Lower leg and foot (raw anatomy, own notes)

Question 1

List and describe the muscles of the anterior compartment of he lower leg

Answer 1

Tibialis anterior:

• Attachments: Originates from the lateral surface of the tibia and attaches to the medial cuneiform and the base of metatarsal I
• Actions: Dorsiflexion and inversion of the foot
• Innervation: Deep fibular nerve (L4-5)

Extensor hallucis longus:
- Origin – middle half of anterior surface of fibula and adjacent interosseous membrane
- Insertion – base of distal phalanx of first toe
- Innervation – Peroneal nerve, L5-S1
- Action – extends interphalangeal joint and assists in extension of metatarsophalangeal joint of the first toe

Extensir digitorum longus:
- Origin – lateral condyle of tibia, proximal 3/4 of anterior surface of fibula and proximal interosseous membrane
- Insertion – by four tendons, one to each of toes 2-5, divides into an intermediate slip attached to the base of the middle phalanx and two lateral slips attached to the base of distal phalanx
- Innervation – Peroneal nerve, L4-5-S1
- Action – extends interphalangeal joint and the metatarsophalangeal joint of the first toe. Assists in dorsiflexion of the ankle joint and eversion of the foot

Question 2

Describe the muscles of the lateral lower leg

Answer 2

Peroneus longus
- Origin – head and proximal 2/3 of lateral surface of fibula
- Insertion – lateral side of the base of the first metatarsal and medial cuneiform
- Innervation – superficial peroneal nerve, L5-S1
- Action – eversion of the foot and assistance in plantar flexion of the ankle

Peroneus brevis
- Origin – distal 2/3 of lateral surface of fibula
- Insertion – base of the fifth metatarsal
- Innervation – superficial peroneal nerve, L5-S1
- Action – eversion of the foot and assistance in plantar flexion of the ankle

Question 3

Describe the muscles of posterior lower leg

Answer 3

Tibialis posterior
- Origin – most of the interosseous membrane, lateral portion of the posterior surface of the tibia, proximal 2/3 medial surface of the fibula
- Insertion – mainly the tuberosity of the navicular
- Innervation – Tibial nerve, L5-S1
- Action – Inversion of the foot and assists in plantar flexion of the ankle

Flexor hallucis longus
- Origin – posterior surface distal 2/3 fibula and interosseous membrane
- Insertion – plantar surface of the base, distal phalanx, 1st toe
- Innervation – Tibial nerve, S2-3
- Action – Flexes distal phalanx of the first toe and assists in plantar flexion of the ankle and inversion of the foot

Flexor digitorum longus
- Origin – posterior surface of tibia, distal to the soleal line
- Insertion – Plantar surfaces of the bases of the distal phalanges of the 2nd to 5th toes
- Innervation – Tibial nerve, S2-3
- Action – Flexes distal phalanges of toes 2-5 and assists in plantar flexion of the ankle and inversion of the foot