Equine Spine and Head Anatomy
Original Editor - Chelsea McLene
Top Contributors - Chelsea Mclene, Tarina van der Stockt, Jess Bell and Kim Jackson
Introduction[edit | edit source]
Equine Anatomy refers to the gross and microscopic anatomy of horses and other equids (donkeys, and zebras).
This page introduces the Anatomy of Equine Spine and Head.
Axial Skeleton[edit | edit source]
The axial skeleton consist of skull, vertebral column, sternum, and ribs. Multiple sternebrae fuse to form one bone, attached to the 8 "true" pairs of ribs, out of a total of 18.
The vertebral column contains 54 bones:
- 7 Cervical vertebrae: includes the atlas (C1) and axis (C2)
- 18-19 Thoracic vertebrae
- 5-6 Lumbar vertebrae
- 5 Sacral vertebrae
- 15-25 Caudal vertebrae[1]
In certain breeds, there may be difference in the number.[2]
Skull[edit | edit source]
The skull consists of the brain and the most important organs of sense including bones and cavities.
Bones in the equine skull[edit | edit source]
There are 34 bones and most of them are flat. During the birth process, these bones overlap, and allow skull to compress as much as possible while it allows easy parturition.
14 Major bones:
- Incisive bone (premaxillary): part of the upper jaw; where the incisors attach
- Nasal bone: covers the nasal cavity
- Maxillary bone: a large bone that contains the roots of the molars
- Mandible: lower portion of the jaw; largest bone in the skull
- Lacrimal bone: contains the nasolacrimal duct, which carries fluid from the surface of the eye, to the nose
- Frontal bone: creates the forehead of the horse
- Parietal bone: extends from the forehead to the back of the skull
- Occipital bone: forms the joint between the skull and the first vertebrae of the neck (the atlas)
- Temporal bone: contains the eternal acoustic meatus, which transmits sound from the ear to the cochlea (eardrum)
- Zygomatic bone: attaches to the temporal bone to form the zygomatic arch (cheek bone)
- Palatine bone: forms the back of the hard palate
- Sphenoid: formed by fusion of the foetal basisphenoid and presphenoid bones, at the base of the skull. Can become fractured in horses that rear over backwards.
- Vomer: forms the top of the inside of the nasal cavity
- Pterygoid: small bone attached to the sphenoid that extends downward
Cavities[edit | edit source]
The Equine skull consists of 4 cavities:
- The cranial cavity: Protects and encloses the brain, supports sense organs. The cranium consists of roof having frontal and parietal bones and floor with sphenoid bone.
- The orbital cavity: It has 5 orbits namely frontal, lacrimal, palatine, sphenoid and zygomatic. It protects and surround the eye.[3] They have unique eyes:
- Monocular vision: The horse can see objects with one eye. This means that the brain receives two images simultaneously.
- Binocular vision: The horse can focus with both eyes just like humans and the brain is receives only one signal.
- The oral cavity: It is a passage into the respiratory and digestive system.
- The nasal cavity: contains bone that protects mucous membrane from inspired warm air.
Foramina of the skull and the structures passing through[edit | edit source]
| Foramina | Structures passing through |
|---|---|
| Infra-orbital foramen | Infra-orbital nerve. CNV |
| Maxillary foramen | |
| Cribriform foramen | Olfactory nerve. CNI |
| Optic canal | Optic nerve. CNII |
| Orbital fissure | CNVII, IV, V and VI (ophthalmic division) |
| Round foramen | CNV (maxillary division) |
| Oval foramen | CNV (mandibular division) |
| Foramen lacerum | Internal carotid artery
CN V3 (horse and pig) |
| Internal accoustic meatus | CNVIII |
| Jugular foramen | CNIX, X, XI |
| Stylomastoid foramen | CNVII |
| Mandibular foramen | CNV (mandibular alveolar nerve) |
| Mental foramen |
Joints and Ligaments[edit | edit source]
Joints and Ligaments of Skull[edit | edit source]
Temporo-mandibular joint is a condylar joint between the mandibular condyles and the mandibular fossae of the temporal bones. It has loose joint capsule with thickening to form lateral ligament, articular disc and mandibular symphysis.
Joints of the hyoid apparatus:
- Tympanohyoid cartilage- skull (syndesmosis)
- Interhyoid joints (synovial)
- Thyrohyoid bone- cranial cornu of thyroid cartilage (synovial)
Cervical Spine[edit | edit source]
Joints[edit | edit source]
Atlanto-occipital joint[edit | edit source]
It is a condylar modified synovial hinge joint having occipital condyles- cranial articular surface of atlas. There are thickenings that strengthen the spacious joint capsule. They are: Dorsal, Ventral, Lateral. It consists of transverse atlantal ligament that holds the dens of the axis against the ventral arch of the atlas.
Atlanto-axial joint[edit | edit source]
It is a pivot joint between atlas (C1) and saddle shaped surface of the axis (C2,which extends upon Dens). It has a loose joint capsule and consists of apical ligament of dense that connects apex of dens to the occipital bone. Considering the ROM, ROT of atlas and head upon axis and some accessory lateral flexion. ROT here makes up 73% of cervical ROT.
Cervical spine C3-C4[edit | edit source]
It is planar, extensive, oval shaped and is obliquely oriented in transverse plane. The cranial articular processes face dorsomedially and the caudal articular processes face ventrolaterally. Spinous process height increases caudally from C6. ROM: Lateral flexion (25-45° each joint; C1/C2- lateral flexion 3,9°)
Ligaments[edit | edit source]
- Dorsal longitudinal ligament
- Ventral longitudinal ligament
- Ligamentum flavum
- Nuchal ligament:
It connects thoracic vertebra to head and assists in supporting its weight.
It consists of 2 paired parts:
- Funicular (cord) part- poll to +/- 2nd to 4th thoracic spinous process
- Lamellar part- arises from 2nd and 3rd thoracic spinous processes and the funicular part, and inserts on C2-C6 spinous process. 1st digitation going to the axis is very strong and decreases in strength caudally.
Thoracic Spine (T1-T18)[edit | edit source]
Articular processes[edit | edit source]
Caudal articular processes face ventrally and at base of spinous process. Cranial articular processes are oval facets on arch of vertebra and face dorsally. Each thoracic vertebrae has a pair of costal facets on dorsal body (except last) forming costal fovea.
Anticlinal vertebrae: It is a point in the caudal thoracic vertebral column at which vertebral anatomic features change[4]. Here its the 13th vertebra.
ROM: Flexion- T17/T18 greatest amount, T3-T9 least amount; Extention- T14-T18 greatest amount, T2-T9 least amount.
Rib neck[edit | edit source]
It has 2 converse facets: Cranial and Caudal.
Rib 1= C7 and T1 and IV disc
ROM: ROT of rib, greater caudal.
Costovertebral Joint[edit | edit source]
Joints[edit | edit source]
It has two distinct articulations between most ribs and the vertebral column:
- Head of the rib: Cranial and caudal costal facets of adjacent vertebrae; Ball and socket synovial joint.
- Tubercle of the rib: Transverse process of vertebrae; Plane synovial joint.
Ligaments[edit | edit source]
- Radiate longitudinal ligament
- Intercapital ligament
- Costotransverse ligament
- Ligament of the neck
Lumbar Spine[edit | edit source]
Joints[edit | edit source]
They usually have 6 lumbar vertebrae (L1-L6) while some arabians have only 5 (L1-L5).
Articular processes[edit | edit source]
Cranial articular processes is fused with mammillary processes. It is concave dorsally and mostly in sagittal alignment.
Caudal processes are convex ventrally, correspond with convexity of cranial articular processes. It is differentiated from last thoracic vertebra by lack of costal facets.
ROM: Lateral flexion and rotation is very limited especially at L4-L6 due to intertransverse joints.
Ligaments of Thoraco-lumbar spine[edit | edit source]
- Supraspinous ligament: It is a heavy band of connective tissue running over the top of spinous processes ( T2/T3 caudally). It prevents abnormal separation of spinous processes during flexion.
- Ventral Longitudinal ligament: It marks the ventral surface of vertebrae from axis to sacrum. It is strongest and is wide caudally. It plays a major role in preventing spine over extension.
- Dorsal longitudinal ligament: It extends from floor of vertebral canal from axis to sacrum and helps to prevent spine hyper-flexion.
- Annulus fibrosis of IVD: thick ventrally.
- Intertransverse ligament
- Interarcuate ligament/ yellow ligament/ ligamentum flavum: It is a elastic ligament that fills dorsal space between arch of adjacent vertebra.
Lumbosacral Joint[edit | edit source]
The cranial articular process of the first sacral vertebra are concave and face dorsomedially.
ROM: Flexion/ Extension 23,4°
Sacrum[edit | edit source]
It is a fused sacral vertebrae having dorsal and ventral sacral foramina.
Myology and Neurology[edit | edit source]
Muscles of the Head[edit | edit source]
Muscles of the Face[edit | edit source]
Muscles of facial expressions are innervated by motor fibers of CNVII (facial nerve)
| Muscle | Origin | Insertion | Action | |
|---|---|---|---|---|
| M. Levator labii maxillaris | Lacrimal, Zygomatic and Maxillary bones | The maxillary lip | Elevates the Maxillary lip | |
| M. Levator nasolabialis | Nasal and Frontal bones | The lateral wing of nostril
The maxillary lip |
To elevate and retract the Angle of the mouth | |
| M. Zygomaticus | The fascia covering the Masseter | The commissure of the lips | ||
| M. Buccinator | Maxilla and Mandible | To flatten the cheeks and thus pressing the food between the teeth | ||
| M. Depressor labii mandibulars | The alveolar border of the Mandible | The mandibular lip | To depress and retract the Mandibular lip | |
| M. Orbicularis oris | It is the sphincter muscle of the skin and the muscles of the lips
Corner of the mouth |
Into the lips as it surrounds the mouth | To close the mouth | |
| M. Risorius | Part of M. cutaneous faciei | The angle of the mouth | To retract the angle of the mouth | |
| M. Dilator naris | Alar cartillage | Alar cartillage | Dilate the nostril | |
| M. Lateralis nasi | Dorsal part |
Nasal bone |
Parietal cartilage |
Dilate the nostril and Nasal vestibule |
| Ventral part | Nasal process of Incisive bone | Lateral wall of the Nasal vestibule | ||
| M. Caninus | Maxilla close to the rostral extremity of the facial crest | Lateral wing of the nostril | Dilate the nostril laterally | |
| M. Levator nasolabialis | Frontal and Nasal bones | Lateral wing of the nostril | Elevate the maxillary lip and the commissure of the mouth
Dilate the nostril | |
Ear[edit | edit source]
The ear is an organ of hearing and balance. It consists of the outer, middle, and inner ear.
Outer Ear[edit | edit source]
The outer ear includes:
- Pinna: It is mobile and can move independently. It can hear multiple sounds at same time.[5]
- Ear canal
Cartilages: Cartilages of the ear are for the purpose of collecting and transmitting sound to the essential organ of hearing within the temporal bone, and to affect this purpose they, and especially the concha, require to be moved in various directions. This is affected by means of muscles connected to them.
There are 3 cartilages:
- Conchal: It forms framework of all that portion of ear which stands erect. It presents a large vertical opening on one side for the reception of sound, and is attached below to the annular cartilage.
- Annular: It is a small ring of gristle connected with the auditory process of petrous temporal bone.
- Scutiform: It is a small, flat and somewhat triangular cartilaginous plate situated in front of the base of concha, to which it is attached.
The muscles of outer ear:
- Rostral
- Dorsal
- Caudal
- Ventral
Middle Ear[edit | edit source]
The middle ear includes:
- Eardrum
- Small, air-filled chamber containing 3 tiny bones: the hammer, anvil, and stirrup. It also includes 2 muscles, the oval window, and the eustachian tube.
Inner Ear[edit | edit source]
The inner ear is a complex structure that includes the cochlea and the vestibular system.[5]
Muscles of Mastication[edit | edit source]
Muscles of mastication are innervated by Mandibular branch of trigeminal nerve CNV.
| Muscle | Origin | Insertion | Action |
|---|---|---|---|
| M. Masseter | The zygomatic arch and the facial crest | The lateral border of Ramus of the mandible | Close the mouth |
| M. Temporalis | The temporal fossa and the temporal crest | The coronoid process of the Mandible | Close the mouth (to raise the mandible) |
| M. Pterygoideus medialis | The crest formed by the pterygoid processes of the Basisphenoid and the Palatine bones | The medial surface of the Ramus of the mandible | |
| M. Pterygoideus lateralis | The pterygoid process of the Sphenoid bone | Rostral border of the condyle of the Mandible | To draw and move the mandible rostrally |
| M. Digastricus | The jugular process of Occipital bone | Medial surface of the ventral border of the molar part of the body of the Mandible | Open the mouth |
| M. Occipitomandibularis | The jugular process | The caudal border of the ramus of the Mandible |
Muscles of Eyes[edit | edit source]
| Muscle | Origin | Insertion | Action | Innervation |
|---|---|---|---|---|
| M. Orbicularis oculi | Palpebral branch of CN VII | |||
| M. Levator palpebrae superioris | Posterior orbit | Fibers of the orbicularis oculi muscle of the upper eyelid | Elevate the upper eyelid | CN III, the oculomotor nerve |
| M. Malaris | Orbicularis oculi fibers of the lower eyelid | Lower the ventral eyelid | CN VII (facial nerve) | |
| Muller's muscle | Sympathetic nerves | |||
| Ciliary muscles | ||||
| M. Retractor anguli | Retracts and anchors the Lateral canthus | |||
| M. Levator anguli oculi medialis | Slight elevation of the upper eyelid | |||
| M. Frontalis |
Muscles of Tongue[edit | edit source]
The equine tongue is made up of twelve different muscles[8] including styloglossus, genioglossus and hyoglossus. These muscles are covered by mucosa on the sides and underneath.
The tongue’s action: Prehension, Mastication or Chewing.
Innervation: Hypoglossus (CNXII)
Muscles of Pharynx and Soft palate.[edit | edit source]
| Muscle | Origin | Insertion | Action | Innervation | |
|---|---|---|---|---|---|
| INTRINSIC MUSCLES | |||||
| M. Tensor veli palatini | Muscular process of the petrous part of the Temporal bone, Pterygoid bone, and Lateral lamina of the Auditory tube | Palatine aponeurosis | Retracts the soft palate away from the Dorsal pharyngeal wall, expanding the nasopharynx and slightly depressing it ventrad during inspiration | Mandibular branch of the Trigeminal nerve | |
| M. Levator veli palatini | Muscular process of the Petrous part of the Temporal bone and the lateral lamina of the Auditory tube and passes along the lateral wall of the Nasopharynx | Soft palate dorsal to the glandular layer | Elevates the soft palate during swallowing | Pharyngeal branch of the Vagus nerve | |
| M. Palatinus | Caudal aspect of the palatine aponeurosis | Caudal free margin of the soft palate | Shorten the soft palate and depress it toward the tongue | ||
| M. Palatopharyngeus | Palatine aponeurosis and from the palatine and Pterygoid bones | Upper edge of the Thyroid cartilage | |||
| M. Stylopharyngeus | Rostral | Medial surface of the rostral end of the Stylohyoid bone | Pharyngeal raphe | Pharyngeal constrictor | Glossopharyngeal nerve |
| Caudal | Medial aspect of the caudal third of the Stylohyoid bone | Dorsolateral wall of the pharynx | Pharyngeal dilator | ||
| EXTRINSIC MUSCLES | |||||
| M. Genioglossus | Median plane of the Tongue | Oral surface of the Mandible | Protracts the tongue | Hypoglossal nerve | |
| M. Geniohyoideus | Medial surface of the Mandible | Basihyoid bone | Protrudes the tongue | ||
| M. Thyrohyoideus | Lateral lamina of the Thyroid cartilage | Caudal aspect of the Thyrohyoid bone | Move the larynx rostrad | ||
| M. Hyoglossus | Hyoid bones | Median plane of the Dorsum of the tongue | Retract and depress the base of the tongue | ||
| M. Hyoepiglotticus | |||||
| M. Styloglossus | Lateral aspect of the stylohyoid bone | Tip of the tongue | Retraction of the tongue | ||
| M. Sternohyoideus | Sternal manubrium | Basihyoid bone and lingual process of the Hyoid apparatus | Caudal traction | Branches of the first and second Cervical nerves | |
| M. Sternothyroideus | Caudolateral aspect of the Thyroid cartilage | ||||
Muscles of Hyoid apparatus and Larynx[edit | edit source]
Muscles of Hyoid apparatus and Larynx are innervated by CNX.
Hyoid apparatus[edit | edit source]
Muscles are attached to the hyoid apparatus; the contraction of these muscles determine the position and shape which in turn determines the shape of the larynx and nasopharynx. The hyoid apparatus has muscular connections from the throat to the forelimbs, shoulder, and sternum. Sterohyoid and omohyoid provide a direct connection from the hyoid apparatus to the shoulder of the horse via the ventral neck. The tongue connects to the hyoid apparatus. Small muscles of the hyoid apparatus connect to the TMJ and the poll and the TMJ articulates with the hyoid apparatus.[11][12]
Larynx[edit | edit source]
Intrinsic muscles:
- Cricoarytenoideus dorsalis: Abduction of arytenoids and tensing of vocal chords.
- Thyroarytenoideus: Adduction of arytenoids.
- Arytenoideus transversus: Adduction of arytenoids.
- Cricoarytenoideus lateralis: Adduction of arytenoids.[13]
Muscles of Cervical spine[edit | edit source]
| Muscle | Origin | Insertion | Action | Innervation | |
|---|---|---|---|---|---|
| M. Omotransversarius | Fascia of shoulder | Scapular cartilage and transverse processes of C2-4 | Advances limb
Adducts limb Moves neck laterally |
Ventral branch of Local cervical spinal nerve | |
| M. Brachiocephalicus | Mastoid process of temporal bone and first cervical vertebra | Deltoid tuberosity and crest of the humerus | Shoulder extension
Protraction Fexion the neck towards the side of the protracting limb. |
Accessory nerve | |
| M. Cleidobrachialis | Inscription of clavicle | Crest of the humerus | Advances limb
Adducts limb |
Axillary nerve | |
| M. Cleidomastoideus | Clavicular intersection | Mastoid process of temporal bone | Advances limb
Flexes neck Turns head |
Ventral branch of Accessory nerve
(cranial nerve XI) | |
| M. Sternocephalicus
(Sternomandibularis) |
Manubrium of the sternum | Caudal border of mandible | Turns head
Opens mouth | ||
| M. Omohyoideus | Subscapular fascia | Lingual process of basihyoid bone | Retracts basihyoid bone and tongue | Spinal nerve C1 | |
| M. Trapezius | Nuchal ligament and supraspinous ligaments of C2-10 | Cervical part: Entire scapular spine | Advances thoracic limb
Abducts thoracic limb Elevates shoulder |
Dorsal branch of Accessory nerve
(cranial nerve XI) | |
| Thoracic part: Dorsal third of scapular spine | |||||
| M. Rhomboideus
(cervicis and thoracis) |
Nuchal ligament and dorsoscapular ligaments of C2-T8 | Scapular cartilage | Elevates neck
Draws scapula cranially and dorsally |
Local thoracic nerve and Local cervical nerve | |
| M. Serratus ventralis (cervicis) | Transverse processes of C4-7 | Scapular cartilage and medial scapula | Supports trunk between forelimbs
Raises neck when limb is fixed |
Ventral branch of Local ervical nerve | |
| M. Splenius
(capitus and cervicis) |
Nuchal ligament and spinous processes of T3-T5 | Nuchal crest and mastoid process of temporal bone | Extends neck
Elevates neck Bends neck laterally |
Dorsal branch of Accessory nerve and Dorsal branch of Local spinal nerve | |
| M. Longissimus
(cervicis, capitus, atlantis) |
Transverse processes of cervical and thoracic vertebrae | Wing of Atlas and mastoid process of temporal bone | Elevates head and neck
Bends head and neck laterally Stabilizes and extends vertebral column |
Dorsal branch of Local spinal nerve | |
| M. Semispinalis capitis | Articular processes of C2/3-7 and transverse processes of T1-6/7 | Occipital bone | Elevates head and neck
Bends head and neck laterally | ||
| M. Longus capitis | Transverse processes of C3-5 | Base of skull | Bends head and neck | Ventral branch of Local spinal nerve | |
| M. Longus colli | Cervical part | Transverse processes of C3-7 | Ventral tubercle of Atlas and Bodies of Cervical vertebrae | Flexes head | |
| Thoracic part | Bodies of T1-6 | Transverse processes of C6-7 | Flexes head
Bends head laterally | ||
| M. Obliqus capitis caudalis | Spinous process of the axis | Wing of the Atlas | Rotates atlas and Head | Dorsal branch of C2 | |
| M. Rectus capitis dorsalis | Major | Nuchal crest | Elevates head | Dorsal branch of C1 | |
| Minor | Dorsal arch of the Atlas | Occipital bone | |||
| M. Scalenes | Transverse processes of the last 4 cervical vertebrae | Anterior border and Outer surface of first rib | Assists inspiration by drawing the first rib forward.
With the rib fixed, draws the neck downward and to one side. |
Cervical nerves | |
Muscles of Trunk[edit | edit source]
| Muscles | Origin | Insertion | Action | Innervation | |
|---|---|---|---|---|---|
| M. Latissimus dorsi | Supraspinous ligaments from T3 and Thoracolumbar fascia | Teres major tuberosity of Humerus | Flexes shoulder and draws limb caudally.
Draws trunk cranially when limb is flexed. |
Thoracodorsal nerve | |
| M. Serratus ventralis
(thoracis) |
Ribs 1-8/9 | Scapular cartilage and Medial scapula | Supports trunk between forelimbs.
Raises neck when limb is flexed. |
Long thoracic nerve | |
| M. Serratus dorsalis | Cranialis | Supraspinous ligament | Cranial border of Ribs 5-11 | Inspiration | Intercostal nerve |
| Caudalis | Thoracolumbar fascia | Caudal borders of Ribs 11-18 | Expiration | ||
| M. External intercostal | Muscles run caudodorsally in the intercostal spaces | Inspiration | Intercostal nerve | ||
| M. Internal intercostal | Muscles run cranioventrally in the intercostal spaces | Expiration | |||
| M. External abdominal oblique | Thoracolumbar fascia and Lateral aspect of Ribs 4-18 | Linea alba
Prepubic tendon Pelvic tendon Coxal tendon Inguinal ligament |
Flexes trunk | Ventral branch of Lumbar nerve and Local intercostal nerve | |
| M. Internal abdominal oblique | Coxal tuber and Inguinal ligament | Linea alba
Prepubic tendon Last rib Cartilages of ribs 14-18 |
Flexes the trunk | Ventral branches of Lumbar nerve and Local intercostal nerve | |
| M. Transversus abdominis | Medial surface of Costal cartilage 7-18 and Transverse processes of Lumbar vertebrae | Linea alba | |||
| M. Rectus abdominis | Lateral surface of Costal cartilages 4-9 | Prepubic tendon and the Head of the femur | Flexes the trunk
Flexes lumbar spine and lumbosacral joint | ||
| M. Longissimus thoracis et lumborum | Spinous processes of Thoracic, Lumbar and Sacral vertebrae and Wing of Ilium | Transverse processes of Vertebrae and Tubercles of Ribs | Stabilizes and extends vertebral column | Dorsal branch of Local spinal nerve | |
| M. Semispinalis thoracis and lumborum | Sacrum, the articular processes of the lumbar vertebrae and the transverse processes of the dorsa vertebrae | Spinous processes of third or fourth vertebra in front of the one from which it arises | Fixes the bone during the action of the large spinal muscle, and assists in spine extension | ||
| M. Iliocostalis thoracis and lumborum | Transverse processes of vertebrae | Bodies of the adjacent vertebrae and/or the tuberosities of the ribs | Expiration
Thoracolumbar extension | ||
| M. Cutaneous trunci | Superficial trunk fascia | Superficial shoulder fascia and medial surface of Humerus | Moves the skin of the abdomen | Lateral thoracic nerve and Intercostobrachial nerve | |
| M. Multifidus lumborum | Articular processes of each vertebra fromC2 to sacrum | Spinous process of the preceding vertebrae | Stabilizes and rotates vertebral column | Dorsal branches of Local spinal nerve | |
| M. Psoas major | Lumbar transverse processes and Ventral surface of the last two ribs | Lesser trochanter of Femur | Rotates pelvic limb outward
Flexed hip Advances limb Stabilizes vertebral column when limb is fixed |
Ventral branches of Lumbar and Local Intercostal nerve and Lumbar plexus | |
References[edit | edit source]
- ↑ King, Christine, BVSc, MACVSc, and Mansmann, Richard, VMD, PhD. "Equine Lameness." Equine Research, Inc. 1997.
- ↑ Riegal, Ronald J. DVM, and Susan E. Hakola RN. Illustrated Atlas of Clinical Equine Anatomy and Common Disorders of the Horse Vol. II. Equistar Publication, Limited. Marysville, OH. Copyright 2000.
- ↑ Budras, K. Sack, W.O., Anatomy of the Horse, 6th Edition (2012), Schlutersche Verlagsgesellschaft mbH & Co. KG
- ↑ Baines EA, Grandage J, Herrtage ME, Baines SJ. Radiographic definition of the anticlinal vertebra in the dog. Veterinary Radiology & Ultrasound. 2009 Jan;50(1):69-73.
- ↑ 5.0 5.1 Aiello SE, Moses MA, Allen DG, editors. The Merck veterinary manual. Whitehouse Station, NJ, USA: Merck; 1998.
- ↑ Gilger BC, Stoppini R. Diseases of the eyelids, conjunctiva, and nasolacrimal system. GILGER BC. 2005.
- ↑ Brooks DE, Matthews AG. Equine ophthalmology. Veterinary ophthalmology. 1999;2:1108.
- ↑ Nicole Kitchener. Horse Sport. Available fromhttps://horsesport.com/magazine/health/horse-tongues-101/ [last accessed 01/05/2021]
- ↑ Norm G. Ducharme, Jonathan Cheetham, Equine Surgery (Fifth Edition), 2019
- ↑ Derksen FJ. Overview of upper airway function. InEquine Surgery 2012 Jan 1 (pp. 530-536). WB Saunders.
- ↑ Cornelisse CJ, Rosenstein DS, Derksen FJ, Holcombe SJ. Computed tomographic study of the effect of a tongue-tie on hyoid apparatus position and nasopharyngeal dimensions in anesthetized horses. American journal of veterinary research. 2001 Dec 1;62(12):1865-9.
- ↑ Chalmers HJ, Cheetham J, Yeager AE, Ducharme NG. Ultrasonography of the equine larynx. Veterinary Radiology & Ultrasound. 2006 Sep;47(5):476-81.
- ↑ Kelly PG. Studies on serial resting and dynamic endoscopic examination of thoroughbred yearlings (Doctoral dissertation, University of Glasgow).
- ↑ Payne RC, Veenman P, Wilson AM. The role of the extrinsic thoracic limb muscles in equine locomotion. Journal of Anatomy. 2005 Feb;206(2):193-204.
- ↑ Wikivet. Online Veterinary Encyclopedia. Thoracic Limb Extrinsic Muscles - Horse Anatomy. Available from https://en.wikivet.net/Thoracic_Limb_Extrinsic_Muscles_-_Horse_Anatomy#:~:text=Innervation%3A%20Dorsal%20and%20ventral%20branches,cervical%20and%207th%20thoracic%20vertebrae [last accessed 01/05/2021]
