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Carpal and Digital Muscles - Horse Anatomy (view source)
Revision as of 17:35, 15 October 2012
, 17:35, 15 October 2012Created page with "==Introduction== The horse, as well as other domestic mammals, have a limited range of motion in the carpal joints compared with humans; therefore these muscles act as either ..."
==Introduction==
The horse, as well as other domestic mammals, have a limited range of motion in the carpal joints compared with humans; therefore these muscles act as either extensors or flexors.
=='''Extensors'''==
The craniolateral position on the forearm, almost all originate from the lateral epicondyle of the humerus. All innervated by the radial n. from the brachial plexus.
'''''Extensor carpi radialis'''''
:The most medial
::'''Insertion''': Metacarpal tuberosity of the proximal third metacarpal (cannon) bone. Uniquely in the horse, the lacertus fibrosus (detachment of the ''biceps brachii'') joins this muscle prior to its insertion.
::'''Action''': Extends and fixes the carpus, flexes the elbow
'''''Extensor carpi obliquus''''' (aka '''''abductor pollicis longus''''')
:'''Origin''': Cranial radius
:'''Insertion''': Head of second metacarpal (medial splint) bone
'''''Common Digital Extensor'''''
: Deep to the ''extensor carpi radialis''
:'''Insertion''': Extensor process of the distal phalanx via the [[Tendons - Horse Anatomy|common digital extensor tendon]].
:'''Action''': Extends carpus and digit
'''''Lateral Digital Extensor'''''
: Caudal to the ''common digital extensor'' muscle on the lateral antebrachium
:'''Insertion''': Dorsoproximal phalanx via the [[Tendons - Horse Anatomy|lateral digital extensor tendon]].
:'''Action''': Extends the carpus and metacarpophalangeal (fetlock) joint
=='''Flexors'''==
Caudal position on the forearm, originate from the caudal medial epicondyle of the humerus. All innervated by the median or ulnar n. of the brachial plexus.
'''''Flexor carpi radialis'''''
:The most medial, inserts on the proximal part of the second metacarpal(medial splint)bone
'''''Flexor carpi ulnaris'''''
:The most lateral, inserts on the accessory carpal bone.
'''''Ulnaris lateralis'''''
:The most caudolateral
:'''Insertion''': Accessory carpal bone and the fourth metacarpal (lateral splint) bone.
:'''Action''': Flexes the carpus rather than extends it, due to its insertion caudal to the carpal joint axis.
'''''Superficial Digital Flexor'''''
: Overlies, and is partially fused with, the ''deep digital flexor'' muscle.
:'''Insertion''': Proximal extremity of middle phalanx and the distal extremity of proximal phalanx via the [[Tendons - Horse Anatomy|superficial digital flexor tendon]].
'''''Deep Digital Flexor'''''
:Deep to the ''superficial digital flexor'' muscle and flexor muscles of the carpus. Passes through the carpal canal before branching and continues to insert on the palmar distal phalanx via the [[Tendons - Horse Anatomy|deep digital flexor tendon]].
'''''Interosseus muscle/Suspensory ligament'''''
:This is covered in more detail in the [[Tendons - Horse Anatomy|Equine Tendons]] section.
The horse, as well as other domestic mammals, have a limited range of motion in the carpal joints compared with humans; therefore these muscles act as either extensors or flexors.
=='''Extensors'''==
The craniolateral position on the forearm, almost all originate from the lateral epicondyle of the humerus. All innervated by the radial n. from the brachial plexus.
'''''Extensor carpi radialis'''''
:The most medial
::'''Insertion''': Metacarpal tuberosity of the proximal third metacarpal (cannon) bone. Uniquely in the horse, the lacertus fibrosus (detachment of the ''biceps brachii'') joins this muscle prior to its insertion.
::'''Action''': Extends and fixes the carpus, flexes the elbow
'''''Extensor carpi obliquus''''' (aka '''''abductor pollicis longus''''')
:'''Origin''': Cranial radius
:'''Insertion''': Head of second metacarpal (medial splint) bone
'''''Common Digital Extensor'''''
: Deep to the ''extensor carpi radialis''
:'''Insertion''': Extensor process of the distal phalanx via the [[Tendons - Horse Anatomy|common digital extensor tendon]].
:'''Action''': Extends carpus and digit
'''''Lateral Digital Extensor'''''
: Caudal to the ''common digital extensor'' muscle on the lateral antebrachium
:'''Insertion''': Dorsoproximal phalanx via the [[Tendons - Horse Anatomy|lateral digital extensor tendon]].
:'''Action''': Extends the carpus and metacarpophalangeal (fetlock) joint
=='''Flexors'''==
Caudal position on the forearm, originate from the caudal medial epicondyle of the humerus. All innervated by the median or ulnar n. of the brachial plexus.
'''''Flexor carpi radialis'''''
:The most medial, inserts on the proximal part of the second metacarpal(medial splint)bone
'''''Flexor carpi ulnaris'''''
:The most lateral, inserts on the accessory carpal bone.
'''''Ulnaris lateralis'''''
:The most caudolateral
:'''Insertion''': Accessory carpal bone and the fourth metacarpal (lateral splint) bone.
:'''Action''': Flexes the carpus rather than extends it, due to its insertion caudal to the carpal joint axis.
'''''Superficial Digital Flexor'''''
: Overlies, and is partially fused with, the ''deep digital flexor'' muscle.
:'''Insertion''': Proximal extremity of middle phalanx and the distal extremity of proximal phalanx via the [[Tendons - Horse Anatomy|superficial digital flexor tendon]].
'''''Deep Digital Flexor'''''
:Deep to the ''superficial digital flexor'' muscle and flexor muscles of the carpus. Passes through the carpal canal before branching and continues to insert on the palmar distal phalanx via the [[Tendons - Horse Anatomy|deep digital flexor tendon]].
'''''Interosseus muscle/Suspensory ligament'''''
:This is covered in more detail in the [[Tendons - Horse Anatomy|Equine Tendons]] section.