33 Tarsus & Foot

Bones of the Foot

Fig. 33.1 Subdivisions of the pedal skeleton
Right foot, dorsal view. Descriptive anatomy divides the skeletal elements of the foot into the tarsus, metatarsus, and forefoot (antetarsus). Functional and clinical criteria divide the pedal skeleton into hindfoot, midfoot, and forefoot.

Fig. 33.2 Bones of the foot

Articulationes Pedis (I)

Fig. 33.3 Articulationes pedis
Right foot with art. talocruralis in plantar flexion.

Fig. 33.4 Proximal articular surfaces
Right foot, proximal view.

Fig. 33.5 Distal articular surfaces
Right foot, distal view.

Articulationes Pedis (II)

Fig. 33.6 Artt. talocruralis and subtalaris
Right foot. The os talocruralis is formed by the distal ends of the tibia and fibula (ankle mortise) articulating with the trochlea of the talus. The art. subtalaris consists of an anterior and a posterior compartment (the artt. talocalcanea and talocalcaneonavicularis, respectively) divided by the lig. talocalcaneum interosseum (see p. 452).

Fig. 33.7 Articulationes talocruralis and subtalaris: Sagittal section
Right foot, medial view.

Fig. 33.8 Articulatio talocruralis
Right foot.

Articulationes Pedis (III)

Fig. 33.9 Articulatio subtalaris and ligaments
Right foot with opened art. subtalaris. The art. subtalaris consists of two distinct articulations separated by the lig. talocalcaneum interosseum: the posterior compartment (art. talocalcanea) and the anterior compartment (art. talocalcaneonavicularis).

Fig. 33.10 Talus and calcaneus
The two tarsal bones (ossa tarsi) have been separated at the art. subtalaris to demonstrate their articular surfaces.

Ligaments of the Tarsus & Foot

The ligaments of the foot are classified as belonging to the art. talocruralis, art. subtalaris, metatarsus, forefoot, or planta pedis. The ligg. collateralia mediale and laterale, along with the ligg. syndesmosis tibiofibularis, are of major importance in the stabilization of the art. subtalaris.

Fig. 33.11 Ligaments of the tarsus and foot
Right foot. See p. 452 for inferior view.

Table 33.1 Ligaments of the articulatio talocruralis

Lig. collaterale laterale	Lig. talofibulare anterius
	Lig. talofibulare posterius
	Lig. calcaneofibulare
Lig. collaterale mediale	Lig. deltoideum	Pars tibiotalaris anterior
		Pars tibiotalaris posterior
		Pars tibionavicularis
		Pars tibiocalcanea
Ligg. syndesmosis tibiofibularis	Lig. tibiofibulare anterius
	Lig. tibiofibulare posterius

Plantar Vault & Arches of the Foot

Fig. 33.12 Plantar vault
Right foot. The forces of the foot are distributed among two lateral (fibular) and three medial (tibial) rays. The arrangement of these rays creates an arcus longitudinalis and arcus transversi in the planta pedis, helping the foot absorb vertical loads.

Fig. 33.13 Stabilizers of the arcus pedis transversus
Right foot. The arcus pedis transversi are supported by both active and passive stabilizing structures (muscles and ligaments, respectively). Note: The arch of the forefoot has only passive stabilizers, whereas the arcus pedis transversus distalis and proximalis have only active stabilizers.

Fig. 33.14 Stabilizers of the arcus pedis longitudinalis
Right foot, medial view.

Muscles of the Planta Pedis

Fig. 33.15 Aponeurosis plantaris
Right foot, plantar view. The aponeurosis plantaris is a tough aponeurotic sheet, thickest at the center, that blends with the fascia dorsalis pedis (not shown) at the borders of the foot.

Fig. 33.16 Intrinsic muscles of the planta pedis
Right foot, plantar view.

Muscles & Vaginae Tendinum of the Foot

Fig. 33.17 Deep intrinsic muscles of the planta pedis
Right foot, plantar view.

Fig. 33.18 Vaginae tendinum and retinacula of the ankle
Right foot. The retinacula musculorum extensorum superius and inferius retain the long extensor tendons, the retinacula musculorum fibularium hold the mm. fibulares tendons in place, and the retinaculum musculum flexorum retains the long flexor tendons.

Muscle Facts (I)

The dorsal surface (dorsum pedis) of the foot contains only two muscles, the m. extensor digitorum brevis and the m. extensor hallucis brevis. The planta pedis, however, is composed of four complex layers that maintain the arches of the foot.

Fig. 33.19 Intrinsic muscles of the dorsum pedis
Right foot, dorsal view.

Fig. 33.20 Superficial intrinsic muscles of the planta pedis
Right foot, plantar view.

Muscle Facts (II)

Fig. 33.21 Deep intrinsic muscles of the planta pedis
Right foot, plantar view, schematics.

Fig. 33.22 Deep intrinsic muscles of the planta pedis
Right foot, plantar view.