of cranial nerves responsible for the control of muscles of the head. It is in part a cervical nerve due to its caudal position on the [[Hindbrain - Anatomy & Physiology|brain stem]]. The nerve is composed of '''general somatic efferent fibres''' which control the intrinsic and extrinsic muscles of the tongue (together with other nerves including the lingual nerve, facial nerve, lingual branch of the glossopharyngeal nerve and the vagus nerve). The nucleus of the nerve is located within the ''medulla oblongata'' of the brain stem and it passes through the '''hypoglossal canal'''.

The hypoglossal nerve is part of the group of cranial nerves responsible for the control of muscles of the head. It is in part a cervical nerve due to its caudal position on the [[Equine Brain - Horse Anatomy#Hindbrain|brainstem]]. The nerve is composed of '''general somatic efferent fibres''' which control the intrinsic and extrinsic muscles of the tongue (together with other nerves including the lingual nerve, facial nerve, lingual branch of the glossopharyngeal nerve and the vagus nerve). The nucleus of the nerve is located within the ''medulla oblongata'' of the [[Equine Brain - Horse Anatomy#Hindbrain|brainstem]] and it passes through the '''hypoglossal canal'''.

During a clinical examination any deviation of the tongue may indicate a problem with this nerve. Deviation of the tongue is always to the side of the lesion initially.

During a clinical examination any deviation of the tongue may indicate a problem with this nerve. Deviation of the tongue is always to the side of the lesion initially.