- Tibia and fibula
- Tarsal bones of the hock
- Three metacarpals (cannon and splint bones)
- Long pastern (first phalanx)
- Short pastern (second phalanx)
- Pedal bone (third phalanx)
- Two sesamoid bones
- Navicular bone (also a type of sesamoid bone).
Pelvic girdle (Fig. 4.3)
The pelvic girdle consists of the sacrum comprising fused sacral vertebrae, two pelvic bones, and the first three coccygeal vertebrae. Each pelvic bone (os coxae) is made up of three flat bones, the ilium, pubis and ischium, which are fused into one. All three bones meet at the acetabulum which articulates with the head of the femur to form the hip joint.
The ilium is the largest of the three bones making up the os coxae; its outermost angle is seen as the point of the hip or tuber coxae, and the internal angles (tuber sacrale) of the two ilia together form the croup at the highest point of the hindquarters immediately behind the loins. The ilium attaches to the sacrum at the sacroiliac joint, a combined synovial and fibrocartilagenous joint which is supported by ventral, dorsal and lateral sacroiliac ligaments (see Chapter 6).
This bone forms the front of the pelvic floor; the right and left pubis meet at the pelvic symphysis which ossifies with age.
This bone forms the rear part of the pelvis; its thickened end is known as the tuber ischii and forms the point of the buttock.
Femur (Figs 4.4–4.6)
The femur is a very strong bone between the hip joint and the stifle joint and is adapted for the attachment of the muscles of the hindquarter.
The hock or tarsus consists of six or seven short, flat tarsal bones arranged in three rows. In the upper row are the talus and calcaneus: in the middle row is the central tarsus and below that the fused first and second tarsal and the third tarsal. The fourth tarsal occupies both the middle and lower row.
The patella is a sesamoid bone associated with the stifle and is the equivalent of the human kneecap.
Point of hock
The long bony process, the tuber calcis of the calcaneus, gives rise to the point of the hock and guides the Achilles tendon of the gastrocnemius muscle over the hock, allowing tremendous leverage.
The tibia is a long bone running down and back between the stifle and the hock joints. The upper end provides attachment for the muscles acting on the hock and lower limb. The horse’s fibula is so reduced in size as to be practically vestigial.
Lower limb (Fig. 4.7)
Below the hock the anatomical arrangement is the same as in the forelimb.