Sole of foot |Anatomy| Ashwini sir|

Summary

This video provides an in-depth exploration of the anatomy of the sole of the foot, focusing on its four layers: superficial to deep. It discusses the muscles, including abductor hallucis, flexor digitorum brevis, lumbricals, and interossei, and their nerve supply by the medial and lateral plantar nerves. The video also explains the role of tendons like flexor hallucis longus and flexor digitorum longus, and the functions of the muscles in movement such as flexion, abduction, and adduction. A key takeaway is the progressive dominance of the lateral plantar nerve as you move deeper into the foot's anatomy.

Takeaways

• 😀 The foot's sole is divided into four layers, with each layer containing specific muscles and tendons. These layers are important for understanding the anatomy and function of the foot.
• 😀 The medial and lateral plantar nerves supply different muscles in the foot. The lateral plantar nerve becomes more dominant as you move deeper into the foot.
• 😀 The first layer of the foot consists of three muscles: abductor hallucis, abductor digiti minimi, and flexor digitorum brevis, with the lateral plantar nerve only supplying the abductor digiti minimi.
• 😀 The second layer contains two tendons (from flexor hallucis longus and flexor digitorum longus) and two muscles: quadratus plantae and the lumbricals. The lumbricals differ from those in the hand, with the first being unipinnate and the rest being bipinnate.
• 😀 The second layer of the sole shows a progression where the lateral plantar nerve dominates over the medial plantar nerve, with the first lumbrical being the only muscle supplied by the medial plantar nerve.
• 😀 The third layer contains three muscles: flexor hallucis brevis, flexor digiti minimi brevis, and adductor hallucis. Adductor muscles are always supplied by the dominant lateral plantar nerve.
• 😀 The fourth layer consists of the interossei muscles, which include three plantar interossei (unipinnate) and four dorsal interossei (bipinnate). All interossei are supplied by the lateral plantar nerve.
• 😀 The second digit (not the third) is the axis for abduction and adduction in the foot, just as the middle finger is the axis in the hand.
• 😀 The flexor digitorum longus tendon runs obliquely in the foot, and the quadratus plantae (flexor digitorum accessorius) corrects the angle of pull to prevent excessive medial flexion of the toes.
• 😀 As you progress deeper into the layers of the sole, the lateral plantar nerve gradually takes over more of the muscle innervation, especially in the deeper layers, highlighting its dominance in the foot's neurovascular supply.

Q & A

What are the four layers of muscles in the sole of the foot?

The four layers of muscles in the sole of the foot are: 1) First layer: Abductor hallucis, Abductor digiti minimi, and Flexor digitorum brevis, along with plantar aponeurosis. 2) Second layer: Two tendons (Flexor hallucis longus and Flexor digitorum longus) and two muscles (Quadratus plantae and Lumbricals). 3) Third layer: Flexor hallucis brevis, Flexor digiti minimi brevis, and Adductor hallucis. 4) Fourth layer: Dorsal and plantar interossei muscles.

What is the dominant nerve of the foot?

The dominant nerve of the foot is the lateral plantar nerve (LPN). This nerve's dominance increases as we go deeper into the layers of the sole, starting from the second layer.

Which muscles in the first layer of the foot are supplied by the lateral plantar nerve?

In the first layer of the foot, only the Abductor digiti minimi is supplied by the lateral plantar nerve (LPN). The other two muscles, Abductor hallucis and Flexor digitorum brevis, are supplied by the medial plantar nerve (MPN).

Why is the lateral plantar nerve considered the dominant nerve in the foot?

The lateral plantar nerve is considered the dominant nerve in the foot because it supplies a majority of the muscles, particularly from the second layer onwards. The medial plantar nerve primarily supplies the first layer and some muscles in the second layer.

What is the function of the Quadratus plantae muscle in the second layer of the foot?

The Quadratus plantae muscle corrects the oblique line of pull of the Flexor digitorum longus tendon, ensuring the toes flex straight instead of medially. It also helps in the inversion of the foot by pulling the tendon laterally.

How are the lumbricals in the foot different from those in the hand?

The lumbricals in the foot are different from those in the hand in terms of their structure and nerve supply. In the foot, the first lumbrical is unipinate, while the second, third, and fourth are bipinate. The bipinate lumbricals are supplied by the dominant nerve, the lateral plantar nerve, while the first unipinate lumbrical is supplied by the medial plantar nerve.

How is the second digit important in terms of adduction and abduction in the foot?

The second digit serves as the axis for adduction and abduction in the foot. Movements toward the second digit are considered adduction, while movements away from it are considered abduction. This is similar to the middle finger being the axis in the hand.

What muscles are found in the third layer of the foot?

The third layer of the foot contains three muscles: Flexor hallucis brevis, Flexor digiti minimi brevis, and Adductor hallucis. The Adductor hallucis has two heads: an oblique head and a transverse head.

What are the two types of interossei muscles found in the fourth layer of the foot?

The fourth layer of the foot contains two types of interossei muscles: plantar interossei (3 muscles) and dorsal interossei (4 muscles). The plantar interossei are unipinate, while the dorsal interossei are bipinate. All interossei muscles are supplied by the lateral plantar nerve.

Which layer of the foot contains the most complex arrangement of muscles?

The second layer of the foot contains the most complex arrangement, with two tendons (Flexor hallucis longus and Flexor digitorum longus) and two muscles (Quadratus plantae and Lumbricals). The muscles originate from the tendons of the deep calf muscles.