level. One specific question in your exam
will be the anterior interosseous nerve.
There’s something called the anterior interosseous nerve
syndrome. You can get patients with anterior
interosseous nerve compression. What’s anterior
interosseous nerve? Where does it come from?
What does it supply? The anterior interosseous
nerve is the continuation
of the median nerve.
Very good, yeah.
As it extends beyond the cubital fossa, as it gets into the
forearm, it kind of extends and supplies the flexors.
All the flexors? I think so, yeah, and it goes
into the forearm
and then it gives recurrent branches.
Okay. You got pretty much that. The anterior
interosseous nerve is a branch of the median
nerve. That’s the first thing you need to
remember, branch of the median nerve. One
of the MCQ questions will be, as the median
nerve comes into the forearm, it lies between
the two heads of the pronator teres. It lies
between the two heads of the pronator teres
then it gives off an anterior interosseous
branch which is also called the deep branch.
That goes and supplies the flexor pollicis
longus to the thumb, flexor digitorum profundus,
and pronator quadratus. So the three deep
muscles in the forearm are supplied by the
anterior interosseous nerve.
Then your median nerve on its own continues
in the forearm, and then it goes under
the carpal tunnel. So that’s all you need
to know about the anterior interosseous nerve
syndrome. So in a patient with anterior
interosseous nerve injury, the patient will
have lots of normal function because the FCR
is intact. So the patient will be able to
flex their wrist. They’ll have some pronation
because the pronator teres is working, but
then they’ll have specific loss of function in the
thumb, in the DIPJ, and the final pronator
quadratus. So that is the anterior interosseous
Right. I’m just going to go back there now.
The reason I brought it here is to get you
an understanding of the all the nerves from
the lateral cord, all the nerves from the
medial cord. The only thing that’s remaining
is the posterior cord. It’s very easy to
remember the posterior cord. If you recall what
we discussed, we've discussed only the anterior
side of the arm and the forearm. So everything
posterior is from the posterior cord.
So everything posterior, this much, the entire
posterior aspect of the arm, posterior aspect
of forearm, wrist, fingers, thumb, they’re
all from the posterior cord. So it’s very
easy to remember. If you just imagine all
the nerves coming from the posterior cord,
have to supply something posterior. Okay?
What are the nerves from the posterior cord?
Do you want to take that?
Axillary. Axillary, very good.
And superior scapula.
Upper and lower, fine, okay. Upper and lower,
that’s fine, yup, very good. And one more.
Nerve to latissimus dorsi or also called the
thoracodorsal nerve. So that is a mnemonic
ulnar. So upper subscapular nerve, lower subscapular
nerve, nerve to latissimus dorsi also called
thoracodorsal nerve, axillary, and radial.
So, we’ll go through each nerve. Upper subscapular
nerve, what does it supply?
No. Anyone? Upper subscapular nerve, lower
subscapular, what do these supply?
The subscapular muscle. Subscapularis, okay.
So imagine your scapula.
The scapula here, then the inside surface
is the subscapularis. So the upper and the
lower subscapular nerve supply the subscapularis.
Nerve to latissimus dorsi, also called the
thoracodorsal nerve as the name says, supplies
the latissimus dorsi. So again, the posterior
muscle. Axillary nerve supplies the
deltoid. Radial nerve supplies all the muscles
in the posterior surface of the arm and the
forearm. So, radial nerve supplies the in-depth
triceps, all the three heads of the triceps,
all the forearm extensors, wrist extensors,
They’re all the radial nerve.
Okay. So, that’s the spine of the scapula,
supraspinatus, infraspinatus, what supply