The body part which we ignore most is our feet. It carries our whole body mass and plays an important role for in our daily activities.
Do you ever think, you should know little about it? I think everyone should be. From this point of view, I have written this post. It will give you a very basic anatomical knowledge of feet.
Our foot consists of 26 bones, 33 joints, 100+ muscles, tendons & ligaments, artery, and all these are covered by a supportive thick skin.
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Total 26 bones locate in three main portions of our foot: Forefoot, Midfoot, and Hindfoot. It separates into three parts; tarsals, metatarsals, and Phalanges.
Seven tarsal bones locate in two sections (hind-foot, and mid-foot) of our foot. Where hind-foot contains two tarsal bones named talus & calcaneus; and mid-foot contains five metatarsal bones.
[The following two are hindfoot bones]
- Talus: This bone is located in the hindfoot section of the foot. It joins our foot with the upper two bones of lower leg named tibia and fibula. It is one of the bones of the human body that is covered with articular cartilage. The unusual fact of this bone is it contains a retrograde blood supply. Arterial blood enters this bone at its distal end.
- Calcaneus: Calcaneus comes from Latin calcaneus or calcaneum means heel or heel bone. It is the largest bone of the foot. It is located beneath the talus bone. Our heel forms with this calcaneus bone.
[The following five are mid-foot bones]
- Medial Cuneiform 2. Middle Cuneiform 3. Lateral Cuneiform 4. Navicular and 5. Cuboid
Metatarsal bones consist of five long bones. It locates between the tarsal bones and phalanges. There is no separate name of these bones. It is always pointed out as a numerical (depicted as roman numerals) order from the medial side. These metatarsal bones are analogous to the metacarpal bones of the hand.
Phalanges (singular: phalanx)
Phalanges bones from our toes. Toes of foot consist of 14 bones. The big toe has two phalanges; distal and proximal. And each other has three.
Our foot has two types of muscles. And those are extrinsic muscles and intrinsic muscles.
Extrinsic muscles come from various portions of leg and connect with the foot. These muscles help us to perform activities like eversion, inversion, plantarflexion, and dorsiflexion of the foot.
On the flip side, intrinsic muscles located within the foot. These muscles work on all foot activities and movements. They work collectively to form the arches of the foot, and separately to regulate the activities of digits.
Basically, intrinsic muscles are responsible for almost every foot-work. For this article, we only try to know the basic of intrinsic muscles. There are 10 intrinsic muscles in our foot. And they are described as four layers from the plantar view.
The muscles of this layer locate closely beneath the plantar fascia. There are three muscles in this layer. And it is the most superficial layer to the sole.
The three muscles of this layer are abductor hallucis, abductor digiti minimi, and flexor digitorum brevis. Each of these muscles has their own functionality. Let’s see.
- Abductor hallucis muscle works on the great toe. It helps to abduct and flex the great toe.
- Abductor digiti minimi works on the fifth digit or fifth toe from the great toe. It abducts and flexes this toe.
- Flexor digitorum brevis is the big muscle among these three. It flexes the lateral four digits that locate at the proximal interphalangeal joints.
Some nerves innervate within these muscles. And they are medial plantar nerve and lateral plantar nerve.
There are two intrinsic muscles in the second layer. And they are quadratus plantae, and lumbricals. An extrinsic muscle called digitorum longus’s tendons pass through this layer. Let’s talk about the activities of these muscles.
- Digitorum longus muscle tendons control the movement of lateral four digits. And quadratus plantae helps digitorum longus to work well.
- Lumbrical muscles located at the medial to their respective tendon of the flexor digitorum longus. These muscles help to flexes the metatarsophalangeal joints through extending interphalangeal joints.
This layer is innervated by medial plantar nerve and lateral plantar nerve.
There are three muscles locate in the third layer. They are flexor halluces brevis, adductor halluces, and flexor digiti minimi brevis. These muscles work on the toes of the foot.
- Flexor hallucis brevis muscle helps to the movement of the great toe. It flexes the proximal phalanx of the great toe at the metatarsophalangeal joint.
- Adductor halluces muscle abducts the great toe. With this muscle, the foot can create the transverse arch movement.
- And digiti minimi brevis moves the proximal phalanx of the fifth digit.
Medial plantar nerve and lateral plantar nerve pass within this layer. Where medial plantar nerve is associated with flexor hallucis brevis. Deep branch of lateral plantar nerve is associated with adductor halluces muscle. And superfacial branch is associated with digiti minimi brevis muscle.
The fourth layer of intrinsic muscles is made with the plantar and dorsal interossei muscles. These two muscles work differently. The plantar interossei made with unipennate morphology and dorsal interossei made with bipennate.
- There are three plantar interossei muscles in the foot. These muscles adduct digits three to five and help to move the metatarsophalangeal joints.
- There are four dorsal interossei muscles in the foot. And they locate between the metatarsal. These muscles abduct digit two to four and flex the metatarsophalangeal joints.
The only lateral plantar nerve passes within these muscles.
Skin is the outer part of our body. It covers our body and protects from the outer environment. It also does many vital functions such as thermoregulation, sensory perception, immunologic surveillance, resistor of insensible fluid loss, etc.
Our skin have of two layers; dermis and epidermis. These two layers is developed on a subcutaneous layer. These layers have different formation and activities.
The skin of foot sole is little different from the other body parts. This skin part is the thickest skin of the body. It is about 1.5 mm thick. And men’s skin is anatomically thicker than the women.
Sole skin contains more sweat glands and sensory nerve-ending than other body parts. There are 250,000 sweat glands in our feet. It produces approximately half a pint of sweat perspiration every day. Source
Our hand palm and foot sole have prints. Only these skin parts possess these tiny undulating folds. The pattern of our hand and footprint are fully different from man to man. It doesn’t change over time. For this, it is used for person’s identity. And it helps us to grab and walk well with proper traction.