Week 26 - MSK Flashcards
A complete lesion of the deep peroneal nerve would cause a loss of which movement?
- a) Ankle plantarflexion
- b) Knee flexion
- c) Ankle dorsiflexion
- d) Knee extension
- e) Ankle eversion
c) Ankle dorsiflexion - can’t lift ankle upward (foot drop) because anterior compartment paralysed
NOTE - posterior compartment = plantar flexion = tibial nerve
In the leg, the deep peroneal nerve supplies muscular branches to the anterior compartment of extensor muscles in the leg which include the tibialis anterior, extensor digitorum longus, peroneus tertius, and extensor hallucis longus (propius), and an articular branch to the ankle-joint.
- Nerve roots: L4-S1.
- Motor function: Innervates the muscles in the anterior compartment of the leg, as well as some of the intrinsic muscles of the foot.
- Sensory function: Supplies the triangular region of skin between the 1st and 2nd toes.
A fracture to the mid-shaft of the humerus may injure a nerve that travels around the shaft at this site. What would be the motor effect at the level of the wrist?
- = Radial Nerve*
- Supplies posterior forearm = EXTENSORS*
The radial nerve is the terminal continuation of the posterior cord of the brachial plexus. It therefore contains fibres from nerve roots C5 – T1.
The nerve arises in the axilla region, where it is situated posteriorly to the axillary artery. It exits the axilla inferiorly (via the triangular interval), and supplies branches to the long and lateral heads of the triceps brachii.
The radial nerve then descends down the arm, travelling in a shallow depression within the surface of the humerus, known as the radial groove.
As it descends, the radial nerve wraps around the humerus laterally, and supplies a branch to the medial head of the triceps brachii. During much of its course within the arm, it is accompanied by the deep branch of the brachial artery.
To enter the forearm, the radial nerve travels anterior to the lateral epicondyle of the humerus, through the cubital fossa. The nerve then terminates by dividing into two branches:
- Deep branch (motor) – innervates the muscles in the posterior compartment of the forearm.
- Superficial branch (sensory) – contributes to the cutaneous innervation of the dorsal hand and fingers.
Rupture of the quadriceps tendon will result in a loss of which active movement at the knee?
Extension of the knee
The quadriceps femoris consists of four individual muscles; three vastus muscles and the rectus femoris. They form the main bulk of the thigh, and collectively are one of the most powerful muscles in the body.
The muscles that form the quadriceps femoris unite proximal to the knee and attach to the patella via the quadriceps tendon. In turn, the patella is attached to the tibia by the patella ligament.
The quadriceps femoris is the main extensor of the knee.
An isolated fracture of the medial epicondyle of the humerus may injure which nerve?
- a) Radial
- b) Ulnar
- c) Median
- d) Musculocutaneous
- e) Lateral cutaneous nerve of the forearm
Medial epicondyle fracture = b) Ulnar nerve = FLEXOR ORIGIN for anterior forearm
Lateral epicondyle = Radial nerve = Extensors (posterior compartment of forearm)
List the three muscles that have their origin at the coracoid process.
Coracoid process of scapula
- pec minor
- coracobrachialis
- short head of biceps brachii
List the three muscles that have their origin at the coracoid process.
Coracoid process of scapula
- pec minor
- coracobrachialis
- short head of biceps brachii
Name the common origin of the hamstring muscles.
= Ischial tuberosity
The muscles in the posterior compartment of the thigh are collectively known as the hamstrings. They consist of the biceps femoris, semitendinosus and semimembranosus, which form prominent tendons medially and laterally at the back of the knee.
As group, these muscles act to extend at the hip, and flex at the knee. They are innervated by the sciatic nerve (L4-S3).
