The Foot - Intrinsic Muscles Flashcards
Where are the intrinsic muscles of the foot located? What movements are they responsible for?
The intrinsic muscles are located within the foot and are responsible for the fine motor actions of the foot, for example movement of individual digits.
What 2 groups can the intrinsic muscles of the foot be divided into?
Dorsal and plantar aspect
Which intrinsic muscles are located in the dorsal aspect of the foot?
- Extensor digitorum brevis
- Extensor hallucis brevis
- A group of 4 dorsal interossei (between the metatarsals)
Where does EDB lie?
Lies deep to EDL
Origin and insertion of EDB?
Origin: calcaneus
Inserts: proximal phalanges of digits 2-5
Action of EDB?
Aids the extensor digitorum longus in extending the medial four toes at the metatarsophalangeal and interphalangeal joints.
Innervation of EDB?
Deep fibular nerve
Origin and insertion of EHB?
Origin: calcaneus
Inserts: proximal phalanx of big toe
Action of EHB?
Aids the extensor hallucis longus in extending the great toe at the metatarsophalangeal joint.
Innervation of EHB?
Deep fibular nerve
Where are the 4 dorsal interossei located?
Between the metatarsals. Each arises from two metatarsals.
Origin and insertion of the dorsal interossei?
Originates from the sides of metatarsals one to five. The first muscle attaches to the medial side of the proximal phalanx of the second digit. The second to fourth interossei attach to the lateral sides of the proximal phalanxes of digits two to four.
Action of the dorsal interossei?
Abduct digits two to four and flex the metatarsophalangeal joints.
Innervation of the dorsal interossei?
Lateral plantar nerve
How are the intrinsic muscles of the plantar aspect of the foot arranged?
Arranged in four layers, superficial to deep
What muscles are found in the most superficial layer of the plantar aspect?
Flexor digitorum brevis, abductor hallucis, abductor digiti minimi
What muscles are found in the second most superficial layer of the plantar aspect?
The tendons of FHL and FDL (extrinsic muscles), the lumbricals, quadratus plantae
What muscles are found in the third most superficial layer of the plantar aspect?
Flexor hallucis brevis, flexor digiti minimi and adductor hallucis
What muscles are found in the deepest layer of the plantar aspect of the foot?
The plantar interossei - there are 3 of these
Function of the muscles of the superficial layer of the plantar aspect?
- Abductor Hallucis - abducts and flexes the great toe
- Flexor Digitorum Brevis - Flexes the lateral four digits at the proximal interphalangeal joints.
- Abductor Digiti Minimi - Abducts and flexes the 5th digit.
Function of the second layer of the muscles of the plantar aspect?
- Quadratus Plantae - Assists flexor digitorum longus in flexing the lateral four digits.
- Lumbricals - Flexes at the metatarsophalangeal joints, while extending the interphalangeal joints.
Function of the third layer of the muscles of the plantar aspect?
- Flexor Hallucis Brevis - Flexes the proximal phalanx of the great toe at the metatarsophalangeal joint.
- Adductor Hallucis - Adduct the great toe. Assists in forming the transverse arch of the foot.
- Flexor Digiti Minimi Brevis - Flexes the proximal phalanx of the fifth digit
Function of the deepest layer of muscles of the plantar aspect?
Plantar interossei - Adduct digits three to five and flex the metatarsophalangeal joints.
Where does flexor hallucis longus insert?
Distal phalanx of big toe (sole of foot)
Where does fibularis longus insert?
Sole of the foot –> medial cuneiform and 1st metatarsal
Where does extensor digitorum longus insert?
Dorsum of foot –> distal phalanges of digits 2-5
What is being pointed to?
Subtalar joint - between the calcaneum and talus
Eversion and inversion happens here
What?
Navicular
What?
Cuboid
What?
Lateral cuneiform
The foot can deform according to what surface it is walking on. What is the purpose of this?
Helps to dissipate the forces –> shock absorber
Normal foot xrays
A 50 year old woman presented to her GP with deformity and pain in her feet.
This had been going on for some time, but the pain was now becoming severe and she was finding it painful to wear shoes.
What’s the diagnosis?
Bunions - ‘hallux valgus’
How would you describe the abnormalities seen? What are some causative factors?
- Deformities at the MTP joints of both feet
- Bony protrustion is the head of the first metatarsal
- Causative factors:
- High heels
- Poorly fitting shoes over a long period of time
- Genetic element
A 48 year old man presented to his GP with with sudden onset severe pain, swelling and redness of his left foot, as shown. The patient was hobbling and wearing a flip-flop, as it was too painful for him to put on a shoe or sock.
What’s the diagnosis?
- Gout
- Typically first attack in 1st MTP joint
- Sudden onset of pain
How would you describe the abnormalities seen in this X-ray?
What’s happening inside the affected joints?
- X-ray of gout
- Joint erosion
This patient had a history of pain and swelling in his right foot.
How would you describe the abnormalities seen?
- X-ray of gout
- Long term chronic gout can cause tophi –> nodular masses of monosodium urate crystals deposited in the soft tissues of the body
- Punched out regions
This patient had a history of chronic left foot pain and previous episodes of gout.
How would you describe the abnormalities seen?
- Erosions at 1st MTPJ
A 26 year old man presented to A&E one evening with severe pain in his right heel. Earlier that day he had fallen about 2m from scaffolding at work, but had landed on his feet. His foot was painful immediately after but he thought it would get better. The pain however is worsening and he can’t walk on that foot because of pain.
- What’s the diagnosis?
- What action should be taken now?
- 2 radiolucent lines in the calcaneum –> fracture of the calcaneum
- Need to examine lower limbs, joints, pelvis, vertebral column
- Large forces required to break calcaneum
On a Radiology placement the registrar asks you what you think about this X-ray.
- How would you describe the abnormalities in this X-ray?
- Which joints are affected? What has happened to them?
- What’s the diagnosis?
- Rheumatoid arthritis
- Predominantly affects the MTP joints and PIP joints
The intrinsic muscles in the sole of the foot are innervated by which nerves?
- Lateral and medial plantar nerves