Problem Set #3 by Erin Williams-Hatala

Question #1: Derive the somatic efferent impulse for the innervation of triceps brachii, starting at the appropriate place in the spinal column.

ewilliamshatala2 — 2022-10-06 17:50:02 UTC

ANSWER:

Radial C6, C7, C8

anterior grey horn C6, C7, C8 / anterior white column C6, C7, C8 / anterior roots (normal roots) / spinal nerve / anterior rami (roots of BP)

C6 / superior trunk / posterior division / posterior cord

C7 / middle trunk / posterior division / posterior cord

C8 / inferior trunk / posterior division / posterior cord

They converge to form the radial nerve

Question #3: Which "terminal nerves" from the brachial plexus are present in a transverse section at the surgical neck of the humerus? Justify your response.

ewilliamshatala2 — 2022-10-06 17:55:49 UTC

ANSWER:
This is a transition point from cords to terminal nerves. All three cords are transitioning into all four terminal nerves at this level.

Question #4: Which terminal nerves are present in a transverse section at the level of a line drawn through the epicondyles of the humerus? Justify your response.

ewilliamshatala2 — 2022-10-06 18:08:39 UTC

ANSWER:
Option #1: Radial, median and ulnar b/c they are all there pre-branching. Musculocutaneous has become lateral cutaneous nerve of the arm/forearm
Option #2: Radial, median and ulnar b/c they are all there pre-branching. Also lateral cutaneous nerve of the arm/forearm b/c it is just the continuation of the musculocutaneous nerve.

QUESTION #5: Arm adduction:

ewilliamshatala2 — 2023-10-23 14:15:43 UTC

A) Describe arm adduction in terms the direction of movement of ALL relevant bones and joints.

B) List all of the muscles that are directly involved in arm adduction.

C) List all of the muscles that are indirectly involved in arm adduction and provide their function. Be specific on parts or heads, if necessary.

ANSWER:
A) SC moves superiorly

AC moves inferiorly

medial rotation of scapula

scapular depression

humerus is adducting

B) Teres major

Teres minor

Pec major

Lats

LH triceps

C) middle trap and rhomboids: medial scapular rotators

inferior traps, subclavious, pec minor: scapular depression

QUESTION #6

ewilliamshatala2 — 2023-10-23 14:26:11 UTC

A patient presents with a reduction in the range of motion during extension and external rotation of the arm at the glenohumeral joint, but full range of motion in all other arm movements.

A) What is one potential cause for the limited range of motion?

B) Which muscles are implicated?

C) Is this likely to be a nerve problem? Why or why not?

ANSWER:

QUESTION #2: Derive the somatic efferent impulse for the innervation of triceps brachii, starting at the appropriate place in the spinal column. Include all landmarks and communicating regions.

ewilliamshatala2 — 2024-10-16 13:05:13 UTC

ANSWER:

Radial C6, C7, C8

anterior grey horn C6, C7, C8 / anterior white column C6, C7, C8 / anterior roots (normal roots) / spinal nerve (intervertebral foramina) / anterior rami (roots of BP)

C6 / superior trunk (btw clavicle & 1st rib) / posterior division (posterior to the clavicle) / posterior cord (deep to 2nd part of axillary artery)

C7 / middle trunk (btw clavicle & 1st rib) / posterior division (posterior to the clavicle) / posterior cord (deep to 2nd part of axillary artery)

C8 / inferior trunk (btw clavicle & 1st rib) / posterior division (posterior to the clavicle) / posterior cord (deep to 2nd part of axillary artery)

They converge to form the radial nerve (triangular interval, deep to triceps brachii, lateral head of triceps in radial groove)