Anatomy Revision Papers. Part 4. Internal Structure of the Foot

Size: px

Start display at page:

Download "Anatomy Revision Papers. Part 4. Internal Structure of the Foot"

Alan Spencer
5 years ago
Views:

1 Anatomy Revision Papers Part 4 Internal Structure of the Foot Page 2 Page 3 Page 4 Page 5 Page 5 Page 6 Page 6 Page 6 Sagittal Section of the Foot Frontal Section of Foot Ligaments within the foot Corium of the Foot ( Dermis) Corium of the Foot (3D) Perioplic Corium Coronary Corium Lamina Corium Solar Corium Frog Corium Digital Cushion, Coronary cushion Navicular bursa. (podotrochlear bursa)

2 Sagittal Section of the Foot Fig 1

3 Frontal Section of the Foot Fig 2

4 Internal Structures of the foot The internal foot has its core structure that consists of the bony column which are the middle and distal phalanx, the porpoise of which is to support the weight of the horse. The bones of the lower leg act as leavers that move the limb by the muscles and tendons that are attached to them. Within the foot the Distal Phalanx has attachments from the Deep Digital Flexor Tendon and the Common Digital Extensor Tendon, the Middle Phalanx has attachments from the Superficial Digital Flexor Tendon and the Common Digital Flexor Tendon. Ligament The bones with in the foot are held together by the ligaments of the Distal Interphalangeal joint and the Proximal Interphalangeal joint. These are : Collateral ligament of the Pastern Palmar / Plantar ligament of the Pastern Collateral ligament of the Distal Interphalangeal Joint Navicular Suspensory Ligament, ( Collateral sesamoidean ligament ) Distal impar Ligament

highly vascular and consists of germinative layer.

5 Corium of the Foot ( Dermis) The Corium (dermis) of the foot is the sensitive layer that is a continuation of the skin and covers the whole foot, They are highly vascular and consists of germinative layer. The coria of the foot can be divided into 5 parts. Perioplic Corium Coronary Corium Lamina Corium Solar Corium Frog Corium

6 Perioplic Corium The Perioplic Corium has short curved papillae that produces the Periople as well as continuing to provide nutrition. It lies within the Perioplic groove proximally to the Coronary Corium. At its proximal border it blends with the corium of the skin and continues around the foot, at the heels it blends with the corium of the frog. Coronary Corium The Coronary Corium is positioned distally to the Perioplic Corium and lies in the Coronary Groove. It produces most of the hoof wall from long papillae which insert into the Epidermal Papillae sockets within the stratum medium. It is thicker Dorsally and thins towards the heels where it blends with the Frog Corium. The deep surface is attached to the Collateral Cartilages and the CDET, the blood supply is drain by the Coronary Plexus. The germinative layer that covers the papillae produce Tubular horn and the germinative cell layer between the papillae produce inter tubular horn. Lamina Corium & Sensitive laminae The deep surface of the Lamina Corium blends with the periosteum of the Distal Phalanx, the outer layer of germinal cells do not produce the horn that attaches to them, this is produced by the Coronary Corium. From the periosteum the sensitive laminae are attached with around primary leaves and secondary leaves that are non pigmented and interdigitate with the laminae of the hoof wall and bars, this suspends the Distal Phalanx from the ground taking most of the weight from the wall. At the distal border of the Distal Phalanx there are terminal papillae that produce more horn cells that are also non pigmented that crates the white line.

7 Solar Corium The Solar Corium corresponds the shape of the solar surface of the Distal Phalanx and as it attaches through a modified periosteum that is also highly vascular( has a good Blood Supply). It is often pigmented and has a varying sizes of papillae which produce the horn tubules of the horny sole. Due to the crossing of the papillae and the difference in length, this is what allows the sole to selfexfoliate. At its border with the frog it blends with the Frog Corium. Frog Corium The Frog Corium Is distal the Digital Cushion and has small papilla that insert into sockets within the horny frog. These papillae produce the horny frog from the germinative layer of cells covering the Frog Corium. Other Internal Structures The other internal structures of the foot consists of the Digital Cushion, Coronary cushion, distal impar ligament and the Navicular bursa. The Digital Cushion The Digital cushion is a wedge shape fibro elastic pad that is positioned deep to the solar and frog Coriums. It is made up of Collagen, Elastic Tissue, Cartilage islands and fat. it has a poor blood supply and also contains sweat gland that drain into the central sulcus of the frog. The proximal Palmar / Plantar proportion of the Digital Cushion is called the bulbar cushion as it is divided (Medial / Lateral) to form the heel bulbs. Distal border is firmly attached the Frog Corium and the (Medial / Lateral) aspects attach to the collateral cartilage and the deep surface is attached to the Distal Fibrous sheath of the Deep Digital Flexor Tendon. Its main function is to help is the anti concussions mechanism. Coronary Cushion The Coronary Cushion is situated deep the Coronary Corium and attached to the Coronary Corium and the Common Digital Extensor Tendon as well as the Collateral cartilages and within the Coronary cushion is the Coronary Venous Plexus.

8 Distal impar ligament The Distal impar ligament forms part of the distal interphalangeal joint connecting the Distal Phalanx and the Distal Sesamoid. This short but tough ligament allows for little movement between the two bones. The distal impar ligament also gives way for the 2/3 of the blood supply to the distal Sesamoid, (the is involved in the vascular theory of navicular syndrome ) Navicular bursa (podotrochlear bursa) The Navicular bursa is situated between the Deep Digital Flexor Tendon and the distal Sesamoid, it s a thin fluid filled sack that compose of 2 layer, an inner synovial layer( that produces Synovial fluid) and as outer fibrous layer for strength. This bursa protects both the tendon & bone from friction & abrasion.

Figure 6.1 Transparency Master 37

Figure 6.1 Transparency Master 37 Pore Hair shaft Epidermis Dermal papillae (papillary layer of dermis) Meissner s corpuscle Dermis Free nerve ending Reticular layer of dermis Sebaceous (oil) gland Arrector pili muscle Sensory nerve fiber