Ruminant Head and Horn

What is the dental formula for adult cattle?

2(I 0/3, C 0/1, P 3/3, M 3/3) = 32

What is the dental formula for adult sheep and goats?

2(I 0/4, C 0/0, P 3/3, M 3/3) = 32

What structure do ruminants have instead of upper incisors?

A dental pad

At what age do cattle typically have all their permanent incisors?

4-5 years old

What is the term for when a ruminant has lost some of its incisor teeth?

Broken mouth

Which muscle is divided into two layers in ruminants, with horizontal and vertical fibers?

Masseter muscle

Which nerve supplies the muscles of the external ear and eyelids in ruminants?

Auriculopalpebral nerve

What is the consequence of damage to the auriculopalpebral nerve?

Drooping of the ear and sagging of the eyelids

Which branch of the facial nerve supplies the muscles of the nose and upper lip in ruminants?

Dorsal buccal branch

What is the main consequence of injury to the dorsal buccal branch of the facial nerve?

Distortion of the face, pulled towards the unaffected side

Where is the mandibular lymph node located in ruminants?

In the angle of the jaw

What is the function of the infraorbital pouch in sheep and goats?

It contains a sebaceous gland

What structure do goats have on the medial aspect of each horn?

A sebaceous gland

What is the function of the nasolabial plate in cattle?

It is kept moist by eccrine glands and has a unique pattern like a nose print

How many permanent teeth do ruminants have?

32

What is the term for teeth with long crowns that continue to erupt?

Hypsodont teeth

What is the typical chewing pattern in ruminants?

Unilateral with three phases: drop and lateral movement, raise and further lateral movement, swift upward and medial movement

Which muscles are most important for the work stroke during mastication in ruminants?

Pterygoids of the active side and masseter of the passive side

What is the function of the dental pad in ruminants?

It meets with the mandibular incisors for grasping food

What is the term for the space between the incisors and premolars in ruminants?

Diastema

How are the cheek teeth arranged in ruminants?

They increase in size from rostral to caudal

What is the typical slope of the masticatory surfaces of ruminant cheek teeth?

The buccal edge is raised on maxillary teeth, the lingual edge on mandibular teeth

What is the function of the alternating soft and hard tissues on worn ruminant teeth?

It creates an efficient shredding tool

What is the main nerve supplying the sensitive dermis of the horn in cattle?

The cornual nerve

Where does the cornual nerve originate?

Within the orbit

What is the landmark for blocking the cornual nerve in cattle?

Upper third of the lateral temporal ridge of the frontal bone, 2-3 cm in front of the base of the horn

Which nerve is blocked to anaesthetize the nose and upper lip for placing a bull nose ring?

The infraorbital nerve

Where is the auriculopalpebral branch of the facial nerve blocked?

Where the supraorbital process of the frontal bone meets the zygomatic arch

What is the main lymphoid tissue in the nasopharynx?

The pharyngeal tonsil

Where is the palatine tonsil located?

Within the lateral wall of the oropharynx

Which lymph node collects lymph from most of the head in ruminants?

The parotid lymph node

What is the collecting center for the entire head's lymph drainage?

The lateral retropharyngeal lymph node

Where is the superficial cervical (prescapular) lymph node located?

Cranial to the shoulder, on the deep muscles of the cervical vertebrae

What is the function of horns in ruminants?

Attack, defense, maintaining social hierarchy, and foraging

At what age does an extension from the frontal sinus typically invade the cornual process in cattle?

Around 6 months old

What is the name for breeds with more than two pairs of horns?

Polycerate

Which artery supplies blood to the horn?

The cornual artery

Why is it difficult to achieve hemostasis when dehorning cattle?

The arteries retract when severed and cannot be easily grasped

What is the largest and most clinically relevant frontal sinus compartment?

The caudal compartment

What is a common sequel to dehorning in cattle?

Inflammation of the frontal sinus mucosa

How do the frontal sinuses differ in sheep compared to cattle?

Sheep have separate medial and lateral compartments

What parasitic condition commonly affects the frontal sinuses in sheep?

Invasion by larvae of the nasal bot fly

Where is the thymus located in young ruminants?

Extends from the larynx to the pericardium

Additional questions:

What is the typical shape of goat horns in cross-section?

Oval

How do sheep horns typically grow?

In a helical course

What creates the corrugated surface of horn growth in small ruminants?

Intermittent growth, particularly with changing seasons

At what age does the thymus reach its greatest relative size in ruminants?

Very early in life, before 6-9 months

What is the process called when the thymus regresses with age?

Involution