Describe the scapula of the Ox in detail.

3 November 2023

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SCAPULA (OX) – LONG TYPE QUESTIONS-1st Year B.V.Sc & A.H (Veterinary Anatomy)

The scapula is classified as a flat bone in anatomy.
Present on the cranial part of the lateral thoracic wall.
It is oriented in a downward and forward direction.
The long axis of the scapula runs obliquely from the 3rd to 4th thoracic spine to the ventral (distal) extremity of the first rib.
Scapula is triangular in shape.
Displaying a triangular outline, it features two surfaces, three borders, and three angles.

1. Lateral surface

The lateral surface of the scapula is divided into two fossae by its spine.
The supraspinous fossa is positioned cranially to the spine, while the infraspinous fossa is located caudally.
A rudimentary prominence (tuber), known as the tuberosity of the spine (Tuber spine), is present at its midpoint, serving as the attachment site for the trapezius muscle.
The spine extends further into a pointed projection known as the acromion, which serves as the origin point for a portion of the deltoideus muscle.
Supraspinous fossa:
The supraspinous fossa, the smaller of the two, is smooth and houses the supraspinatus muscle.
Infraspinous fossa:
The infraspinous fossa accommodates the infraspinatus muscle.

The medial surface features a subscapular fossa (shallow) that runs its length.
Subscapular fossa:
The subscapular fossa occupies the majority of the ventral part of the surface, providing space for the subscapularis muscle.
Dorsally , it separates two rough triangular areas, facies serrata, where the serratus ventralis muscle attaches.
The cranial triangular area is designated for the attachment of the serratus cervicis muscle.
The caudal triangular area is intended for the attachment of the serratus thoracis muscle.

The caudal border is thick and convex.
The nutrient foramen is typically located in the ventral third of the caudal border.
3. Dorsal border:
The dorsal border carries the scapular cartilage.
The cartilage, an unossified part of the fetal scapula, fits into these depressions and elevations.

Angles of scapula (cranial, caudal, ventral):
1. Cranial angle:
The cranial angle is located at the junction of the cranial and dorsal borders.
It is relatively thin and approaches a right angle.
2. Caudal angle:
The caudal angle is thick and rough.
It is formed by dorsal border and caudal border.
3. Ventral angle:
It bears glenoid cavity and supraglenoid tubercle (tuber scapulae).
In oxen, the glenoid cavity is nearly circular without a distinct notch.
Glenoid cavity articulates with head of humerus.
The supraglenoid tubercle (tuber scapulae) in oxen is small and close to the glenoid cavity.
The tendon of origin of the biceps brachii muscles arises from tuber scapulae.
The short and rounded coracoid process, from which the coracobrachialis muscle arises, projects from the medial side of the tuber scapulae.